WorldWideScience

Sample records for nanoflagellate-specific grazing rates

  1. Optimising stocking rate and grazing management to enhance environmental and production outcomes for native temperate grasslands

    Badgery, Warwick; Zhang, Yingjun; Huang, Ding; Broadfoot, Kim; Kemp, David; Mitchell, David

    2015-04-01

    Stocking rate and grazing management can be altered to enhance the sustainable production of grasslands but the relative influence of each has not often been determined for native temperate grasslands. Grazing management can range from seasonal rests through to intensive rotational grazing involving >30 paddocks. In large scale grazing, it can be difficult to segregate the influence of grazing pressure from the timing of utilisation. Moreover, relative grazing pressure can change between years as seasonal conditions influence grassland production compared to the relative constant requirements of animals. This paper reports on two studies in temperate native grasslands of northern China and south eastern Australia that examined stocking rate and regionally relevant grazing management strategies. In China, the grazing experiment involved combinations of a rest, moderate or heavy grazing pressure of sheep in spring, then moderate or heavy grazing in summer and autumn. Moderate grazing pressure at 50% of the current district average, resulted in the better balance between maintaining productive and diverse grasslands, a profitable livestock system, and mitigation of greenhouse gases through increased soil carbon, methane uptake by the soil, and efficient methane emissions per unit of weight gain. Spring rests best maintained a desirable grassland composition, but had few other benefits and reduced livestock productivity due to lower feed quality from grazing later in the season. In Australia, the grazing experiment compared continuous grazing to flexible 4- and 20-paddock rotational grazing systems with sheep. Stocking rates were adjusted between systems biannually based on the average herbage mass of the grassland. No treatment degraded the perennial pasture composition, but ground cover was maintained at higher levels in the 20-paddock system even though this treatment had a higher stocking rate. Overall there was little difference in livestock production (e.g. kg

  2. Seasonal variations in abundance, biomass and grazing rates of microzooplankton in a tropical monsoonal estuary

    Gauns, M.; Mochemadkar, S.; Patil, S.; Pratihary, A.K.; Naqvi, S.W.A.; Madhupratap, M.

    Seasonal abundance, composition and grazing rates of microzooplankton (20–200 µm) in the Zuari estuary were investigated to evaluate their importance in food web dynamics of a tropical monsoonal estuary. Average abundances of microzooplankton...

  3. Effects of livestock species and stocking density on accretion rates in grazed salt marshes

    Nolte, Stefanie; Esselink, Peter; Bakker, Jan P.; Smit, Christian

    2015-01-01

    Coastal ecosystems, such as salt marshes, are threatened by accelerated sea-level rise (SLR). Salt marshes deliver valuable ecosystem services such as coastal protection and the provision of habitat for a unique flora and fauna. Whether salt marshes in the Wadden Sea area are able to survive accelerated SLR depends on sufficient deposition of sediments which add to vertical marsh accretion. Accretion rate is influenced by a number of factors, and livestock grazing was recently included. Livestock grazing is assumed to reduce accretion rates in two ways: (a) directly by increasing soil compaction through trampling, and (b) indirectly by affecting the vegetation structure, which may lower the sediment deposition. For four years, we studied the impact of two livestock species (horse and cattle) at two stocking densities (0.5 and 1.0 animal ha-1) on accretion in a large-scale grazing experiment using sedimentation plates. We found lower cumulative accretion rates in high stocking densities, probably because more animals cause more compaction and create a lower canopy. Furthermore, a trend towards lower accretion rates in horse-compared to cattle-grazed treatments was found, most likely because (1) horses are more active and thus cause more compaction, and (2) herbage intake by horses is higher than by cattle, which causes a higher biomass removal and shorter canopy. During summer periods, negative accretion rates were found. When the grazing and non-grazing seasons were separated, the impact of grazing differed among years. In summer, we only found an effect of different treatments if soil moisture (precipitation) was relatively low. In winter, a sufficiently high inundation frequency was necessary to create differences between grazing treatments. We conclude that stocking densities, and to a certain extent also livestock species, affect accretion rates in salt marshes. Both stocking densities and livestock species should thus be taken into account in management

  4. Grazing rates of Calanus finmarchicus on Thalassiosira weissflogii cultured under different levels of ultraviolet radiation.

    David M Fields

    Full Text Available UVB alters photosynthetic rate, fatty acid profiles and morphological characteristics of phytoplankton. Copepods, important grazers of primary production, select algal cells based upon their size, morphological traits, nutritional status, and motility. We investigated the grazing rates of the copepod Calanus finmarchicus on the diatom Thalassiosira weissflogii cultured under 3 levels of ultraviolet radiation (UVR: photosynthetically active radiation (PAR only (4 kJ-m(-2/day, and PAR supplemented with UVR radiation at two intensities (24 kJ-m(-2/day and 48 kJ-m(-2/day. There was no significant difference in grazing rates between the PAR only treatment and the lower UVR treatment. However, grazing rates were significantly (∼66% higher for copepods feeding on cells treated with the higher level of UVR. These results suggest that a short-term increase in UVR exposure results in a significant increase in the grazing rate of copepods and, thereby, potentially alters the flow rate of organic matter through this component of the ecosystem.

  5. Ingestive behavior and performance of female lambs grazing on Marandu palisadegrass under different stocking rates

    Luiz Carlos Vieira Júnior

    2011-11-01

    Full Text Available The ingestive behavior and performance of female lambs grazing on Marandu pasture submitted to different stocking rates during the rainy and transition season were evaluated. The experimental area with 4,500 m² was divided into 45 paddocks of 100 m². Twenty-seven Santa Ines female lambs (purebred with 4 months age and 22 kg of initial body weight were distributed in a completely randomized design, with nine replicates. Lambs were divided into 9 groups with the same initial weight and submitted to three stocking rates: 2, 3 and 4 lambs/paddock, which corresponded to 40, 60 and 80 lambs/ha, respectively. Each group of animals had a module of five paddocks, managed on intermittent grazing system, with 7 days of occupation and 28 d of rest. Increase on time grazing and reduction on time ruminating and resting were observed as stocking rates increased. There was 14% raise in time grazing and 41% decline on time resting by lambs subjected to the highest stocking rate compared with those in the lower stocking rate. The number of animals/ha promoted linear effect on average daily gain, which was higher for animals in the lowest stocking rate of 90 g/d. For gain per area, the best result was obtained with 60 animals/ha featuring an average value of 426 kg/ha.

  6. Gut evacuation rate and grazing impact of the krill Thysanoessa raschii and T. inermis

    Teglhus, Frederik Wolff; Agersted, Mette Dalgaard; Arendt, Kristine Engel

    2015-01-01

    Gut evacuation rates and ingestion rates were measured for the krill Thysanoessa raschii and T. inermis in Godthåbsfjord, SW Greenland. Combined with biomass of the krill community, the grazing potential on phytoplankton along the fjord was estimated. Gut evacuation rates were 3.9 and 2.3 h−1 for...... standing stock being removed per day during this late spring study...

  7. Monitoring and assessment of ingestive chewing sounds for prediction of herbage intake rate in grazing cattle.

    Galli, J R; Cangiano, C A; Pece, M A; Larripa, M J; Milone, D H; Utsumi, S A; Laca, E A

    2018-05-01

    Accurate measurement of herbage intake rate is critical to advance knowledge of the ecology of grazing ruminants. This experiment tested the integration of behavioral and acoustic measurements of chewing and biting to estimate herbage dry matter intake (DMI) in dairy cows offered micro-swards of contrasting plant structure. Micro-swards constructed with plastic pots were offered to three lactating Holstein cows (608±24.9 kg of BW) in individual grazing sessions (n=48). Treatments were a factorial combination of two forage species (alfalfa and fescue) and two plant heights (tall=25±3.8 cm and short=12±1.9 cm) and were offered on a gradient of increasing herbage mass (10 to 30 pots) and number of bites (~10 to 40 bites). During each grazing session, sounds of biting and chewing were recorded with a wireless microphone placed on the cows' foreheads and a digital video camera to allow synchronized audio and video recordings. Dry matter intake rate was higher in tall alfalfa than in the other three treatments (32±1.6 v. 19±1.2 g/min). A high proportion of jaw movements in every grazing session (23 to 36%) were compound jaw movements (chew-bites) that appeared to be a key component of chewing and biting efficiency and of the ability of cows to regulate intake rate. Dry matter intake was accurately predicted based on easily observable behavioral and acoustic variables. Chewing sound energy measured as energy flux density (EFD) was linearly related to DMI, with 74% of EFD variation explained by DMI. Total chewing EFD, number of chew-bites and plant height (tall v. short) were the most important predictors of DMI. The best model explained 91% of the variation in DMI with a coefficient of variation of 17%. Ingestive sounds integrate valuable information to remotely monitor feeding behavior and predict DMI in grazing cows.

  8. Growth rates, grazing, sinking, and iron limitation of equatorial Pacific phytoplankton

    Chavez, F.P.; Buck, K.R.; Coale, K.H.; Martin, J.H.; DiTullio, G.R.; Welschmeyer, N.A.; Barber, R.T.; Jacobson, A.C.

    1991-01-01

    Concentrations of phytoplankton and NO 3 are consistently low and high in surface waters of the oceanic eastern and central equatorial Pacific, and phytoplankton populations are dominated by small solitary phytoplankton. Growth rates of natural phytoplankton populations, needed to assess the relative importance of many of the processes considered in the equatorial Pacific, were estimated by several methods. The growth rates of natural phytoplankton populations were found to be ∼0.7 d -1 or 1 biomass doubling d -1 and were similar for all methods. To keep this system in its observed balance requires that loss rates approximate observed growth rates. Grazing rates, measured with a dilution grazing experiment, were high, accounting for a large fraction of the daily production. Additions of various forms of Fe to 5-7-d incubations utilizing ultraclean techniques resulted in significant shifts in autotrophic and heterotrophic assemblages between initial samples, controls, and Fe enrichments, which were presumably due to Fe, grazing by both protistan and metazoan components, and incubation artifacts. Estimated growth rates of small pennate diatoms showed increases in Fe enrichments with respect to controls. The growth rates of the pennate diatoms were similar to those estimated for the larger size fraction of the natural populations

  9. The reliability of grazing rate estimates from dilution experiments: Have we over-estimated rates of organic carbon consumption by microzooplankton?

    J. R. Dolan,

    2005-01-01

    Full Text Available According to a recent global analysis, microzooplankton grazing is surprisingly invariant, ranging only between 59 and 74% of phytoplankton primary production across systems differing in seasonality, trophic status, latitude, or salinity. Thus an important biological process in the world ocean, the daily consumption of recently fixed carbon, appears nearly constant. We believe this conclusion is an artefact because dilution experiments are 1 prone to providing over-estimates of grazing rates and 2 unlikely to furnish evidence of low grazing rates. In our view the overall average rate of microzooplankton grazing probably does not exceed 50% of primary production and may be even lower in oligotrophic systems.

  10. BITES RATE ON NATIVE VEGETATION BY TRASHUMANCE GOATS GRAZING IN MOUNTAIN RANGELAND IN NUDO MIXTECO, MEXICO

    F.J. Franco-Guerra

    2014-08-01

    Full Text Available The objective of the present study was to determine the habits of grazing-browsing by the rate of bites and rate of consumption in the dry matter (MS of the diet of goats under transhumance grazing in mountain rangelands of Nudo Mixteco, being the natural vegetation in the different strata. Six animals of different age and sex were randomly chosen. Direct observation of grazing method was used to determine the rate of bites/min and the rate of consumption by layers. Analyzes of variance was performed and the Tukey test was used for mean comparison test was used (HSD Tukey (α, 0.05. The values of both variables were small, which may be due to the great diversity of plants and their varied morphology which induces the goat won on the one hand to spend more time in the choice of food becoming more selective and on the other, to carry out bites smaller in those plants whose leaf surface is of the type megafilia or in those woody whose leaves are very small (microphilia 2.25 cm2 to 20.25 cm2.

  11. Grazing rate of zebra mussel in a shallow eutrophicated bay of the Baltic Sea.

    Oganjan, Katarina; Lauringson, Velda

    2014-12-01

    Benthic suspension feeding is an important process in coastal ecosystems. Among all the World's oceans, coastal ecosystems are the most modified by human impact and changing at accelerating pace. It is complicated to understand, how various environmental factors affect feeding rates of suspension feeders in their natural habitats. Thus, shapes of such relationships are poorly described for several intersections of environmental gradients. In this study, relationships between grazing rates of an invasive bivalve Dreissena polymorpha and ambient environmental factors were investigated in a turbid eutrophic bay of the central Baltic Sea using a novel modelling method of Boosted Regression Trees (BRT), a statistical tool able to handle non-normal distributions, complex relationships, and interactive effects. Feeding rates of mussels were derived from field populations by measuring the content of algal pigments in specimens collected from their natural habitat. The content of pigments was converted to feeding rate separately each time using field experiments measuring simultaneously the content of pigments and biodeposition of mussels. The results suggest that feeding rates of D. polymorpha are related to several environmental factors which gradients outreach the optimal range for the local mussel population. All the observed effects were non-linear with complex shapes. Variability along the resource gradient was the most important predictor of mussel feeding, followed by salinity and disturbance caused by wind. The most important interaction occurred between disturbance and resource gradient, while feeding function showed more plasticity along the latter. Mapping of environmental tipping points with the aid of machine learning methods may enable to concentrate the most relevant information about ecological functions worldwide. Copyright © 2014 Elsevier Ltd. All rights reserved.

  12. Oesophageal fistula/tritium-labelled water technique for determining dry matter intake and saliva secretion rates of grazing herbivores

    Luick, J.R.

    1982-01-01

    Seven assumptions on which the use of tritium-labelled water and oesophageal fistula depend, for determining the dry matter intake and saliva secretion rates of grazing herbivores, were tested experimentally. It is concluded that many of the possible sources of error can be ignored, but that a correction is necessary for the saliva dry matter content when calculating the dry matter of ingested food from fistula samples. (author)

  13. Particle-associated flagellates: swimming patterns, colonization rates, and grazing on attached bacteria

    Kiørboe, Thomas; Grossart, H.P.; Ploug, H.

    2004-01-01

    Some pelagic flagellates colonize particles, such as marine snow, where they graze on bacteria and thus impact the dynamics of the attached microbial communities. Particle colonization is governed by motility. Swimming patterns of 2 particle-associated flagellates, Bodo designis and Spumella sp......., are very different, the former swimming slowly in an erratic, random pattern, and the latter faster and along smooth helixes of variable amplitude and frequency. At spatial scales exceeding ca. 50 mum, the motility of B. designis can be described as a random walk and modeled as diffusion. Spumella sp...

  14. External validation of the GrazeIn model of pasture dry matter intake and milk yield prediction for cows managed at different calving dates and stocking rates

    Roca-Fernández, A.I.; González-Rodríguez, A.

    2017-01-01

    The aim was to evaluate the prediction accuracy of pasture dry matter intake (PDMI) and milk yield (MY) predicted by the GrazeIn model using a database representing 124 PDMI measurements at paddock level and 2232 MY measurements at cow level. External validation of the model was conducted using data collected from a trial carried out with Holstein-Friesian cows (n=72) while grazed 28 paddocks and were managed in a 2×2 factorial design by considering two calving dates (CD), with different number of days in milk (DIM), early (E, 29 DIM) vs. middle (M, 167 DIM), and two stocking rates (SR), medium (M, 3.9 cows ha-1) vs. high (H, 4.8 cows ha-1), under a rotational grazing system. Cows were randomly assigned to four grazing scenarios (EM, EH, MM and MH). The mean observed PDMI of the total database was 14.2 kg DM cow-1 day-1 while GrazeIn predicted a mean PDMI for the database of 13.8 kg DM cow-1 day-1. The mean bias was −0.4 kg DM cow-1 day-1. GrazeIn predicted PDMI for the total database with a relative prediction error (RPE) of 10.0% at paddock level. The mean observed MY of the database was 23.2 kg cow-1 day-1 while GrazeIn predicted a MY for the database of 23.1 kg cow-1 day-1. The mean bias was –0.1 kg cow-1 day-1. GrazeIn predicted MY for the total database with a mean RPE of 17.3% at cow level. For the scenarios investigated, GrazeIn predicted PDMI and MY with a low level of error which made it a suitable tool for decision support systems.

  15. External validation of the GrazeIn model of pasture dry matter intake and milk yield prediction for cows managed at different calving dates and stocking rates

    Roca-Fernández, A.I.; González-Rodríguez, A.

    2017-07-01

    The aim was to evaluate the prediction accuracy of pasture dry matter intake (PDMI) and milk yield (MY) predicted by the GrazeIn model using a database representing 124 PDMI measurements at paddock level and 2232 MY measurements at cow level. External validation of the model was conducted using data collected from a trial carried out with Holstein-Friesian cows (n=72) while grazed 28 paddocks and were managed in a 2×2 factorial design by considering two calving dates (CD), with different number of days in milk (DIM), early (E, 29 DIM) vs. middle (M, 167 DIM), and two stocking rates (SR), medium (M, 3.9 cows ha-1) vs. high (H, 4.8 cows ha-1), under a rotational grazing system. Cows were randomly assigned to four grazing scenarios (EM, EH, MM and MH). The mean observed PDMI of the total database was 14.2 kg DM cow-1 day-1 while GrazeIn predicted a mean PDMI for the database of 13.8 kg DM cow-1 day-1. The mean bias was −0.4 kg DM cow-1 day-1. GrazeIn predicted PDMI for the total database with a relative prediction error (RPE) of 10.0% at paddock level. The mean observed MY of the database was 23.2 kg cow-1 day-1 while GrazeIn predicted a MY for the database of 23.1 kg cow-1 day-1. The mean bias was –0.1 kg cow-1 day-1. GrazeIn predicted MY for the total database with a mean RPE of 17.3% at cow level. For the scenarios investigated, GrazeIn predicted PDMI and MY with a low level of error which made it a suitable tool for decision support systems.

  16. Laboratory-measured grazing and ingestion rates of the salp, Thalia democratica Forskal, and the doliolid, Dolioletta gegenbauri Uljanin (Tunicata, Thaliacea)

    Deibel, D.

    1982-01-01

    Grazing and ingestion rates of laboratory-born Thalia democratica aggregates and Dolioletta gegenbauri gonozooids, phorozooids and oozooids were determined while fed Isochrysis galbana (4-5 ..mu..m diameter) alone or in combination with Peridinium trochoideum (16-18 ..mu..m diameter) at concentrations of 0.15-0.70 mm/sup 3/ x 1/sup -1/. Grazing rates (ml x zooid/sup -1/ x 24 h/sup -1/) ranged from 10 to 355, and at zooid weights greater than 5..mu..g carbon were in order oozooid > gonozooid > aggregate. Grazing rates increased exponentially with increasing zooid weight. Weight-specific grazing rates (ml x ..mu..gC/sup -1/ x 24 h/sup -1/) were independent of the four-fold initial food concentration. Mean weight-specific grazing rates increased linearly with increasing zooid weight for the aggregates and oozooids, but gonozooid mean rates were independent of zooid weight. Aggregate and gonozooid ingestion rates (10/sup 6/..mu..m/sup 3/ x zooid/sup -1/ x 24 h/sup -1/) ranged from 4 to 134 while oozooid rates ranged from 3 to 67. All ingestion rates were independent of the initial food concentration but increased linearly with increasing zooid weight at similar rates. All mean weight-specific ingestion rates (ml x ..mu..gC/sup -1/ x 24 h/sup -1/) were independent of zooid weight. The mean aggregate daily ration (..mu..gC ingested x ..mu..g body C/sup -1/) was 59% and the mean doliolid ration was 132%. Field studies indicate that normal concentrations of D. gegenbauri in the Georgia Bight clear their resident water volume (1 m/sup 3/) in about 4 months, but that highly concentrated, swarm populations which occur along thermohaline fronts clear their resident water volume in less than 1 day.

  17. Genotype x environmental interaction for mature size and rate of maturing for Angus, Brahman, and reciprocal-cross cows grazing bermudagrass or endophyte infected fescue.

    Sandelin, B A; Brown, A H; Brown, M A; Johnson, Z B; Kellogg, D W; Stelzleni, A M

    2002-12-01

    Mature weight and rate of maturing were estimated in 177 Angus, Brahman, and reciprocal-cross cows grazing bermudagrass or endophyte-infected tall fescue over a 4-yr period to evaluate genotype x environment interactions. Data were collected every 28 d until cows were approximately 18 mo of age and then at prebreeding, postcalving, and weaning of calf. All cows with weight data to at least 42 mo of age were included in the analysis. Mature weight and rate of maturing were estimated using the three-parameter growth curve model described by Brody (1945). Data were pooled over year and analyzed by the general linear model procedure of SAS. Included in the models for mature weight and rate of maturing were the independent variables of genotype, environment, and genotype x environment interaction. There was a genotype x environment interaction (P < 0.01) for mature body weight (BW) but not for rate of maturing. Angus cows grazing fescue pastures had greater (P < 0.01) mean mature BW than Angus x Brahman cows grazing bermudagrass (611 +/- 17 vs 546 +/- 16 kg). Angus x Brahman cows grazing bermudagrass had lower (P < 0.05) mean mature BW than Brahman x Angus cows grazing bermudagrass or endophyte-infected fescue and Brahman cows grazing bermudagrass (546 +/- 16 vs 624 +/- 19, 614 +/- 22 and 598 +/- 20 kg, respectively). Brahman cows grazing endophyte-infected fescue had smaller (P < 0.05) mean mature BW than all genotype x forage combinations except for Angus x Brahman cows grazing bermudagrass. Angus cows had a smaller (P < 0.05) mean rate of maturing than Angus x Brahman and Brahman x Angus cows (0.039 +/- 0.002 vs 0.054 +/- 0.002 and 0.049 +/- 0.002%/mo, respectively), respectively, and Angus x Brahman cows had a larger (P < 0.05) mean rate of maturing than Brahman x Angus and Brahman cows (0.054 +/- 0.002 vs 0.049 +/- 0.002 and 0.041 +/- 0.002 %/mo, respectively). There was a direct breed x forage interaction (P < 0.05) for mature BW. These data suggest that the

  18. Effect of Duddingtonia flagrans against Ostertagia ostertagi in cattle grazing at different stocking rates

    Fernández, A.S.; Larsen, M.; Henningsen, E.

    1999-01-01

    divided into 3 comparable groups and allocated to 3 similar paddocks in each of the 2 trials. Two of the 3 groups received fungal material once per day during the initial 2 months, either at high dose (10(6) fungal spores/kg body weight) or low dose (5 x 10(5) or 2.5 x 10(5) fungal spores/kg body weight......The efficacy of an isolate of the nematophagous fungus Duddingtonia flagrans against gastrointestinal nematodes of cattle was examined at 2 dose levels on 2 permanent pastures, with high and low stocking rates, respectively. Thirty calves, experimentally infected with Ostertagia ostertagi, were...... seemed not to be very heavy, and a conclusive effect of the fungi at the dose-level used could not be detected....

  19. High turnover rates of copepod fecal pellets due to Noctiluca scintillans grazing

    Kiørboe, Thomas

    2003-01-01

    Copepod fecal pellet production and vertical flux, as well as vertical distributions of copepods, fecal pellets and the heterotrophic dinoflagellate Noctiluca scintillans were monitored in an upwelling plume off the coast of Brazil during 5 d in austral spring. Less than half (20 to 45%) of the p......Copepod fecal pellet production and vertical flux, as well as vertical distributions of copepods, fecal pellets and the heterotrophic dinoflagellate Noctiluca scintillans were monitored in an upwelling plume off the coast of Brazil during 5 d in austral spring. Less than half (20 to 45...... for fecal pellets at about 0.6 l cell-1 d-1. A simple encounter model suggests that such high clearance rates are feasible. Since N. scintillans occurs at typical abundances of about 106 cells m-2 in temperate seas during spring, summer and autumn, it may contribute significantly to the recycling of rapidly...

  20. Do bells affect behaviour and heart rate variability in grazing dairy cows?

    Julia Johns

    Full Text Available In alpine regions cows are often equipped with bells. The present study investigated the impact of wearing a bell on behaviour and heart rate variability in dairy cows. Nineteen non-lactating Brown-Swiss cows with bell experience were assigned to three different treatments. For 3 days each, cows were equipped with no bell (control, with a bell with inactivated clapper (silent bell or with a functional bell (functional bell. The bells weighed 5.5 kg and had frequencies between 532 Hz and 2.8 kHz and amplitudes between 90 and 113 dB at a distance of 20 cm. Data were collected on either the first and third or on all 3 days of each treatment. Whereas duration of rumination was reduced with a functional bell and a silent bell compared with no bell, feeding duration was reduced with a silent bell and was intermediate with a functional bell. Head movements were reduced when wearing a silent bell compared with no bell and tended to be reduced when wearing a functional compared to no bell. With a functional bell, lying duration was reduced by almost 4 hours on the third day of treatment compared with the first day with a functional bell and compared with no bell or a silent bell. All additional behavioural measures are consistent with the hypothesis of a restriction in the behaviour of the cows wearing bells, although this pattern did not reach significance. There was no treatment effect on heart rate variability, suggesting that the bells did not affect vago-sympathetic balance. An effect of experimental day was found for only 1 out of 10 behavioural parameters, as shown by a decrease in lying with a functional bell on day 3. The results indicate behavioural changes in the cows wearing a bell over 3 days, without indication of habituation to the bell. Altogether, the behavioural changes suggest that the behaviour of the cows was disturbed by wearing a bell. If long-lasting, these effects may have implications for animal welfare.

  1. Do Bells Affect Behaviour and Heart Rate Variability in Grazing Dairy Cows?

    Johns, Julia; Patt, Antonia; Hillmann, Edna

    2015-01-01

    In alpine regions cows are often equipped with bells. The present study investigated the impact of wearing a bell on behaviour and heart rate variability in dairy cows. Nineteen non-lactating Brown-Swiss cows with bell experience were assigned to three different treatments. For 3 days each, cows were equipped with no bell (control), with a bell with inactivated clapper (silent bell) or with a functional bell (functional bell). The bells weighed 5.5 kg and had frequencies between 532 Hz and 2.8 kHz and amplitudes between 90 and 113 dB at a distance of 20 cm. Data were collected on either the first and third or on all 3 days of each treatment. Whereas duration of rumination was reduced with a functional bell and a silent bell compared with no bell, feeding duration was reduced with a silent bell and was intermediate with a functional bell. Head movements were reduced when wearing a silent bell compared with no bell and tended to be reduced when wearing a functional compared to no bell. With a functional bell, lying duration was reduced by almost 4 hours on the third day of treatment compared with the first day with a functional bell and compared with no bell or a silent bell. All additional behavioural measures are consistent with the hypothesis of a restriction in the behaviour of the cows wearing bells, although this pattern did not reach significance. There was no treatment effect on heart rate variability, suggesting that the bells did not affect vago-sympathetic balance. An effect of experimental day was found for only 1 out of 10 behavioural parameters, as shown by a decrease in lying with a functional bell on day 3. The results indicate behavioural changes in the cows wearing a bell over 3 days, without indication of habituation to the bell. Altogether, the behavioural changes suggest that the behaviour of the cows was disturbed by wearing a bell. If long-lasting, these effects may have implications for animal welfare. PMID:26110277

  2. Metabolizable protein supply while grazing dormant winter forage during heifer development alters pregnancy and subsequent in-herd retention rate.

    Mulliniks, J T; Hawkins, D E; Kane, K K; Cox, S H; Torell, L A; Scholljegerdes, E J; Petersen, M K

    2013-03-01

    Two studies were conducted to evaluate the effects of postweaning management of British crossbred heifers on growth and reproduction. In Exp. 1, 239 spring-born, crossbred heifers were stratified by weaning BW (234 ± 1 kg) and allotted randomly to 1 of 2 treatments. Treatments were fed at a rate equivalent to 1.14 kg/d while grazing dormant forage (6.5% CP and 80% NDF, DM basis) and were 1) 36% CP containing 36% RUP (36RUP) or 2) 36% CP containing 50% RUP (50RUP). Supplementation was initiated in February (1995 and 1996) or November (1997 and 1998) and terminated at the onset of breeding season (mid May). Heifers were weighed monthly up to breeding and again at time of palpation. After timed AI, heifers were exposed to breeding bulls for 42 ± 8 d. In Exp. 2, 191 spring-born, crossbred heifers were stratified by weaning BW to treatments. Heifer development treatments were 1) pasture developed and fed 0.9 kg/day of a 36% CP supplement containing 36% RUP (36RUP), 2) pasture developed and fed 0.9 kg/day of a 36% CP supplement containing 50% RUP (50RUP), and 3) corn silage-based growing diet in a drylot (DRYLOT). Heifers receiving 36RUP and 50RUP treatments were developed on dormant forage. Treatments started in February and ended at the onset of a 45-d breeding season in May. Heifer BW and hip height were taken monthly from initiation of supplementation until breeding and at pregnancy diagnosis. In Exp. 1, BW was not different (P ≥ 0.27) for among treatments at all measurement times. However, 50RUP heifers had greater (P = 0.02; 80 and 67%) pregnancy rates than 36RUP heifers. In Exp. 2, DRYLOT heifers had greater (P RUP or 50RUP developed heifers. However, BW at pregnancy diagnosis was not different (P = 0.24) for between treatments. Pregnancy rates tended to be greater (P = 0.10) for 50RUP heifers than 36RUP and DRYLOT. Net return per heifer was US$99.71 and $87.18 greater for 50RUP and 36RUP heifers, respectively, compared with DRYLOT heifers due to differences

  3. Increases of Chamber Height and Base Diameter Have Contrasting Effects on Grazing Rate of Two Cladoceran Species: Implications for Microcosm Studies

    Pan, Ying; Zhang, Yunshu; Peng, Yan; Zhao, Qinghua; Sun, Shucun

    2015-01-01

    Aquatic microcosm studies often increase either chamber height or base diameter (to increase water volume) to test spatial ecology theories such as “scale” effects on ecological processes, but it is unclear whether the increase of chamber height or base diameter have the same effect on the processes, i.e., whether the effect of the shape of three-dimensional spaces is significant. We orthogonally manipulated chamber height and base diameter and determined swimming activity, average swimming velocity and grazing rates of the cladocerans Daphnia magna and Moina micrura (on two algae Scenedesmus quadricauda and Chlorella vulgaris; leading to four aquatic algae-cladoceran systems in total) under different microcosm conditions. Across all the four aquatic systems, increasing chamber height at a given base diameter significantly decreased the duration and velocity of horizontal swimming, and it tended to increase the duration but decrease the velocity of vertical swimming. These collectively led to decreases in both average swimming velocity and grazing rate of the cladocerans in the tall chambers (at a given base diameter), in accordance with the positive relationship between average swimming velocity and grazing rate. In contrast, an increase of base diameter at a given chamber height showed contrasting effects on the above parameters. Consistently, at a given chamber volume increasing ratio of chamber height to base diameter decreased the average swimming velocity and grazing rate across all the aquatic systems. In general, increasing chamber depth and base diameter may exert contrasting effects on zooplankton behavior and thus phytoplankton-zooplankton interactions. We suggest that spatial shape plays an important role in determining ecological process and thus should be considered in a theoretical framework of spatial ecology and also the physical setting of aquatic microcosm experiments. PMID:26273836

  4. Changes in bacterial community composition and dynamics and viral mortality rates associated with enhanced flagellate grazing in a mesoeutrophic reservoir

    Šimek, Karel; Pernthaler, J.; Weinbauer, M. G.; Horňák, K.; Dolan, J. R.; Nedoma, Jiří; Mašin, M.; Amann, R.

    2001-01-01

    Roč. 67, č. 6 (2001), s. 2723-2733 ISSN 0099-2240 R&D Projects: GA ČR GA206/99/0028; GA AV ČR IPP1011802 Grant - others:CNRS(FR) PICS1111 Keywords : bacterial community composition * protozoan grazing * viral lysis Subject RIV: EE - Microbiology, Virology Impact factor: 3.688, year: 2001

  5. Substitution rate and milk yield response to corn silage supplementation of late-lactation dairy cows grazing low-mass pastures at 2 daily allowances in autumn.

    Pérez-Prieto, L A; Peyraud, J L; Delagarde, R

    2011-07-01

    Feed costs in dairy production systems may be decreased by extending the grazing season to periods such as autumn when grazing low-mass pastures is highly probable. The aim of this autumn study was to determine the effect of corn silage supplementation [0 vs. 8 kg of dry matter (DM) of a mixture 7:1 of corn silage and soybean meal] on pasture intake (PI), milk production, and grazing behavior of dairy cows grazing low-mass ryegrass pastures at 2 daily pasture allowances (PA; low PA=18 vs. high PA=30 kg of DM/cow above 2.5 cm). Twelve multiparous Holstein cows were used in a 4 × 4 Latin square design with 14-d periods. Pre-grazing pasture mass and pre-grazing plate meter pasture height averaged 1.8 t of DM/ha (above 2.5 cm) and 6.3 cm, respectively. The quality of the offered pasture (above 2.5 cm) was low because of dry conditions before and during the experiment (crude protein=11.5% of DM; net energy for lactation=5.15 MJ/kg of DM; organic matter digestibility=61.9%). The interaction between PA and supplementation level was significant for PI but not for milk production. Supplementation decreased PI from 11.6 to 7.6 kg of DM/d at low PA and from 13.1 to 7.3 kg of DM/d at high PA. The substitution rate was, therefore, lower at low than at high PA (0.51 vs. 0.75). Pasture intake increased with increasing PA in unsupplemented treatments, and was not affected by PA in supplemented treatments. Milk production averaged 13.5 kg/d and was greater at high than at low PA (+1.4 kg/d) and in supplemented than unsupplemented treatments (+5.2 kg/d). Milk fat concentration averaged 4.39% and was similar between treatments. Milk protein concentration increased from 3.37 to 3.51% from unsupplemented to supplemented treatments, and did not vary according to PA. Grazing behavior parameters were only affected by supplementation. On average, daily grazing time decreased (539 vs. 436 min) and daily ruminating time increased (388 vs. 486 min) from 0 to 8 kg of supplement DM. The PI

  6. Application of Overall Dynamic Body Acceleration as a Proxy for Estimating the Energy Expenditure of Grazing Farm Animals: Relationship with Heart Rate

    Miwa, Masafumi; Oishi, Kazato; Nakagawa, Yasuhiro; Maeno, Hiromichi; Anzai, Hiroki; Kumagai, Hajime; Okano, Kanji; Tobioka, Hisaya; Hirooka, Hiroyuki

    2015-01-01

    Estimating the energy expenditure of farm animals at pasture is important for efficient animal management. In recent years, an alternative technique for estimating energy expenditure by measuring body acceleration has been widely performed in wildlife and human studies, but the availability of the technique in farm animals has not yet been examined. In the present study, we tested the potential use of an acceleration index, overall dynamic body acceleration (ODBA), as a new proxy for estimating the energy expenditure of grazing farm animals (cattle, goats and sheep) at pasture with the simultaneous evaluation of a conventional proxy, heart rate. Body accelerations in three axes and heart rate for cows (n = 8, two breeds), goats (n = 6) and sheep (n = 5) were recorded, and the effect of ODBA calculated from the body accelerations on heart rate was analyzed. In addition, the effects of the two other activity indices, the number of steps and vectorial dynamic body acceleration (VeDBA), on heart rate were also investigated. The results of the comparison among three activity indices indicated that ODBA was the best predictor for heart rate. Although the relationship between ODBA and heart rate was different between the groups of species and breeds and between individuals (Panimals, and the results indicated that ODBA is a good proxy for estimating the energy expenditure of grazing farm animals across species and breeds. The utility and simplicity of the procedure with acceleration loggers could make the accelerometry technique a worthwhile option in field research and commercial farm use. PMID:26030931

  7. Application of overall dynamic body acceleration as a proxy for estimating the energy expenditure of grazing farm animals: relationship with heart rate.

    Miwa, Masafumi; Oishi, Kazato; Nakagawa, Yasuhiro; Maeno, Hiromichi; Anzai, Hiroki; Kumagai, Hajime; Okano, Kanji; Tobioka, Hisaya; Hirooka, Hiroyuki

    2015-01-01

    Estimating the energy expenditure of farm animals at pasture is important for efficient animal management. In recent years, an alternative technique for estimating energy expenditure by measuring body acceleration has been widely performed in wildlife and human studies, but the availability of the technique in farm animals has not yet been examined. In the present study, we tested the potential use of an acceleration index, overall dynamic body acceleration (ODBA), as a new proxy for estimating the energy expenditure of grazing farm animals (cattle, goats and sheep) at pasture with the simultaneous evaluation of a conventional proxy, heart rate. Body accelerations in three axes and heart rate for cows (n = 8, two breeds), goats (n = 6) and sheep (n = 5) were recorded, and the effect of ODBA calculated from the body accelerations on heart rate was analyzed. In addition, the effects of the two other activity indices, the number of steps and vectorial dynamic body acceleration (VeDBA), on heart rate were also investigated. The results of the comparison among three activity indices indicated that ODBA was the best predictor for heart rate. Although the relationship between ODBA and heart rate was different between the groups of species and breeds and between individuals (Pheart rate (beats/min) = 147.263∙M-0.141 + 889.640∙M-0.179∙ODBA (g). Combining this equation with the previously reported energy expenditure per heartbeat, we estimated the energy expenditure of the tested animals, and the results indicated that ODBA is a good proxy for estimating the energy expenditure of grazing farm animals across species and breeds. The utility and simplicity of the procedure with acceleration loggers could make the accelerometry technique a worthwhile option in field research and commercial farm use.

  8. Livestock and elk grazing effects on stream morphology, brown trout population dynamics, movement, and growth rate, Valles Caldera National Preserve, New Mexico

    Michael C. Anderson

    2009-01-01

    Ungulate grazing in riparian areas has been shown to detrimentally impact stream morphology and fish populations. Goals of this research were to assess changes in stream morphology and responses of a brown trout (Salmo trutta) population to exclusion of cattle (Bos taurus) and elk (Cervus elaphus) from riparian...

  9. Grazing function g and collimation angular acceptance

    Stephen G. Peggs

    2009-11-01

    Full Text Available The grazing function g is introduced—a synchrobetatron optical quantity that is analogous (and closely connected to the Twiss and dispersion functions β, α, η, and η^{′}. It parametrizes the rate of change of total angle with respect to synchrotron amplitude for grazing particles, which just touch the surface of an aperture when their synchrotron and betatron oscillations are simultaneously (in time at their extreme displacements. The grazing function can be important at collimators with limited acceptance angles. For example, it is important in both modes of crystal collimation operation—in channeling and in volume reflection. The grazing function is independent of the collimator type—crystal or amorphous—but can depend strongly on its azimuthal location. The rigorous synchrobetatron condition g=0 is solved, by invoking the close connection between the grazing function and the slope of the normalized dispersion. Propagation of the grazing function is described, through drifts, dipoles, and quadrupoles. Analytic expressions are developed for g in perfectly matched periodic FODO cells, and in the presence of β or η error waves. These analytic approximations are shown to be, in general, in good agreement with realistic numerical examples. The grazing function is shown to scale linearly with FODO cell bend angle, but to be independent of FODO cell length. The ideal value is g=0 at the collimator, but finite nonzero values are acceptable. Practically achievable grazing functions are described and evaluated, for both amorphous and crystal primary collimators, at RHIC, the SPS (UA9, the Tevatron (T-980, and the LHC.

  10. Grazing behavior and intake of goats rotationally grazing Tanzania-grass pasture with different post-grazing residues

    Marcia H.M.R. Fernandes

    2016-05-01

    Full Text Available This study aimed to evaluate intake and ingestive behavior of goats rotationally grazing Tanzania (Panicum maximum cv. Tanzânia 1 pastures with 2 levels of post-grazing residue. The experimental area consisted of 1.2 ha of Tanzania pasture divided into 12 paddocks (24 areas, managed under 2 post-grazing residues: low green (leaf + stem herbage mass (GHM post-grazing (LR, approximately 1,500 kg/ha GHM; and high GHM post-grazing (HR, approximately 3,000 kg/ha GHM. Each paddock was grazed for 3 consecutive days (D1, D2, D3 followed by 33 days rest and evaluated from October 2005 to April 2006. Animal behavior (grazing time, bite rate and bite size/weight was evaluated on each grazing day. While goats spent more time grazing on LR than HR (P=0.02, bite rate did not differ between treatments or among days (P=0.31 and averaged 26.5 bites/min. In contrast, bite weight was greater in HR (0.15 g/bite than in LR (0.12 g/bite, and decreased from D1 to D3 (P<0.001. Absolute dry matter intake of goats was greater in the HR (2.19 kg/d than the LR (1.89 kg/d treatment; however, differences were not significant (P>0.05 when intake was determined on a body weight or metabolic weight basis. Our findings are consistent with the general assumption that bite weight is a trade-off between quantity and quality of the herbage mass and is the main determinant of animal performance. More studies are needed to determine animal performance on the various treatments and to determine management strategies to provide a desirable balance between animal weight gain and pasture stability.Keywords: Animal behavior, foraging, grazing systems, Megathyrsus maximus, plant - animal relations.DOI: 10.17138/TGFT(491-100

  11. Herbage availability €rs a stress factor on grazed Coastcross II ...

    ) relationships for Coastcross ll Bermuda grass grazed for four consecutive summer periods by young growing beef cattle. Stocking rate affected the daily. LWG/animal through its influence on herbage availability. Rota- tional grazing showed a ...

  12. Grass species selection patterns on rotationally-grazed Dohne ...

    Herbaceous species preference was studied during autumn and winter periods of occupation, on rotationally-grazed Dohne Sourveld, at four different stocking rates. Reports on species selection by cattle and sheep grazing together. Illustrates with graphsLanguage: English. Keywords: Grass species; Herbage availibility; ...

  13. Prescribed grazing for management of invasive vegetation in a hardwood forest understory

    Ronald A. Rathfon; Songlin Fei; Jason Tower; Kenneth Andries; Michael. Neary

    2014-01-01

    Land managers considering prescribed grazing (PG) face a lack of information on animal stocking rates, timing of grazing, and duration of grazing to achieve desired conditions in natural ecosystems under invasion stress from a variety of nonnative invasive plant (NNIP) species. In this study we tested PG treatments using goats for reducing NNIP brush species and...

  14. White clover regenerative ability under N fertilizing and grazing

    Josip Leto

    2008-12-01

    Full Text Available Recently, ecological and economic factors in milk and meat production stimulate use of legumes and grass-legumes mixtures, with zero or minimum mineral N as alternative to grass monoculture with high rate of mineral N. Research objective was to examine the effect of N application (0-N0 and 150 kg ha-1 year-1-N150 and rotational grazing by cattle (C and sheep (S on white clover: growing points number, stolon lenght, stolon dry weight, dry matter yield and clover contribution to total annual herbage production. N150 significantly reduced the growing points number, stolon length and stolon dry weight for more than 70 % compared to N0. Grazing treatment affected stolon population density only in interaction with N application because of N150 significantly reduced white clover population density only in sheep grazing. S-treatment had higher clover DM yield (0.21 t ha-1 than C-treatment (0.13 t ha-1. N0 had higher clover DM yield (0.25 t ha-1 than N150 (0.09 t ha-1. However, the interaction grazing management x N rate was significant for clover DM yield and clover contribution to total DM yield. N150 reduced both parameters for 80 % only in sheep grazing while difference in DM yield and clover contribution to total DM yield between grazing treatment was recorded only in N0 Sheep grazing increased DM yield for 150 % and clover contribution for 99 % compared to cattle grazing.

  15. Riparian Meadow Response to Modern Conservation Grazing Management

    Oles, Kristin M.; Weixelman, Dave A.; Lile, David F.; Tate, Kenneth W.; Snell, Laura K.; Roche, Leslie M.

    2017-09-01

    Riparian meadows occupy a small proportion of the public lands in the western United States but they provide numerous ecosystem services, including the production of high-quality forage for livestock grazing. Modern conservation management strategies (e.g., reductions in livestock stocking rates and adoption of new riparian grazing standards) have been implemented to better balance riparian conservation and livestock production objectives on publicly managed lands. We examined potential relationships between long-term changes in plant community, livestock grazing pressure and environmental conditions at two spatial scales in meadows grazed under conservation management strategies. Changes in plant community were not associated with either livestock stocking rate or precipitation at the grazing allotment (i.e., administrative) scale. Alternatively, both grazing pressure and precipitation had significant, albeit modest, associations with changes in plant community at the meadow (i.e., ecological site) scale. These results suggest that reductions in stocking rate have improved the balance between riparian conservation and livestock production goals. However, associations between elevation, site wetness, precipitation, and changes in plant community suggest that changing climate conditions (e.g., reduced snowpack and changes in timing of snowmelt) could trigger shifts in plant communities, potentially impacting both conservation and agricultural services (e.g., livestock and forage production). Therefore, adaptive, site-specific management strategies are required to meet grazing pressure limits and safeguard ecosystem services within individual meadows, especially under more variable climate conditions.

  16. Effects of Grazing Abandoned Grassland on Herbage Production and Utilization, and Sheep Preference and Performance

    Håvard Steinshamn

    2018-05-01

    Full Text Available Large areas of farmland are abandoned in Norway, which for various reasons are regarded as undesirable. Loss of farmland may have negative implications for biodiversity and ecosystem function and food production potential. The objectives of this study were to assess forage mass production and utilization, botanical composition, lamb performance, and grazing distribution pattern when reintroducing livestock grazing to an abandoned grassland. The study area was located in Central Norway, unmanaged for 12 years. Sheep grazed the area for 10 weeks in 2013 and 4 weeks in spring and autumn, respectively, in 2014 and 2015. During the summer of 2014 and 2015, the area was subjected to the following replicated treatments: (1 No grazing, (2 grazing with heifers, and (3 grazing with ewes and their offspring. The stocking rate was similar in the grazed treatments. Forage biomass production and animal intake were estimated using grazing exclosure cages and botanical composition by visual assessment. Effect on lamb performance was evaluated by live weight gain and slaughter traits in sheep subjected to three treatments: (1 Common farm procedure with summer range pasturing, (2 spring grazing period extended by 1 month on the abandoned grassland before summer range pasturing, and (3 spring and summer grazing on the abandoned grassland. Grazing distribution patterns were studied using GPS position collars on ewes. Total annual biomass production was on average 72% higher with summer grazing than without. Annual consumption and utilization was on average 218 g DM/m2 and 70% when summer grazed, and 25 g DM/m2 and 18% without grazing, respectively. Botanical composition did not differ between treatments. Live weight gain was higher in lambs subjected to an extended spring grazing period (255 g/d compared to common farm practice (228 g/d and spring and summer grazing on the abandoned grassland (203 g/d, and carcass value was 14% higher in lambs on extended spring

  17. Bivalve grazing can shape phytoplankton communities

    Lucas, Lisa; Cloern, James E.; Thompson, Janet K.; Stacey, Mark T.; Koseff, Jeffrey K.

    2016-01-01

    The ability of bivalve filter feeders to limit phytoplankton biomass in shallow waters is well-documented, but the role of bivalves in shaping phytoplankton communities is not. The coupled effect of bivalve grazing at the sediment-water interface and sinking of phytoplankton cells to that bottom filtration zone could influence the relative biomass of sinking (diatoms) and non-sinking phytoplankton. Simulations with a pseudo-2D numerical model showed that benthic filter feeding can interact with sinking to alter diatom:non-diatom ratios. Cases with the smallest proportion of diatom biomass were those with the fastest sinking speeds and strongest bivalve grazing rates. Hydrodynamics modulated the coupled sinking-grazing influence on phytoplankton communities. For example, in simulations with persistent stratification, the non-sinking forms accumulated in the surface layer away from bottom grazers while the sinking forms dropped out of the surface layer toward bottom grazers. Tidal-scale stratification also influenced vertical gradients of the two groups in opposite ways. The model was applied to Suisun Bay, a low-salinity habitat of the San Francisco Bay system that was transformed by the introduction of the exotic clam Potamocorbula amurensis. Simulation results for this Bay were similar to (but more muted than) those for generic habitats, indicating that P. amurensis grazing could have caused a disproportionate loss of diatoms after its introduction. Our model simulations suggest bivalve grazing affects both phytoplankton biomass and community composition in shallow waters. We view these results as hypotheses to be tested with experiments and more complex modeling approaches.

  18. Zooplankton grazing in a eutrophic lake: implications of diel vertical migration

    Lampert, W.; Taylor, B.E.

    1985-01-01

    During summer and fall, depth profiles of zooplankton community grazing were determined in situ during day and night in the Schoehsee, a small eutrophic lake. Labeled algae of two different sizes were mixed with the natural suspension of phytoplankton in a grazing chamber. A small blue-green alga (Synechococcus, 1 μm) was labeled with 32 P; a larger green alga (Scenedesmus, 4-15 μm) was labeled with 14 C. During summer, grazing in the upper 5 m was negligible during day but strong at night. Hence, algae grow relatively unimpeded by grazing during daytime but are harvested at night. Vertical and diel differences in grazing rates disappeared when the vertical migration ceased in fall. Selectivity of grazing was controlled by the zooplankton species composition. Eudiaptomus showed a strong preference for Scenedesmus. Daphnia showed a slight preference for Scenedesmus, but Ceriodaphnia preferred Synechococcus. Cyclopoid copepodites did not ingest the small blue-green. Because Daphnia and Eudiaptomus were dominant, grazing rates on larger cells were usually higher than grazing rates on the small cells. Negative electivity indices for scenedesmus occurred only when the biomass of large crustaceans was extremely low (near the surface, during day). Zooplankton biomass was the main factor controlling both vertical and seasonal variations in grazing. Highest grazing rates (65%/d) were measured during fall when zooplankton abundance was high. Because differential losses can produce substantial errors in the results, it was necessary to process the samples on the boat immediately after collection, without preservation

  19. Morphogenesis in guinea grass pastures under rotational grazing strategies

    Denise Baptaglin Montagner

    2012-04-01

    Full Text Available This study was conducted in order to evaluate the morphogenetic and structural characteristics of guinea grass cv. Mombasa under three post-grazing heights (intense - 30 cm, lenient - 50 cm and variable - 50 in spring-summer and 30 cm in autumn-winter when sward light interception reached 95% during regrowth. Post-grazing heights were allocated to experimental units (0.25 ha in a completely randomized block design with three replications. Post-grazing heights affected only leaf elongation rate and the number of live leaves. Pastures managed with variable post-grazing height showed higher leaf elongation rate in the summer of 2007. This management strategy also resulted in a higher number of live leaves. During the spring of 2006, plants showed lower leaf elongation rate, leaf appearance rate and number of live leaves, and greater phyllochron and leaf lifespan. In contrast, during the summer of 2007, the leaf appearance rate, leaf elongation rate, number of live leaves, and final leaf length were greater while phyllochron, stem elongation rate, and leaf senescence rate were lower. The management of the guinea grass cv. Mombasa with intense or variable post-grazing height throughout the year seems to represent an interesting management target, in terms of leaf appearance rate and number of live leaves.

  20. Woodlands Grazing Issues in Mediterranean Basin

    Campos, P.

    2009-04-01

    's family ownerships. These poor livestockeepers could maintain their livestock regimen on the basis of low cash-income earnings and crops self-consumption in extremely poor family living conditions. In this state woodlands, social an environmental goals -as they were noted above- could generate high trade off between family basic needs and soil degradation because woodlands and crops operations. As result, grazing rent is pending on the low opportunity cost for family labour. In this context, Tunisian Mediterranean woodlands maintain the highest livestock rate population, which woodland economy could be called for poor people subsistence and environmentally unsustainable because soil erosion, forest degradation and over/under grazing. These study present three study cases where Mediterranean basin grazing resources economies are analyzed in the contexts of Tunisian developing economy (Iteimia woodlands, North West of Tunisia) and Spanish developed economy (Jerez de la Frontera and Monfragüe woodlands, South and West of Spain). The results show the crucial role that livestock (goat, sheep and cattle) play in maintaining the working Mediterranean woodlands landscape. People, woodlands and livestock grazing dependences are changing so fast in Mediterranean basin that they appear too complex for being accurately forecasting by rangeland economists. In this context, perhaps a question might be a more suitable concluding remark: ¿will does woodlands extensive livestock become a quasi-wild management for urban landowners pleasure aims in rich Mediterranean basin countries?

  1. Grazing incidence beam expander

    Akkapeddi, P.R.; Glenn, P.; Fuschetto, A.; Appert, Q.; Viswanathan, V.K.

    1985-01-01

    A Grazing Incidence Beam Expander (GIBE) telescope is being designed and fabricated to be used as an equivalent end mirror in a long laser resonator cavity. The design requirements for this GIBE flow down from a generic Free Electron Laser (FEL) resonator. The nature of the FEL gain volume (a thin, pencil-like, on-axis region) dictates that the output beam be very small. Such a thin beam with the high power levels characteristic of FELs would have to travel perhaps hundreds of meters or more before expanding enough to allow reflection from cooled mirrors. A GIBE, on the other hand, would allow placing these optics closer to the gain region and thus reduces the cavity lengths substantially. Results are presented relating to optical and mechanical design, alignment sensitivity analysis, radius of curvature analysis, laser cavity stability analysis of a linear stable concentric laser cavity with a GIBE. Fabrication details of the GIBE are also given.

  2. High motility reduces grazing mortality of planktonic bacteria

    Matz, Carsten; Jurgens, K.

    2005-01-01

    We tested the impact of bacterial swimming speed on the survival of planktonic bacteria in the presence of protozoan grazers. Grazing experiments with three common bacterivorous nanoflagellates revealed low clearance rates for highly motile bacteria. High-resolution video microscopy demonstrated...... size revealed highest grazing losses for moderately motile bacteria with a cell size between 0.2 and 0.4 mum(3). Grazing mortality was lowest for cells of >0.5 mum(3) and small, highly motile bacteria. Survival efficiencies of >95% for the ultramicrobacterial isolate CP-1 (less than or equal to0.1 mum......(3), >50 mum s(-1)) illustrated the combined protective action of small cell size and high motility. Our findings suggest that motility has an important adaptive function in the survival of planktonic bacteria during protozoan grazing....

  3. Lucerne varieties for continuous grazing

    Søegaard, Karen

    2012-01-01

    severe grazing with heifers in two cutting/grazing managements. Two new varieties, Verbena and Camporegio, and an older variety Luzelle were established in 2009 in pure stands and in two different mixtures with perennial ryegrass (Lolium perenne). Camporegio had the lowest yield, the lowest competitive...... strength, the lowest plant density in spring, and the density was most reduced during grazing. The results could not confirm significant differences between the new and the older varieties. The results for Luzelle were generally between Verbena and Camporegio. The varieties did not differ in herbage...

  4. Dynamics of forage accumulation in Elephant grass subjected to rotational grazing intensities

    Braulio Maia de Lana Sousa

    2013-09-01

    Full Text Available We assessed the accumulation dynamics of forage and its components in Elephant grass cv. Napier (Pennisetum purpureum Schum. that were subjected to three post-grazing height treatments (30, 50, and 70 cm from February through May 2009 (experiment one and December 2009 through May 2010 (experiment two. In experiment one, the grazing events started when the light interception by the canopy reached 95%. The same was adopted for experiment two, except for the first grazing event, which was based on the height of the apical meristems of basal tillers. The experimental design for both experiments was a randomized complete block with three replications. The pastures that were managed at a post-grazing height of 30 cm exhibited lower rates of leaf and stem growth, total growth and forage accumulation than those that were managed at 50 or 70 cm, indicating that post-grazing height affects Elephant grass. The pastures that were managed at 50 cm exhibited relatively stable accumulation rates and less stem accumulation. Pastures managed at 70 cm of pos-grazing height presented more leaf and stem accumulation. Most apical meristems of Elephant grass should be removed in the first grazing when they reach the post-grazing target height of 50 cm. The elevation in the residual post-grazing height, especially in the summer, raises the regrowth vigor in the Elephant grass cv. Napier pasture. The post-grazing height of 30 cm reduces the growth of the Elephant grass cv. Napier.

  5. Grazing Incidence Optics Technology

    Ramsey, Brian; Smith, W. Scott; Gubarev, Mikhail; McCracken, Jeff

    2015-01-01

    This project is to demonstrate the capability to directly fabricate lightweight, high-resolution, grazing-incidence x-ray optics using a commercially available robotic polishing machine. Typical x-ray optics production at NASA Marshall Space Flight Center (MSFC) uses a replication process in which metal mirrors are electroformed on to figured and polished mandrels from which they are later removed. The attraction of this process is that multiple copies can be made from a single master. The drawback is that the replication process limits the angular resolution that can be attained. By directly fabricating each shell, errors inherent in the replication process are removed. The principal challenge now becomes how to support the mirror shell during all aspects of fabrication, including the necessary metrology to converge on the required mirror performance specifications. This program makes use of a Zeeko seven-axis computer-controlled polishing machine (see fig. 1) and supporting fabrication, metrology, and test equipment at MSFC. The overall development plan calls for proof-of-concept demonstration with relatively thick mirror shells (5-6 mm, fig. 2) which are straightforward to support and then a transition to much thinner shells (2-3 mm), which are an order of magnitude thinner than those used for Chandra. Both glass and metal substrates are being investigated. Currently, a thick glass shell is being figured. This has enabled experience to be gained with programming and operating the polishing machine without worrying about shell distortions or breakage. It has also allowed time for more complex support mechanisms for figuring/ polishing and metrology to be designed for the more challenging thinner shells. These are now in fabrication. Figure 1: Zeeko polishing machine.

  6. Milk production, grazing behavior and nutritional status of dairy cows grazing two herbage allowances during winter

    Miguel Ruiz-Albarran

    2016-03-01

    Full Text Available Winter grazing provides a useful means for increasing the proportion of grazed herbage in the annual diet of dairy cows. This season is characterized by low herbage growth rate, low herbage allowance, and low herbage intake and hence greater needs for supplements to supply the requirements of lactating dairy cows. The aim of this study was to determine the influence of herbage allowance (HA offered to autumn calving dairy cows grazing winter herbage on milk production, nutritional status, and grazing behavior. The study took 63 d using 32 multiparous Holstein-Friesian dairy cows. Prior to experimental treatment, milk production averaged 20.2 ± 1.7 kg d-1, body weight was 503 ± 19 kg, and days in milking were 103 ± 6. Experimental animals were randomly assigned to two treatments according to HA offered above ground level: low (17 kg DM cow-1 d-1 vs. high HA (25 kg DM cow¹ d¹. All cows were supplemented with grass silage supplying daily 6.25 and 4.6 kg DM of concentrate (concentrate commercial plus high corn moisture. Decreasing HA influenced positively milk production (+25%, milk protein (+20 kg, and milk fat (+17 kg per hectare; however no effects on milk production per cow or energy metabolic status were observed in the cows. In conclusion, a low HA showed to be the most significant influencing factor on milk and milk solids production per hectare in dairy cows grazing restricted winter and supplemented with grass silage and concentrate; but no effect on the milk production per cow was found.

  7. Density and success of bird nests relative to grazing on western Montana grasslands

    Fondell, Thomas F.; Ball, I.J.

    2004-01-01

    Grassland birds are declining at a faster rate than any other group of North American bird species. Livestock grazing is the primary economic use of grasslands in the western United States, but the effects of this use on distribution and productivity of grassland birds are unclear. We examined nest density and success of ground-nesting birds on grazed and ungrazed grasslands in western Montana. In comparison to grazed plots, ungrazed plots had reduced forb cover, increased litter cover, increased litter depth, and increased visual obstruction readings (VOR) of vegetation. Nest density among 10 of 11 common bird species was most strongly correlated with VOR of plots, and greatest nest density for each species occurred where mean VOR of the plot was similar to mean VOR at nests. Additionally, all bird species were relatively consistent in their choice of VOR at nests despite substantial differences in VOR among plots. We suggest that birds selected plots based in part on availability of suitable nest sites and that variation in nest density relative to grazing reflected the effect of grazing on availability of nest sites. Nest success was similar between grazed plots and ungrazed plots for two species but was lower for nests on grazed plots than on ungrazed plots for two other species because of increased rates of predation, trampling, or parasitism by brown-headed cowbirds (Molothrus ater). Other species nested almost exclusively on ungrazed plots (six species) or grazed plots (one species), precluding evaluation of the effects of grazing on nest success. We demonstrate that each species in a diverse suite of ground-nesting birds preferentially used certain habitats for nesting and that grazing altered availability of preferred nesting habitats through changes in vegetation structure and plant species composition. We also show that grazing directly or indirectly predisposed some bird species to increased nesting mortality. Management alternatives that avoid

  8. Contrasting responses of insect communities to grazing intensity in lowland heathlands

    Wallis de Vries, Michiel; Noordijk, Jinze; Colijn, Ed O.; Smit, John T.; Veling, Kars

    2016-01-01

    Grazing at low stocking rates is often recommended for the preservation of the characteristic biodiversity of open landscapes. However, the fine-tuning of grazing management still lacks a good evidence base. This is particularly true for insect communities, as available evidence indicates that

  9. Ecology of grazing lawns in Africa

    Hempson, GP

    2014-09-01

    Full Text Available otherwise outcompete lawn species for light. Regular grazing that prevents shading and maintains sward quality is thus the cornerstone of grazing lawn dynamics. The strong interplay between abiotic conditions and disturbance factors, which are central...

  10. Traditional cattle grazing in a mosaic alkali landscape: effects on grassland biodiversity along a moisture gradient.

    Péter Török

    Full Text Available Extensively managed pastures are of crucial importance in sustaining biodiversity both in local- and landscape-level. Thus, re-introduction of traditional grazing management is a crucial issue in grassland conservation actions worldwide. Traditional grazing with robust cattle breeds in low stocking rates is considered to be especially useful to mimic natural grazing regimes, but well documented case-studies are surprisingly rare on this topic. Our goal was to evaluate the effectiveness of traditional Hungarian Grey cattle grazing as a conservation action in a mosaic alkali landscape. We asked the following questions: (i How does cattle grazing affect species composition and diversity of the grasslands? (ii What are the effects of grazing on short-lived and perennial noxious species? (iii Are there distinct effects of grazing in dry-, mesophilous- and wet grassland types? Vegetation of fenced and grazed plots in a 200-ha sized habitat complex (secondary dry grasslands and pristine mesophilous- and wet alkali grasslands was sampled from 2006-2009 in East-Hungary. We found higher diversity scores in grazed plots compared to fenced ones in mesophilous- and wet grasslands. Higher cover of noxious species was typical in fenced plots compared to their grazed counterparts in the last year in every studied grassland type. We found an increasing effect of grazing from the dry- towards the wet grassland types. The year-to-year differences also followed similar pattern: the site-dependent effects were the lowest in the dry grassland and an increasing effect was detected along the moisture gradient. We found that extensive Hungarian Grey cattle grazing is an effective tool to suppress noxious species and to create a mosaic vegetation structure, which enables to maintain high species richness in the landscape. Hungarian Grey cattle can feed in open habitats along long moisture gradient, thus in highly mosaic landscapes this breed can be the most suitable

  11. Temporal profiles of vegetation indices for characterizing grazing intensity on natural grasslands in Pampa biome

    Amanda Heemann Junges

    2016-08-01

    Full Text Available ABSTRACT The Pampa biome is an important ecosystem in Brazil that is highly relevant to livestock production. The objective of this study was to analyze the potential use of vegetation indices to discriminate grazing intensities on natural grasslands in the Pampa biome. Moderate Resolution Imaging Spectroradiometer (MODIS Normalized Difference Vegetation Index (NDVI and Enhanced Vegetation Index (EVI images from Jan to Dec, 2000 to 2013 series, were analyzed for natural grassland experimental units managed under high (forage allowance of 5 ± 2 % live weight – LW, moderate (13 ± 5 % LW and low grazing intensity (19 ± 7 % LW. Regardless of intensity, the temporal profiles showed lower NDVI and EVI during winter, increased values in spring because of summer species regrowth, slightly decreased values in summer, especially in years when there is a water deficit, and increased values in the fall associated with the beginning of winter forage development. The average temporal profiles of moderate grazing intensity exhibited greater vegetation index values compared with low and high grazing intensities. The temporal profiles of less vegetation index were associated with lower green biomass accumulation caused by the negative impact of stocking rates on the leaf area index under high grazing intensity and a floristic composition with a predominance of tussocks under low grazing intensity. Vegetation indices can be used for distinguishing moderate grazing intensity from low and high intensities. The average EVI values can discriminate moderate grazing intensity during any season, and the NDVI values can discriminate moderate grazing intensity during spring and winter.

  12. Livestock grazing, wildlife habitat, and rangeland values

    Paul R. Krausman; David E. Naugle; Michael R. Frisina; Rick Northrup; Vernon C. Bleich; William M. Block; Mark C. Wallace; Jeffrey D. Wright

    2009-01-01

    Livestock managers make and implement grazing management decisions to achieve a variety of objectives including livestock production, sustainable grazing, and wildlife habitat enhancement. Assessed values of grazing lands and ranches are often based on aesthetics and wildlife habitat or recreational values, which can exceed agricultural values, thus providing...

  13. 50 CFR 35.9 - Livestock grazing.

    2010-10-01

    ... 50 Wildlife and Fisheries 6 2010-10-01 2010-10-01 false Livestock grazing. 35.9 Section 35.9... NATIONAL WILDLIFE REFUGE SYSTEM WILDERNESS PRESERVATION AND MANAGEMENT General Rules § 35.9 Livestock grazing. (a) The grazing of livestock, where established prior to the date of legislation which designates...

  14. 7 CFR 760.305 - Eligible grazing losses.

    2010-01-01

    ... 7 Agriculture 7 2010-01-01 2010-01-01 false Eligible grazing losses. 760.305 Section 760.305... grazing losses. (a) A grazing loss due to drought is eligible for LFP only if the grazing loss for the... period for the specific type of grazing land or pastureland for the county.) (b) A grazing loss is not...

  15. Phytoplankton growth and microzooplankton grazing in the subtropical Northeast Atlantic.

    Carlos Cáceres

    Full Text Available Dilution experiments were performed to estimate phytoplankton growth and microzooplankton grazing rates during two Lagrangian surveys in inner and eastern locations of the Eastern North Atlantic Subtropical Gyre province (NAST-E. Our design included two phytoplankton size fractions (0.2-5 µm and >5 µm and five depths, allowing us to characterize differences in growth and grazing rates between size fractions and depths, as well as to estimate vertically integrated measurements. Phytoplankton growth rates were high (0.11-1.60 d(-1, especially in the case of the large fraction. Grazing rates were also high (0.15-1.29 d(-1, suggesting high turnover rates within the phytoplankton community. The integrated balances between phytoplankton growth and grazing losses were close to zero, although deviations were detected at several depths. Also, O2 supersaturation was observed up to 110 m depth during both Lagrangian surveys. These results add up to increased evidence indicating an autotrophic metabolic balance in oceanic subtropical gyres.

  16. Phytoplankton Growth and Microzooplankton Grazing in the Subtropical Northeast Atlantic

    Cáceres, Carlos; Taboada, Fernando González; Höfer, Juan; Anadón, Ricardo

    2013-01-01

    Dilution experiments were performed to estimate phytoplankton growth and microzooplankton grazing rates during two Lagrangian surveys in inner and eastern locations of the Eastern North Atlantic Subtropical Gyre province (NAST-E). Our design included two phytoplankton size fractions (0.2–5 µm and >5 µm) and five depths, allowing us to characterize differences in growth and grazing rates between size fractions and depths, as well as to estimate vertically integrated measurements. Phytoplankton growth rates were high (0.11–1.60 d−1), especially in the case of the large fraction. Grazing rates were also high (0.15–1.29 d−1), suggesting high turnover rates within the phytoplankton community. The integrated balances between phytoplankton growth and grazing losses were close to zero, although deviations were detected at several depths. Also, O2 supersaturation was observed up to 110 m depth during both Lagrangian surveys. These results add up to increased evidence indicating an autotrophic metabolic balance in oceanic subtropical gyres. PMID:23935946

  17. Stability, resilience and animal production in continuously grazed ...

    The Jones-Sandland model, popularly used in southern Africa, may be criticised because it ignores firstly the long-term effects of grazing intensity on the acceptability and productivity of pasture or veld, and secondly possible discontinuities in the animal performance - stocking rate relationship. A mathematical model is ...

  18. Carcass mass gains of steers grazing star grass, with different ...

    Carcass mass gains of steers grazing dryland Cynodon aethiopicus cv. No. 2 Star grass pastures during the growing season were determined for each of 16 treatments comprising four levels of nitrogen fertilisation in combination with four overlapping sets of stocking rates. The treatments were repeated over four growing ...

  19. Effects of UV-B irradiated algae on zooplankton grazing

    Lange, de H.J.; Lürling, M.F.L.L.W.

    2003-01-01

    We tested the effects of UV-B stressed algae on grazing rates of zooplankton. Four algal species ( Chlamydomonas reinhardtii, Cryptomonas sp., Scenedesmus obliquus and Microcystis aeruginosa) were used as food and fed to three zooplankton species ( Daphnia galeata, Bosmina longirostris and

  20. Tillering dynamics in pastures of guinea grass subjected to grazing severities under intermittent stocking

    Denise Baptaglin Montagner

    2012-03-01

    Full Text Available This experiment was carried out to analyze the tillering dynamics of the species Panicum maximum cv. Mombaca subjected to three post-grazing heights: residue of 30 cm (30; residue of 50 cm (50; and residue of 50 cm during spring and summer, lowered to 40 cm in the first fall season grazing and to 30 cm in the following grazing cycle, resuming to 50 cm after the first grazing of the following spring season (50-30. Grazings were initiated whenever the swards intercepted 95% of the incident light. The post-grazing heights were allocated in the experimental units in a completely randomized block design with three replications. The density of basal tillers did not vary between the residual heights evaluated. Swards managed with variable residual height (50-30 presented higher rates of appearance and mortality of basal tillers during the summer of 2007, indicating high tiller renovation. Regardless of the post-grazing height evaluated, lower rates of appearance of basal tillers were found in the spring of 2006. The stability index of guinea grass cv. Mombaca was close to 1.0 throughout the experimental period. Swards managed with variable post-grazing present structural changes able to improve the regrowth vigor, which may be important to maximize the use of the forage species in the production system.

  1. Multisensor sampling of pelagic ecosystem variables in a coastal environment to estimate zooplankton grazing impact

    Sutton, Tracey; Hopkins, Thomas; Remsen, Andrew; Burghart, Scott

    2001-01-01

    Sampling was conducted on the west Florida continental shelf ecosystem modeling site to estimate zooplankton grazing impact on primary production. Samples were collected with the high-resolution sampler, a towed array bearing electronic and optical sensors operating in tandem with a paired net/bottle verification system. A close biological-physical coupling was observed, with three main plankton communities: 1. a high-density inshore community dominated by larvaceans coincident with a salinity gradient; 2. a low-density offshore community dominated by small calanoid copepods coincident with the warm mixed layer; and 3. a high-density offshore community dominated by small poecilostomatoid and cyclopoid copepods and ostracods coincident with cooler, sub-pycnocline oceanic water. Both high-density communities were associated with relatively turbid water. Applying available grazing rates from the literature to our abundance data, grazing pressure mirrored the above bio-physical pattern, with the offshore sub-pycnocline community contributing ˜65% of grazing pressure despite representing only 19% of the total volume of the transect. This suggests that grazing pressure is highly localized, emphasizing the importance of high-resolution sampling to better understand plankton dynamics. A comparison of our grazing rate estimates with primary production estimates suggests that mesozooplankton do not control the fate of phytoplankton over much of the area studied (<5% grazing of daily primary production), but "hot spots" (˜25-50% grazing) do occur which may have an effect on floral composition.

  2. Grazing effects on species composition in different vegetation types (La Palma, Canary Islands)

    Arévalo, J. R.; de Nascimento, L.; Fernández-Lugo, S.; Mata, J.; Bermejo, L.

    2011-05-01

    Grazing management is probably one of the most extensive land uses, but its effects on plant communities have in many cases been revealed to be contradictory. Some authors have related these contradictions to the stochastic character of grazing systems. Because of that, it is necessary to implement specific analyses of grazing effects on each community, especially in natural protected areas, in order to provide the best information to managers. We studied the effects of grazing on the species composition of the main vegetation types where it takes place (grasslands, shrublands and pine forests) on the island of La Palma, Canary Islands. We used the point-quadrat intersect method to study the species composition of grazed and ungrazed areas, which also were characterized by their altitude, distance to farms, distance to settlements, year of sampling, herbaceous aboveground biomass and soil organic matter. The variables organic matter, productivity and species richness were not significantly affected by grazing. The species composition of the analyzed plant communities was affected more by variables such as altitude or distance to farms than by extensive grazing that has been traditionally carried out on the island of La Palma involving certain practices such as continuous monitoring of animals by goat keepers, medium stocking rates adjusted to the availability of natural pastures, supplementation during the dry season using local forage shrubs or mown pastures and rotating animals within grazing areas Although some studies have shown a negative effect of grazing on endangered plant species, these results cannot be freely extrapolated to the traditional grazing systems that exert a low pressure on plant communities (as has been found in this study). We consider extensive grazing as a viable way of ensuring sustainable management of the studied ecosystems.

  3. The impact of cattle and goats grazing on vegetation in oak stands of varying coppicing age

    Papachristou, Thomas G.; Platis, Panayiotis D.

    2011-01-01

    half of the herbaceous vegetation was removed through grazing but it had no positive effect on the growth rate of oak shoots. It seems that goats, which selected almost half of their diet from oak shoots, are responsible for that relative negative growth of shoots. However, cattle grazed only herbs and may therefore control herbaceous vegetation.

  4. Grassland Fire and Cattle Grazing Regulate Reptile and Amphibian Assembly Among Patches

    Larson, Danelle M.

    2014-12-01

    Fire and grazing are common management schemes of grasslands globally and are potential drivers of reptilian and amphibian (herpetofauna) metacommunity dynamics. Few studies have assessed the impacts of fire and cattle grazing on herpetofauna assemblages in grasslands. A patch-burn grazing study at Osage Prairie, MO, USA in 2011-2012 created landscape patches with treatments of grazing, fire, and such legacies. Response variables were measured before and after the application of treatments, and I used robust-design occupancy modeling to estimate patch occupancy and detection rate within patches, and recolonization and extinction (i.e., dispersal) across patches. I conducted redundancy analysis and a permuted multivariate analysis of variance to determine if patch type and the associated environmental factors explained herpetofauna assemblage. Estimates for reptiles indicate that occupancy was seasonally constant in Control patches ( ψ ~ 0.5), but declined to ψ ~ 0.15 in patches following the applications of fire and grazing. Local extinctions for reptiles were higher in patches with fire or light grazing ( ɛ ~ 0.7) compared to the controls. For the riparian herpetofaunal community, patch type and grass height were important predictors of abundance; further, the turtles, lizards, snakes, and adult amphibians used different patch types. The aquatic amphibian community was predicted by watershed and in-stream characteristics, irrespective of fire or grazing. The varying responses from taxonomic groups demonstrate habitat partitioning across multiple patch types undergoing fire, cattle grazing, and legacy effects. Prairies will need an array of patch types to accommodate multiple herpetofauna species.

  5. A comparison of some methods used to estimate the grazing capacity of a game ranch in Northern Province, South Africa

    A.G. Schmidt

    1995-08-01

    Full Text Available The grazing capacity of a game ranch in Northern Province was estimated in a number of different ways using rainfall and herbaceous composition and phytomass data. The results indicate that the grazing capacity under the present environmental conditions should be approximately 50 of the recommended agricultural grazer stocking rate. This is in agreement with recent literature, indicating that the methods used should be suitable for determining a first approximation of grazing capacity in the mixed bushveld of Northern Province.

  6. Arbuscular mycorrhizal fungi associated with vegetation and soil parameters under rest grazing management in a desert steppe ecosystem.

    Bai, Gegenbaoleer; Bao, Yuying; Du, Guoxin; Qi, Yunlong

    2013-05-01

    The impact of rest grazing on arbuscular mycorrhizal fungi (AMF) and the interactions of AMF with vegetation and soil parameters under rest grazing condition were investigated between spring and late summer in a desert steppe ecosystem with different grazing managements (rest grazing with different lengths of resting period, banned or continuous grazing) in Inner Mongolia, China. AMF diversity and colonization, vegetation biomass, soil properties and soil phosphatase activity were examined. In rest grazing areas of 60 days, AMF spore number and diversity index at a 0-10 cm soil depth as well as vesicular and hyphal colonization rates were higher compared with other grazing treatments. In addition, soil organic matter and total N contents were highest and soil alkaline phosphatase was most active under 60-day rest grazing. In August and September, these areas also had the highest amount of aboveground vegetation. The results indicated that resting grazing for an appropriate period of time in spring has a positive effect on AMF sporulation, colonization and diversity, and that under rest grazing conditions, AMF parameters are positively correlated with some soil characteristics.

  7. DMSP and DMS dynamics and microzooplankton grazing in the Labrador Sea: application of the dilution technique

    Wolfe, Gordon V.; Levasseur, Maurice; Cantin, Guy; Michaud, Sonia

    2000-12-01

    We adapted the dilution technique to study microzooplankton grazing of algal dimethylsulfoniopropionate (DMSP) vs. Chl a, and to estimate the impact of microzooplankton grazing on dimethyl sulfide (DMS) production in the Labrador Sea. Phytoplankton numbers were dominated by autotrophic nanoflagellates in the Labrador basin, but diatoms and colonial Phaeocystis pouchetii contributed significantly to phytomass at several high chlorophyll stations and on the Newfoundland and Greenland shelfs. Throughout the region, growth of algal Chl a and DMSP was generally high (0.2-1 d -1), but grazing rates were lower and more variable, characteristic of the early spring bloom period. Production and consumption of Chl a vs. DMSP followed no clear pattern, and sometimes diverged greatly, likely because of their differing distributions among algal prey taxa and size class. In several experiments where Phaeocystis was abundant, we observed DMS production proportional to grazing rate, and we found clear evidence of DMS production by this haptophyte following physical stress such as sparging or filtration. It is possible that grazing-activated DMSP cleavage by Phaeocystis contributes to grazer deterrence: protozoa and copepods apparently avoided healthy colonies (as judged by relative growth and grazing rates of Chl a and DMSP), and grazing of Phaeocystis was significant only at one station where cells were in poor condition. Although we hoped to examine selective grazing on or against DMSP-containing algal prey, the dilution technique cannot differentiate selective ingestion and varying digestion rates of Chl a and DMSP. We also found that the dilution method alone was poorly suited for assessing the impact of grazing on dissolved sulfur pools, because of rapid microbial consumption and the artifactual release of DMSP and DMS during filtration. Measuring and understanding the many processes affecting organosulfur cycling by the microbial food web in natural populations remain a

  8. Grass composition and rangeland condition of the major grazing ...

    One area represented lightly grazed government ranches or parks which were used as benchmarks, another area represented the seasonal grazing areas with an intermediate grazing pressure and the remaining were the heavily grazed roadsides, lakeshores and other communal grazing lands. The range condition ...

  9. The grazing pattern of Muturu cattle under range system | Nweze ...

    Eighty Muturu cattle were grazed on rangeland, twice daily for two years to determine their grazing pattern. Twenty bulls and cows each between two to four years and forty calves between one to three months were used. The field grazing time (FGT), active grazing time (GT) and grazing travel time (GTT) were monitored.

  10. Annual methane budgets of sheep grazing systems were regulated by grazing intensities in the temperate continental steppe: A two-year case study

    Ma, Lei; Zhong, Mengying; Zhu, Yuhao; Yang, Helong; Johnson, Douglas A.; Rong, Yuping

    2018-02-01

    Methane (CH4) emission from animal husbandry accounts for a large percentage of anthropogenic contributions to CH4 emissions. Fully understanding of grazing management effects on the CH4 budget is essential for mitigating CH4 emissions in the temperate grazing steppe systems. Annual CH4 budgets for the sheep grazed steppes at various grazing intensities, un-grazing (UG, 0 sheep ha-1year-1), defer grazing (DG, 1.0 sheep ha-1 year-1), moderate grazing (MG, 1.43 sheep ha-1year-1), and heavy grazing (HG, 2.43 sheep ha-1year-1) were assessed across 2012-2014 in the agro-pastoral region of northern China. Annual soil CH4 uptake averaged across 2012-2014 were 1.1 ± 0.1, 2.4 ± 0.2, 2.2 ± 0.2, and 1.3 ± 0.1 kg CH4-C ha-1 for UG, DG (only 2013-2014), MG and HG sites. Non-growing season CH4 uptake comprised 50.0 ± 4.3% of annual CH4 uptake in 2012-2013 and 37.7 ± 2.0% in 2013-2014. DG and MG significantly promoted annual soil CH4 uptake (P 0.05). Bell-shaped relationship was presented between stocking rates and soil CH4 uptake (r2 = 0.59, P budgets for the grazed grasslands were -1.1 ± 0.1, 5.7 ± 0.6, 11.5 ± 1.5 and 15.5 ± 1.3 kg CH4-C ha-1 year-1 in UG, DG (only 2013-2014), MG and HG across 2012-2014. Soil CH4 uptake could offset 29.7 ± 5.6, 15.9 ± 4.3 and 6.8 ± 1.0% of total annual CH4 emissions from sheep, sheepfold and faeces in DG, MG, and HG. All grazed steppes are sources for atmospheric CH4 and the magnitude is regulated by grazing intensities. Sheep CH4 emissions for 1-g liveweight gain were 0.21, 0.32 and 0.37 g CH4-C in DG, MG and HG, respectively. DG is the recommended grazing management in this region to achieve greater herbage mass, higher sheep performance and lower CH4 emissions simultaneously.

  11. Grazing incidence diffraction : A review

    Gilles, B [LTPCM, ENSEEG. St. Martin d` Heres. (France)

    1996-09-01

    Different Grazing Incidence Diffraction (GID) methods for the analysis of thin films and multilayer structures are reviewed in three sections: the reflectivity is developed in the first one, which includes the non-specular diffuse scattering. The second one is devoted to the extremely asymmetric Bragg diffraction and the third one to the in-plane Bragg diffraction. Analytical formulations of the scattered intensities are developed for each geometry, in the framework of the kinetical analysis as well as the dynamical theory. Experimental examples are given to illustrate the quantitative possibility of the GID techniques.

  12. Investigations on the effect of grazing intensity on the transfer of radionuclides to cow`s milk

    Voigt, G. [GSF - Forschungszentrum fuer Umwelt und Gesundheit Neuherberg GmbH, Oberschleissheim (Germany). Inst. fuer Strahlenschutz; Schotola, C. [GSF - Forschungszentrum fuer Umwelt und Gesundheit Neuherberg GmbH, Oberschleissheim (Germany). Inst. fuer Strahlenschutz; Crout, N.M.J. [Nottingham Univ. (United Kingdom). Dept. of Physiology and Environmental Science; Absalom, J. [Nottingham Univ. (United Kingdom). Dept. of Physiology and Environmental Science

    1997-03-01

    For these investigations two farms were chosen. Farm A carries out a rotational grazing regime with 4 grazed pastures which is the more commonly used farm practice in Bavaria, farm B practises a continuous grazing regime with one grazed pasture only. In farm B a tenfold lower Cs-137 activity concentration was observed in milk though activity concentrations in soil and pasture grass were the same as that at farm A, indicating the same transfer rate soil-plant at both locations. It could be shown under normal agricultural conditions that with a higher grazing pressure lower activity concentrations in milk (in this case a factor of about 2 to 3) were obtained. Therefore changing stock density in combination with a continuous grazing regime on a given pasture after a major nuclear accident can be considered as a possible countermeasure which can be easily applied. Mainly to get more synchronised growth rates and a homogeneous distribution of radiocontamination plot experiments were performed to simulate the influence of grazing intensity. Under the experimental design used here no effect of grazing intensity on the transfer of radionuclides to vegetation could be found. Effects of grazing intensity as found for the farm experiment, therefore must be due to other sources than vegetation activities, and are presumably due to soil ingestion preventing uptake of soluble plant incorporated radiocaesium in the animal rumen. (orig./MG)

  13. Grazer-induced chain lenght plasticity reduces grazing risk in a marine diatom

    Bergkvist, Johanna; Thor, Peter; Jakobsen, Hans Henrik

    2012-01-01

    . marinoi was exposed to chemical cues from caged A. tonsa without physical contact with the responding cells. The reductions in chain length significantly reduced copepod grazing; grazing rates on chains (four cells or more) were several times higher compared to that of single cells. This suggests...... that chain length plasticity is a means for S. marinoi to reduce copepod grazing. In contrast, chain length was not suppressed in cultures exposed to the microzooplankton grazer Gyrodinium dominans. Size-selective predation may have played a key role in the evolution of chain formation and chain length...... plasticity in diatoms...

  14. Herbage intake by grazing dairy cows

    Meijs, J.A.C.

    1981-01-01

    An extensive review of the literature is given of
    - nine possible methods for estimating herbage intake by grazing ruminants, with special attention to the sward-cutting and indirect animal methods
    - the factors determining the herbage intake by grazing ruminants.

    The

  15. 75 FR 29572 - Information Collection; Grazing Management

    2010-05-26

    ... Control Number 1004-0019] Information Collection; Grazing Management AGENCY: Bureau of Land Management... submitted an information collection request to the Office of Management and Budget (OMB) for a 3-year... INFORMATION: Title: Grazing Management (43 CFR 4120). OMB Number: 1004-0019. Forms: 4120-6 (Cooperative Range...

  16. Effect of pre-grazing herbage mass on dairy cow performance, grass dry matter production and output from perennial ryegrass (Lolium perenne L.) pastures.

    Wims, C M; Delaby, L; Boland, T M; O'Donovan, M

    2014-01-01

    A grazing study was undertaken to examine the effect of maintaining three levels of pre-grazing herbage mass (HM) on dairy cow performance, grass dry matter (DM) production and output from perennial ryegrass (Lolium perenne L.) pastures. Cows were randomly assigned to one of three pre-grazing HM treatments: 1150 - Low HM (L), 1400 - Medium HM (M) or 2000 kg DM/ha - High HM (H). Herbage accumulation under grazing was lowest (Ppastures required more grass silage supplementation during the grazing season (+73 kg DM/cow) to overcome pasture deficits due to lower pasture growth rates (Ppasture intake, although cows grazing the L pastures had to graze a greater daily area (Ppasture reduces pasture DM production and at a system level may increase the requirement for imported feed.

  17. Grazing and metabolism of Euphausia pacifica in the Yellow Sea.

    Zhencheng Tao

    Full Text Available Grazing and metabolism of Euphausia pacifica in the Yellow Sea were studied from September 2006 to August 2007. Euphausia pacifica is a selective-feeding omnivore and grazing rates among different months were monitored using a Coulter Counter and batch culture feeding experiments. Euphausia pacifica mainly grazed microzooplankton in August and September, which resulted in an increase in chlorophyll a concentration. Oxygen consumption rate of E. pacifica was 38.7-42.5 μmol O2 g(-1 DW h(-1 in March, which was four times higher than the oxygen consumption rates in September and December. The vigorous metabolism of E. pacifica in March consumed 3.1% of body carbon daily, which is likely related to its high reproduction and grazing rate. Respiration and metabolism of E. pacifica in September and December were similar and were lower. O:N ratio of E. pacifica was the highest (17.3-23.8 in March when spawning activity occurred and when food was abundant. The energetic source of E. pacifica during September and December was mostly protein from eating a carnivorous diet, including such items as microzooplankton. Euphausia pacifica was found in cold water at the bottom of the Yellow Sea in summer and autumn and maintained a low consumption status. O:N ratios of E. pacifica in March, September, and December were negatively correlated with SSTs and no significant correlation was found between O:N ratios and chlorophyll a concentration. Seawater temperature is clearly the most important parameter influencing the metabolism of E. pacifica.

  18. Herds of methane chambers grazing bubbles

    Grinham, Alistair; Dunbabin, Matthew

    2014-05-01

    Water to air methane emissions from freshwater reservoirs can be dominated by sediment bubbling (ebullitive) events. Previous work to quantify methane bubbling from a number of Australian sub-tropical reservoirs has shown that this can contribute as much as 95% of total emissions. These bubbling events are controlled by a variety of different factors including water depth, surface and internal waves, wind seiching, atmospheric pressure changes and water levels changes. Key to quantifying the magnitude of this emission pathway is estimating both the bubbling rate as well as the areal extent of bubbling. Both bubbling rate and areal extent are seldom constant and require persistent monitoring over extended time periods before true estimates can be generated. In this paper we present a novel system for persistent monitoring of both bubbling rate and areal extent using multiple robotic surface chambers and adaptive sampling (grazing) algorithms to automate the quantification process. Individual chambers are self-propelled and guided and communicate between each other without the need for supervised control. They can maintain station at a sampling site for a desired incubation period and continuously monitor, record and report fluxes during the incubation. To exploit the methane sensor detection capabilities, the chamber can be automatically lowered to decrease the head-space and increase concentration. The grazing algorithms assign a hierarchical order to chambers within a preselected zone. Chambers then converge on the individual recording the highest 15 minute bubbling rate. Individuals maintain a specified distance apart from each other during each sampling period before all individuals are then required to move to different locations based on a sampling algorithm (systematic or adaptive) exploiting prior measurements. This system has been field tested on a large-scale subtropical reservoir, Little Nerang Dam, and over monthly timescales. Using this technique

  19. Reproductive performance of ewes grazing lucerne during different periods around mating.

    Robertson, S M; Clayton, E H; Friend, M A

    2015-11-01

    High intake of lucerne pastures or feeding of other high quality diets during early pregnancy may increase embryo mortality, negating any benefit of improved nutrition on ovulation rate in ewes. This study was conducted to determine whether grazing ewes on lucerne (Medicago sativa) pastures for 7 days prior to and throughout joining would result in greater foetal numbers than if ewes were removed 7 days after the commencement of joining, or if ewes grazed senescent pasture throughout the joining period. Merino ewes (300) were allocated to two replicates of three treatments, grazing pastures between Days -7 and 36 of an unsynchronised, natural autumn joining. Grazing lucerne to Day 7 of joining resulted in 30% more (Pewe than grazing senescent pasture (1.60±0.07 and 1.31±0.07, respectively), and 19% more lambs marked per ewe joined. Extending grazing of lucerne past Day 7 of joining did not result in additional foetuses per ewe (1.61±0.06) in comparison with only grazing lucerne to Day 7 of joining. Greater than 80% of ewes mated during the first 14 days of joining, and the proportions of ewes returning to oestrus and re-mating (0.18±0.022) and of non-pregnant (0.09±0.017) ewes were similar (P>0.05) among all treatment groups, suggesting no differences between treatments in embryo mortality. Grazing naturally cycling ewes on lucerne prior to and during joinings in autumn is recommended as a means to increase the number of lambs born, although additional gains may not be obtained by grazing past day seven of joining. Copyright © 2015 Elsevier B.V. All rights reserved.

  20. Reaction of cocksfoot (Dactylis glomerata L. in grass-clover mixture on N fertilization and grazing

    Marcela Andreata-Koren

    2009-09-01

    Full Text Available Grazing is the most common way of using a hill and mountain areas because of their specific agro-ecological conditions. Cocksfoot is a grass with high productivity and quality, and it is very good for sowing in the sward for grazing. Because of its good adaptability to different growing conditions, especially in very dry and cold areas, it is excellent in relation to some other good grasses, which can not be raised in such areas. The aim of the experiment was to determine effect of N application (0-N0 and 150 kg ha-1 year-1-N150 and rotational grazing by cattle (C and sheep (S, and their interaction on the cocksfoot sown in a mixture of smooth-stalked meadow grass (Poa pratensis L. and white clover (Trifolium repens L. in hill mountain areas. In a three-year average, the application of 150 kg ha-1 N had significant impact on cocksfoot population density (number of tillers m-2, and it was 51.4 % higher than the recorded one before grazing (P<0.05 and 42.2 % higher after grazing (P<0.01 in comparison to N0. The application of 150 kg ha-1 N resulted in significantly higher cocksfoot dry matter (DM yield for 38.6 % (P<0.01 and 15.3 % higher cocksfoot share in the total mixture in relation to N0 (P<0.01. Grazing management and grazing management interaction with N rate did not significantly affect the population density of individual years. However, in the three-year average, grazing management significantly affected cocksfoot DM (P<0.01 and its percentage in the total DM mixture (P<0.01. Cattle grazing resulted in 9.9 % higher cocksfoot DM yield and 15.2 % higher cocksfoot percentage in pasture. Interaction of grazing management and N-level had significant influence on the percentage of cocksfoot DM in grass-clover mixture. On cattle grazed areas fertilized with 150 kg ha-1 N, the percentage of cocksfoot DM was the highest (74. 07%, while the lowest percentage of cocksfoot DM was recorded on the sheep grazed areas without N (55.12%.

  1. Ingestive behavior of cattle kept in Brachiaria brizantha cv. Xaraés grass managed under different grazing heights

    Marco Aurélio Alves de Freitas Barbosa

    2014-02-01

    Full Text Available This experiment was conducted to evaluate the effect of grazing heights on daytime behavioral activities of Nellore beef cattle in the rainy season. The experimental area was 12 hectares divided into paddocks of one hectare each. The treatments consisted of four defoliation heights (15, 30, 45 and 60 cm in pastures of Brachiaria brizantha cv. Xaraés with three replicates each. It was used the continuos grazing method, with variable stocking rate. Forage samples collected on the plots were sent to the laboratory for separation of the botanical components, weighing and determination of dry matter, with the material collected by simulated grazing. The variables: grazing time, idle time and ruminating time were evaluated for 12 consecutive hours on days 15 and 16 February 2011, considering the morning and afternoon periods. It was used a completely randomized design. The height of the canopy significantly influenced the daily grazing time and ruminating time, with a quadratic response as a function of time of defoliation. The bite rate decreased as a function of heights studied. However the chemical composition of the material collected by simulated grazing did not differ between treatments. Xaraés grass swards grazed at around 45 cm height provide greater ease of apprehension by grazing cattle.

  2. 36 CFR 293.7 - Grazing of livestock.

    2010-07-01

    ... 36 Parks, Forests, and Public Property 2 2010-07-01 2010-07-01 false Grazing of livestock. 293.7...-PRIMITIVE AREAS § 293.7 Grazing of livestock. (a) The grazing of livestock, where such use was established..., shall be permitted to continue under the general regulations covering grazing of livestock on the...

  3. Productivity of grasslands under continuous and rotational grazing

    Lantinga, E.A.

    1985-01-01

    In the Netherlands, rotational grazing, with grazing periods of 2 to 5 days, is the most common grazing system at present. In contrast with other countries of North-western Europe, the continuous grazing system is used here only to a limited extent. However, the results of numerous

  4. [Relation between species distribution of plant community and soil factors under grazing in alpine meadow].

    Niu, Yu Jie; Yang, Si Wei; Wang, Gui Zhen; Liu, Li; Du, Guo Zhen; Hua, Li Min

    2017-12-01

    The research selected the alpine meadow located in the northeastern margin of the Qinghai-Tibet Plateau to study the changes of vegetation community and soil properties under different grazing intensities, as well as the quantitative relation between the distribution patterns of plant species and the physical and chemical properties of soil. The results showed that the grazing caused the differentiation of the initial vegetation community with the dominant plants, Elymus nutans and Stipa grandis. In the plots with high and low grazing intensities, the dominant plants had changed to Kobresia humilis and Melissitus ruthenica, and E. nutans and Poa crymophila, respectively. With the increase of grazing intensity, the plant richness, importance value and biomass were significantly decreased. The sequence of plant species importance value in each plot against grazing intensity could be fitted by a logarithmic model. The number of required plant species was reduced while the importance value of the remaining plant species accounted for 50% of the importance value in the whole vegetation community. The available P, available K, soil compaction, soil water content, stable infiltration rate and large aggregate index were significantly changed with grazing intensity, however, the changes were different. The CCA ordination showed that the soil compaction was the key factor affecting the distribution pattern of the plant species under grazing. The variance decomposition indicated that the soil factors together explained 30.5% of the distribution of the plant species, in particular the soil physical properties alone explained 22.8% of the distribution of the plant species, which had the highest rate of contribution to the plant species distribution. The soil physical properties affected the distribution pattern of plant species on grazed alpine meadow.

  5. [A comparative study on soil respiration between grazing and fenced typical Leymus chinensis steppe, Inner Mongolia].

    Jia, Bingrui; Zhou, Guangsheng; Wang, Fengyu; Wang, Yuhui

    2004-09-01

    With enclosed chamber Method, this paper studied the soil respiration in grazing and fenced typical Leymus chinensis steppes, Inner Mongolia, and its relationships with environmental factors. The results showed that the daily pattern of soil respiration could be expressed as a one-humped curve, and the highest values appeared at 13:00-15:00 in the fenced and grazing plots. The diurnal dynamics of soil respiration mainly depended on the surface temperature at the fenced plots and the soil temperature at 5 cm depth at the grazing plots. In June and July, the average soil respiration rate was 2.7 times greater at the fenced plots than that at the grazing plots, while the difference was not distinct in August and September, which was similar with the change of the belowground biomass. The reason was probably that the plant was influenced differently in different phenological phases by grazing and the change of environmental factors. It showed that human activity may not result in the increase of soil respiration rate. The seasonal dynamics of soil respiration was closely correlated with soil water content at the 0-10 cm depth at the fenced and grazing sites, and the maximum R2 was 0.853 and 0.741, respectively. The difference was that the correlation of soil respiration seasonal dynamics with soil water content was larger at the fenced plots than at the grazing plots. The correlations of soil respiration diurnal and seasonal dynamics with temperature and soil water content at lower profiles were larger than those at deeper profiles at the fenced and grazing sites.

  6. Grazing management that regenerates ecosystem function and ...

    Grazing management that regenerates ecosystem function and grazingland ... in ecosystem improvement, productivity, soil carbon and fertility, water-holding ... for sufficient time to produce resource improvement, sound animal production, and ...

  7. The effect of prolonged heavy grazing pressure on the regrowth of ...

    A clipping experiment was done in the field using T. triandra and U. mosambicensis tufts. Regrowth was lower (P0.01) in the heavy grazing sites for both species. This was more a function of tiller production rate, in terms of numbers of tillers, than of tiller extension rate. Rate of regrowth was not strongly affected by tuft ...

  8. Mineral supplementation for grazing ruminants

    McDowell, L.R.; Conrad, J.H.; Ellis, G.L.

    1986-01-01

    Grazing ruminants to which concentrate feeds cannot be economically fed must rely on self-feeding of mineral supplements. A number of factors affect mineral consumption of free-choice mixtures. Livestock exhibit little nutritional wisdom and will select palatable mixtures in preference to mixtures designed to meet their requirements. Palatability and appetite stimulators are often used to achieve a more uniform herd-wide consumption. It is best to formulate free-choice mixtures on the basis of analyses or other available data. However, when no information on mineral status is known, a free-choice complete mineral supplement is warranted. A 'complete' mineral mixture usually includes salt, a low fluoride P source, Ca, Co, Cu, I, Mn and Zn. Selenium, Mg, K, S, Fe or additional elements can be incorporated into a mineral supplement as new information suggests a need. The detriment to ruminant production caused by providing Ca, Se and Cu in excess can be greater than any benefit derived by providing a mineral supplement. In regions where high forage Mo predominates, three to five times the Cu content in mineral mixtures is needed to counteract Mo toxicity. Supplemental minerals are most critical during the wet season, when cattle are gaining weight rapidly and energy and protein supplies are adequate. Economic return on mineral supplementation is high. (author)

  9. Reduced fine-scale spatial genetic structure in grazed populations of Dianthus carthusianorum.

    Rico, Y; Wagner, H H

    2016-11-01

    Strong spatial genetic structure in plant populations can increase homozygosity, reducing genetic diversity and adaptive potential. The strength of spatial genetic structure largely depends on rates of seed dispersal and pollen flow. Seeds without dispersal adaptations are likely to be dispersed over short distances within the vicinity of the mother plant, resulting in spatial clustering of related genotypes (fine-scale spatial genetic structure, hereafter spatial genetic structure (SGS)). However, primary seed dispersal by zoochory can promote effective dispersal, increasing the mixing of seeds and influencing SGS within plant populations. In this study, we investigated the effects of seed dispersal by rotational sheep grazing on the strength of SGS and genetic diversity using 11 nuclear microsatellites for 49 populations of the calcareous grassland forb Dianthus carthusianorum. Populations connected by rotational sheep grazing showed significantly weaker SGS and higher genetic diversity than populations in ungrazed grasslands. Independent of grazing treatment, small populations showed significantly stronger SGS and lower genetic diversity than larger populations, likely due to genetic drift. A lack of significant differences in the strength of SGS and genetic diversity between populations that were recently colonized and pre-existing populations suggested that populations colonized after the reintroduction of rotational sheep grazing were likely founded by colonists from diverse source populations. We conclude that dispersal by rotational sheep grazing has the potential to considerably reduce SGS within D. carthusianorum populations. Our study highlights the effectiveness of landscape management by rotational sheep grazing to importantly reduce genetic structure at local scales within restored plant populations.

  10. Soil physical attributes in forms of sowing the annual winter pasture and intervals between grazing

    Milton da Veiga

    Full Text Available The sowing of winter pastures in areas used for summer grain production and their management under direct cattle grazing can cause changes in soil physical attributes, whose intensity depends on the degree of soil mobilization, grazing interval, stocking rate and weather. To study these aspects it was conducted over four years an experiment in a randomized block with split plots design and four replications. In the main plots were applied two forms of sowing the annual winter pasture (direct seeding and seeding + harrowing and, in the subplots, four intervals between grazing (7, 14 and 28 days and ungrazed. Undisturbed soil cores were sampled at the end of each grazing cycle, in the 0-0.05 m layer to determine the saturated hydraulic conductivity and aggregate stability and in the layers of 0-0.05, 0.05-0.10, 0.10-0.15 and 0.15-0.20 m depth to determine bulk density and classes of soil pores. The direct seeding of annual winter pasture increases hydraulic conductivity and reduces soil bulk density in relation to seeding + harrowing while dairy cows trampling increases soil density and reduces macroporosity in the most superficial soil layer. The variation in climatic conditions among grazing cycles affects the soil physical attributes more markedly than forms of sowing and intervals between grazing of the annual winter pasture.

  11. The grazing capacity of sweetveld: 2. A model to estimate grazing ...

    The relations between grazing capacity and three independent variables were investigated in the False Thornveld of the Eastern Cape. The variables were veld condition, rainfall and density of woody species. These relations were used to develop a preliminary model to assess grazing capacity in the veld type. Despite its ...

  12. Mingled Mortality: the Interplay Between Protist Grazing and Viral Lysis on Emiliania huxleyi Cell Fate

    Harvey, E.; Bidle, K. D.; Johnson, M. D.

    2016-02-01

    The coccolithophore, Emiliania huxleyi plays a prominent role in global carbon cycling, as their calcite coccoliths account for a third of all oceanic calcite production. Mortality due to grazing by microzooplankton is the largest contributor to phytoplankton loss in the marine environment. However, viral infection of E. huxleyi is now thought to be as important as grazing pressure in contributing to its mortality. To understand the influence of viral infection on grazing dynamics, we examined the response of the dinoflagellate predator, Oxyrrhis marina to E. huxleyi infected with four different strains of the E. huxleyi virus (EhV). Grazing rate was significantly slower on E. huxleyi cultures that had been infected for 48 h compared to an uninfected control and this reduction in grazing rate was dependent on the strain identity of infecting EhVs. Additional experimentation indicated that grazing was the primary source of E. huxleyi loss ( 78-98%) during the first 24 h of exposure to both predator and virus. However, as viral infection progressed into the late lytic phase (48 h hour post infection), the relative contribution of grazing to total E. huxleyi mortality decreased ( 5-60%). These results suggest that mortality is partitioned along a gradient between predator-based consumption and virus-induced cell lysis, dependent on the timing of infection. Deciphering the relative importance and interactive nature of these alga-predator-viral interactions will help to elucidate the mechanisms that drive bulk measurements of phytoplankton loss, a necessary understanding to interpret and predict phytoplankton population dynamics and associated biogeochemical cycling.

  13. Strategic grazing management towards sustainable intensification at tropical pasture-based dairy systems.

    Congio, Guilhermo F S; Batalha, Camila D A; Chiavegato, Marília B; Berndt, Alexandre; Oliveira, Patrícia P A; Frighetto, Rosa T S; Maxwell, Thomas M R; Gregorini, Pablo; Da Silva, Sila C

    2018-05-01

    Agricultural systems are responsible for environmental impacts that can be mitigated through the adoption of more sustainable principles. Our objective was to investigate the influence of two pre-grazing targets (95% and maximum canopy light interception during pasture regrowth; LI 95% and LI Max , respectively) on sward structure and herbage nutritive value of elephant grass cv. Cameroon, and dry matter intake (DMI), milk yield, stocking rate, enteric methane (CH 4 ) emissions by Holstein × Jersey dairy cows. We hypothesized that grazing strategies modifying the sward structure of elephant grass (Pennisetum purpureum Schum.) improves nutritive value of herbage, increasing DMI and reducing intensity of enteric CH 4 emissions, providing environmental and productivity benefits to tropical pasture-based dairy systems. Results indicated that pre-sward surface height was greater for LI Max (≈135 cm) than LI 95% (≈100 cm) and can be used as a reliable field guide for monitoring sward structure. Grazing management based on LI 95% criteria improved herbage nutritive value and grazing efficiency, allowing greater DMI, milk yield and stocking rate by dairy cows. Daily enteric CH 4 emission was not affected; however, cows grazing elephant grass at LI 95% were more efficient and emitted 21% less CH 4 /kg of milk yield and 18% less CH 4 /kg of DMI. The 51% increase in milk yield per hectare overcame the 29% increase in enteric CH 4 emissions per hectare in LI 95% grazing management. Thereby the same resource allocation resulted in a 16% mitigation of the main greenhouse gas from pasture-based dairy systems. Overall, strategic grazing management is an environmental friendly practice that improves use efficiency of allocated resources through optimization of processes evolving plant, ruminant and their interface, and enhances milk production efficiency of tropical pasture-based systems. Copyright © 2018 Elsevier B.V. All rights reserved.

  14. Emergy analysis of cropping-grazing system in Inner Mongolia Autonomous Region, China

    Zhang, L.X.; Yang, Z.F.; Chen, G.Q.

    2007-01-01

    An ecological energetic evaluation is presented in this paper as a complement to economic account for the cropping-grazing system in the Inner Mongolia Autonomous Region in China in the year 2000. Based on Odum's well-known concept of emergy in terms of embodied solar energy as a unified measure for environmental resources, human or animal labors and industrial products, a systems diagram is developed for the crop and livestock productions with arms and sub-arms for free renewable natural resource input, purchased economic investment, yields of and interactive fluxes between the cropping and grazing sub-industries. In addition to conventional systems indices of the emergy yield ratio (EYR), emergy investment ratio (EIR), environmental load ratio (ELR) and environmental sustainability index (ESI) introduced for congregated systems ecological assessment with essential implication for sustainability, new indicators of soil emergy cost (SEC), self-support intensity (SSI) and self-support orientation (SSO) are defined to characterize the desertification and internal recycling associated with the special agricultural system. Extensive emergy accounting is made for the cropping-grazing system as a whole as well as for the cropping and grazing subsystems. The overall cropping-grazing system is shown with outstanding production competence compared with agricultural systems in some other provinces and the national average in China, though confronted with severe desertification associated with soil loss. The production of crops has higher emergy density and yield rate per unit area as well as higher rate of soil loss than grazing system. The soil emergy cost defined as the soil loss emergy divided by the yield emergy is estimated to be of the same value for both of the subsystems, but the grazing activity is with less extraction intensity, leaving rangeland to rest and rehabilitate. Suggestions with regard to the local sustainability and national ecological security in

  15. Dissolution of coccolithophorid calcite by microzooplankton and copepod grazing

    Antia, A. N.; Suffrian, K.; Holste, L.; Müller, M. N.; Nejstgaard, J. C.; Simonelli, P.; Carotenuto, Y.; Putzeys, S.

    2008-01-01

    Independent of the ongoing acidification of surface seawater, the majority of the calcium carbonate produced in the pelagial is dissolved by natural processes above the lysocline. We investigate to what extent grazing and passage of coccolithophorids through the guts of copepods and the food vacuoles of microzooplankton contribute to calcite dissolution. In laboratory experiments where the coccolithophorid Emiliania huxleyi was fed to the rotifer Brachionus plicatilis, the heterotrophic flagellate Oxyrrhis marina and the copepod Acartia tonsa, calcite dissolution rates of 45-55%, 37-53% and 5-22% of ingested calcite were found. We ascribe higher loss rates in microzooplankton food vacuoles as compared to copepod guts to the strongly acidic digestion and the individual packaging of algal cells. In further experiments, specific rates of calcification and calcite dissolution were also measured in natural populations during the PeECE III mesocosm study under differing ambient pCO2 concentrations. Microzooplankton grazing accounted for between 27 and 70% of the dynamic calcite stock being lost per day, with no measurable effect of CO2 treatment. These measured calcite dissolution rates indicate that dissolution of calcite in the guts of microzooplankton and copepods can account for the calcite losses calculated for the global ocean using budget and model estimates.

  16. Towards evenly distributed grazing patterns: including social context in sheep management strategies

    Agustina di Virgilio

    2016-06-01

    flocks by classes are common practices to increase flock productivity, we are proposing an alternative that employs behavioural interactions in heterogeneous flocks to generate more evenly distributed grazing patterns. This practice can be combined with other practices such as rotational grazing and guardian dogs (to decrease mortality levels that may be generated by sheep grazing on more risky habitats. This does not imply any modifications of livestock stocking rates and densities or any additional investments for labour and materials. Considering livestock behaviour is critical for the design of sustainable management practices that balance landscape conservation and livestock productivity.

  17. Towards evenly distributed grazing patterns: including social context in sheep management strategies.

    di Virgilio, Agustina; Morales, Juan Manuel

    2016-01-01

    are common practices to increase flock productivity, we are proposing an alternative that employs behavioural interactions in heterogeneous flocks to generate more evenly distributed grazing patterns. This practice can be combined with other practices such as rotational grazing and guardian dogs (to decrease mortality levels that may be generated by sheep grazing on more risky habitats). This does not imply any modifications of livestock stocking rates and densities or any additional investments for labour and materials. Considering livestock behaviour is critical for the design of sustainable management practices that balance landscape conservation and livestock productivity.

  18. Salt as a mitigation option for decreasing nitrogen leaching losses from grazed pastures.

    Ledgard, Stewart F; Welten, Brendon; Betteridge, Keith

    2015-12-01

    The main source of nitrogen (N) leaching from grazed pastures is animal urine with a high N deposition rate (i.e. per urine patch), particularly between late summer and early winter. Salt is a potential mitigation option as a diuretic to induce greater drinking-water intake, increase urination frequency, decrease urine N concentration and urine N deposition rate, and thereby potentially decrease N leaching. This hypothesis was tested in three phases: a cattle metabolism stall study to examine effects of salt supplementation rate on water consumption, urination frequency and urine N concentration; a grazing trial to assess effects of salt (150 g per heifer per day) on urination frequency; and a lysimeter study on effects of urine N rate on N leaching. Salt supplementation increased cattle water intake. Urination frequency increased by up to 69%, with a similar decrease in urine N deposition rate and no change in individual urination volume. Under field grazing, sensors showed increased urination frequency by 17%. Lysimeter studies showed a proportionally greater decrease in N leaching with decreased urine N rate. Modelling revealed that this could decrease per-hectare N leaching by 10-22%. Salt supplementation increases cattle water intake and urination frequency, resulting in a lower urine N deposition rate and proportionally greater decrease in urine N leaching. Strategic salt supplementation in autumn/early winter with feed is a practical mitigation option to decrease N leaching in grazed pastures. © 2015 Society of Chemical Industry.

  19. The role of grazing in nutrient-rich areas of the open sea

    Frost, B.W.

    1991-01-01

    No single factor accounts fully for the persistently low phytoplankton stocks in the nutrient-rich areas of the open sea. However, grazing plays the necessary role of consuming phytoplankton produced in excess of losses due to physical processes and sinking. Without grazing, even if specific growth rate of the phytoplankton is less than optimal for the prevailing light and temperature conditions, as might be so under limitation by a trace nutrient such as Fe, the phytoplankton stock would still accumulate with attendant depletion of nutrients. Observations during spring and summer in the open subarctic Pacific argue against limitation of phytoplankton growth to the point where phytoplankton stock could not increase in the absence of grazing. An ecosystem process model of the phytoplankton-grazer interaction suggests that two processes - grazing control of phytoplankton stock and preferential utilization of NH 4 by the phytoplankton - are sufficient to explain the continuously low phytoplankton stock and high concentrations of macronutrients. However, the grazing control may be exerted on a phytoplankton assemblage structured by Fe limitation. In particular, the intrinsic growth rates of potentially fast-growing diatoms seem to be depressed in the open subarctic Pacific. These conditions probably apply to two other nutrient-rich areas of the open sea, the Pacific equatorial upwelling region and the subantarctic circumpolar ocean, although in the latter region light limitation of phytoplankton growth may be more severe and silica limitation may influence the specific composition of the phytoplankton assemblage

  20. Phosphorus fertilizer and grazing management effects on phosphorus in runoff from dairy pastures.

    Dougherty, Warwick J; Nicholls, Paul J; Milham, Paul J; Havilah, Euie J; Lawrie, Roy A

    2008-01-01

    Fertilizer phosphorus (P) and grazing-related factors can influence runoff P concentrations from grazed pastures. To investigate these effects, we monitored the concentrations of P in surface runoff from grazed dairy pasture plots (50 x 25 m) treated with four fertilizer P rates (0, 20, 40, and 80 kg ha(-1) yr(-1)) for 3.5 yr at Camden, New South Wales. Total P concentrations in runoff were high (0.86-11.13 mg L(-1)) even from the control plot (average 1.94 mg L(-1)). Phosphorus fertilizer significantly (P pasture biomass (P dairy pastures should be the maintenance of soil P at or near the agronomic optimum by the use of appropriate rates of P fertilizer.

  1. Grazing-incident PIXE Analysis Technology

    Li Hongri; Wang Guangpu; Liang Kun; Yang Ru; Han Dejun

    2009-01-01

    In the article, the grazing incidence technology is first applied to the PIXE (proton induced X-ray emission) analysis. Three pieces of samples were investigated, including the contaminated aluminium substrate, the SIMOX (separated by oxygen implantation) SOI (Silicon on Insulator) sample and the silicon wafer implanted with Fe + . The results reveal that the grazing-incident proton can improve the sensitivity of PIXE in trace analysis, especially for samples contaminated on surface. With the penetration depth of the proton bean decreased, the ratio of the peak area to the detection limit raised observably and the sensitivity near the sample surface increased. (authors)

  2. Effects of nitrogen deposition and cattle grazing on productivity, invasion impact, and soil microbial processes in a serpentine grassland

    Pasari, J.; Hernandez, D.; Selmants, P. C.; Keck, D.

    2010-12-01

    In recent decades, human activities have vastly increased the amount of biologically available nitrogen (N) in the biosphere. The resulting increase in N availability has broadly affected ecosystems through increased productivity, changes in species composition, altered nutrient cycles, and increases in invasion by exotic plant species, especially in systems that were historically low in N. California serpentine grasslands are N-limited ecosystems historically dominated by native species including several threatened and endangered plants and animals. Cattle grazing has emerged as the primary tool for controlling the impact of nitrophilic exotic grasses whose increased abundance has paralleled the regional traffic-derived increase in atmospheric N deposition. We examined the interactive effects of cattle grazing and N deposition on plant community composition, productivity, invasion resistance, and microbial processes in the Bay Area's largest serpentine grassland to determine the efficacy of current management strategies as well as the biogeochemical consequences of exotic species invasion. In the first two years of the study, aboveground net primary productivity decreased in response to grazing and increased in response to nitrogen addition. However, contrary to our hypotheses the change in productivity was not due to an increase in exotic species cover as there was little overall effect of grazing or N addition on species composition. Microbial activity was more responsive to grazing and N. Potential net N mineralization rates increased with N addition, but were not affected by grazing. In contrast, soil respiration rates were inhibited by grazing, but were not affected by N addition; suggesting strong carbon-limitation of soil microbial activity, particularly under grazing. Site differences in soil depth and grazing intensity were often more important than treatment effects. We suspect that the unusually dry conditions in the first two growing seasons inhibited

  3. Modeling the grazing effect on dry grassland carbon cycling with modified Biome-BGC grazing model

    Luo, Geping; Han, Qifei; Li, Chaofan; Yang, Liao

    2014-05-01

    Identifying the factors that determine the carbon source/sink strength of ecosystems is important for reducing uncertainty in the global carbon cycle. Arid grassland ecosystems are a widely distributed biome type in Xinjiang, Northwest China, covering approximately one-fourth the country's land surface. These grasslands are the habitat for many endemic and rare plant and animal species and are also used as pastoral land for livestock. Using the modified Biome-BGC grazing model, we modeled carbon dynamics in Xinjiang for grasslands that varied in grazing intensity. In general, this regional simulation estimated that the grassland ecosystems in Xinjiang acted as a net carbon source, with a value of 0.38 Pg C over the period 1979-2007. There were significant effects of grazing on carbon dynamics. An over-compensatory effect in net primary productivity (NPP) and vegetation carbon (C) stock was observed when grazing intensity was lower than 0.40 head/ha. Grazing resulted in a net carbon source of 23.45 g C m-2 yr-1, which equaled 0.37 Pg in Xinjiang in the last 29 years. In general, grazing decreased vegetation C stock, while an increasing trend was observed with low grazing intensity. The soil C increased significantly (17%) with long-term grazing, while the soil C stock exhibited a steady trend without grazing. These findings have implications for grassland ecosystem management as it relates to carbon sequestration and climate change mitigation, e.g., removal of grazing should be considered in strategies that aim to increase terrestrial carbon sequestrations at local and regional scales. One of the greatest limitations in quantifying the effects of herbivores on carbon cycling is identifying the grazing systems and intensities within a given region. We hope our study emphasizes the need for large-scale assessments of how grazing impacts carbon cycling. Most terrestrial ecosystems in Xinjiang have been affected by disturbances to a greater or lesser extent in the past

  4. Effect of grazing frequency and intensity on Lolium perenne L ...

    ) system. Low frequency, low intensity grazing produced lower CDMD and herbage N levels than higher grazing frequencies and intensities. These differences were, however, generally small. Overall, levels of herbage digestibility (estimated ...

  5. Effect of day or night grazing on behaviour of swamp buffalo heifers

    Somparn, P.

    2007-03-01

    Full Text Available An experiment was conducted to examine the effect of day or night grazing on behaviour by swamp buffaloes. A grazing trial was conducted over 42 days in the late rainy season, during September to November2005 at Surin Livestock Research and Breeding Center, Surin province. The experimental period was divided into two 21-day periods. Twelve 2-year-old swamp buffalo heifers were allocated to four groups, eachcontaining three heifers, with the mean group weights being as similar as possible. Each group was allowed to graze either from 06:20 to 18:00 h (daytime treatment or from 18:20 to 06:00 h (nighttime treatment infour separate paddocks, each of 5 rai, using a cross-over design. When not at pasture the animals in each group were kept in the common corral with free access to fresh drinking water and mineral blocks. Individualanimal activity was recorded by visual observation at 1-min intervals during the period at pasture. Individual groups within each period were treated as replicates. Differences between group means weretested using MIXED procedure of SAS.The buffaloes on daytime treatment spent longer (P<0.05 grazing than those on nighttime treatment (423 vs 332 min. The number of meals differed (P<0.05 between treatments, but overall mean meal durationswere similar (73 min. Buffaloes allowed to graze during daylight had a tendency (P<0.10 toward a higher bite and step rates than those grazing during the night. With the reduction in grazing activity duringthe night on nighttime treatment, the animals ruminated for longer during the period at pasture (327 and 191 min, P<0.001. Live-weight change over periods of 20 days did not differ significantly. The difference intemporal behaviour patterns between treatments indicated that animals have to adapt foraging strategies appropriate for different situations in order to maintain feed intake and subsequently production.

  6. Rotational Grazing System for Beef Cows on Dwarf Elephantgrass Pasture for Two Years after Establishment

    M Mukhtar

    2011-01-01

    Full Text Available An intensive rotational grazing system for dwarf and late heading (DL elephant grass (Pennisetum purpureum Schumach pasture was examined in a summer period for two years following establishment. Four 0.05 of DL elephant grass pastures (20×25 m were established on May 2003. They were rotationally grazed for 1 week, followed by a 3-week rest period by three breeding or raising beef cattle for three and six cycles during the first and second years of establishment respectively. Before grazing, the plant height, leaf area index and the ratio of leaf blade to stem were at the highest, while tiller number increased and herbage mass tended to increase, except for the first grazing cycle both two years and for one paddock in the second year. Herbage consumption, the rate of herbage consumption and dry matter intake tended to decrease in three paddocks from the first to the third cycle in the first year, but increase as grazing occurred in the second year. Dry matter intake averaged 10.2-14.5 and 15.4–23.2 g DM/kg/live weight (LW/day over the four paddocks in the first and second year, respectively, and average daily gains were 0.09 and 0.35 kg/head/day in the first and second year respectively. The carrying capacities were estimated at 1,016 and 208 cow-days (CD/ha (annual total 1,224 CD/ha in the first year and 1,355 and 207 CD/ha (annual total 1,562 CD/ha in the second year. Thus, DL elephant grass pasture can expand the grazing period for beef cows for the following two-year establishment. (Animal Production 13(1:10-17 (2011 Key Words: dwarf elephant grass, herbage mass, plant characters, rotational grazing

  7. Microzooplankton grazing and phytoplankton growth in marine mesocosms with increased CO2 levels

    Y. Carotenuto

    2008-08-01

    Full Text Available Microzooplankton grazing and algae growth responses to increasing pCO2 levels (350, 700 and 1050 μatm were investigated in nitrate and phosphate fertilized mesocosms during the PeECE III experiment 2005. Grazing and growth rates were estimated by the dilution technique combined with taxon specific HPLC pigment analysis. Microzooplankton composition was determined by light microscopy. Despite a range of up to 3 times the present CO2 levels, there were no clear differences in any measured parameter between the different CO2 treatments. During days 3–9 of the experiment the algae community standing stock, measured as chlorophyll a (Chl-a, showed the highest instantaneous grow rates (k=0.37–0.99 d−1 and increased from ca. 2–3 to 6–12 μg l−1, in all mesocosms. Afterwards the phytoplankton standing stock decreased in all mesocosms until the end of the experiment. The microzooplankton standing stock, that was mainly constituted by dinoflagellates and ciliates, varied between 23 and 130 μg C l−1 (corresponding to 1.9 and 10.8 μmol C l−1, peaking on day 13–15, apparently responding to the phytoplankton development. Instantaneous Chl-a growth rates were generally higher than the grazing rates, indicating only a limited overall effect of microzooplankton grazing on the most dominant phytoplankton. Diatoms and prymnesiophytes were significantly grazed (12–43% of the standing stock d−1 only in the pre-bloom phase when they were in low numbers, and in the post-bloom phase when they were already affected by low nutrients and/or viral lysis. The cyanobacteria populations appeared more affected by microzooplankton grazing which generally removed 20–65% of the standing stock per day.

  8. Dairy cows increase ingestive mastication and reduce ruminative chewing when grazing chicory and plantain.

    Gregorini, P; Minnee, E M K; Griffiths, W; Lee, J M

    2013-01-01

    , and increased ingestive mastications 5 and 3 times for chicory and plantain, respectively. Cows allocated to chicory and plantain reduced bite rate and bites per grazing step linearly, and increased the number of mastications per bite of pasture dry matter intake while grazing pasture after having grazed chicory and plantain. These results indicate that cows grazing chicory and plantain masticate more during ingestion and reduce rumination time and chewing. They also suggest that chicory presents greater constraints to ingestion than does plantain. Thus, although chicory has been considered to have a greater nutritive value than plantain, its overall feeding value may be no greater than that of plantain. Copyright © 2013 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.

  9. Effects of previous grazing nutrition and management on feedlot performance of cattle.

    Drouillard, J S; Kuhl, G L

    1999-01-01

    Management strategies designed to improve grazing animal performance can influence feedlot performance and carcass traits both positively and negatively. In spite of the economic relevance of potential interactions between grazing and finishing performance, controlled experiments evaluating integrated production systems are limited in number. Effects of grazing treatments can result from, or be overshadowed by, changes in gut fill, thus making it difficult to assign precise costs to different phases of production. Published reports have considered the effects of stocking rate, duration of grazing, forage characteristics, supplementation, and growth-promoting implants on subsequent finishing performance. Improvements in cattle performance attributed to changes in stocking rate generally have been neutral to positive with respect to effects on finishing performance. Comparisons among forages have led to the suggestion that forage species may contribute to differences in gastrointestinal fill of grazing cattle, thereby influencing gain and efficiency during the subsequent finishing phase. Creep-feeding suckling calves generally has increased preweaning performance but has had relatively little influence on performance during the subsequent finishing phase. Grain supplementation of stocker cattle during the grazing period has improved grazing performance, but effects on subsequent feedlot performance have been inconsistent. Potential carryover effects from protein and mineral supplementation also have been inconclusive. Lack of congruence among studies is puzzling but may be the consequence of highly varied production systems, differences in experimental procedures, and changes in gut fill or mass of internal organs. Based on the studies reviewed, the expression or absence of compensatory growth during the finishing phase appears to be related to the nutritional quality of forages utilized in the grazing period, with higher quality forages tending to yield greater

  10. A review of experiments comparing systems of grazing management ...

    Experiments comparing different systems of grazing management on natural pastures in various parts of the world are reviewed. In experiments in which various rotational systems were tested against continuous grazing, fewer than half revealed pasture improvement relative to continuous grazing. In the majority of ...

  11. Performance and Grazing Pattern of West African Dwarf Sheep to ...

    Sixty (60) West African Dwarf sheep managed semi intensively and grazing on natural pastures were used in a study to determine the performance and grazing pattern to seasonal forage supply and quality. The animals were allowed to graze for about 6 hours daily for four months each in the dry and wet seasons, ...

  12. How Does “Hunger” Level Impact Grazing Behavior?

    Grazing behavior can be influenced through feeding and grazing management decisions. Research at our USDA-ARS lab showed that ruminal fill, or how ‘hungry’ the cow is, can affect grazing behavior. Cows that had less ruminal fill took a bigger bite that was shallow and wide, compared to a ‘full’ cow ...

  13. Longer rest periods for intensive rotational grazing limit diet quality ...

    Longer rest periods for intensive rotational grazing limit diet quality of sheep without enhancing environmental benefits. ... This experiment was established to compare three intensive rotational grazing strategies (fast rotation [FR], average 57-day rest; slow rotation [SR], average 114-day rest; and flexible grazing [FX], based ...

  14. Forage patch use by grazing herbivores in a South African grazing ecosystem

    Venter, J.A.; Nabe-Nielsen, J.; Prins, H.H.T.; Slotow, R.

    2014-01-01

    Understanding how different herbivores make forage patch use choices explains how they maintain an adequate nutritional status, which is important for effective conservation management of grazing ecosystems. Using telemetry data, we investigated nonruminant zebra (Equus burchelli) and ruminant red

  15. Grazing incidence polarized neutron scattering in reflection ...

    journal of. January 2012 physics pp. 1–58. Grazing incidence polarized ..... atomic distances, the neutron has an energy which is low compared to molecular binding ...... cores and that of the Co ions in the AF oxide coatings. ...... [32] C Leighton, M R Fitzsimmons, P Yashar, A Hoffmann, J Nogus, J Dura, C F Majkrzak and.

  16. Dietary selection by steers grazing kikuyu

    being grazeA for a period of 3,5 days in a four-week rotation, at ... Cattle improve the quality of their diet by actively seeking ... of stem in their diet. This would explain why the stem fraction mad~ no significant contribution to the equation predicting diet~ry selection. A:1unusual fact which emerged is that the animals selected.

  17. 25 CFR 700.722 - Grazing associations.

    2010-04-01

    ... recognition by the Commissioner are: (1) The members of the association must be grazing permittees and.... (d) The Commissioner may withdraw his recognition of the association whenever: (1) The majority of... constitution and bylaws. All of the association's livestock will be run under an association brand properly...

  18. Grazing management for Nordic organic dairy farming

    Kuusela, Eeva

    2005-01-01

    The aims of this study were to identify limiting factors and to develop adjusted grazing management for Nordic organic dairy farming conditions. The focus was to combine the aspects of plant, animal and organic production, as they are all involved in organic dairy pastures.

  19. Phosphorus supplementation of Karakul sheep grazing natural ...

    The phosphorus (P) status of adult Karakul ewes grazing natural pasture was determined by measuring the P content of blood, saliva, faecal, and bone samples. The ewes were divided into four groups of 20 ewes each, viz. ewes supplemented with P+ and P- which lambed during May and October. All lambs born were ...

  20. Grazing effects on ecosystem CO2 fluxes differ among temperate steppe types in Eurasia.

    Hou, Longyu; Liu, Yan; Du, Jiancai; Wang, Mingya; Wang, Hui; Mao, Peisheng

    2016-07-01

    Grassland ecosystems play a critical role in regulating CO2 fluxes into and out of the Earth's surface. Whereas previous studies have often addressed single fluxes of CO2 separately, few have addressed the relation among and controls of multiple CO2 sub-fluxes simultaneously. In this study, we examined the relation among and controls of individual CO2 fluxes (i.e., GEP, NEP, SR, ER, CR) in three contrasting temperate steppes of north China, as affected by livestock grazing. Our findings show that climatic controls of the seasonal patterns in CO2 fluxes were both individual flux- and steppe type-specific, with significant grazing impacts observed for canopy respiration only. In contrast, climatic controls of the annual patterns were only individual flux-specific, with minor grazing impacts on the individual fluxes. Grazing significantly reduced the mean annual soil respiration rate in the typical and desert steppes, but significantly enhanced both soil and canopy respiration in the meadow steppe. Our study suggests that a reassessment of the role of livestock grazing in regulating GHG exchanges is imperative in future studies.

  1. Carbon and nitrogen cycling in an integrated soybean-beef cattle production system under different grazing intensities

    Joice Mari Assmann

    2015-10-01

    Full Text Available Abstract:The objective of this work was to evaluate the effect of grazing intensity on the decomposition of cover crop pasture, dung, and soybean residues, as well as the C and N release rates from these residues in a long-term integrated soybean-beef cattle system under no-tillage. The experiment was initiated in 2001, with soybean cultivated in summer and black oat + Italian ryegrass in winter. The treatments consisted of four sward heights (10, 20, 30, and 40 cm, plus an ungrazed area, as the control. In 2009-2011, residues from pasture, dung, and soybean stems and leaves were placed in nylon-mesh litter bags and allowed to decompose for up to 258 days. With increasing grazing intensity, residual dry matter of the pasture decreased and that of dung increased. Pasture and dung lignin concentrations and C release rates were lower with moderate grazing intensity. C and N release rates from soybean residues are not affected by grazing intensity. The moderate grazing intensity produces higher quality residues, both for pasture and dung. Total C and N release is influenced by the greater residual dry matter produced when pastures were either lightly grazed or ungrazed.

  2. Contrasting Effects of Cattle Grazing Intensity on Upland-Nesting Duck Production at Nest and Field Scales in the Aspen Parkland, Canada

    Jeffrey M. Warren

    2008-12-01

    field was 33.9% (95% CI = 17.0-51.8%. Across the range of residual cover observed in this study, nests with above-average nest-site vegetation density had nesting success rates that exceeded the levels believed necessary to maintain duck populations. Our findings on complex and previously unreported relationships between grazing, nest density, and nesting success provide useful insights into the management and conservation of ground-nesting grassland birds.

  3. Grazing livestock are exposed to terrestrial cyanobacteria.

    McGorum, Bruce C; Pirie, R Scott; Glendinning, Laura; McLachlan, Gerry; Metcalf, James S; Banack, Sandra A; Cox, Paul A; Codd, Geoffrey A

    2015-02-25

    While toxins from aquatic cyanobacteria are a well-recognised cause of disease in birds and animals, exposure of grazing livestock to terrestrial cyanobacteria has not been described. This study identified terrestrial cyanobacteria, predominantly Phormidium spp., in the biofilm of plants from most livestock fields investigated. Lower numbers of other cyanobacteria, microalgae and fungi were present on many plants. Cyanobacterial 16S rDNA, predominantly from Phormidium spp., was detected in all samples tested, including 6 plant washings, 1 soil sample and ileal contents from 2 grazing horses. Further work was performed to test the hypothesis that ingestion of cyanotoxins contributes to the pathogenesis of some currently unexplained diseases of grazing horses, including equine grass sickness (EGS), equine motor neuron disease (EMND) and hepatopathy. Phormidium population density was significantly higher on EGS fields than on control fields. The cyanobacterial neurotoxic amino acid 2,4-diaminobutyric acid (DAB) was detected in plant washings from EGS fields, but worst case scenario estimations suggested the dose would be insufficient to cause disease. Neither DAB nor the cyanobacterial neurotoxins β-N-methylamino-L-alanine and N-(2-aminoethyl) glycine were detected in neural tissue from 6 EGS horses, 2 EMND horses and 7 control horses. Phormidium was present in low numbers on plants where horses had unexplained hepatopathy. This study did not yield evidence linking known cyanotoxins with disease in grazing horses. However, further study is warranted to identify and quantify toxins produced by cyanobacteria on livestock fields, and determine whether, under appropriate conditions, known or unknown cyanotoxins contribute to currently unexplained diseases in grazing livestock.

  4. 25 CFR 166.307 - Will the grazing capacity be increased if I graze adjacent trust or non-trust rangelands not...

    2010-04-01

    ... § 166.307 Will the grazing capacity be increased if I graze adjacent trust or non-trust rangelands not... trust or non-trust rangeland in common with the permitted land. Grazing capacity will be established... 25 Indians 1 2010-04-01 2010-04-01 false Will the grazing capacity be increased if I graze...

  5. Modeling dynamics of tundra plant communities on the Yamal Peninsula, Russia, in response to climate change and grazing pressure

    Yu, Q; Epstein, H E; Frost, G V; Walker, D A; Forbes, B C

    2011-01-01

    Understanding the responses of the arctic tundra biome to a changing climate requires knowledge of the complex interactions among the climate, soils and biological system. This study investigates the individual and interaction effects of climate change and reindeer grazing across a variety of climate zones and soil texture types on tundra vegetation community dynamics using an arctic vegetation model that incorporates the reindeer diet, where grazing is a function of both foliar nitrogen concentration and reindeer forage preference. We found that grazing is important, in addition to the latitudinal climate gradient, in controlling tundra plant community composition, explaining about 13% of the total variance in model simulations for all arctic tundra subzones. The decrease in biomass of lichen, deciduous shrub and graminoid plant functional types caused by grazing is potentially dampened by climate warming. Moss biomass had a nonlinear response to increased grazing intensity, and such responses were stronger when warming was present. Our results suggest that evergreen shrubs may benefit from increased grazing intensity due to their low palatability, yet a growth rate sensitivity analysis suggests that changes in nutrient uptake rates may result in different shrub responses to grazing pressure. Heavy grazing caused plant communities to shift from shrub tundra toward moss, graminoid-dominated tundra in subzones C and D when evergreen shrub growth rates were decreased in the model. The response of moss, lichen and forbs to warming varied across the different subzones. Initial vegetation responses to climate change during transient warming are different from the long term equilibrium responses due to shifts in the controlling mechanisms (nutrient limitation versus competition) within tundra plant communities.

  6. A study of short term grazing patterns on Coastcross 2 under ...

    In this study the disc meter was successfully used to measure pasture yield in situ and thus provide an objective basis to adjust animal numbers on treatments with variable stocking rates. Realistic estimates of pasture dry matter consumption and production were made on rotational grazing systems and animal selection ...

  7. Response of mountain meadows to grazing by recreational pack stock

    Cole, David N.; Van Wagtendonk, Jan W.; McClaran, Mitchel P.; Moore, Peggy E.; McDougald, Neil K.

    2004-01-01

    Effects of recreational pack stock grazing on mountain meadows in Yosemite National Park were assessed in a 5-year study. Yosemite is a designated wilderness, to be managed such that its natural conditions are preserved. Studies were conducted in 3 characteristic meadow types: shorthair sedge (Carex filifolia Nutt.), Brewer's reed grass (Calamagrostis breweri Thurber), and tufted hairgrass [Deschampsia cespitosa (L.) Beauv.]. Horses and mules grazed experimental plots at intensities of 15 to 69% utilization for 4 seasons. In all 3 meadows, grazing caused decreases in productivity. The mean reduction after 4 years of grazing was 18% in the shorthair sedge meadow, 17% in the Brewer's reed grass meadow, and 22% in the tufted hairgrass meadow. Grazing also caused shifts in basal groundcover (usually a reduction in vegetation cover and increase in bare soil cover), and changes in species composition. Productivity and vegetation cover decreased as percent utilization increased, while bare soil cover increased as utilization increased. Changes in species composition were less predictably related to differences in grazing intensity. Passive management of grazing is insufficient in wilderness areas that are regularly used by groups with recreational stock. Wilderness managers need to monitor meadow conditions and the grazing intensities that occur. Our study suggests that biomass and ground cover are more sensitive indicators of grazing impact than species composition. Managers must make decisions about maximum acceptable levels of grazing impact and then develop guidelines for maximum use levels, based on data such as ours that relates grazing intensity to meadow response.

  8. Effect of the Silica Content of Diatoms on Protozoan Grazing

    Shuwen Zhang

    2017-06-01

    Full Text Available This study examined the effect that silica content in diatom cells has on the behavior of protists. The diatoms Thalassiosira weissflogii and T. pseudonana were cultured in high or low light conditions to achieve low and high silica contents, respectively. These cells were then fed to a heterotrophic dinoflagellate Noctiluca scintillans and a ciliate Euplotes sp. in single and mixed diet experiments. Our results showed that in general, N. scintillans and Euplotes sp. both preferentially ingested the diatoms with a low silica content rather than those with a high silica content. However, Euplotes sp. seemed to be less influenced by the silica content than was N. scintillans. In the latter case, the clearance and ingestion rate of the low silica diatoms were significantly higher, both in the short (6-h and long (1-d duration grazing experiments. Our results also showed that N. scintillans required more time to digest the high silica-containing cells. As the high silica diatoms are harder to digest, this might explain why N. scintillans exhibits a strong preference for the low silica prey. Thus, the presence of high silica diatoms might limit the ability of the dinoflagellate to feed. Our findings suggest that the silica content of diatoms affects their palatability and digestibility and, consequently, the grazing activity and selectivity of protozoan grazers.

  9. The current status of grazing incidence optics

    Aschenbach, B.

    1983-01-01

    The developments in the area of grazing incidence optics with emphasis on telescopes for use in X-ray astronomy are reviewed. The performance of existing high-resolution telescopes is outlined and compared with those expected from future missions like ROSAT and AXAF. Starting from the basic principles of X-ray reflection and scattering, an attempt is made to highlight the current understanding of X-ray mirror physics using new theoretical ideas as well as experimental laboratory results. (author)

  10. Seasonality constraints to livestock grazing intensity.

    Fetzel, Tamara; Havlik, Petr; Herrero, Mario; Erb, Karl-Heinz

    2017-04-01

    Increasing food production is essential to meet the future food demand of a growing world population. In light of pressing sustainability challenges such as climate change and the importance of the global livestock system for food security as well as GHG emissions, finding ways to increasing food production sustainably and without increasing competition for food crops is essential. Yet, many unknowns relate to livestock grazing, in particular grazing intensity, an essential variable to assess the sustainability of livestock systems. Here, we explore ecological limits to grazing intensity (GI; i.e. the fraction of net primary production consumed by grazing animals) by analysing the role of seasonality in natural grasslands. We estimate seasonal limitations to GI by combining monthly net primary production data and a map of global livestock distribution with assumptions on the length of nonfavourable periods that can be bridged by livestock (e.g. by browsing dead standing biomass, storage systems or biomass conservation). This allows us to derive a seasonality-limited potential GI, which we compare with the GI prevailing in 2000. We find that GI in 2000 lies below its potential on 39% of the total global natural grasslands, which has a potential for increasing biomass extraction of up to 181 MtC/yr. In contrast, on 61% of the area GI exceeds the potential, made possible by management. Mobilizing this potential could increase milk production by 5%, meat production by 4% or contribute to free up to 2.8 Mio km² of grassland area at the global scale if the numerous socio-ecological constraints can be overcome. We discuss socio-ecological trade-offs, which may reduce the estimated potential considerably and require the establishment of sound monitoring systems and an improved understanding of livestock system's role in the Earth system. © 2017 John Wiley & Sons Ltd.

  11. Grazing livestock are exposed to terrestrial cyanobacteria

    McGorum , Bruce C; Pirie , R Scott; Glendinning , Laura; McLachlan , Gerry; Metcalf , James S; Banack , Sandra A; Cox , Paul A; Codd , Geoffrey A

    2015-01-01

    While toxins from aquatic cyanobacteria are a well-recognised cause of disease in birds and animals, exposure of grazing livestock to terrestrial cyanobacteria has not been described. This study identified terrestrial cyanobacteria, predominantly Phormidium spp., in the biofilm of plants from most livestock fields investigated. Lower numbers of other cyanobacteria, microalgae and fungi were present on many plants. Cyanobacterial 16S rDNA, predominantly from Phormidium spp., was detected in al...

  12. Evaluation of dairy cows intake behavior grazing Brachiaria brizantha fed different levels of concentrate at diet

    Fabrício Bacelar Lima Mendes

    2013-12-01

    Full Text Available The objective with this research was to evaluate the dairy cows intake behavior grazing Brachiaria brizantha submitted to different levels of concentrate supplementation in the diet. Used 16 lactating cows ½ Holstein x ½ Zebu, with an average of 80 ±10.14 days of lactation and body weight of 454.7 ± 54.51 kg. The animals were distributed in four treatments, using a 4x4 Latin square. The evaluation of behavior was done every ten minutes, during 24 hours on the 16th day of period. We used analysis of variance and regression probability of 0.05. The time spent grazing, ruminating and other activities, the numbers of grazing, ruminating, of bites per day and chews per cake, the grazing times, total power and total chewing, bit rate, time to swallow; time per bolus ruminated; chewing speed and power efficiency for NDF were not altered by increased levels of concentrate. The time of trough, the trough period, the bit size, the chews time for bolus, feeding efficiency for DM, NFC, and TDN and rumination efficiency linearly increased. Periods of rumination, deglutition bits, number of rumination chews per day, decreased linearly with increasing levels of concentrate. Significant quadratic effect of concentrate level on the number of periods in other activities and over time on other activities. Supplementation with 33.8% concentrate in the diet of cows grazing not promote changes in the activity of grazing, ruminating and other activities, but increases the time of trough. The increase in concentrate diet improves the efficiencies of feeding and rumination

  13. The Effect of Different Type of Herbivores, Grazing Types and Grazing Intensities on Alpine Basiphillous Vegetation of the Romanian Carpathians

    Ballová, Zuzana; Pekárik, Ladislav; Šibík, Jozef

    2017-04-01

    The major purpose of the present study was to test the hypothesis that there are significant differences in vegetation structure, plant species composition, and soil chemical properties in relation to type of grazing animals, various levels of grazing intensity and grazing type, and if potential differences alter with ecosystem productivity (increase in more productive ecosystems). The study was conducted in three mountain ranges of the Romanian Carpathians with a predominance of alkaline substrates (the Bucegi Mts, the Little Retezat Mts and the Ceahlău Massif). Statistical analyses were performed in R statistical software environment. The effects of grazing animals (cattle, horses and sheep), grazing types (fence, regular, irregular) and grazing intensity (low, medium, high) on the community structure were tested using ordination methods. In the case of soil properties, General Linear Mixed Model was applied. Special statistical approach eliminated the differences between the examined mountains and sites. Type of grazing animal does not significantly influence species cover but it is related to specific species occurrence. According to our results, grazing horses had similar effects as cattle compared to sheep. Grazing in restricted areas (surrounded by fence) and regular unrestricted grazing were more similar if compared to irregular grazing. When comparing the intensity of grazing, high and medium intensity were more similar to each other than to the low intensity grazing. Cattle grazed sites had significantly higher lichens cover, while the sheep patches were covered with increased overall herb layer (forbs, graminoids and low shrubs together). Medium grazing intensity decreased the lichens cover, cover of overall herb layer, and total vegetation cover compared to high and low grazing intensity. Grazing type had important impact on the lichens cover and cover of overall herb layer. The lichens cover appeared to decrease while the cover of overall herb layer

  14. Grazing disturbance increases transient but decreases persistent soil seed bank.

    Ma, Miaojun; Walck, Jeffrey L; Ma, Zhen; Wang, Lipei; Du, Guozhen

    2018-04-30

    Very few studies have examined whether the impacts of grazing disturbance on soil seed banks occur directly or indirectly through aboveground vegetation and soil properties. The potential role of the seed bank in alpine wetland restoration is also unknown. We used SEM (structural equation modeling) to explore the direct effect of grazing disturbance on the seed bank and the indirect effect through aboveground vegetation and soil properties. We also studied the role of the seed bank on the restoration potential in wetlands with various grazing intensities: low (fenced, winter grazed only), medium (seasonally grazed), and high (whole-year grazed). For the seed bank, species richness and density per plot showed no difference among grazing intensities for each depth (0-5, 5-10, 10-15 cm) and for the whole depth (0-15 cm) in spring and summer. There was no direct effect of grazing disturbance on seed bank richness and density both in spring and summer, and also no indirect effect on the seed bank through its direct effect on vegetation richness and abundance. Grazing disturbance indirectly increased spring seed bank density but decreased summer seed bank density through its direct effect (negative correlation) on soil moisture and total nitrogen and its indirect effect on vegetation abundance. Species composition of the vegetation changed with grazing regime, but that of the seed bank did not. An increased trend of similarity between the seed bank and aboveground vegetation with increased grazing disturbance was found in the shallow depth and in the whole depth only in spring. Although there was almost no change in seed bank size with grazing intensities, grazing disturbance increased the quantity of transient seeds but decreased persistent seeds. Persistent seeds stored in the soil could play a crucial role in vegetation regeneration and in restoration of degraded wetland ecosystems. The seed bank should be an integral part of alpine wetland restoration programs.

  15. Effect of Grazing Intensity on Some Soil Chemical Characteristics in Gardaneh Zanburi Rangeland of Arsanjan

    zeinab khademolhosseini

    2016-02-01

    percentage at 1.72 numbers. PH was determined with measuring the PH of saturated soil by PH meter machine. Measurement of soil EC was performed by the electrical conductivity meter. Data analysis was conducted by SPSS software. Comparing of mean values for each factor and between areas with different grazing intensity was done by the Tukey test. Results and Discussion: Two-way analysis of variance and Tukey test showed no significant differences in term of N, OM and PH between critical and reference areas. But the amount of N and OM in the key area is lower than that of the reference and critical areas. While value of PH is higher than the other regions. Also values of P and K decreased within creasing grazing intensity but the EC factor increased. Conclusion: Since vegetation removal and its exclusion from the ecosystem followed by considerable effect on the cycle of nutrient elements and their absorbability, it seems that in the studied ranges, the P and K elements decrease through the use and leaving of vegetation in the area. The results of N and OM showed that moderate grazing causes further decomposition of plant residues and organic nitrogen mineralization but there was no difference between the two treatments of heavy grazing and enclosure areas. In heavy grazing intensity, the amount of OM and N increases by several mechanisms. First, with soil bulk density and increased soil compaction, the oxygen supply and degradation rate decreases. In the second mechanism, intensive grazing changes the vegetation composition and root to shoot ratio. In the third mechanism, animal urine and feces can speed up the nitrogen cycle in grassland ecosystems. It seems that the simultaneous effect of the above factors studied in the related range causes no significant difference between heavy grazing and enclosure areas in the percentage of total nitrogen. EC is the lowest in the enclosure area. This is due to the absence of livestock and therefore no stepping on the soil and also more

  16. Grazing patterns on signalgrass pasture according to location of cattle feces

    Manoel Eduardo Rozalino Santos

    2012-04-01

    Full Text Available This study was conducted to evaluate the defoliation patterns on B. decumbens cv. Basilisk (signalgrass tiller as a function of influence of feces deposited naturally by cattle. The signalgrass was managed with an average height of 25 cm, under continuous stocking and variable stocking rate. Interval and intensity of defoliation, grazing efficiency and forage loss were evaluated in two sites on pasture - one close and the other distant from feces. The completely randomized block design with three replications was adopted. The defoliation rate of the pasture site close to feces was 40% lower than at that distant from feces. This response pattern was similar to defoliation intensity of leaf blade. The leaf blade of the tiller close to feces also achieved lower de foliation (1.64 than that in the tiller distant from feces (3.97. The relative number of grazed leaf per tiller in the tillers distant from feces was approximately 185% higher than those close to feces. The grazing efficiency was lower in the local close to feces compared with that distant, unlike forage loss. The natural deposition of feces by cattle modifies the grazing and use patterns of B. decumbens under continuous stocking.

  17. Carbon budgets for an irrigated intensively grazed dairy pasture and an unirrigated winter-grazed pasture

    Hunt, John E.; Laubach, Johannes; Barthel, Matti; Fraser, Anitra; Phillips, Rebecca L.

    2016-05-01

    Intensification of pastoral agriculture is occurring rapidly across New Zealand, including increasing use of irrigation and fertiliser application in some regions. While this enables greater gross primary production (GPP) and livestock grazing intensity, the consequences for the net ecosystem carbon budget (NECB) of the pastures are poorly known. Here, we determined the NECB over one year for an irrigated, fertilised and rotationally grazed dairy pasture and a neighbouring unirrigated, unfertilised, winter-grazed pasture. Primary terms in the NECB calculation were: net ecosystem production (NEP), biomass carbon removed by grazing cows and carbon (C) input from their excreta. Annual NEP was measured using the eddy-covariance method. Carbon removal was estimated with plate-meter measurements calibrated against biomass collections, pre- and post-grazing. Excreta deposition was calculated from animal feed intake. The intensively managed pasture gained C (NECB = 103 ± 42 g C m-2 yr-1) but would have been subject to a non-significant C loss if cattle excreta had not been returned to the pasture. The unirrigated pasture was C-neutral (NECB = -13 ± 23 g C m-2 yr-1). While annual GPP of the former was almost twice that of the latter (2679 vs. 1372 g C m-2 yr-1), ecosystem respiration differed by only 68 % between the two pastures (2271 vs. 1352 g C m-2 yr-1). The ratio of GPP to the total annual water input of the irrigated pasture was 37 % greater than that of the unirrigated pasture, i.e. the former used the water input more efficiently than the latter to produce biomass. The NECB results agree qualitatively with those from many other eddy-covariance studies of grazed grasslands, but they seem to be at odds with long-term carbon-stock studies of other New Zealand pastures.

  18. Ingestion rates and grazing impact of the brackwater mussel ...

    Bivalves feed on a combination of phytoplankton and zooplankton and have the potential to impact considerably the planktonic biomass, especially when they occur in high densities, such as in oyster and mussel beds. The brackwater mussel Brachidontes virgiliae is numerically dominant during wet phases within Africa's ...

  19. Developmental instability and fitness in Periploca laevigata experiencing grazing disturbance

    Alados, C.L.; Giner, M.L.; Dehesa, L.; Escos, J.; Barroso, F.; Emlen, J.M.; Freeman, D.C.

    2002-01-01

    We investigated the sensitivity of developmental instability measurements (leaf fluctuating asymmetry, floral radial asymmetry, and shoot translational asymmetry) to a long‐standing natural stress (grazing) in a palatable tannin‐producing shrub (Periploca laevigata Aiton). We also assessed the relationship between these measures of developmental instability and fitness components (growth and floral production). Developmental instability, measured by translational asymmetry, was the most accurate estimator of a plant’s condition and, consequently, environmental stress. Plants with less translational asymmetry grew more and produced more flowers. Plants from the medium‐grazed population were developmentally more stable, as estimated by translational and floral asymmetry, than either more heavily or more lightly grazed populations. Leaf fluctuating asymmetry was positively correlated with tannin concentration. The pattern of internode growth also responded to grazing impact. Plants under medium to heavy grazing pressure accelerated early growth and consequently escaped herbivory later in the season, i.e., at the beginning of the spring, when grazing activity was concentrated in herbaceous plants. Periploca laevigata accelerated growth and finished growing sooner than in the other grazing treatment. Thus, its annual growth was more mature and less palatable later in the season when grazers typically concentrate on shrubs. The reduction of developmental instability under medium grazing is interpreted as a direct effect of grazing and not as the release from competition.

  20. Ecological Effects of Grazing in the Northern Tianshan Mountains

    Xiaotao Huang

    2017-11-01

    Full Text Available Identifying the effects of grazing is critical for the conservation, protection and sustainable use of arid grassland ecosystems. However, research regarding the ecological effects of grazing along mountainous elevation gradients is limited in arid areas, particularly at the regional scale. Using the Biome-BGC grazing model, we explored the effects of grazing on grassland net primary productivity (NPP, evapotranspiration (ET and water use efficiency (WUE from 1979 to 2012 along an elevation gradient in the northern Tianshan Mountains. The NPP, ET and WUE values were generally lower under the grazing scenario than under the ungrazed scenario; the differences between the grazing and ungrazed scenarios showed increasing trends over time; and distinct spatial heterogeneity in these differences was observed. Distinct decreases in NPP and WUE under the grazing scenario mainly occurred in regions with high livestock consumption. The decrease in ET was greater in mountainous areas with high grazing intensity due to decreased transpiration and increased surface runoff. This study contributes to a better understanding of the ecological effects of grazing along an elevation gradient in the northern Tianshan Mountains and provides data to support the scientific management of grassland ecosystems.

  1. Livestock grazing and the desert tortoise in the Mojave Desert

    Oldemeyer, John L.

    1994-01-01

    A large part of the Mojave Desert is not in pristine condition, and some current conditions can be related to past grazing-management practices. No information could be found on densities of the desert tortoise (Gopherus agassizii) or on vegetative conditions of areas that had not been grazed to allow managers a comparison of range conditions with data on tortoises. Experimental information to assess the effect of livestock grazing on tortoises is lacking, and researchers have not yet examined whether the forage that remains after grazing is sufficient to meet the nutritional needs of desert tortoises.

  2. Summertime grazing impact of the dominant macrozooplankton off the Western Antarctic Peninsula

    Bernard, Kim S.; Steinberg, Deborah K.; Schofield, Oscar M. E.

    2012-04-01

    The Western Antarctic Peninsula (WAP) is a region of rapid climate change that is altering plankton community structure. To investigate how these changes may impact carbon and energy transfer in the pelagic food web, grazing rates of the five dominant macrozooplankton species (euphausiids Euphausia superba, Euphausia crystallorophias, and Thysanöessa macrura; the pteropod Limacina helicina, and the salp Salpa thompsoni) in the WAP were measured in January 2009 and 2010 as part of the Palmer Antarctica Long-Term Ecological Research (LTER) study. Measurements were made across the coastal-shelf-offshore and north-south gradients of the LTER survey grid. Highest grazing rates occurred offshore in both years, and in the south during 2009 and north during 2010, all associated with the presence of large localized salp blooms. During both years, E. superba was the major grazer at the coast, while S. thompsoni dominated grazing offshore. L. helicina was an important grazer throughout the study area during both years, but especially so over the shelf during 2009. During 2009, there was little difference in the relative importance of the macrozooplankton grazers along the north-south gradient. The presence of a salp bloom in the north during 2010, though, resulted in a distinct shift in the relative importance of major grazers from the euphausiids and L. helicina in the south to salps in the north. Grazing impact was low in coastal waters (≤0.3% of phytoplankton standing stock and ≤0.6% of primary productivity). In contrast, in the offshore waters, where salp blooms were observed, grazing impacts of up to 30% of standing stock and 169% of primary productivity were recorded. If S. thompsoni and L. helicina continue to expand their ranges and increase in abundance, the associated shift in the food web dynamics of the WAP will alter the regional flow of carbon through the WAP food webs and the export of carbon to depth.

  3. Modelling carbon and water exchange of a grazed pasture in New Zealand constrained by eddy covariance measurements.

    Kirschbaum, Miko U F; Rutledge, Susanna; Kuijper, Isoude A; Mudge, Paul L; Puche, Nicolas; Wall, Aaron M; Roach, Chris G; Schipper, Louis A; Campbell, David I

    2015-04-15

    We used two years of eddy covariance (EC) measurements collected over an intensively grazed dairy pasture to better understand the key drivers of changes in soil organic carbon stocks. Analysing grazing systems with EC measurements poses significant challenges as the respiration from grazing animals can result in large short-term CO2 fluxes. As paddocks are grazed only periodically, EC observations derive from a mosaic of paddocks with very different exchange rates. This violates the assumptions implicit in the use of EC methodology. To test whether these challenges could be overcome, and to develop a tool for wider scenario testing, we compared EC measurements with simulation runs with the detailed ecosystem model CenW 4.1. Simulations were run separately for 26 paddocks around the EC tower and coupled to a footprint analysis to estimate net fluxes at the EC tower. Overall, we obtained good agreement between modelled and measured fluxes, especially for the comparison of evapotranspiration rates, with model efficiency of 0.96 for weekly averaged values of the validation data. For net ecosystem productivity (NEP) comparisons, observations were omitted when cattle grazed the paddocks immediately around the tower. With those points omitted, model efficiencies for weekly averaged values of the validation data were 0.78, 0.67 and 0.54 for daytime, night-time and 24-hour NEP, respectively. While not included for model parameterisation, simulated gross primary production also agreed closely with values inferred from eddy covariance measurements (model efficiency of 0.84 for weekly averages). The study confirmed that CenW simulations could adequately model carbon and water exchange in grazed pastures. It highlighted the critical role of animal respiration for net CO2 fluxes, and showed that EC studies of grazed pastures need to consider the best approach of accounting for this important flux to avoid unbalanced accounting. Copyright © 2015. Published by Elsevier B.V.

  4. Methane Emission By Grazing Livestock. A Synopsis Of 1000 Direct Measurements

    Lassey, K.R. [National Institute of Water and Atmospheric Research (NIWA), Wellington (New Zealand); Ulyatt, M.J. [New Zealand Pastoral Agriculture Research Institute (AgResearch), Palmerston North (New Zealand)

    2000-07-01

    In a series of field campaigns since 1995, a team of atmospheric and ruminant-nutrition scientists have measured methane emissions directly from individual ruminant livestock freely grazing representative New Zealand pastures. The technique collects integrated 'breath' samples during grazing, using an implanted SF6 source as a conservative calibrated tracer, an approach pioneered by Johnson et al. [1994]. Most of these measurements have been on grazing sheep (942 animal-days to Aug 1999), others on grazing dairy cows (283), with some measurements also on sheep under controlled feeding conditions (305) [eg, Lassey et al., 1997; Ulyatt et al., 1999]. The aim is to characterise the variability of emission rates, including their dependence on pasture quality and physiological condition. The research goal is two-fold: (1) to provide a better scientific basis for assessing the national emissions inventory; and (2) to investigate options for mitigating livestock emissions. Here, we discuss the research strategy and overview the principal research findings. We note in particular, that as a source of enterically fermented methane, sheep may not be merely 'small cattle'. 5 refs.

  5. Iodine-129 in thyroids of grazing animals

    Ballad, R.V.; Holman, D.W.; Hennecke, E.W.; Johnson, J.E.; Manuel, O.K.; Nicholson, L.M.

    1976-01-01

    A combination of neutron activation and mass spectrometry has been used to determine the concentrations of fissiogenic 129 I and stable 127 I in thyroids of grazing animals and in mineral iodine. The 129 I/ 127 I ratios are lowest in mineral iodine and in a given area lower in cow thyroids than in deer thyroids. Near saturation levels of mineral iodine in commercial feeds and salt licks may account for differences in the 129 I levels of cows and deer. Values of the 129 I/ 127 I ratio in deer appear to vary inversely with the iodine concentration of the thyroid. (author)

  6. Green leaf allowance and dairy ewe performance grazing on tropical pasture.

    De Souza, J; Batistel, F; Ticiani, E; Sandri, E C; Pedreira, C G S; Oliveira, D E

    2014-06-01

    The objective of this study was to explain the influence of green leaf allowance levels on the performance of dairy ewes grazing a tropical grass. Seventy-two lactating ewes grazed Aruana guineagrass (Panicum maximum Jacq. cv. Aruana) for 80 d. The treatments were 4 daily levels of green leaf allowance (GLA) on a DM basis corresponding to 4, 7, 10, and 13 kg DM/100 kg BW, which were named low, medium-low, medium-high, and high level, respectively. The experimental design was completely randomized with 3 replications. During the experimental period, 4 grazing cycles were evaluated in a rotational stocking grazing method (4 d of grazing and 16 d of rest). There was a linear effect of GLA on forage mass, and increasing GLA resulted in increased total leaf mass, reaching an asymptotic plateau around the medium-high GLA level. The stem mass increased with increased GLA, and a pronounced increase was observed between medium-high and high GLAs. Increasing GLA increased both forage disappearance rate and postgrazing forage mass. Leaf proportion increased with GLA, peaking at the medium-high level, and the opposite occurred for stem proportions, which reduced until medium-high GLA level, followed by an increase on high GLA. Forage CP decreased linearly with GLA, and increasing GLA from low to high reduced CP content by 31%. On the other hand, NDF increased 14% and ADF increased 26%, both linearly in response to greater GLA levels. Total digestible nutrients decreased linearly by 8% when GLA increased from low to high level. Milk yield increased, peaking at medium-high GLA (1.75 kg ewe(-1) d(-1)) and decreased at high GLA level (1.40 kg ewe(-1) d(-1)). Milk composition was not affected by the GLA levels. There was a reduction in stocking rate from 72 to 43 ewes/ha when GLA increased from low to high level. Productivity (milk yield kg ha(-1) d(-1)) increased as GLA increased, peaking at medium-low level (115 kg ha(-1) d(-1)). Although this tropical grass showed the same

  7. Modelling nitrous oxide emissions from grazed grassland systems

    Wang Junye; Cardenas, Laura M.; Misselbrook, Tom H.; Cuttle, Steve; Thorman, Rachel E.; Li Changsheng

    2012-01-01

    Grazed grassland systems are an important component of the global carbon cycle and also influence global climate change through their emissions of nitrous oxide and methane. However, there are huge uncertainties and challenges in the development and parameterisation of process-based models for grazed grassland systems because of the wide diversity of vegetation and impacts of grazing animals. A process-based biogeochemistry model, DeNitrification-DeComposition (DNDC), has been modified to describe N 2 O emissions for the UK from regional conditions. This paper reports a new development of UK-DNDC in which the animal grazing practices were modified to track their contributions to the soil nitrogen (N) biogeochemistry. The new version of UK-DNDC was tested against datasets of N 2 O fluxes measured at three contrasting field sites. The results showed that the responses of the model to changes in grazing parameters were generally in agreement with observations, showing that N 2 O emissions increased as the grazing intensity increased. - Highlights: ► Parameterisation of grazing system using grazing intensity. ► Modification of UK D NDC for the UK soil and weather conditions. ► Validation of the UK D NDC against measured data of N 2 O emissions in three UK sites. ► Estimating influence of animal grazing practises on N 2 O emissions. - Grazing system was parameterised using grazing intensity and UK-DNDC model was modified and validated against measured data of N 2 O emissions in three UK sites.

  8. Dairy farmers using mob grazing in Pennsylvania and New York

    Proponents of ultra-high stocking density grazing emphasize increased forage use efficiency and soil improvement by grazing mature forage with stocking densities up to 500,000 lb per acre of beef cattle on small paddocks with rest periods up to 180 days. However, it is unclear if this management tec...

  9. Day and night grazing by cattle in the Sahel

    Ayantunde, A.A.; Fernandez-Rivera, S.; Hiernaux, P.H.; Keulen, van H.; Udo, H.M.J.

    2002-01-01

    The influence of night grazing on feeding behavior, nutrition and performance of cattle was studied. Twenty-four steers weighing 367 kg (SD = 76) grazed either from 0900 to 1900 (day grazers), 2100 to 0700 (night grazers) or 0900 to 1900 and 2400 to 0400 (day-and-night grazers) during 13 weeks. Four

  10. Resilience of soils and vegetation subjected to different grazing ...

    The resilience of rangeland soils and vegetation to different levels of grazing is still poorly understood. A study was conducted to determine the recovery of a rangeland grazed at different intensities and allowed a two-year rest period. The following treatments were applied to 0.5 hectare plots: 0, 4, 8 and 16 heifers per ...

  11. Soil contamination of plant surfaces from grazing and rainfall interactions

    Hinton, T.G.; Stoll, J.M.; Tobler, L.

    1995-01-01

    Contaminants often attach to soil particles, and their subsequent environmental transport is largely determined by processes that govern soil movement. We examined the influence of grazing intensity on soil contamination of pastures. Four different grazing densities of sheep were tested against an ungrazed control plot. Scandium concentrations were determined by neutron activation analysis and was used as a tracer of soil adhesion on vegetation. Soil loadings ( g soil kg -1 dry plant) increased 60% when grazing intensity was increased by a factor of four (p 0.003). Rain and wind removed soil from vegetation in the ungrazed control plots, but when grazing sheep were present, an increase in rain from 0.3 to 9.7 mm caused a 130% increase in soil contamination. Multiple regression was used to develop an equation that predicts soil loadings as a function of grazing density, rainfall and wind speed (p = 0.0001, r 2 = 0.78). The model predicts that if grazing management were to be used as a tool to reduce contaminant intake from inadvertent consumption of resuspended soil by grazing animals, grazing densities would have to be reduced 2.5 times to reduce soil loadings by 50%. (author)

  12. Transformation of a savanna grassland by drought and grazing | O ...

    The relative effects of drought and heavy grazing on the floristic composition, population size and and structure, and basal cover of an African savanna grassland were differentiated by comparing changes over eight years over eight years, which included a severe drought year, across a gradient of grazing history. Drought ...

  13. The evaluation of four Eragrostis curvula ecotypes with grazing sheep.

    There were no significant differences in the dry matter production and chemical composition of the clipped samples of the ecotypes. Keywords: afrikaans; chemical composition; dry matter production; ecotypes; eragrostis curvula; grazing; live mass; live mass gains; open rotational grazing system; production; sheep; south ...

  14. Mixed farming in a grazing reserve in Northern Nigeria | Babalobi ...

    Nigeria's main pastoral development strategy is the settlement of pastoralists in grazing reserves. The goal of the strategy is to turn such nomadic pastoralists into mixed farmers who will take up crop farming to supplement livestock farming. Using the Bobi Grazing Reserve, Niger State, Nigeria as case study, the attainment ...

  15. Review: Behavior and daily grazing patterns of cattle

    Gregorini, P.; Tamminga, S.; Gunther, S.A.

    2006-01-01

    Grazing ruminants consume their food in discrete grazing events. The frequency and distribution of these events depend on the current physiological state of the animal and its environment. Within a small spatio-temporal scale, foraging decisions such as when to begin, which frequency, and how to

  16. Environmental Assessment of Beale AFB Grazing Lease Program

    2012-12-01

    Beale AFB will use livestock (cattle, sheep and goats ) on its properties throughout the year as needed for the control of noxious weeds, reduction...initiating a wildfire. California Farm Bureau Federation policy recognizes that grazing is the most practical and environmentally acceptable way to...Site Monitoring Well Installation and Annual Targeted Goat Grazing Project, Placer County, California. 21 September 2011.  

  17. Possibilities and constraints for grazing in high output dairy systems

    Hennessy, D.; Delaby, L.; Pol, van den A.; Shalloo, L.

    2015-01-01

    In temperate and oceanic regions, grazed grass is the lowest cost feed available for milk production. In other regions, grazed grass is less important but can contribute to the diet of livestock. Within high output systems the interaction between the animal and sward is challenging for a host of

  18. The grazing index method of range condition assessment | du Toit ...

    Owing to the difficulty of examining succession theory in the Karoo, it is suggested the ecological index method (EIM), be replaced by the grazing index method (GIM), through the introduction of grazing index values (GIV) for Karoo plant species. The GIM may provide more acceptable range condition scores and more ...

  19. Forage selection and performance of sheep grazing dry annual range.

    Ridder, de N.; Benjamin, R.W.; Keulen, van H.

    1986-01-01

    During 114 days of grazing, sheep grazing a dry annual pasture in Israel selected the fine fraction available with a higher nutritive value. As this fraction became depleted and feed quality dropped, organic matter intake dropped from 1.73 to 0.75 kg/sheep/d. Sheep lost weight, body condition and

  20. Livestock Grazing as a Driver of Vernal Pool Ecohydrology

    Michaels, J.; McCarten, N. F.

    2017-12-01

    Vernal pools are seasonal wetlands that host rare plant communities of high conservation priority. Plant community composition is largely driven by pool hydroperiod. A previous study found that vernal pools grazed by livestock had longer hydroperiods compared with pools excluded from grazing for 10 years, and suggests that livestock grazing can be used to protect plant diversity. It is important to assess whether observed differences are due to the grazing or due to water balance variables including upland discharge into or out of the pools since no a priori measurements were made of the hydrology prior to grazing. To address this question, in 2016 we compared 15 pools that have been grazed continuously and 15 pools that have been fenced off for over 40 years at a site in Sacramento County. We paired pools based on abiotic characteristics (size, shape, slope, soil type) to minimize natural variation. We sampled vegetation and water depth using Solinst level loggers. We found that plant diversity and average hydroperiod was significantly higher in the grazed pools. We are currently measuring groundwater connectivity and upland inputs in order to compare the relative strength of livestock grazing as a driver of hydroperiod to these other drivers.

  1. Effect of mowing and grazing on ramet emergence of Leymus ...

    user

    2011-03-21

    Mar 21, 2011 ... experiment was conducted in the spring of 2004 to investigate the effects on the surface soil temperature caused by mowing, grazing and grazing exclusion, and the influence of these factors on the ramets emergence characteristics. The primary effect of the treatments was significant changes in.

  2. Vegetation patterns and nutrients in relation to grazing pressure and ...

    A major challenge confronting managers of extensive grazing systems is uneven use of erbaceous forage plants by livestock. The concentration of grazing in preferred areas or around foci points (e.g. water points) eventually results in adverse impacts in soil nutrients, vegetation structure, production and composition.

  3. Grasses grazed by springbok and sheep | R. | African Journal of ...

    Grazing habits were determined by analysis of rumina from slaughtered springbok and sheep where springbok grazed together with Merino sheep in False Upper Karoo and together with Dorper sheep in Kalahari Thornveld. Results show that in both veld types, grass constituted about 39 percent of the dry mass intake of ...

  4. Herbage intake of dairy cows in mixed sequential grazing with breeding ewes as followers.

    Jiménez-Rosales, Juan Daniel; Améndola-Massiotti, Ricardo Daniel; Burgueño-Ferreira, Juan Andrés; Ramírez-Valverde, Rodolfo; Topete-Pelayo, Pedro; Huerta-Bravo, Maximino

    2018-03-01

    This study aimed to evaluate the hypothesis that mixed sequential grazing of dairy cows and breeding ewes is beneficial. During the seasons of spring-summer 2013 and autumn-winter 2013-2014, 12 (spring-summer) and 16 (autumn-winter) Holstein Friesian cows and 24 gestating (spring-summer) and lactating (autumn-winter) Pelibuey ewes grazed on six (spring-summer) and nine (autumn-winter) paddocks of alfalfa and orchard grass mixed pastures. The treatments "single species cow grazing" (CowG) and "mixed sequential grazing with ewes as followers of cows" (MixG) were evaluated, under a completely randomized design with two replicates per paddock. Herbage mass on offer (HO) and residual herbage mass (RH) were estimated by cutting samples. The estimate of herbage intake (HI) of cows was based on the use of internal and external markers; the apparent HI of ewes was calculated as the difference between HO (RH of cows) and RH. Even though HO was higher in CowG, the HI of cows was higher in MixG during spring-summer and similar in both treatments during autumn-winter, implying that in MixG the effects on the cows HI of higher alfalfa proportion and herbage accumulation rate evolving from lower residual herbage mass in the previous cycle counteracted that of a higher HO in CowG. The HI of ewes was sufficient to enable satisfactory performance as breeding ewes. Thus, the benefits of mixed sequential grazing arose from higher herbage accumulation, positive changes in botanical composition, and the achievement of sheep production without negative effects on the herbage intake of cows.

  5. Evidence for strain-specific exometabolomic responses of the coccolithophore Emiliania huxleyi to grazing by the dinoflagellate Oxyrrhis marina.

    Kelsey L Poulson-Ellestad

    2016-01-01

    Full Text Available The coccolithophore Emiliania huxleyi forms massive blooms and plays a critical role in global elemental cycles, sequestering significant amounts of atmospheric carbon dioxide on geological time scales via production of calcium carbonate coccoliths and emitting dimethyl sulfoniopropionate (DMSP which has the potential for increasing atmospheric albedo. Because grazing in pelagic systems is a major top-down force structuring microbial communities, the influence of grazers on E. huxleyi populations has been of interest to researchers. Roles of DMSP (and related metabolites in interactions between E. huxleyi and protist grazers have been investigated, however, little is known about the release of other metabolites that may influence, or be influenced by, such grazing interactions. We used high-resolution mass spectrometry in an untargeted approach to survey the suite of low molecular weight compounds released by four different E. huxleyi strains in response to grazing by the dinoflagellate Oxyrrhis marina. Overall, a strikingly small number of metabolites were detected from E. huxleyi and O. marina cells, but these were distinctly informative to construct metabolic footprints. At most, E. huxleyi strains shared 25% of released metabolites. Furthermore, there appeared to be no unified metabolic response in E. huxleyi strains to grazing; rather these responses were strain specific. Concentrations of several metabolites also positively correlated with grazer activities, including grazing, ingestion, and growth rates; however, no single metabolite responded uniformly across all strains of E. huxleyi tested. Regardless, grazing clearly transformed the constituents of dissolved organic matter produced by these marine microbes. This study addresses several technical challenges, and presents a platform to further study the influence of chemical cues in aquatic systems and demonstrates the impact of strain diversity and grazing on the complexity of

  6. Investigating the Effect of Livestock Grazing and Associated Plant Community Shifts on Carbon and Nutrient Cycling in Alberta, Canada

    Hewins, D. B.; Chuan, S.; Stolnikova, E.; Bork, E. W.; Carlyle, C. N.; Chang, S. X.

    2015-12-01

    Grassland ecosystems are ubiquitous across the globe covering an estimated 40 % of Earth's terrestrial landmass. These ecosystems are widely valued for providing forage for domestic livestock and a suite of important ecosystem goods and services including carbon (C) storage. Despite storing more than 30 % of soil C globally, the effect of both livestock grazing and the associated change in plant community structure in response to grazing on C and nutrient cycling remains uncertain. To gain a quantitative understanding of the direct and indirect effects of livestock grazing on C and nutrient cycling, we established study sites at 15 existing site localities with paired long-term grazing (ca. 30 y) and non-grazed treatments (totaling 30 unique plant communities). Our sites were distributed widely across Alberta in three distinct grassland bioclimatic zones allowing us to make comparisons across the broad range of climate variability typical of western Canadian grasslands. In each plant community we decomposed 5 common plant species that are known to increase or decrease in response to grazing pressure, a unique plant community sample, and a cellulose paper control. We measured mass loss, initial lignin, C and N concentrations at 0, 1, 3, 6 and 12 months of field incubation. In addition we assayed hydrolytic and oxidative extracellular enzymes associated with for C (n= 5 hydrolytic; phenoloxidase and peroxidase) and nutrients (i.e. N and P; n=1 ea.) cycling from each litter sample at each collection. Our results suggest that by changing the plant community structure, grazing can affect rates of decomposition and associated biogeochemical cycling by changing plant species and associated litter inputs. Moreover, measures of microbial function are controlled by site-specific conditions (e.g. temperature and precipitation), litter chemistry over the course of our incubation.

  7. Top-down impact through a bottom-up mechanism: the effect of limpet grazing on growth, productivity and carbon allocation of Zostera marina L. (eelgrass).

    Zimmerman, Richard C; Kohrs, Donald G; Alberte, Randall S

    1996-09-01

    The unusual appearance of a commensal eelgrass limpet [Tectura depicta (Berry)] from southern California at high density (up to 10 shoot -1 ) has coincided with the catastrophic decline of a subtidal Zostera marina L. meadow in Monterey Bay, California. Some commensal limpets graze the chloroplast-rich epidermis of eelgrass leaves, but were not known to affect seagrass growth or productivity. We evaluated the effect on eelgrass productivity of grazing by limpets maintained at natural densities (8±2 shoot -1 ) in a natural light mesocosm for 45 days. Growth rates, carbon reserves, root proliferation and net photosynthesis of grazed plants were 50-80% below those of ungrazed plants, but biomass-specific respiration was unaffected. The daily period of irradiance-saturated photosynthesis (H sat ) needed to maintain positive carbon balance in grazed plants approached 13.5 h, compared with 5-6 h for ungrazed plants. The amount of carbon allocated to roots of ungrazed plants was 800% higher than for grazed plants. By grazing the chlorophyll-rich epidermis, T. depicta induced carbon limitation in eelgrass growing in an other-wise light-replete environment. Continued northward movement of T. depicta, may have significant impacts on eelgrass production and population dynamics in the northeast Pacific, even thought this limpet consumes very little plant biomass. This interaction is a dramatic example of top-down control (grazing/predation) of eelgrass productivity and survival operating via a bottom-up mechanism (photosynthesis limitation).

  8. forage systems mixed with forage legumes grazed by lactating cows

    Clair Jorge Olivo

    2017-02-01

    Full Text Available Current research evaluates productivity, stocking and nutritional rates of three forage systems with Elephant Grass (EG + Italian Ryegrass (IR + Spontaneous Growth Species (SGS, without forage legumes; EG + IR + SGS + Forage Peanut (FP, mixed with FP; and EG + IR + SGS + Red Clover (RC, mixed with RC, in rotational grazing method by lactating cows. IR developed between rows of EG. FP was maintained, whilst RC was sow to respective forage systems. The experimental design was completely randomized, with three treatments and two replication, subdivided into parcels over time. Mean rate for forage yield and average stocking rate were 10.6, 11.6 and 14.4 t ha-1; 3.0, 2.8 and 3.1 animal unit ha-1 day-1, for the respective systems. Levels of crude protein and total digestible nutrients were 17.8, 18.7 and 17.5%; 66.5, 66.8 and 64.8%, for the respective forage systems. The presence of RC results in better and higher forage yield in the mixture, whilst FP results in greater control of SGS. The inclusion of forage legumes in pasture systems provides better nutritional rates.

  9. Mixed grazing systems benefit both upland biodiversity and livestock production.

    Mariecia D Fraser

    Full Text Available With world food demand expected to double by 2050, identifying farming systems that benefit both agricultural production and biodiversity is a fundamentally important challenge for the 21(st century, but this has to be achieved in a sustainable way. Livestock grazing management directly influences both economic outputs and biodiversity on upland farms while contributing to potentially damaging greenhouse gas emissions, yet no study has attempted to address these impacts simultaneously.Using a replicated, landscape-scale field experiment consisting of five management 'systems' we tested the effects of progressively altering elements within an upland farming system, viz i incorporating cattle grazing into an upland sheep system, ii integrating grazing of semi-natural rough grazing into a mixed grazing system based on improved pasture, iii altering the stocking ratio within a mixed grazing system, and iv replacing modern crossbred cattle with a traditional breed. We quantified the impacts on livestock productivity and numbers of birds and butterflies over four years.We found that management systems incorporating mixed grazing with cattle improve livestock productivity and reduce methane emissions relative to sheep only systems. Systems that also included semi-natural rough grazing consistently supported more species of birds and butterflies, and it was possible to incorporate bouts of summer grazing of these pastures by cattle to meet habitat management prescriptions without compromising cattle performance overall. We found no evidence that the system incorporating a cattle breed popular as a conservation grazer was any better for bird and butterfly species richness than those based on a mainstream breed, yet methane emissions from such a system were predicted to be higher. We have demonstrated that mixed upland grazing systems not only improve livestock production, but also benefit biodiversity, suggesting a 'win-win' solution for farmers and

  10. Grazing behavior and production characteristics among cows differing in residual feed intake while grazing late season Idaho rangeland

    The objectives were to determine if cows classified as either low- or high-residual feed intake (LRFI or HRFI) differed in BW, BCS, and winter grazing activity over time. Thirty Hereford x Angus (LRFI = 16; HRFI = 14) 2-year-old cows grazed sagebrush-steppe for 78 d beginning 29 September 2016. Body...

  11. Effects of grazing system on production and parasitism of dairy breed heifers and steers grazing wet marginal grasslands

    Kristensen, Troels; Thamsborg, S.M.; Andersen, Refsgaard

    2006-01-01

    Production and endoparasitism of first grazing season Holstein heifers and steers were investigated over two grazing seasons. Studies were conducted on low-lying peaty soil. In year 2000, 40 animals were included in a 2x2 factorial, replicated experiment with two sexes (steers v. heifers) and two...

  12. Effect of early weaning and concentrate supplementation at forage intake and ingestive behavior of sheep grazing Tifton 85 (Cynodon spp.

    Marina Gabriela Berchiol da Silva

    2012-12-01

    Full Text Available The objective of this study was to evaluate then early weaning and concentrate supplementation effect at pasture characteristics, forage intake and ingestive behavior of lambs grazing Tifton 85 (Cynodon spp.. A randomized block design was used with four treatments, three replications and five lambs per replicate. A total of 60 Suffolk lambs, that 36 were females and 24 steers. The treatments had corresponded to the combinations between early weaning precocious and concentrate supplementation strategies, that resulted in the following ones finishing systems: 1 lambs kept with mothers without supplementation; 2 lambs kept with mothers supplemented with concentrate in creep feeding at 2% of body weigh (BW in DM/day; 3 weaned lambs at 45 ± 5 days without supplementation and 4 weaned lambs at 45 ± 5 days and supplemented with concentrate at 2% of BW in DM/day. Grazing utilization method was continuous stocking with adjustment every 21 days, to maintain forage offer at 12% of BW in DM/day. To characterize the pastoral environment was assessed: morphological composition of pasture. There were made four observations the behavioral activities for individually lambs per 24 hours, such as: grazing, ruminating, suckling, supplementation, and others activities. The intake rate was measured using the technique of double sampling and determination of bite rate was made by visual observation of the number of bits made for animal. The behavior and the distribution of daily activities made by the lambs are influenced for the strategies evaluated. The exclusive presence of milk or supplement concentrate in the diet are important modulators of grazing activity, and the absence of these nutrient sources were offset per an increase in grazing time. This response considered the decrease in nutritional support and lower efficiency in harvesting the forage by lambs. The weaning influenced the morphological characteristics of the pasture, which showed favored the

  13. Effects of grazing strategy on limiting nitrate leaching in grazed grass-clover pastures on coarse sandy soil

    Hansen, Elly Møller; Eriksen, Jørgen; Søegaard, Karen

    2012-01-01

    -term mean. The experiment was initiated in a 4-yr-old grass-clover sward in south Denmark. Three treatments were as follows grazing only (G), spring cut followed by grazing (CG) and both spring and autumn cuts with summer grazing (CGC). Nitrate leaching was calculated by extracting water isolates from 80 cm......Urinations of ruminants on grazed pastures increase the risk of nitrate leaching. The study investigated the effect of reducing the length of the grazing season on nitrate leaching from a coarse sandy, irrigated soil during 2006–2007 and 2007–2008. In both years, precipitation was above the long...... depth using ceramic suction cups. Because of considerable variation in measured nitrate concentrations, the 32 installed suction cups per treatment were insufficient to reveal differences between treatments. However, weighted nitrate leaching estimations for G, CG and CGC showed estimated mean nitrate N...

  14. Grazing Affects Exosomal Circulating MicroRNAs in Cattle

    Muroya, Susumu; Ogasawara, Hideki; Hojito, Masayuki

    2015-01-01

    Circulating microRNAs (c-miRNAs) are associated with physiological adaptation to acute and chronic aerobic exercise in humans. To investigate the potential effect of grazing movement on miRNA circulation in cattle, here we profiled miRNA expression in centrifugally prepared exosomes from the plasma of both grazing and housed Japanese Shorthorn cattle. Microarray analysis of the c-miRNAs resulted in detection of a total of 231 bovine exosomal miRNAs in the plasma, with a constant expression level of let-7g across the duration and cattle groups. Expression of muscle-specific miRNAs such as miR-1, miR-133a, miR-206, miR-208a/b, and miR-499 were undetectable, suggesting the mildness of grazing movement as exercise. According to validation by quantitative RT-PCR, the circulating miR-150 level in the grazing cattle normalized by the endogenous let-7g level was down-regulated after 2 and 4 months of grazing (P cattle equalized when the grazing cattle were returned to a housed situation. Likewise, the levels of miR-19b, miR-148a, miR-221, miR-223, miR-320a, miR-361, and miR-486 were temporarily lowered in the cattle at 1 and/or 2 month of grazing compared to those of the housed cattle (P cattle at 2 months of grazing (P = 0.044). The elevation of miR-451 level in the plasma was coincident with that in the biceps femoris muscle of the grazing cattle (P = 0.008), which suggests the secretion or intake of miR-451 between skeletal muscle cells and circulation during grazing. These results revealed that exosomal c-miRNAs in cattle were affected by grazing, suggesting their usefulness as molecular grazing markers and functions in physiological adaptation of grazing cattle associated with endocytosis, focal adhesion, axon guidance, and a variety of intracellular signaling, as predicted by bioinformatic analysis. PMID:26308447

  15. Progress Report: Stratton Ecological Research Site - An Experimental Approach to Assess Effects of Various Grazing Treatments on Vegetation and Wildlife Communities Across Managed Burns and Habitat Controls

    Erickson, Heidi J.; Aldridge, Cameron L.; Hobbs, N. Thompson

    2009-01-01

    Understanding how management practices affect wildlife is fundamental to wise decisions for conservation of public lands. Prescribed fire and grazing timing are two management tools frequently used within publicly owned sagebrush ecosystems. We conducted a variety of surveys in order to assess the impacts of grazing timing strategies (early summer before peak green-up, mid-summer at peak green-up, and late summer after peak green-up) in conjunction with prescribed fire on avian and small mammal populations in a high-elevation sagebrush ecosystem. Avian surveys resulted in a large detection sample size for three bird species: Brewer's sparrow (Spizella breweri), horned lark (Eremophila alpestris), and vesper sparrow (Pooecetes gramineus). Brewer's sparrows had the lowest number of detections within the mid-summer grazing treatment compared to early and late summer grazing treatments, while horned larks and vesper sparrows had higher detection frequencies within the late summer grazing treatment. Summer and fall sage-grouse (Centrocercus urophasianus) pellet counts revealed that the greatest over-winter and over-summer use by sage-grouse occurred within the early summer grazing treatment with minimal use of burn treatment areas across all grazing treatments. Deer-mice (Peromyscus maniculatus) represented approximately 90 percent of small mammals captured and were most prevalent within the mid-summer grazing treatment. Sagebrush cover was greatest within the mid-summer grazing treatment. We monitored 50 and 103 nests in 2007 and 2008, respectively. The apparent success rate for shrub-obligate nesting species was 58 percent in 2007 and 63 percent in 2008. This research will support management of sagebrush ecosystems by providing public land managers with direct comparisons of wildlife response to management regimes.

  16. Resilience of South African communal grazing lands after the removal of high grazing pressure

    Harrison, YA

    1999-05-01

    Full Text Available , et al., 1990; Dahlberg, 1993; Scoones, 1993; Shackleton, 1993; Sullivan, 1996). Invariably `overstocking' and hence overgrazing are deemed to be responsible for the apparent degradation. Despite this o cial perspective, most communal lands have... ones (Kelly and Walker, 1976; O'Connor and Pickett, 1992; Parsons, et al., 1997). However, these studies have not indicated the permanence, or reversibility, of the measured changes, and the magnitude of grazing eC128ects is usually minor relative...

  17. Figure and finish of grazing incidence mirrors

    Takacs, P.Z.; Church, E.L.

    1989-08-01

    Great improvement has been made in the past several years in the quality of optical components used in synchrotron radiation (SR) beamlines. Most of this progress has been the result of vastly improved metrology techniques and instrumentation permitting rapid and accurate measurement of the surface finish and figure on grazing incidence optics. A significant theoretical effort has linked the actual performance of components used as x-ray wavelengths to their topological properties as measured by surface profiling instruments. Next-generation advanced light sources will require optical components and systems to have sub-arc second surface figure tolerances. This paper will explore the consequences of these requirements in terms of manufacturing tolerances to see if the present manufacturing state-of-the-art is capable of producing the required surfaces. 15 refs., 14 figs., 2 tabs

  18. Axial grazing collisions with insulator surfaces

    Gravielle, M.S. [Instituto de Astronomia y Fisica del Espacio (IAFE), Consejo Nacional de Investigaciones Cientificas y Tecnicas, Casilla de Correo 67, Sucursal 28, 1428 Buenos Aires (Argentina) and Departamento de Fisica, FCEN, Universidad de Buenos Aires (Argentina)]. E-mail: msilvia@iafe.uba.ar; Miraglia, J.E. [Instituto de Astronomia y Fisica del Espacio (IAFE), Consejo Nacional de Investigaciones Cientificas y Tecnicas, Casilla de Correo 67, Sucursal 28, 1428 Buenos Aires (Argentina); Departamento de Fisica, FCEN, Universidad de Buenos Aires (Argentina)

    2007-05-15

    Electron capture and emission processes from insulator surfaces produced by grazing impact of fast ions are investigated under axial incidence conditions. For crystal surfaces we develop a model based on distorted wave methods, which allows us to express the coherent transition amplitude along the projectile path as a sum of atomic amplitudes, each one associated with a different lattice site. The method is applied to 100 keV protons colliding with LiF surfaces. For electron transitions from a given initial crystal state, the probabilities display strong interference effects as a function of the crystal orientation. But the interference patterns disappear when these partial probabilities are added to derive the total probability from the surface band.

  19. Axial grazing collisions with insulator surfaces

    Gravielle, M.S.; Miraglia, J.E.

    2007-01-01

    Electron capture and emission processes from insulator surfaces produced by grazing impact of fast ions are investigated under axial incidence conditions. For crystal surfaces we develop a model based on distorted wave methods, which allows us to express the coherent transition amplitude along the projectile path as a sum of atomic amplitudes, each one associated with a different lattice site. The method is applied to 100 keV protons colliding with LiF surfaces. For electron transitions from a given initial crystal state, the probabilities display strong interference effects as a function of the crystal orientation. But the interference patterns disappear when these partial probabilities are added to derive the total probability from the surface band

  20. Poultry performance in different grazing densities: forage characteristics, losses due to grazing and feed intake

    Luciano Cristiano França

    2014-02-01

    Full Text Available Morphological characteristics of three forage species grazed by rustic poultry in stocking were evaluated. Coast-cross fodder, kikuyu grass, and stylosanthes were planted in 33-m2 paddocks with two densities (m2/animal: D1 = 3m2/animal and D2 = 1m2/animal. The design was a randomized complete block with a 3 x 2 factorial (three grasses and two densities and three replications. Grass canopy height, grass mass, morphological composition (leaf, stem, and dead material, losses due to grazing, poultry weight gain and consumption, and concentrate feed conversion ratio and efficiency were evaluated. At the end of the experiment, forage and leaves masses were considered low to stylosanthes in D2 (0.28 to 0.03 kg/m2 and to kikuyu grass in D1 (0.13 to 0.05 kg/m2 and in D2 (0.11 and 0.03 kg/m2, respectively. In addition, the grass canopy height was considered low for stylosanthes (6.50 cm that could jeopardize the entry of new poultry lot. The three grass species had similar weight gain and revealed better results for 3m²/ chicken (3.20 kg/animal. Coast-cross fodder, kikuyu grass, and stylosanthes, with some exceptions, can be considered suitable for grazing fattening poultry at 3m2/animal at the evaluated time of the year (autumn.

  1. Effect of supplement level on herbage intake and feeding behaviour of Italian Brown cows grazing on Alpine pasture

    D. Villa

    2010-01-01

    Full Text Available Summer grazing of dairy cows on mountain pastures often leads to a fall in production or in body condition when the pasture is not adequately supplemented with concentrate feeds (Malossini et al., 1992; Bovolenta et al., 1998. An abundant use of concentrates may result into a reduction of herbage intake according to a substitution rate mechanism (Faverdin et al., 1991. The aim of this trial was to evaluate the effect of the supplementation level on herbage intake, milk yield and feeding behaviour (time spent grazing and ruminating of dairy cows at pasture, combining the use of an electronic bitemeter and a double marker method for the estimation of intake.

  2. Correlation between intake and ingestive behavior of pasture-grazed heifers

    Hermógenes Almeida Santana Junior

    2013-12-01

    Full Text Available The objective of this study was to evaluate the correlation between intake and ingestive behavior of crossbred heifers in grazing tropical. The experiment was conducted on the Princesa do Mateiro Farm, in the city of Ribeirão do Largo, Bahia. A total of 20 heifers with genetic makeup 5/8 dairy Guzerá and 3/8 Holstein, average age of 18 months and body weight of 187 ± 13.1 kg have been used. The experiment lasted 224 days and involved animals raised in a rotational grazing system with Brachiaria brizantha cv. Marandú. Grazing time was not correlated with any of the variables associated with intake. Rumination time showed positive correlations with the intake of forage dry matter (DMIF and neutral detergent fiber (NDFI. Variables associated with the time spent on feeding at the trough, overall feeding and total chewing were not correlated with intake (P>0.05. There have been positive correlations between the number of grazing periods (NGP and rumination periods (NRP and total DM intake (TDMI, organic matter (OMI, forage (DMIF, neutral detergent fiber (NDFI, total carbohydrates (TCHI and ether extract (EEI. Crude protein intake (CPI was positively correlated with NGP and NRP. The mouthful rate was positively correlated with TDMI, OMI, DMIF, NDFI, TCHI, EEI and CPI. Average time per swallow was negatively correlated with TDMI, OMI, NDFI, TCHI and EEI. Positive correlations have been observed between the number of mouthfuls per day and TDMI, OMI, DMIF, NDFI, TCHI, EEI. The number of chews per bolus showed negative correlations with DMIS and CPI. The time per cake ruminated has correlated negatively with the intake of crude protein. The number of chews per bolus showed positive correlations with the intakes of dry matter and neutral detergent fiber. The number of boli per day showed positive correlations with DMIF and TCHI. The time spent on chewing showed no significant correlation with intake. In conflict with the national and international

  3. Selective grazing by adults and larvae of the zebra mussel (Dreissena polymorpha): application of flow cytometry to natural seston

    Pires, L.M.D.; Jonker, R.M.; Van Donk, E.; Laanbroek, H.J.

    2004-01-01

    1. Selective grazing of adults and larvae of the zebra mussel (Dreissena polymorpha) on phytoplankton and detritus from both laboratory cultures and natural seston was quantified using flow cytometry. 2. Mean clearance rate of adult zebra mussels was higher on a mixture of the green alga Scenedesmus

  4. Selective grazing by adults and larvae of the zebra mussel (Dreissena polymorpha): application of flow cytometry to natural seston

    Dionisio Pires, L.M.; Jonker, R.R.; Donk, E.van; Laanbroek, H.J.

    2004-01-01

    1. Selective grazing of adults and larvae of the zebra mussel (Dreissena polymorpha) on phytoplankton and detritus from both laboratory cultures and natural seston was quantified using flow cytometry. 2. Mean clearance rate of adult zebra mussels was higher on a mixture of the green

  5. Plasma protein loss associated with gastrointestinal parasitism in grazing sheep.

    Yakoob, A Y; Holmes, P H; Parkins, J J; Armour, J

    1983-01-01

    Some pathophysiological effects of parasitic gastroenteritis in two groups of lambs grazing paddocks either heavily or lightly contaminated with trichostrongyle larvae were investigated between July and October 1980. The leak of plasma protein was measured on three occasions at pasture using 51chromic chloride. Total faecal output was measured indirectly using chromic oxide. Losses of 51chromic chloride-labelled plasma protein into the gastrointestinal tract were significantly higher in the lambs grazing the heavily contaminated pasture than in those grazing lightly infected ground in both July and August. The increased plasma losses were associated with high faecal egg counts, hypoalbuminaemia and elevated levels of plasma pepsinogen.

  6. Aplanatic grazing incidence diffraction grating: a new optical element

    Hettrick, M.C.

    1986-01-01

    We present the theory of a grazing incidence reflection grating capable of imaging at submicron resolution. The optic is mechanically ruled on a spherical or cylindrical surface with varied groove spacings, delivering diffraction-limited response and a wide field of view at a selected wavelength. Geometrical aberrations are calculated on the basis of Fermat's principle, revealing significant improvements over a grazing incidence mirror. Aplanatic and quasi-aplanatic versions of the grating have applications in both imaging and scanning microscopes, microprobes, collimators, and telescopes. A 2-D crossed system of such gratings, similar to the grazing incidence mirror geometry of Kirkpatrick and Baez, could potentially provide spatial resolutions of --200 A

  7. Parameter constraints of grazing response functions. Implications for phytoplankton bloom initiation

    Jordi Solé

    2016-09-01

    Full Text Available Phytoplankton blooms are events of production and accumulation of phytoplankton biomass that influence ecosystem dynamics and may also have effects on socio-economic activities. Among the biological factors that affect bloom dynamics, prey selection by zooplankton may play an important role. Here we consider the initial state of development of an algal bloom and analyse how a reduced grazing pressure can allow an algal species with a lower intrinsic growth rate than a competitor to become dominant. We use a simple model with two microalgal species and one zooplankton grazer to derive general relationships between phytoplankton growth and zooplankton grazing. These relationships are applied to two common grazing response functions in order to deduce the mathematical constraints that the parameters of these functions must obey to allow the dominance of the lower growth rate competitor. To assess the usefulness of the deduced relationships in a more general framework, the results are applied in the context of a multispecies ecosystem model (ERSEM.

  8. Impact of processing on in vitro digestion of milk from grazing organic and confined conventional herds

    Debate on differences between milk from grazing and non-grazing cows has not addressed the effects that standard processing may have on milk digestibility. In this study, raw milk from grazing organic (ORG) and non-grazing conventional (CONV) herds was adjusted to 0 and 3.25% fat and processed as fo...

  9. How grazing affects soil quality of soils formed in the glaciated northeastern United States.

    Cox, Alissa H; Amador, José A

    2018-02-21

    Historically, much of the New England landscape was converted to pasture for grazing animals and harvesting hay. Both consumer demand for local sustainably produced food, and the number of small farms is increasing in RI, highlighting the importance of characterizing the effects livestock have on the quality of pasture soils. To assess how livestock affect pasture on Charlton and Canton soils series in RI, we examined soil quality in farms raising beef cattle (Bos taurus), sheep (Ovis aries), and horses (Equus ferus caballus), using hayed pastures as a control. We sampled three pastures per livestock type and three control hayed pastures in May, August, and October 2012. Hay fields and pastures grazed by sheep had statistically significant (P soil quality than pastures grazed by beef cattle or horses. This was driven by parameters including penetration resistance, bulk density, aggregate stability, and infiltration rate. Hayfields also showed higher soil quality measures than grazed pastures for organic matter content and active C. In addition, significant differences in nitrate and phosphate concentrations were observed among livestock types. Respiration and infiltration rates, pH, and ammonium concentrations, on the other hand, did not differ significantly among pasture types. When all soil quality indicators in this study were weighed equally, soil quality scores followed the order: hay > sheep > beef cattle > horses. The results of our study provide baseline data on the effect different types of livestock have on pasture soil quality in RI, which may be useful in making sound land use and agricultural management decisions.

  10. The effect of grazing on cow mortality in Danish dairy herds

    Burow, Elke; Thomsen, Peter Thorup; Sørensen, Jan Tind

    2011-01-01

    The effect of summer grazing in large Danish dairy herds and certain management characteristics of grazing were studied for their impact on dairy cow mortality. Mortality data (from the Danish Cattle Database) from 391 Danish dairy herds (>100 cows) were combined with information from...... a questionnaire survey of grazing procedures on these herds in 2008. In all, 131 of the herds were identified as summer grazing and 260 as zero-grazing herds. The mortality was affected by an interaction of summer grazing and milking system. The risk of a cow dying was reduced to 46% in a grazing compared...... and pasture was associated with increased cow mortality....

  11. The effects of burning and grazing on soil carbon dynamics in managed Peruvian tropical montane grasslands

    Oliver, Viktoria; Oliveras, Imma; Kala, Jose; Lever, Rebecca; Arn Teh, Yit

    2017-12-01

    Montane tropical soils are a large carbon (C) reservoir, acting as both a source and a sink of CO2. Enhanced CO2 emissions originate, in large part, from the decomposition and losses of soil organic matter (SOM) following anthropogenic disturbances. Therefore, quantitative knowledge of the stabilization and decomposition of SOM is necessary in order to understand, assess and predict the impact of land management in the tropics. In particular, labile SOM is an early and sensitive indicator of how SOM responds to changes in land use and management practices, which could have major implications for long-term carbon storage and rising atmospheric CO2 concentrations. The aim of this study was to investigate the impacts of grazing and fire history on soil C dynamics in the Peruvian montane grasslands, an understudied ecosystem, which covers approximately a quarter of the land area in Peru. A density fractionation method was used to quantify the labile and stable organic matter pools, along with soil CO2 flux and decomposition measurements. Grazing and burning together significantly increased soil CO2 fluxes and decomposition rates and reduced temperature as a driver. Although there was no significant effect of land use on total soil C stocks, the combination of burning and grazing decreased the proportion of C in the free light fraction (LF), especially at the lower depths (10-20 and 20-30 cm). In the control soils, 20 % of the material recovered was in the free LF, which contained 30 % of the soil C content. In comparison, the burnt-grazed soil had the smallest recovery of the free LF (10 %) and a significantly lower C content (14 %). The burnt soils had a much higher proportion of C in the occluded LF (12 %) compared to the not-burnt soils (7 %) and there was no significant difference among the treatments in the heavy fraction (F) ( ˜ 70 %). The synergistic effect of burning and grazing caused changes to the soil C dynamics. CO2 fluxes were increased and the dominant

  12. A 100-Year Review: A century of change in temperate grazing dairy systems.

    Roche, J R; Berry, D P; Bryant, A M; Burke, C R; Butler, S T; Dillon, P G; Donaghy, D J; Horan, B; Macdonald, K A; Macmillan, K L

    2017-12-01

    From 1917 to 2017, dairy grazing systems have evolved from uncontrolled grazing of unimproved pastures by dual-purpose dairy-beef breeds to an intensive system with a high output per unit of land from a fit-for-purpose cow. The end of World War I signaled significant government investments in agricultural research institutes around the world, which coincided with technological breakthroughs in milk harvesting and a recognition that important traits in both plants and animals could be improved upon relatively rapidly through genetic selection. Uptake of milk recording and herd testing increased rapidly through the 1920s, as did the recognition that pastures that were rested in between grazing events yielded more in a year than those continuously grazed. This, and the invention and refinement of the electric fence, led to the development of "controlled" rotational grazing. This, in itself, facilitated greater stocking rates and a 5 to 10% increase in milk output per hectare but, perhaps more importantly, it allowed a more efficient use of nitrogen fertilizer, further increasing milk output/land area by 20%. Farmer inventions led to the development of the herringbone and rotary milking parlors, which, along with the "unshortable" electric fence and technological breakthroughs in sperm dilution rates, allowed further dairy farm expansion. Simple but effective technological breakthroughs in reproduction ensured that cows were identified in estrus early (a key factor in maintaining the seasonality of milk production) and enabled researchers to quantify the anestrus problem in grazing herds. Genetic improvement of pasture species has lagged its bovine counterpart, but recent developments in multi-trait indices as well as investment in genetic technologies should significantly increase potential milk production per hectare. Decades of research on the use of feeds other than pasture (i.e., supplementary feeds) have provided consistent milk production responses when the

  13. Phosphorus and the grazing ruminant. 2. The effects of ...

    Department of Animal Science, University of Stellenbosch, Stellenbosch. The effects of .... rosis, severely impaired locomotion and therefore grazing behaviour ..... Studies in mineral metabolism. XXXVII. The influence of variations in the dietary ...

  14. Small mammal communities on cattle and game grazing areas in ...

    Small mammal communities on cattle and game grazing areas in Namibia. ... small mammal communities on two differently managed farmlands (cattle and game farm) in Namibia over the course of one year. ... AJOL African Journals Online.

  15. Assessment of the Effects of Emerging Grazing Policies on Land ...

    ADOWIE PERE

    ABSTRACT: This study examines the effects of the emerging grazing policies on land degradation in Nigeria using soil, vegetation ... imposed land use controls divorced from economic and demographic ... may be either positive or negative.

  16. Animal health management practices in zero grazing dairy units in ...

    Animal health management practices in zero grazing dairy units in Arusha City, Tanzania. ... African Journal of Food, Agriculture, Nutrition and Development ... findings, majority (84.6%) of the cow's enclosures were of poor hygiene.

  17. Ecological status of species on grazing gradients on the shallow ...

    Ecological status of species on grazing gradients on the shallow soils of the western ... Open Access DOWNLOAD FULL TEXT ... Vegetation data were gathered in such a way that those of different successional stages could be identified.

  18. Calcium Carbonate Dissolution Above the Lysocline: Implications of Copepod Grazing on Coccolithophores

    White, M. M.; Waller, J. D.; Lubelczyk, L.; Drapeau, D.; Bowler, B.; Wyeth, A.; Fields, D.; Balch, W. M.

    2016-02-01

    Copepod-coccolithophore predator-prey interactions are of great importance because they facilitate the export of particulate inorganic and organic carbon (PIC and POC) from the surface ocean. Coccolith dissolution in acidic copepod guts has been proposed as a possible explanation for the paradox of PIC dissolution above the lysocline, but warrants further investigation. Using a new application of the 14C-microdiffusion technique, we investigated the dissolution of coccoliths in copepod guts. We considered both an estuarine predator-prey model (Acartia tonsa and Pleurochrysis carterae) and an open ocean predator-prey model (Calanus finmarchicus and Emiliania huxleyi). Additionally, we considered the impacts of pCO2 on this process to advance our understanding of the effects of ocean acidification on trophic interactions. In the estuarine predator-prey model, fecal pellets produced immediately after previously-starved copepods grazed on P. carterae had PIC/POC ratios 27-40 % lower than that of the algae, indicating PIC dissolution within the copepod gut, with no impact of pCO2 on this dissolution. Subsequent fecal pellets showed increasing PIC/POC, suggesting that calcite dissolution decreases as the gut fills. The open ocean predator-prey model showed equivocal results, indicating high variability among individual grazing behavior, and therefore no consistent impact of copepod grazing on coccolith dissolution above the lysocline in the open ocean. We will further discuss the effects of fecal pellet PIC/POC ratios on sinking rate.

  19. Methodologies for evaluation of ingestive behavior of heifers supplemented in grazing

    Hermógenes Almeida de Santana Junior

    2014-06-01

    Full Text Available The study was conducted to compare different methodologies for evaluation of ingestive behavior of heifers supplemented in grazing. The experiment was conducted at Princesa do Mateiro farm, Ribeirao do Largo, Bahia. Were used 30 heifers with blood level 5/8 Guzera milk lineage and 3/8 Holstein, with an average of 18 months of age and body weight of 187 ± 13.1 kg. The treatments were: Duration of avaliation (24, 12 and eight hours of observation intervals (10, 20 and 30 minutes; repetitions for observation (three, two and one shifts of observation (two and one. The behavior evaluation was performed on day 25th, 26th, 27th and 28th of each period, then a total of four ratings. The percentage of grazing activity on the duration of 8h and 12h evaluation differed from the standard evaluation period of 24 hours (P0.05. For grazing time, rumination, feeding at the trough, other activities, total feeding and total chewing have not been verified statistical differences between the ranges of observations 20 and 30 minutes compared with 10 minutes (P<0.05. The duration of evaluation of 24 hours is recommended for evaluation of ingestive behavior in terms of nutritional and metabolic parameters, as other promote distortion of the data as a function of the intensity of activities throughout the day.

  20. Impact of cattle grazing on soil and vegetation - a case study in a mountainous region of Austria

    Bohner, Andreas; Foldal, Cecilie; Jandl, Robert

    2015-04-01

    phosphorus saturation was very high. Consequently, the risk of elevated nutrient losses via leaching and surface runoff is increased. This, in turn, may pose a threat to ground water, surface water and adjacent ecosystems. In the intensively grazed cattle pasture we observed considerable changes in plant species composition and species cover. Vegetation cover, plant species richness, pasture yield, forage quality and below-ground phytomass declined due to overgrazing. In contrast, the untrampled and unmanured habitat below the fence of the paddock can be regarded as a retreat area for many plant species which do not tolerate heavy trampling and manuring. Thus, in assessing biodiversity, this corridor should be taken into consideration. Within the paddock, we found a permanent transfer of soil nutrients and organic matter by grazing cattle, leading to a high spatial heterogeneity in some soil properties. Consequently, within intensively grazed paddocks differential manure-application rates and variations in grazing intensity are necessary.

  1. Dry matter intake, performance and carcass characteristics of hair sheep reared under different grazing systems

    Viviane Rodrigues Ventolin dos Santos

    Full Text Available ABSTRACT The aim of this study was to evaluate the effect of three different grazing systems: isolated, alternate and simultaneous, on feed intake, performance and carcass characteristics of sheep. About 5.2 ha area of Tanzania grass (Panicum maximun Jacq cultivate Tanzania was divided into 13 paddocks. This area was used as a stocking rate of two animal units (AU per ha for 7 days’ occupation and 21 days rest. A total number of 58 animals were used consisting of 12 heifers and 30 Santa Ines lambs with the addition of 16 adult ewes that were used to stabilize grazing pressure in the isolated system. The sheep were fed on 200 g per head per day of concentrate and cattle 2 kg per head per day. The parameters determined were the following: weekly weight (WW, total live weight gain (LWG and mean daily weight gain (MDW. Also dry matter intake was estimated 84 days after the start of the experiment using external indicators (Purified and Enriched Lignin in addition to carcass traits and composition which were also estimated. The result obtained for carcass composition revealed that the muscle:bone ratio and bone percentage were better in the alternate system. Moreover, the simultaneous and isolated systems showed higher lamb performance than the alternate system, while there was no effect on dry matter intake. Furthermore, there was no difference of the different systems on carcass traits and feed intake of sheep. Nevertheless, the simultaneous grazing system showed better sheep performance than the alternate grazing system.

  2. Effects of ewes grazing sulla or ryegrass pasture for different daily durations on forage intake, milk production and fatty acid composition of cheese.

    Bonanno, A; Di Grigoli, A; Mazza, F; De Pasquale, C; Giosuè, C; Vitale, F; Alabiso, M

    2016-12-01

    Sulla (Sulla coronarium L.) forage is valued for its positive impact on ruminant production, in part due to its moderate content of condensed tannin (CT). The duration of daily grazing is a factor affecting the feed intake and milk production of ewes. In this study, the effects of grazing sulla pasture compared with annual ryegrass, and the extension of grazing from 8 to 22 h/day, were evaluated with regard to ewe forage intake and milk production, as well as the physicochemical properties and fatty acid (FA) composition of cheese. During 42 days in the spring, 28 ewes of the Comisana breed were divided into four groups (S8, S22, R8 and R22) that grazed sulla (S) or ryegrass (R) for 8 (0800 to 1600 h) or 22 h/day, and received no feeding supplement. In six cheese-making sessions, cheeses were manufactured from the 48 h bulk milk of each group. Compared with ewes grazing ryegrass, those grazing sulla had higher dry matter (DM) intake, intake rate and milk yield, and produced milk that was lower in fat and higher in casein. Ewes grazing for 22 h spent more time eating, which reduced the intake rate, increased DM and nutrient intake and milk yield, and reduced milk fat. Due to the ability of CT to inhibit the complete ruminal biohydrogenation of polyunsaturated fatty acids (PUFA), the FA composition of sulla cheese was more beneficial for consumer health compared with ryegrass cheese, having lower levels of saturated fatty acids and higher levels of PUFA and n-3 FA. The FA profile of S8 cheese was better than that of S22 cheese, as it was higher in branched-chain FA, monounsaturated FA, PUFA, rumenic acid (c9,t11-C18:2), and had a greater health-promoting index. The effect of short grazing time on sulla was attributed to major inhibition of PUFA biohydrogenating ruminal bacteria, presumably stimulated by the higher accumulation of sulla CT in the rumen, which is related to a higher intake rate over a shorter eating time. Thus, grazing sulla improved the performance of

  3. Rotation grazing as a conservation management tool : Vegetation changes after six years of application in a salt marsh ecosystem

    Lagendijk, D. D. Georgette; Howison, Ruth A.; Esselink, Peter; Ubels, Richard; Smit, Christian

    2017-01-01

    Grazing is commonly used in conservation to promote biodiversity, but the search for a grazing management regime that optimises biodiversity is still ongoing. Rotation grazing, where grazing is followed by a relatively long period of non-grazing, is a relative new tool in conservation management,

  4. Population Dynamics and Transcriptomic Responses of Chorthippus albonemus (Orthoptera: Acrididae to Herbivore Grazing Intensity

    Xinghu Qin

    2017-11-01

    Full Text Available Livestock grazing can trigger outbreaks of insect pests in steppe ecosystems of Inner Mongolia in China. However, the physiological responses of the grasshopper Chorthippus albonemus to grazing are not well-understood. Here we investigated the effects of sheep grazing on the population dynamics and transcriptomic response of C. albonemus. We collected the insects three times (about 20 days apart in 1.33-ha plots in which there were no grazing, light grazing, moderate grazing, heavy grazing, or overgrazing. Our results showed that continuous grazing significantly decreased plant biomass and influenced plant succession. Total insect species diversity significantly declined along the grazing intensity gradient and over time. Results of the first two collections of C. albonemus indicated that moderate grazing significantly increased the abundance of C. albonemus. However, abundance was significantly decreased in plots that were overgrazed, possibly because of food stress and environmental pressures. Under moderate grazing, betA and CHDH genes were significantly upregulated in C. albonemus. In response to higher grazing intensity, upregulated genes included those involved in serine-type peptidase activity, anatomical structure development, and sensory organ development; downregulated genes included those involved in the structural constituents of the ribosome and ribosome processes. Genes strongly upregulated in response to heavy grazing pressure included adaptive genes such as those encoding ankyrin repeat domain-containing protein and HSP. These findings improve our understanding of the role of the transcriptome in C. albonemus population response to livestock grazing and may provide useful targets for grasshopper control.

  5. The impact of herbivores on nitrogen mineralization rate: consequences for salt-marsh succession.

    van Wijnen, Harm J; van der Wal, René; Bakker, Jan P

    1999-02-01

    Soil net N-mineralization rate was measured along a successional gradient in salt-marsh sites that were grazed by vertebrate herbivores, and in 5-year-old exclosures from which the animals were excluded. Mineralization rate was significantly higher at ungrazed than at grazed sites. In the absence of grazing, mineralization rate increased over the course of succession, whereas it remained relatively low when sites were grazed. The largest differences in mineralization rate between grazed and ungrazed sites were found at late successional stages where grazing pressure was lowest. The amount of plant litter was significantly lower at grazed sites. In addition, the amount of litter and potential litter (non-woody, live shoots) was linearly related to net N-mineralization rate. This implies that herbivores reduced mineralization rate by preventing litter accumulation. Bulk density was higher at grazed salt-marsh sites than at ungrazed sites. This factor may also have contributed to the differences in net N-mineralization rate between grazed and ungrazed sites.

  6. Effects of past and present livestock grazing on herpetofauna in a landscape-scale experiment.

    Kay, Geoffrey M; Mortelliti, Alessio; Tulloch, Ayesha; Barton, Philip; Florance, Daniel; Cunningham, Saul A; Lindenmayer, David B

    2017-04-01

    Livestock grazing is the most widespread land use on Earth and can have negative effects on biodiversity. Yet, many of the mechanisms by which grazing leads to changes in biodiversity remain unresolved. One reason is that conventional grazing studies often target broad treatments rather than specific parameters of grazing (e.g., intensity, duration, and frequency) or fail to account for historical grazing effects. We conducted a landscape-scale replicated grazing experiment (15,000 km 2 , 97 sites) to examine the impact of past grazing management and current grazing regimes (intensity, duration, and frequency) on a community of ground-dwelling herpetofauna (39 species). We analyzed community variables (species richness and composition) for all species and built multiseason patch-occupancy models to predict local colonization and extinction for the 7 most abundant species. Past grazing practices did not influence community richness but did affect community composition and patch colonization and extinction for 4 of 7 species. Present grazing parameters did not influence community richness or composition, but 6 of the 7 target species were affected by at least one grazing parameter. Grazing frequency had the most consistent influence, positively affecting 3 of 7 species (increased colonization or decreased extinction). Past grazing practice affected community composition and population dynamics in some species in different ways, which suggests that conservation planners should examine the different grazing histories of an area. Species responded differently to specific current grazing practices; thus, incentive programs that apply a diversity of approaches rather than focusing on a change such as reduced grazing intensity should be considered. Based on our findings, we suggest that determining fine-scale grazing attributes is essential for advancing grazing as a conservation strategy. © 2016 Society for Conservation Biology.

  7. The Effects of Timing of Grazing on Plant and Arthropod Communities in High-Elevation Grasslands

    Davis, Stacy C.; Burkle, Laura A.; Cross, Wyatt F.; Cutting, Kyle A.

    2014-01-01

    Livestock grazing can be used as a key management tool for maintaining healthy ecosystems. However, the effectiveness of using grazing to modify habitat for species of conservation concern depends on how the grazing regime is implemented. Timing of grazing is one grazing regime component that is less understood than grazing intensity and grazer identity, but is predicted to have important implications for plant and higher trophic level responses. We experimentally assessed how timing of cattle grazing affected plant and arthropod communities in high-elevation grasslands of southwest Montana to better evaluate its use as a tool for multi-trophic level management. We manipulated timing of grazing, with one grazing treatment beginning in mid-June and the other in mid-July, in two experiments conducted in different grassland habitat types (i.e., wet meadow and upland) in 2011 and 2012. In the upland grassland experiment, we found that both early and late grazing treatments reduced forb biomass, whereas graminoid biomass was only reduced with late grazing. Grazing earlier in the growing season versus later did not result in greater recovery of graminoid or forb biomass as expected. In addition, the density of the most ubiquitous grassland arthropod order (Hemiptera) was reduced by both grazing treatments in upland grasslands. A comparison of end-of-season plant responses to grazing in upland versus wet meadow grasslands revealed that grazing reduced graminoid biomass in the wet meadow and forb biomass in the upland, irrespective of timing of grazing. Both grazing treatments also reduced end-of-season total arthropod and Hemiptera densities and Hemiptera biomass in both grassland habitat types. Our results indicate that both early and late season herbivory affect many plant and arthropod characteristics in a similar manner, but grazing earlier may negatively impact species of conservation concern requiring forage earlier in the growing season. PMID:25338008

  8. In vitro bacterial growth and in vivo ruminal microbiota populations associated with bloat in steers grazing wheat forage.

    Min, B R; Pinchak, W E; Anderson, R C; Hume, M E

    2006-10-01

    The role of ruminal bacteria in the frothy bloat complex common to cattle grazing winter wheat has not been previously determined. Two experiments, one in vitro and another in vivo, were designed to elucidate the effects of fresh wheat forage on bacterial growth, biofilm complexes, rumen fermentation end products, rumen bacterial diversity, and bloat potential. In Exp. 1, 6 strains of ruminal bacteria (Streptococcus bovis strain 26, Prevotella ruminicola strain 23, Eubacterium ruminantium B1C23, Ruminococcus albus SY3, Fibrobacter succinogenes ssp. S85, and Ruminococcus flavefaciens C94) were used in vitro to determine the effect of soluble plant protein from winter wheat forage on specific bacterial growth rate, biofilm complexes, VFA, and ruminal H2 and CH4 in mono or coculture with Methanobrevibacter smithii. The specific growth rate in plant protein medium containing soluble plant protein (3.27% nitrogen) was measured during a 24-h incubation at 39 degrees C in Hungate tubes under a CO2 gas phase. A monoculture of M. smithii was grown similarly, except under H2:CO2 (1:1), in a basal methanogen growth medium supplemented likewise with soluble plant protein. In Exp. 2, 6 ruminally cannulated steers grazing wheat forage were used to evaluate the influence of bloat on the production of biofilm complexes, ruminal microbial biodiversity patterns, and ruminal fluid protein fractions. In Exp. 1, cultures of R. albus (P bloated than for nonbloated steers when grazing wheat forage. The molecular analysis of the 16S rDNA showed that 2 different ruminal microbiota populations developed between bloated and nonbloated animals grazing wheat forage. Bloat in cattle grazing wheat pastures may be caused by increased production of biofilm, resulting from a diet-influenced switch in the rumen bacterial population.

  9. Cyanobacterial crusts linked to soil productivity under different grazing management practices in Northern Australia

    Alchin, Bruce; Williams, Wendy

    2015-04-01

    In arid and semi-arid Australia, the central role of healthy soil ecosystems in broad-acre grazing lands may be attributed to the widespread presence of cyanobacterial crusts. In terms of soil nutrient cycling and stability their role is particularly crucial in a climate dominated by annual dry seasons and variable wet seasons. In this study, we aimed to measure the contribution of cyanobacteria to soil nutrient cycling under contrasting levels of disturbance associated with grazing management. Field sampling was carried out on six paired sites (twelve properties) located across an east-west 3,000 km transect that covered different rangeland types on grazing properties in northern Australia (Queensland, Northern Territory and Western Australia). At each location paired sites were established and two different management systems were assessed, cell-paddock rotations (25-400 ha) and continuous grazing (200-2,000 ha). Cyanobacterial soil crusts were recorded from all of the twelve sites and cyanobacteria with the capacity to fix nitrogen were found at ten of the twelve sites. The overall diversity of cyanobacteria varied from three to ten species under any type of grazing system. As field work was conducted in the dry season, it is likely that the diversity may be greater in the wet season than the initial data may indicate. The average cyanobacterial soil crust cover across soil surfaces, between grass tussocks, during the dry season was estimated to be 50.9% and, 42.6% in the early wet season. This reflected longer established crust cover (dry season) versus newly established crusts. There was a high level of variability in the biomass of cyanobacteria however; the grazing system did not have any marked effect on the biomass for any one rangeland type. The grazing system differences did not appear to significantly influence the diversity at any location except on a floodplain in the Pilbara (WA). Biological nitrogen fixation by cyanobacteria was recorded at all

  10. A conservative spectral method for the Boltzmann equation with anisotropic scattering and the grazing collisions limit

    Gamba, Irene M.; Haack, Jeffrey R.

    2014-01-01

    We present the formulation of a conservative spectral method for the Boltzmann collision operator with anisotropic scattering cross-sections. The method is an extension of the conservative spectral method of Gamba and Tharkabhushanam [17,18], which uses the weak form of the collision operator to represent the collisional term as a weighted convolution in Fourier space. The method is tested by computing the collision operator with a suitably cut-off angular cross section and comparing the results with the solution of the Landau equation. We analytically study the convergence rate of the Fourier transformed Boltzmann collision operator in the grazing collisions limit to the Fourier transformed Landau collision operator under the assumption of some regularity and decay conditions of the solution to the Boltzmann equation. Our results show that the angular singularity which corresponds to the Rutherford scattering cross section is the critical singularity for which a grazing collision limit exists for the Boltzmann operator. Additionally, we numerically study the differences between homogeneous solutions of the Boltzmann equation with the Rutherford scattering cross section and an artificial cross section, which give convergence to solutions of the Landau equation at different asymptotic rates. We numerically show the rate of the approximation as well as the consequences for the rate of entropy decay for homogeneous solutions of the Boltzmann equation and Landau equation

  11. Horse grazing systems: understory biomass and plant biodiversity of a Pinus radiata stand

    Antonio Rigueiro-Rodríguez

    2012-02-01

    Full Text Available Horse grazing systems may affect productivity and biodiversity of understory developed under Pinus radiata D. Don silvopastoral systems, while acting as a tool to reduce the risk of fire. This study compared continuous and rotational grazing systems effect upon biomass, fractions of stem, sprouts, leaves and woody parts of Ulex europaeus L. and alpha (Species Richness, Shannon-Wiener and beta (Jaccard and Magurran biodiversity for a period of four years in a P. radiata silvopastoral system. The experiment consisted of a randomized block design of two treatments (continuous and rotational grazing. Biomass, and species abundances were measured - biodiversity metrics were calculated based on these results for a two years of grazing and two years of post-grazing periods. Both continuous and rotational grazing systems were useful tools for reducing biomass and, therefore, fire risk. The rotational grazing system caused damage to the U. europaeus shrub, limiting its recovery once grazing was stopped. However, the more intensive grazing of U. europaeus plants under rotational had a positive effect on both alpha and beta biodiversity indexes due to the low capacity of food selection in the whole plot rather than continuous grazing systems. Biomass was not affected by the grazing system; however the rotational grazing system is more appropriate to reduce U. europaeus biomass and therefore forest fire risk at a long term and to enhance pasture biodiversity than the continuous grazing system.

  12. Influência da irrigação durante as épocas seca e chuvosa na taxa de lotação, no consumo e no desempenho de novilhos em pastagens de capim-elefante e capim-mombaça Effect of irrigation, during dry and rainy season, on stocking rate, intake and performance of steers grazing 'Mombaça' guineagrass and 'Napier' elephantgrass

    Enílson Geraldo Ribeiro

    2008-09-01

    irrigation on stocking rate (SR, weight gain (WG intake, nutrient intakes and in vivo digestibility in elephantgrass and mombaçagrass, under rotational grazing. Combinations of the two grasses and two irrigation levels (with and without were evaluated. Data from dry season and rainy season were analyzed separately. Irrigation was performed restore up 100% mean evapotranspiration (ET0 of the last ten-year. A total of 40 and 16 crossbred steers European × Zebu was used as tester experimental animals in the rainy and dry seasons, respectively. Similar put-and-take animals were used as to adjust grazing pressure of the green leaves biomass. In the rainy and dry seasons, irrigation has enabled the rise in the stoking rate in both forages. In the dry season, irrigation reduced the weight gain in both forages, while in the rainy season, increased the weight gain in the mombaçagrass. Irrigation did not affect intake in any of the periods evaluated, but affect the digestibility of dry matter, which reduced in the rainy season and increased in the dry season. The highest stocking rates were obtained in the mombaçagrass, while, in the elephant grass, higher values were obtained for weight gain, intake and digestibility. The means stocking rates during the rainy and dry season for the elephant grass with and without irrigation and for the mombaçagrass with and without irrigation were 5.6, 4.5, 7.7, and 4.9 anim/ha and the values of WG of 0.64, 0.68, 0.50 and 0.60 kg/day. The effect of irrigation is more evident in the stocking rate than in weight gain of animals, and in intensive grazing production systems, animal productivity (kg/ha is similar for mombaçagrass and elephantgrass.

  13. Characterization of ion-beam mixed multilayers via grazing x-ray reflectometry

    Le Boite, M.G.; Traverse, A.; Nevot, L.; Pardo, B.; Corno, J.

    1988-01-01

    The grazing x-ray reflectrometry technique was used as a way to study modifications in metallic multilayers induced by ion-beam irradiation. Due to the high sensitivity of the technique, short-range atomic displacements of an atom A in a layer B can be detected so that the first stages of ion-beam mixing can be investigated. The rate of mixing is measured and the compound A/sub 1-//sub x/B/sub x/ formed at the layers' interfaces is characterized

  14. An investigation on forage yield capacity of kermes oak (Quercus coccifera L.) and grazing planning of Mediterranean maquis scrublands for traditional goat farming.

    Tolunay, Ahmet; Adıyaman, Elif; Akyol, Ayhan; İnce, Duygu; Türkoğlu, Türkay; Ayhan, Veysel

    2014-01-01

    This study investigated grazing capacities of maquis scrubland and preparation principles of grazing management in forest resources. Kermes oak (Quercus coccifera L.), which is widespread as a main shrub species in maquis vegetation in Turkey, and pure hair goats (Capra hircus L.) feeding on shoots and leaves of this shrub were selected for study. The study was conducted in two stages. Green leaf and shoot samples were taken from kermes oaks in the first stage and the amount of green herbage yield (g ∗ m(-1)) and dry matter yield (kg ∗ ha(-1)) that may be obtained per unit area from these samples was identified. The considered amount of dry matter consumed by pure hair goats daily and the number of goats being fed within 1 year on land of 1 ha according to different land coverage rates of kermes oaks (goat head ∗ ha ∗ yr) were calculated. In the second stage, grazing capacities of sample areas where kermes oak spread were identified and compared with the grazing plan prepared by the forestry administration for this area. Forage yield variance according to land coverage rates of maquis scrublands should be considered when determining optimum animal numbers for grazing per area for sustainable goat farming.

  15. An Investigation on Forage Yield Capacity of Kermes Oak (Quercus coccifera L. and Grazing Planning of Mediterranean Maquis Scrublands for Traditional Goat Farming

    Ahmet Tolunay

    2014-01-01

    Full Text Available This study investigated grazing capacities of maquis scrubland and preparation principles of grazing management in forest resources. Kermes oak (Quercus coccifera L., which is widespread as a main shrub species in maquis vegetation in Turkey, and pure hair goats (Capra hircus L. feeding on shoots and leaves of this shrub were selected for study. The study was conducted in two stages. Green leaf and shoot samples were taken from kermes oaks in the first stage and the amount of green herbage yield (g*m−1 and dry matter yield (kg*ha−1 that may be obtained per unit area from these samples was identified. The considered amount of dry matter consumed by pure hair goats daily and the number of goats being fed within 1 year on land of 1 ha according to different land coverage rates of kermes oaks (goat head*ha*yr were calculated. In the second stage, grazing capacities of sample areas where kermes oak spread were identified and compared with the grazing plan prepared by the forestry administration for this area. Forage yield variance according to land coverage rates of maquis scrublands should be considered when determining optimum animal numbers for grazing per area for sustainable goat farming.

  16. Graphite irradiated by swift heavy ions under grazing incidence

    Liu, J; Müller, C; Neumann, R

    2002-01-01

    Highly oriented pyrolytic graphite is irradiated with various heavy projectiles (Ne, Ni, Zn, Xe and U) in the MeV to GeV energy range under different oblique angles of incidence. Using scanning tunneling microscopy, the impact zones are imaged as hillocks protruding from the surface. The diameter of surface-grazing tracks varies between 3 nm (Ne) and 6 nm (U), which is about twice as large as under normal beam incidence. Exclusively for U and Xe projectiles, grazing tracks exhibit long comet-like tails consisting of successive little bumps indicating that the damage along the ion path is discontinuous even for highest electronic stopping powers.

  17. 1000 years of sustainable grazing in Nordic conditions?

    Brandt, Jesper

    landscapes at different spatial levels. Information on much of this sort of regulation has however been lost through modern times, tended to prefer modern (nature) scientific methods primarily developed as general (meaning not spatially contextual) recommendations for raising productivity. During the later...... years this modern tradition has also been preferred by investigations to find solutions for non-sustainable types of land use in grazing systems. However, much sustainability-relevant wisdom has been accumulated in historical grazing-systems that should be included in the repertoire of knowledge...

  18. X-ray grazing incidence diffraction from multilayers

    Tixier, S.; Boeni, P.; Swygenhoven, H. van; Horisberger, M. [Paul Scherrer Inst. (PSI), Villigen (Switzerland)

    1997-09-01

    Grazing incidence scattering geometries using synchrotron radiation have been applied in order to characterise the roughness profiles and the structural coherence of multilayers. The lateral correlation length of the roughness profiles was evaluated using diffuse reflectivity in the `out of plane` geometry. This type of measurement is the only diffuse reflectivity technique allowing large lateral momentum transfer. It is typically suitable for correlation lengths smaller than 1000 A. The lateral structural coherence length of Ni{sub 3}Al/Ni multilayers as a function of the layer thickness was obtained by grazing incidence diffraction (GID). 3 figs., 1 ref.

  19. Modelagem comparativa da cinética de fluxo da fase sólida do capim-elefante (Pennisetum purpureum, Schumack consumido sob pastejo por vacas mestiças Holandês × Zebu em lactação Evaluation of mathematical models to estimate the passage rate of solids in Holstein × Zebu lactating cows grazing on elephantgrass (Pennisetum purpureum, Schumack

    F.C.F. Lopes

    2003-12-01

    treatments: 1- resting period of 30 days without concentrate, 2- resting period of 30 days with concentrate and 3- resting period of 45 days with concentrate. In the dry season cows grazed elephantgrass during the night and were fed on chopped sugarcane plus 1% ammonium sulphate:urea (9:1 between milkings. The rate of passage was estimated by using chromium complexed to the cellular wall of elephantgrass extrusas collected during the first, second and third grazing days of each treatment. In the second trial carried out during the rainy season 12 lactating crossbred cows (four rumen fistulated were used. The treatments were resting periods of 30 or 45 days without supplementation. Parameters of particulate passage kinectics were estimated by two models (age-independent double-compartmental and age-dependent multicompartmental which provided similar results of ruminal passage rates values. However, larger values of post-ruminal passage rates were generally obtained with the age-dependent multicompartmental model. In the dry season, the ruminal and post-ruminal passage rates were, respectively, 0.042 and 0.087/h (age-independent double-compartmental model and 0.041 and 0.109/h (age-dependent multicompartmental model. In the rainy season, values of 0.035 and 0.056/h, and 0.029 and 0.090/h, were observed, respectively.

  20. Relationships among Body Condition, Insulin Resistance and Subcutaneous Adipose Tissue Gene Expression during the Grazing Season in Mares.

    Shaimaa Selim

    Full Text Available Obesity and insulin resistance have been shown to be risk factors for laminitis in horses. The objective of the study was to determine the effect of changes in body condition during the grazing season on insulin resistance and the expression of genes associated with obesity and insulin resistance in subcutaneous adipose tissue (SAT. Sixteen Finnhorse mares were grazing either on cultivated high-yielding pasture (CG or semi-natural grassland (NG from the end of May to the beginning of September. Body measurements, intravenous glucose tolerance test (IVGTT, and neck and tailhead SAT gene expressions were measured in May and September. At the end of grazing, CG had higher median body condition score (7 vs. 5.4, interquartile range 0.25 vs. 0.43; P=0.05 and body weight (618 kg vs. 572 kg ± 10.21 (mean ± SEM; P=0.02, and larger waist circumference (P=0.03 than NG. Neck fat thickness was not different between treatments. However, tailhead fat thickness was smaller in CG compared to NG in May (P=0.04, but this difference disappeared in September. Greater basal and peak insulin concentrations, and faster glucose clearance rate (P=0.03 during IVGTT were observed in CG compared to NG in September. A greater decrease in plasma non-esterified fatty acids during IVGTT (P<0.05 was noticed in CG compared to NG after grazing. There was down-regulation of insulin receptor, retinol binding protein 4, leptin, and monocyte chemoattractant protein-1, and up-regulation of adiponectin (ADIPOQ, adiponectin receptor 1 and stearoyl-CoA desaturase (SCD gene expressions in SAT of both groups during the grazing season (P<0.05. Positive correlations were observed between ADIPOQ and its receptors and between SCD and ADIPOQ in SAT (P<0.01. In conclusion, grazing on CG had a moderate effect on responses during IVGTT, but did not trigger insulin resistance. Significant temporal differences in gene expression profiles were observed during the grazing season.

  1. Effect of grazing on the cow welfare of dairy herds evaluated by a multidimensional welfare index

    Burow, E.; Rousing, T.; Thomsen, P. T.

    2013-01-01

    Structural development in the prime sector has led to increasing herd sizes and new barn systems, followed by less summer grazing for dairy cows in Denmark. Effects of grazing on single welfare measures in dairy cows - for example, the presence of integument alterations or mortality - have been......) inspired multidimensional dairy cow welfare assessment protocol, the within-herd effect of summer grazing compared with winter barn housing in Danish dairy herds with cubicle free-stall systems for the lactating cows. Our hypothesis was that cow welfare in dairy herds was better during summer grazing than...... out to be more beneficial than few daily grazing hours (range average above 9 to 21 h) for the welfare of the dairy herds. In conclusion, this study reports a positive within-herd effect of summer grazing on dairy cow welfare, where many daily grazing hours were more beneficial than few daily grazing...

  2. Corticosterone metabolite concentrations in greater sage-grouse are positively associated with the presence of cattle grazing

    Jankowski, M.D.; Russell, Robin E.; Franson, J. Christian; Dusek, Robert J.; Hines, M.K.; Gregg, M.; Hofmeister, Erik K.

    2014-01-01

    The sagebrush biome in the western United States is home to the imperiled greater sage-grouse (Centrocercus urophasianus) and encompasses rangelands used for cattle production. Cattle grazing activities have been implicated in the range-wide decline of the sage-grouse, but no studies have investigated the relationship between the physiological condition of sage-grouse and the presence of grazing cattle. We sampled 329 sage-grouse across four sites (two grazed and two ungrazed) encompassing 13 600 km2 during the spring and late summer–early autumn of 2005 to evaluate whether demographic factors, breeding status, plasma protein levels, and residence in a cattle-grazed habitat were associated with the stress hormone corticosterone. Corticosterone was measured in feces as immunoreactive corticosterone metabolites (ICM). Males captured during the lekking season exhibited higher ICM levels than all others. Prenesting female sage-grouse captured in a grazed site had higher ICM levels than those in ungrazed sites and prenesting female plasma protein levels were negatively correlated with ICM concentrations. With the use of a small-scale spatial model, we identified a positive correlation between cattle pat count and sage-grouse ICM levels. Our model indicated that ICM levels increased by 2.60 ng · g-1 dry feces for every increase in the number of cow pats found in the vicinity. Management practices will benefit from future research regarding the consistency and mechanism(s) responsible for this association and, importantly, how ICM levels and demographic rates are related in this species of conservation concern.

  3. Impact of Graze-­‐Out in Hard Red Winter Wheat Production

    Neupane, Diwash; Moss, Charles B.

    2014-01-01

    We investigate the relationship between wheat graze-­‐out and cattle-­‐wheat price ratio and moisture level and examine the impact of graze-­‐out on wheat yield in major wheat-­‐producing states in US. Results indicate that cattle-­‐wheat price ratio and moisture level affect farmers’ graze out decision and graze-­‐out have significant impact on wheat yield.

  4. Effect of corn dry distiller grains plus solubles supplementation level on performance and digestion characteristics of steers grazing native range during forage growing season.

    Martínez-Pérez, M F; Calderón-Mendoza, D; Islas, A; Encinias, A M; Loya-Olguín, F; Soto-Navarro, S A

    2013-03-01

    linearly increased (P = 0.01) and slowly degradable CP fraction linearly decreased (P = 0.05) with increasing DDGS supplementation level. Forage in situ masticate DM and NDF disappearance rate decreased (quadratic; P ≤ 0.05) and DDGS in situ DM disappearance rate increased (linear; P = 0.03) with increasing supplementation levels. These results indicate that DDGS supplementation enhanced grazing performance and total-tract digestion of steers grazing native range during the forage growing season.

  5. Influence of grazing regimes on cattle nutrition and performance and vegetation dynamics in Sahelian rangelands

    Ayantunde, A.A.

    1998-01-01

    In the West African Sahel, common herd management practices such as night grazing and corralling influence time available for grazing. When animals are used to deposit manure in the cropping fields, conflicts often arise between the need for animals to graze long enough for adequate feed

  6. 36 CFR 251.103 - Mediation of term grazing permit disputes.

    2010-07-01

    ... 36 Parks, Forests, and Public Property 2 2010-07-01 2010-07-01 false Mediation of term grazing... Lands § 251.103 Mediation of term grazing permit disputes. (a) Decisions subject to mediation. In those States with Department of Agriculture certified mediation programs, any holder of a term grazing permit...

  7. 36 CFR 222.53 - Grazing fees in the East-noncompetitive procedures.

    2010-07-01

    ... lands and the total costs (other than grazing fee costs) of operating on National Forest System lands... the percentage change in the cost of alternative livestock feed. (3) Computation of Annual Grazing Fee... 36 Parks, Forests, and Public Property 2 2010-07-01 2010-07-01 false Grazing fees in the East...

  8. Steers grazing of a rye cover crop influences growth of rye and no-till cotton

    Small grain cover crops offer opportunities for grazing but effects on following row crops are not well understood. From 1999 through 2008, stocker steers sequence grazed small grains in a 2-paddock rye-cotton-wheat-fallow- rye rotation. Treatments imposed on rye included 1) zero-grazing from 1999; ...

  9. The impact of herbivores on nitrogen mineralization rate : consequences for salt-marsh succession

    van Wijnen, HJ; van der Wal, R; Bakker, JP

    Soil net N-mineralization rate was measured along a successional gradient in salt-marsh sites that were grazed by vertebrate herbivores, and in 5-year-old exclosures from which the animals were excluded. Mineralization rate was significantly higher at ungrazed than at grazed sites. In the absence of

  10. Biomass requirements from natural pastures for livestock grazing ...

    The problem of seasonal shortages of herbage production from natural pastures in the Ethiopian highlands was investigated. This was done by comparing the available biomass amounts on the pastures with biomass amounts required for livestock grazing and for protecting land slope from soil erosion within a given slope ...

  11. Livestock grazing has minimal effect on the species richness and ...

    The Succulent Karoo, one of two arid biodiversity hotspots in the world, is known for its high plant species richness, but little is known about the influence of topography and how it mediates the potentially deleterious effects of grazing. Changes in vegetation species composition, cover and species diversity were examined ...

  12. Ingestive Behaviour of Grazing Ewes Given Two Levels of Concentrate

    It was expected that concentrate supplementation would reflect directly on forage intake owing to the substitution effect, which causes sheep where the supplement supplied a small proportion of net energy requirement, to have a greater grazing intensity. The two breeds differed in the time spent ruminating or lying, with the ...

  13. Radiobiological problems concerning grazing animals following the Chernobyl accident

    Prister, B.S.; Lazarev, N.M.; Romanov, L.M.

    1997-01-01

    Chernobyl accident took place on April 26 1986, which was the beginning of the grazing season, when there was not enough fodder on the farms and the cattle was grazed on the open territory. Therefore grazing animal-breeding was the most radioactively affected branch. The consumption of contaminated fodder and surface contamination with radioactive precipitation caused the accumulation of considerable ingested doses in the organisms of animals (up to 1 GY). Radioactive damage caused to the thyroid by the selective accumulation of radioiodine (mainly 131 I) is of particular attention. Cumulative doses of thyroid irradiation in mammals were much higher than for the other organs. Thus, in cows during their grazing on the contaminated pastures outside 30-km zone the ratio of ingested doses of the thyroid and whole body was 130:1 and more, therefore, radiation effects could have a certain negative effect, concerning the agricultural animals in the zone of accidental release influence. Accumulated ingested doses in the thyroid of cows on the contaminated territory in a number of cases caused the complete destruction of the thyroid (doses above 600 Gy), which provided the loss of milk productivity and reproductive qualities of the animals. Lower doses caused the functional disturbances, which in most cases have been levelled during the years after the accident

  14. The evolution of institutions and rules governing communal grazing ...

    This paper traces the tradition and evolution of the institutions and rules governing communal grazing lands in Botswana. It shows how the problem of resource overuse arose partly from the dismantling and delegitimization of traditional resource management institutions that occurred during the colonial period, and was ...

  15. Bacterial production, protozoan grazing, and mineralization in stratified Lake Vechten

    Bloem, J.

    1989-01-01

    The role of heterotrophic nanoflagellates (HNAN, size 2-20 μm) in grazing on bacteria and mineralization of organic matter in stratified Lake Vechten was studied.

    Quantitative effects of manipulation and fixation on HNAN were checked. Considerable losses were caused by

  16. Assessment of the Effects of Emerging Grazing Policies on Land ...

    Journal of Applied Sciences and Environmental Management ... policies on land degradation in Nigeria using soil, vegetation and sustainability as variables for the assessment. ... animals per kilometer square of land and 15,000 persons and 12,500 grazing animals per kilometer square of water. ... OTHER RESOURCES.

  17. Influence of sward characteristics on grazing behaviour and short ...

    Relative to temperate systems, there has been few reported detailed assessments of sward characteristics and associated grazing behavior from natural and ... in highly heterogeneous pastures has the potential to provide integrated (sward, animal, management) strategies for sustainable livestock production in Nigeria.

  18. The national grazing strategy of the Republic of South Africa ...

    The White Paper on Agricultural Policy, tabled in May 1984, made reference to the alarming deterioration of natural rangelands and led to the drawing up of the National Grazing Strategy (NGS), released to parliament in May 1985, which was endorsed by the Department of Agriculture and accepted in its entirety by the ...

  19. The impact of grazing on forage quality of the herbaceous ...

    Reports on research conducted in the Mamoro cork oak forest of Morocco to describe the impacts of sheep grazing in March, April, May and June of 1987 and 1988 on seasonal changes in forage quality of the herbaceous vegetation. The study showed that trends in herbage quality were related mainly to plant maturity.

  20. Grazing on Regeneration Sites Encourages Pine Seedling Growth

    Raymond D. Ratliff; Renee G. Denton

    1995-01-01

    Effects of season-long, deferred-rotation, and rest-rotation grazing, on ponderosa pine (Pinus ponderosa Dougl. ex Laws.) seedling growth and herbaceous vegetation control were studied in regeneration sites at Boyd Hill, Modoc National Forest, California. Seedlings were planted in 1989. Pine seedling survival and damage did not differ, but the...

  1. The Occurrence and Toxicity of Indospicine to Grazing Animals

    Mary T. Fletcher

    2015-07-01

    Full Text Available Indospicine is a non-proteinogenic amino acid which occurs in Indigofera species with widespread prevalence in grazing pastures across tropical Africa, Asia, Australia, and the Americas. It accumulates in the tissues of grazing livestock after ingestion of Indigofera. It is a competitive inhibitor of arginase and causes both liver degeneration and abortion. Indospicine hepatoxicity occurs universally across animal species but the degree varies considerably between species, with dogs being particularly sensitive. The magnitude of canine sensitivity is such that ingestion of naturally indospicine-contaminated horse and camel meat has caused secondary poisoning of dogs, raising significant industry concern. Indospicine impacts on the health and production of grazing animals per se has been less widely documented. Livestock grazing Indigofera have a chronic and cumulative exposure to this toxin, with such exposure experimentally shown to induce both hepatotoxicity and embryo-lethal effects in cattle and sheep. In extensive pasture systems, where animals are not closely monitored, the resultant toxicosis may well occur after prolonged exposure but either be undetected, or even if detected not be attributable to a particular cause. Indospicine should be considered as a possible cause of animal poor performance, particularly reduced weight gain or reproductive losses, in pastures where Indigofera are prevalent.

  2. Holistic Management: Misinformation on the Science of Grazed Ecosystems

    John Carter

    2014-01-01

    Full Text Available Over 3 billion hectares of lands worldwide are grazed by livestock, with a majority suffering degradation in ecological condition. Losses in plant productivity, biodiversity of plant and animal communities, and carbon storage are occurring as a result of livestock grazing. Holistic management (HM has been proposed as a means of restoring degraded deserts and grasslands and reversing climate change. The fundamental approach of this system is based on frequently rotating livestock herds to mimic native ungulates reacting to predators in order to break up biological soil crusts and trample plants and soils to promote restoration. This review could find no peer-reviewed studies that show that this management approach is superior to conventional grazing systems in outcomes. Any claims of success due to HM are likely due to the management aspects of goal setting, monitoring, and adapting to meet goals, not the ecological principles embodied in HM. Ecologically, the application of HM principles of trampling and intensive foraging are as detrimental to plants, soils, water storage, and plant productivity as are conventional grazing systems. Contrary to claims made that HM will reverse climate change, the scientific evidence is that global greenhouse gas emissions are vastly larger than the capacity of worldwide grasslands and deserts to store the carbon emitted each year.

  3. Research note: Grazing-index method procedures of vegetation ...

    In the past, veld condition in the Karoo was assessed using the ecological index methods. This recently changed to the graxing-index method on account of the of the differently estimated grazing-index values being used. The principles governing the method of survey remain the same. The method employs ...

  4. Phosphorus and the grazing ruminant. 1. The effect of ...

    M.Sc.-tesis,. Universiteit Stellenbosch. DUDZINSKI, M.L. & ARNOLD, G.W., 1973. Comparison of diets of sheep and cattle grazing together on sown pastures on the southern tablelands of New South Wales by principal components analysis. Aust. J. Agric. Res. 24, 899. DU TOlT, P.J., MALAN, AI. & ROSSOUW, S.D., 1930.

  5. Research Note Identifying key grazing indicators to monitor trends in ...

    Research Note Identifying key grazing indicators to monitor trends in the veld condition of Lambert's Bay Strandveld, South Africa. ... from which a minimum number of species necessary to monitor trends in the condition of the veld were determined, making it user-friendly for land-users, extension officers and others. The key ...

  6. Grazing animal husbandry based on sustainable nutrient management

    Hermans, C.; Vereijken, P.H.

    1995-01-01

    Sustainable husbandry systems for grazing animals (cattle and sheep) can be achieved by sustainable nutrient management (SNM). This implies the tuning of inputs to outputs of nutrients, to achieve and maintain optimum ranges of agronomically wanted and ecologically acceptable reserves of single

  7. Improved grazing activity of dairy heifers in shaded tropical grasslands

    Andréia Cristina Tavares de Mello

    Full Text Available ABSTRACT: Trees in the production systems can effectively reduce hot weather-induced stress in the Brazilian Midwest. High temperatures cause changes in animals daily routine, and trees into pastures can promote benefits. The aim of this research was to evaluate the behavior of dairy heifers in silvopastoral systems in the state of Mato Grosso, Brazil. A herd of 24 crossbreed heifers (3/4 and 7/8 Holstein/Zebu, 350kg average weight, was evaluated over three seasons. Piatã grass was managed under three shade levels: full-sun, moderate-shade, and intensive-shade provided by 10 to 12m high Eucalyptus trees. Behavior data were collected every 15 minutes from 8:30h to 16h. Shade availability significantly impacted heifer behavior, mainly affecting grazing frequency and time during the hottest hours. Grazing behavior was affected by shade levels during the different seasons. Heifers showed preferred grazing times. Heifers in the intensive-shade system visited shady areas during the hottest hours throughout the seasons. Heifers in the full sun-system avoided grazing during the warmer times, ceasing feeding activities. Our results from the Brazilian Midwest showed that shade availability causes breed heifers to change their daily routine.

  8. Surface - atmosphere exchange of ammonia over grazed pasture

    Plantaz, M.A.H.G.

    1998-01-01

    This thesis deals with the exchange of ammonia between the atmosphere and grazed pasture in an area of intensive livestock breeding. The term exchange is used because gaseous ammonia can be taken up (dry deposition) as well as released (emission) by this type of surface.
    Ammonia exchange

  9. Assessment of the Effects of Emerging Grazing Policies on Land ...

    ADOWIE PERE

    carbon sequestration and water filtration. ... temperature of 13oc in the north during the harmattan in ... vegetation cover is removed with the view to obtain ... data concerning environmental degradation mitigation ... in terrestrial ecosystems and driving processes that .... Grazing systems, ecosystem response, and global.

  10. Effects of rainfall, competition and grazing on flowering of ...

    Birds, hares and small antelope consumed 10-50% of the flowers. Size-class distributions indicated that little recent recruitment had taken place on a ranch where palatable plants were scarce and where O. sinuatum flower production was severely depressed by grazing sheep.Language: English. Keywords: Asteraceae ...

  11. Response of mountain meadows to grazing by recreational pack stock

    David N. Cole; Jan W. van Wagtendonk; Mitchel P. McClaran; Peggy E. Moore; Neil K. McDougald

    2004-01-01

    Effects of recreational pack stock grazing on mountain meadows in Yosemite National Park were assessed in a 5-year study. Yosemite is a designated wilderness, to be managed such that its natural conditions are preserved. Studies were conducted in 3 characteristic meadow types: shorthair sedge (Carex filifolia Nutt.), Brewer’s reed grass (...

  12. Preliminary survey on tsetse flies and trypanosomosis at grazing ...

    Preliminary survey on tsetse flies and trypanosomosis were conducted between. July and August 2007 at grazing fields and villages in and around the Nech Sar national park, with the ultimate intention of forwarding baseline information on the extent of the problem and possible control strategies. . Entomological (Tsetse.

  13. Determining grazing capacity in Namibia with the aid of remote ...

    The Namibian rangelands consist of a mixture of herbaceous and woody components. The main source of income is from farming systems with grass production the predominant source of forage. For rangeland managers to utilise this source sustainably, the accurate determination of grazing capacity is vital since it allows ...

  14. Magnetic alignment in grazing and resting cattle and deer

    Begall, S.; Červený, Jaroslav; Neef, J.; Burda, H.; Vojtěch, O.

    2008-01-01

    Roč. 105, č. 36 (2008), s. 13451-13455 ISSN 0027-8424 Institutional research plan: CEZ:AV0Z60930519 Keywords : grazing behavior * magnetic alignment * magnetoreception * resting behavior * spatial orientation Subject RIV: EH - Ecology, Behaviour Impact factor: 9.380, year: 2008

  15. Butterfly responses to prairie restoration through fire and grazing

    Vogel, Jennifer A.; Debinski, Diane M.; Koford, Rolf R.; Miller, J.R.

    2007-01-01

    The development of land for modern agriculture has resulted in losses of native prairie habitat. The small, isolated patches of prairie habitat that remain are threatened by fire suppression, overgrazing, and invasion by non-native species. We evaluated the effects of three restoration practices (grazing only, burning only, and burning and grazing) on the vegetation characteristics and butterfly communities of remnant prairies. Total butterfly abundance was highest on prairies that were managed with burning and grazing and lowest on those that were only burned. Butterfly species richness did not differ among any of the restoration practices. Butterfly species diversity was highest on sites that were only burned. Responses of individual butterfly species to restoration practices were highly variable. In the best predictive regression model, total butterfly abundance was negatively associated with the percent cover of bare ground and positively associated with the percent cover of forbs. Canonical correspondence analysis revealed that sites with burned only and grazed only practices could be separated based on their butterfly community composition. Butterfly communities in each of the three restoration practices are equally species rich but different practices yield compositionally different butterfly communities. Because of this variation in butterfly species responses to different restoration practices, there is no single practice that will benefit all species or even all species within habitat-specialist or habitat-generalist habitat guilds. ?? 2007 Elsevier Ltd. All rights reserved.

  16. Production response of lambs receiving creep feed while grazing ...

    The aim of the study was to determine the production responses of lambs receiving either creep feed or not while grazing two different pastures. The production of ewes within each treatment was also recorded. The study was conducted at both the Kromme Rhee and Langgewens Research Farms. At Kromme Rhee, sheep ...

  17. Semi-arid grassland bird responses to patch-burn grazing and drought

    Skagen, Susan K.; Augustine, David J.; Derner, Justin D.

    2018-01-01

    As grassland birds of central North America experience steep population declines with changes in land use, management of remaining tracts becomes increasingly important for population viability. The integrated use of fire and grazing may enhance vegetation heterogeneity and diversity in breeding birds, but the subsequent effects on reproduction are unknown. We examined the influence of patch-burn grazing management in shortgrass steppe in eastern Colorado on habitat use and reproductive success of 3 grassland bird species, horned lark (Eremophila alpestris), lark bunting (Calamospiza melanocorys), and McCown’s longspur (Rhynchophanes mccownii), at several spatial scales during 2011 and 2012. Although no simple direct relationship to patch-burn grazing treatment existed, habitat selection depended on precipitation- and management-induced vegetation conditions and spatial scale. All species selected taller-than-expected vegetation at the nest site, whereas at the territory scale, horned larks and McCown’s longspurs selected areas with low vegetation height and sparse cover of tall plants (taller than the dominant shortgrasses). Buntings nested primarily in unburned grassland under average rainfall. Larks and longspurs shifted activity from patch burns during average precipitation (2011) to unburned pastures during drought (2012). Daily survival rate (DSR) of nests varied with time in season, species, weather, and vegetation structure. Daily survival rate of McCown’s longspur nests did not vary with foliar cover of relatively tall vegetation at the nest under average precipitation but declined with increasing cover during drought. At the 200-m scale, increasing cover of shortgrasses, rather than taller plant species, improved DSR of larks and longspurs. These birds experience tradeoffs in the selection of habitat at different spatial scales: tall structure at nests may reduce visual detection by predators and provide protection from sun, wind, and rain, yet

  18. Simulating grazing practices in a complete livestock system model: estimating soil carbon storage and greenhouse gas emissions in grazed versus un-grazed agroecosystems using the Manure-DNDC model

    Campbell, E. E.; Dorich, C.; Contosta, A.; Varner, R. K.

    2017-12-01

    In livestock agroecosystems, the combined contributions of enteric fermentation, manure management, and livestock grazing and/or feed production play an important role in agroecosystem carbon (C) storage and GHG losses, with complete livestock system models acting as important tools to evaluate the full impacts of these complex systems. The Manure-DeNitrification-DeComposition (DNDC) model is one such example, simulating impacts on C and nitrogen cycling, estimating methane, carbon dioxide, nitrous oxide, and ammonium dynamics in fields, manure storage, and enteric emissions. This allows the evaluation of differences in GHG and soil C impacts between conventional and organic dairy production systems, which differ in their use of grazed pasture versus confined feeding operations. However, Manure-DNDC has received limited testing in representing variations in grazed pasture management (i.e. intensive rotational grazing versus standard grazing practices). Using a set of forage biomass, soil C, and GHG emissions data collected at four sites across New England, we parameterized and validated Manure-DNDC estimations of GHG emissions and soil C in grazed versus un-grazed systems. Soil observations from these sites showed little effect from grazing practices, but larger soil carbon differences between farms. This may be due to spatial variation in SOC, making it difficult to measure and model, or due to controls of edaphic properties that make management moot. However, to further address these questions, model development will be needed to improve Manure-DNDC simulation of rotational grazing, as high stocking density grazing over short periods resulted in forage not re-growing sufficiently within the model. Furthermore, model simulations did not account for variation in interactions between livestock and soil given variability in field microclimates, perhaps requiring simulations that divide a single field into multiple paddocks to move towards more accurate evaluation of

  19. Evaluating pasture and soil allowance of manganese for Kajli rams grazing in semi-arid environment.

    Khan, Zafar Iqbal; Ahmad, Kafeel; Ashraf, Muhammad; Naqvi, Syed Ali Hassan; Seidavi, Alireza; Akram, Nudrat Aisha; Laudadio, Vito; Tufarelli, Vincenzo

    2015-03-01

    The current research on the manganese (Mn) transfer from soil to plant as well as to grazing Kajli rams in the form of sampling periods was carried out under semi-arid environmental conditions. Forage, soil and blood plasma samples were collected during 4 months of the year after a 1-month interval, and Mn concentrations were assessed after wet digestion using an atomic absorption spectrophotometer. Results showed that Mn concentration in soil ranged from 48.28 to 59.44 mg/kg, with incoherent augment and decline across sampling periods, and effect of sampling period on soil Mn was also found to be significant (P soil appeared higher than the critical value and sufficient for forage crop requirement. The Mn concentration in forage ranged between 24.8 and 37.2 mg/kg, resulting deficient based on the requirement allowance of Mn for livestock grazing animals, therein with almost unchanged forage Mn concentration. The Mn values in blood plasma of rams varied from 0.066 to 0.089 mg/l, with a consistent increase based on sampling period, and the effect of sampling periods on plasma Mn was found to be highly significant (P soil and plant species amassing capability on the transport of Mn in the soil-plant-animal system. Results indicated a much higher accumulation rate at the sampling characterized by vegetation dominated by legumes in comparison to grasses, crop residues and mixed pasture and a pronounced seasonal supply of Mn at the four sampling period of grazing land of diverse botanical composition.

  20. Algal grazing by the planktonic copepods Centropages hamatus and Pseudocalanus sp.: Diurnal and seasonal variation during the spring phytoplankton bloom in the Øresund Denmark

    Nicolajsen, Hanne; Møhlenberg, Flemming; Kiørboe, Thomas

    1983-01-01

    Seasonal and diel variation in rate of algal grazing were estimated from measurements of gut content (plant pigments) and gut turnover in the copepods C. hamatus and Pseudocalanus sp. during spring (Jan.-May) in the Oresund. Both species exhibited significant diel variation in gut content...

  1. Patterns in Greater Sage-grouse population dynamics correspond with public grazing records at broad scales.

    Monroe, Adrian P; Aldridge, Cameron L; Assal, Timothy J; Veblen, Kari E; Pyke, David A; Casazza, Michael L

    2017-06-01

    Human land use, such as livestock grazing, can have profound yet varied effects on wildlife interacting within common ecosystems, yet our understanding of land-use effects is often generalized from short-term, local studies that may not correspond with trends at broader scales. Here we used public land records to characterize livestock grazing across Wyoming, USA, and we used Greater Sage-grouse (Centrocercus urophasianus) as a model organism to evaluate responses to livestock management. With annual counts of male Sage-grouse from 743 leks (breeding display sites) during 2004-2014, we modeled population trends in response to grazing level (represented by a relative grazing index) and timing across a gradient in vegetation productivity as measured by the Normalized Vegetation Difference Index (NDVI). We found grazing can have both positive and negative effects on Sage-grouse populations depending on the timing and level of grazing. Sage-grouse populations responded positively to higher grazing levels after peak vegetation productivity, but populations declined when similar grazing levels occurred earlier, likely reflecting the sensitivity of cool-season grasses to grazing during peak growth periods. We also found support for the hypothesis that effects of grazing management vary with local vegetation productivity. These results illustrate the importance of broad-scale analyses by revealing patterns in Sage-grouse population trends that may not be inferred from studies at finer scales, and could inform sustainable grazing management in these ecosystems. © 2017 by the Ecological Society of America.

  2. Livestock grazing intensity affects abundance of Common shrews (Sorex araneus) in two meadows in Denmark

    Schmidt, Niels M; Olsen, Henrik; Leirs, Herwig

    2009-01-01

    Background Current nature conservation in semi-natural grasslands often includes grazing and hay cutting, as well as the abandonment of draining. Semi-natural grassland and in particular meadows constitute important habitat type for a large number of animal species in today's fragmented and intensively cultivated landscape of Europe. Here we focus on the population characteristics of Common shrews Sorex araneus in relation to livestock grazing intensity in two wet meadows in western Denmark. Results High grazing intensity had a significant negative effect on Common shrew number compared to low grazing intensity and no grazing. Common shrew abundance was generally, but not significantly, higher on the low grazing intensity plots than on the ungrazed controls. No differences in body mass, sex ratio, or reproductive output between Common shrew individuals from the various grazing treatments were found. Conclusion No negative effects of low intensity grazing on Common shrew abundance were found compared to the ungrazed control. Low intensity grazing thus seems a suitable management regime for Common shrews, when grazing is needed as part of the meadow management scheme. High intensity grazing on the other hand is not a suitable management tool. PMID:19152713

  3. Livestock grazing intensity affects abundance of Common shrews (Sorex araneus in two meadows in Denmark

    Olsen Henrik

    2009-01-01

    Full Text Available Abstract Background Current nature conservation in semi-natural grasslands often includes grazing and hay cutting, as well as the abandonment of draining. Semi-natural grassland and in particular meadows constitute important habitat type for a large number of animal species in today's fragmented and intensively cultivated landscape of Europe. Here we focus on the population characteristics of Common shrews Sorex araneus in relation to livestock grazing intensity in two wet meadows in western Denmark. Results High grazing intensity had a significant negative effect on Common shrew number compared to low grazing intensity and no grazing. Common shrew abundance was generally, but not significantly, higher on the low grazing intensity plots than on the ungrazed controls. No differences in body mass, sex ratio, or reproductive output between Common shrew individuals from the various grazing treatments were found. Conclusion No negative effects of low intensity grazing on Common shrew abundance were found compared to the ungrazed control. Low intensity grazing thus seems a suitable management regime for Common shrews, when grazing is needed as part of the meadow management scheme. High intensity grazing on the other hand is not a suitable management tool.

  4. The influence of grazing on surface climatological variables of tallgrass prairie. Final Technical Report

    Seastedt, T.R.; Dyer, M.I.; Turner, C.L.

    1992-01-01

    Mass and energy exchange between most grassland canopies and the atmosphere are mediated by grazing activities. Ambient temperatures can be increased or decreased by grazers. Data have been assembled from simulated grazing experiments on Konza Prairie Research Natural Area and observations on adjacent pastures grazed by cattle show significant changes in primary production, nutrient content, and bidirectional reflectance characteristics as a function of grazing intensity. The purpose of this research was to provide algorithms that would allow incorporation of grazing effects into models of energy budgets using remote sensing procedures. The approach involved: (1) linking empirical measurements of plant biomass and grazing intensities to remotely sensed canopy reflectance, and (2) using a higher resolution, mechanistic grazing model to derive plant ecophysiological parameters that influence reflectance and other surface climatological variables

  5. The effects of burning and grazing on soil carbon dynamics in managed Peruvian tropical montane grasslands

    V. Oliver

    2017-12-01

    Full Text Available Montane tropical soils are a large carbon (C reservoir, acting as both a source and a sink of CO2. Enhanced CO2 emissions originate, in large part, from the decomposition and losses of soil organic matter (SOM following anthropogenic disturbances. Therefore, quantitative knowledge of the stabilization and decomposition of SOM is necessary in order to understand, assess and predict the impact of land management in the tropics. In particular, labile SOM is an early and sensitive indicator of how SOM responds to changes in land use and management practices, which could have major implications for long-term carbon storage and rising atmospheric CO2 concentrations. The aim of this study was to investigate the impacts of grazing and fire history on soil C dynamics in the Peruvian montane grasslands, an understudied ecosystem, which covers approximately a quarter of the land area in Peru. A density fractionation method was used to quantify the labile and stable organic matter pools, along with soil CO2 flux and decomposition measurements. Grazing and burning together significantly increased soil CO2 fluxes and decomposition rates and reduced temperature as a driver. Although there was no significant effect of land use on total soil C stocks, the combination of burning and grazing decreased the proportion of C in the free light fraction (LF, especially at the lower depths (10–20 and 20–30 cm. In the control soils, 20 % of the material recovered was in the free LF, which contained 30 % of the soil C content. In comparison, the burnt–grazed soil had the smallest recovery of the free LF (10 % and a significantly lower C content (14 %. The burnt soils had a much higher proportion of C in the occluded LF (12 % compared to the not-burnt soils (7 % and there was no significant difference among the treatments in the heavy fraction (F ( ∼  70 %. The synergistic effect of burning and grazing caused changes to the soil C dynamics. CO2

  6. Use of metabolic inhibitors to estimate protozooplankton grazing and bacterial production in a monomictic eutrophic lake with an anaerobic hypolimnion

    Sanders, R.W.; Porter, K.G.

    1986-01-01

    Inhibitors of eucaryotes (cycloheximide and amphotericin B) and procaryotes (penicillin and chloramphenical) were used to estimate bacterivory and bacterial production in a eutrophic lake. Bacterial production appeared to be slightly greater than protozoan grazing in the aerobic waters of Lake Oglethorpe. Use of penicillin and cycloheximide yielded inconsistent results in anaerobic water and in aerobic water when bacterial production was low. Production measured by inhibiting eucaryotes with cycloheximide did not always agree with [ 3 H]thymidine estimates or differential filtration methods. Laboratory experiments showed that several common freshwater protozoans continued to swim and ingest bacterium-size latex beads in the presence of the eucaryote inhibitor. Penicillin also affected grazing rates of some ciliates. The authors recommended that caution and a corroborating method be used when estimating ecologically important parameters with specific inhibitors

  7. Optimal grazing management strategies: evaluating key concepts ...

    Finally, overstocking will override key management initiatives, such as effective recovery periods, leading to rangeland degradation. Thus, in variable climates, stocking rate should be set conservatively to allow easier adaptation of animal numbers to rainfall variability from year to year. We suggest several key concepts that ...

  8. Timing of grazing to reduce cheatgrass fuels

    The introduction and subsequent invasion of cheatgrass onto millions of acres of Great Basin rangelands has revolutionized secondary succession by providing a fine-textured early maturing fuel that has increased the chance, rate, spread and season of wildfires. With such vast acreages of landscapes ...

  9. Response of soil methane uptake to simulated nitrogen deposition and grazing management across three types of steppe in Inner Mongolia, China.

    Li, Xianglan; He, Hong; Yuan, Wenping; Li, Linghao; Xu, Wenfang; Liu, Wei; Shi, Huiqiu; Hou, Longyu; Chen, Jiquan; Wang, Zhiping

    2018-01-15

    The response of soil methane (CH 4 ) uptake to increased nitrogen (N) deposition and grazing management was studied in three types of steppe (i.e., meadow steppe, typical steppe, and desert steppe) in Inner Mongolia, China. The experiment was designed with four simulated N deposition rates such as 0, 50, 100, and 200kgNha -1 , respectively, under grazed and fenced management treatments. Results showed that the investigated steppes were significant sinks for CH 4 , with an uptake flux of 1.12-3.36kgha -1 over the grass growing season and that the magnitude of CH 4 uptake significantly (Prates. The soil CH 4 uptake rates were highest in the desert steppe, moderate in the typical steppe, and lowest in the meadow steppe. Compared with grazed plots, fencing increased the CH 4 uptake by 4.7-40.2% with a mean value of 20.2% across the three different steppe types. The responses of soil CH 4 uptake to N deposition in the continental steppe varied depending on the N deposition rate, steppe type, and grazing management. A significantly positive correlation between CH 4 uptake and soil temperature was found in this study, whereas no significant relationship between soil moisture and CH 4 uptake occurred. Our results may contribute to the improvement of model parameterization for simulating biosphere-atmosphere CH 4 exchange processes and for evaluating the climate change feedback on CH 4 soil uptake. Copyright © 2017 Elsevier B.V. All rights reserved.

  10. Effects of nitrogen fertilization and grazing on the emission of nitrous oxide from grassland

    Velthof, G.L.; Brader, A.B.; Oenema, O. [NMI, Dept. of Soil Science and Plant Nutrition, Wageningen Agricultural Univ. (Netherlands)

    1995-11-01

    In the Netherlands, managed grasslands are potentially a large source of nitrous oxide (N{sub 2}O), because of the large nitrogen (N) input and the relatively high ground water levels. To provide insight into the major factors that contribute to N{sub 2}O emission from grassland and to provide quantitative N{sub 2}O emission rates, a monitoring study was carried out on four sites, during March 1992 to March 1994. Fluxes of N{sub 2}O increased after N fertilizer application and grazing, especially during wet conditions. Fluxes were higher from peat soils than from sand and clay soils. Fluxes were low during the winter periods. Total N{sub 2}O losses were 2 to 4.5 times higher on grassland fertilized with 160-460 kg N ha{sup -1} yr{sup -1} than on unfertilized grassland. Losses from grazed grasslands were 1.5 to 3.5 times higher than losses from mown grassland. This study shows that management practice of grassland and soil type are major factors controlling N{sub 2}O emission from grasslands. 2 figs., 3 refs.

  11. Grazing of leaf-associated Cercomonads (Protists: Rhizaria: Cercozoa) structures bacterial community composition and function.

    Flues, Sebastian; Bass, David; Bonkowski, Michael

    2017-08-01

    Preferential food selection in protists is well documented, but we still lack basic understanding on how protist predation modifies the taxonomic and functional composition of bacterial communities. We conducted feeding trials using leaf-associated cercomonad Cercozoa by incubating them on a standardized, diverse bacterial community washed from plant leaves. We used a shotgun metagenomics approach to investigate the taxonomic and functional changes of the bacterial community after five days protist predation on bacteria. Predation-induced shifts in bacterial community composition could be linked to phenotypic protist traits. Protist reproduction rate, morphological plasticity and cell speed were most important in determining bacterial community composition. Analyses of co-occurrence patterns showed less complex correlations between bacterial taxa in the protist-grazed treatments with a higher proportion of positive correlations than in non-grazed controls, suggesting that predation reduced the influence of strong competitors. Protist predation influenced 14 metabolic core functions including membrane transport from which type VI secretion systems were in particular upregulated. In view of the functional importance of bacterial communities in the phyllosphere and rhizosphere of plants, a more detailed understanding of predator-prey interactions, changes in microbial composition and function, and subsequent repercussions on plant performance are clearly required. © 2017 Society for Applied Microbiology and John Wiley & Sons Ltd.

  12. Grazing Impact of the Copepod Calanus sinicus on Phytoplankton in the Northern East China Sea in Late Spring

    Kim, Garam; Kang, Hyung-Ku

    2018-03-01

    We investigated the feeding habits of Calanus sinicus during its four developmental stages as copepodite 4 (CIV), copepodite 5 (CV), adult males and females in early June 2015 at 12 sampling stations along the southern coast of Korea to the northern East China Sea, to better understand the role of C. sinicus in controlling phytoplankton stocks. Ingestion rate, daily ration as body carbon, population ingestion rate, and grazing impact were estimated using the gut pigment method. The mean biomass of CVs was the greatest (13.5 mg C m-3) and that of adult males was the lowest (0.7 mg C m-3). The ingestion rate per C. sinicus individual tended to increase with developmental stage, with the highest rate in adult females (519 ng chl ind-1 d-1) and the lowest rate in CIVs (305 ng chl ind-1 d-1). A significant correlation was found between ingestion rate and temperature, but not salinity or chlorophyll-a concentration. The daily ration of C. sinicus as body carbon significantly decreased with increased body weight, with the highest value found in CIVs (66.4%) and the lowest value in adult males (30%). Despite the high ingestion rate of the adults, the mean grazing impact of C. sinicus on phytoplankton biomass, in terms of chlorophyll-a concentration, was the highest in CVs (2.6%), followed by CIVs and adult females, and was the lowest in adult males (0.1%). The higher grazing impact of copepodites than adults underscores the importance of evaluating copepodite stages in the feeding studies of marine food webs.

  13. An X-ray grazing incidence phase multilayer grating

    Chernov, V A; Mytnichenko, S V

    2001-01-01

    An X-ray grazing incidence phase multilayer grating, representing a thin grating placed on a multilayer mirror, is proposed. A high efficiency of grating diffraction can be obtained by the possibility of changing the phase shift of the wave diffracted from the multilayer under the Bragg and total external reflection conditions. A grazing incidence phase multilayer grating consisting of Pt grating stripes on a Ni/C multilayer and optimized for the hard X-ray range was fabricated. Its diffraction properties were studied at photon energies of 7 and 8 keV. The obtained maximum value of the diffraction efficiency of the +1 grating order was 9% at 7 keV and 6.5% at 8 keV. The data obtained are in a rather good accordance with the theory.

  14. Invariant polygons in systems with grazing-sliding.

    Szalai, R; Osinga, H M

    2008-06-01

    The paper investigates generic three-dimensional nonsmooth systems with a periodic orbit near grazing-sliding. We assume that the periodic orbit is unstable with complex multipliers so that two dominant frequencies are present in the system. Because grazing-sliding induces a dimension loss and the instability drives every trajectory into sliding, the system has an attractor that consists of forward sliding orbits. We analyze this attractor in a suitably chosen Poincare section using a three-parameter generalized map that can be viewed as a normal form. We show that in this normal form the attractor must be contained in a finite number of lines that intersect in the vertices of a polygon. However the attractor is typically larger than the associated polygon. We classify the number of lines involved in forming the attractor as a function of the parameters. Furthermore, for fixed values of parameters we investigate the one-dimensional dynamics on the attractor.

  15. Adjustable Grazing-Incidence X-Ray Optics

    O'Dell, Stephen L.; Reid, Paul B.

    2015-01-01

    With its unique subarcsecond imaging performance, NASA's Chandra X-ray Observatory illustrates the importance of fine angular resolution for x-ray astronomy. Indeed, the future of x-ray astronomy relies upon x-ray telescopes with comparable angular resolution but larger aperture areas. Combined with the special requirements of nested grazing-incidence optics, mass, and envelope constraints of space-borne telescopes render such advances technologically and programmatically challenging. The goal of this technology research is to enable the cost-effective fabrication of large-area, lightweight grazing-incidence x-ray optics with subarcsecond resolution. Toward this end, the project is developing active x-ray optics using slumped-glass mirrors with thin-film piezoelectric arrays for correction of intrinsic or mount-induced distortions.

  16. Active Full-Shell Grazing-Incidence Optics

    Davis, Jacqueline M.; Elsner, Ronald F.; Ramsey, Brian D.; O'Dell, Stephen L.; Kolodziejczak, Jeffery; Weisskopf, Martin C.; Gubarev, Mikhail V.

    2016-01-01

    MSFC has a long history of developing full-shell grazing-incidence x-ray optics for both narrow (pointed) and wide field (surveying) applications. The concept presented in this paper shows the potential to use active optics to switch between narrow and wide-field geometries, while maintaining large effective area and high angular resolution. In addition, active optics has the potential to reduce errors due to mounting and manufacturing lightweight optics. The design presented corrects low spatial frequency error and has significantly fewer actuators than other concepts presented thus far in the field of active x-ray optics. Using a finite element model, influence functions are calculated using active components on a full-shell grazing-incidence optic. Next, the ability of the active optic to effect a change of optical prescription and to correct for errors due to manufacturing and mounting is modeled.

  17. Bite frequency measured by head pitch movements in grazing experiment

    Oudshoorn, Frank W.; S. Nadimi, Esmaeil; Jørgensen, Rasmus Nyholm

    2010-01-01

    . ECPLF      2007 Skiathos, Greece. p 111-116 Pulido, R.G. & Leaver, J.D., 2001. Quantifying the influence of sward height, concentrate level and initial      milk yield on the milk production and grazing behaviour of continuously stocked dairy cows. Grass      and Forage Science 56, 57-67.    ...

  18. Spatial Distribution of Nitrogen on Grazed Karst Landscapes

    Douglas G. Boyer

    2001-01-01

    Full Text Available The impact on water quality by agricultural activity in karst terrain is an important consideration for resource management within the Appalachian region. Karst areas comprise about 18% of the region’s land area. An estimated one-third of the region’s farms, cattle, and agricultural market value are located on karst terrain. Mean nitrate concentrations in several karst springs in southeastern West Virginia exhibit a strong linear relationship with the percentage of agriculture land cover. Development of best management practices for efficient nitrogen (N use and reduction of outflow of N to water from karst areas requires knowledge about N dynamics on those landscapes. Water extractable NO3-N and NH4-N were measured along transects at four soil depths in two grazed sinkholes and one wooded sinkhole. Distribution of soil NO3-N and NH4-N were related to frequency of animal presence and to topographic and hydrologic redistribution of soil and fecal matter in the grazed sinkholes. Karst pastures are characterized by under drainage and funneling of water and contaminants to the shallow aquifer. Control of NO3-N leaching from karst pasture may depend on management strategies that change livestock grazing behavior in sinkholes and reduce the opportunity for water and contaminants to quickly reach sinkhole drains.

  19. The ability of winter grazing to reduce wildfire size, intensity ...

    A recent study by Davies et al. sought to test whether winter grazing could reduce wildfire size, fire behavior metrics, and fire-induced plant mortality in shrub-grasslands. The authors concluded that ungrazed rangelands may experience more fire-induced mortality of native perennial bunchgrasses. The authors also presented several statements regarding the benefits of winter grazing on post-fire plant community responses. However, this commentary will show that the study by Davies et al. has underlying methodological flaws, lacks data necessary to support their conclusions, and does not provide an accurate discussion on the effect of grazing on rangeland ecosystems. Importantly, Davies et al. presented no data on the post-fire mortality of the perennial bunchgrasses or on the changes in plant community composition following their experimental fires. Rather, Davies et al. inferred these conclusions based off their observed fire behavior metrics of maximum temperature and a term described as the “heat load”. However, neither metric is appropriate for elucidating the heat flux impacts on plants. This lack of post-fire data, several methodological flaws, and the use of inadequate metrics describing heat cast doubts on the authors’ ability to support their stated conclusions. This article is a commentary highlights the scientific shortcomings in a forthcoming paper by Davies et al. in the International Journal of Wildland Fire. The study has methodological flaw

  20. Introducing cattle grazing to a noxious weed-dominated rangeland shifts plant communities

    Josh S. Davy

    2015-10-01

    Full Text Available Invasive weed species in California's rangelands can reduce herbaceous diversity, forage quality and wildlife habitat. Small-scale studies (5 acres or fewer have shown reductions of medusahead and yellow starthistle using prescribed grazing on rangelands, but little is published on the effects of pasture-scale (greater than 80 acres prescribed grazing on weed control and plant community responses. We report the results of a 6-year collaborative study of manager-applied prescribed grazing implemented on rangeland that had not been grazed for 4 years. Grazing reduced medusahead but did not alter yellow starthistle cover. Medusahead reductions were only seen in years that did not have significant late spring rainfall, suggesting that it is able to recover from heavy grazing if soil moisture is present. Later season grazing appears to have the potential to suppress medusahead in all years. In practice, however, such grazing is constrained by livestock drinking water availability and forage quality, which were limited even in years with late spring rainfall. Thus, we expect that grazing treatments under real-world constraints would reduce medusahead only in years with little late spring rainfall. After 10 years of grazing exclusion, the ungrazed plant communities began to shift, replacing medusahead with species that have little value, such as ripgut and red brome.

  1. Milk production and physiological traits of ewes and goats housed indoor or grazing at different daily timing in summer

    Massimo Todaro

    2010-01-01

    Full Text Available During a 6 week trial in summer, 3 homogeneous groups, each consisting of 5 Comisana ewes and 5 Rossa Mediterranea goats, grazed watered forage resources during day (D or night (N, or were housed indoor and supplied with mowed herbage(H. Maximum THI peaked at 94 at the end of July, and was almost constantly higher of 80. Milk yield was higher in N than in D and H goats, whereas N ewes produced more milk than H group, but their milk yield was higher than D ewes only in the period with the highest THI values. The lower urea in N goat milk, and the higher casein in N ewe milk, seem to indicate a better efficiency in dietary nitrogen utilization of night grazing animals. N ewes showed lower SCC in milk, and higher incidence of clotting milk samples, in comparison to other ewes. N goats and ewes showed lower rectal temperature and pulse rate in the afternoon and, among metabolic parameters, higher hematic level of sodium. Night grazing was confirmed to be a management practice for increasing heat tolerance, to which goats appeared to be more sensitive in terms of milk yield.

  2. A model for predicting livemass gain from stocking rate and annual ...

    The relationship between livemass gain and stocking rate was established for young beef animals grazing kikuyu and Coastcross II pastures in each of five grazing seasons. The annual rainfall within these seasons ranges from 506mm to 990mm. Relationships between pasture production variables and annual rainfall are ...

  3. Grazing exclusion, substrate type, and drought frequency affect plant community structure in rangelands of the arid unpredictable Arabian Deserts

    El-Keblawy, Ali; El-Sheikh, Mohamed

    2017-04-01

    Grazing and drought can adversely affect the ecology and management of rangeland ecosystems. Several management actions have been applied to restore species diversity and community structure in degraded rangelands of the unpredictable arid environment. Protection from grazing is considered as a proper approach for restoration of degraded rangelands, but this depends on substrate type and sometime is hindered with water deficiency (drought). In this study, the effect of protection from grazing animals on species diversity and plant community structure was assessed after a dry and wet periods in both sandy and gravelly substrates in the Dubai Desert Conservation reserve (DDCR), United Arab Emirates. Two sites were selected during November 2012 on the two substrate types (fixed sandy flat and gravel plain) in the arid DDCR. An enclosure was established in each site. Plant community attributes (plant cover, density, frequency, species composition, and diversity indices) were assessed in a number of permanent plots laid inside and outside each enclosure during November 2012, April 2014 and April 2016. The results showed that protection improved clay content, but decreased the organic matters. Interestingly, the protection reduced the concentrations of most estimated nutrients, which could be attributed to the high turnover rate of nutrients associated grazing and low decomposition of accumulated dry plants of non-protected sites. Protection significantly increased all plant community attributes, but the only significant effect was for plant density. Plant density was almost twice greater inside than outside the enclosures. During the dry period, protection resulted in significantly greater deterioration in cover, density and all diversity indices in gravel, compared to sandy sites. Most of the grasses and shrubby plants had died in the gravel plains. However, plant community of the gravel plains was significantly restored after receiving considerable rainfalls. The

  4. Grazing exit versus grazing incidence geometry for x-ray absorption near edge structure analysis of arsenic traces

    Meirer, F.; Streli, C.; Wobrauschek, P.; Zoeger, N.; Pepponi, G.

    2009-01-01

    In the presented study the grazing exit x-ray fluorescence was tested for its applicability to x-ray absorption near edge structure analysis of arsenic in droplet samples. The experimental results have been compared to the findings of former analyses of the same samples using a grazing incidence (GI) setup to compare the performance of both geometries. Furthermore, the investigations were accomplished to gain a better understanding of the so called self-absorption effect, which was observed and investigated in previous studies using a GI geometry. It was suggested that a normal incidence-grazing-exit geometry would not suffer from self-absorption effects in x-ray absorption fine structure (XAFS) analysis due to the minimized path length of the incident beam through the sample. The results proved this assumption and in turn confirmed the occurrence of the self-absorption effect for GI geometry. Due to its lower sensitivity it is difficult to apply the GE geometry to XAFS analysis of trace amounts (few nanograms) of samples but the technique is well suited for the analysis of small amounts of concentrated samples

  5. Transitions and coexistence along a grazing gradient in the Eurasian steppe

    Ren, Haiyan; Taube, Friedelm; Zhang, Yingjun; Bai, Yongfei; Hu, Shuijin

    2017-04-01

    Ecological resilience theory has often been applied to explain species coexistence and range condition assessment of various community states and to explicate the dynamics of ecosystems. Grazing is a primary disturbance that can alter rangeland resilience by causing hard-to-reverse transitions in grasslands. Yet, how grazing affects the coexistence of plant functional group (PFG) and transition remains unclear. We conducted a six-year grazing experiment in a typical steppe of Inner Mongolia, using seven grazing intensities (0, 1.5, 3.0, 4.5, 6.0, 7.5 and 9.0 sheep/ hectare) and two grazing systems (i.e. a continuous annual grazing as in the traditional grazing system, and a mixed grazing system combining grazing and haymaking), to examine grazing effects on plant functional group shifts and species coexistence in the semi-arid grassland system. Our results indicate that the relative richness of dominant bunchgrasses and forbs had a compensatory coexistence at all grazing intensities, and the richness of rhizomatous grasses fluctuated but was persistent. The relative productivity of dominant bunchgrasses and rhizomatous grasses had compensatory interactions with grazing intensity and grazing system. Dominant bunchgrasses and rhizomatous grasses resist grazing effects by using their dominant species functional traits: high specific leaf area and low leaf nitrogen content. Our results suggest that: 1. Stabilizing mechanisms beyond grazing management are more important in determining plant functional group coexistence and ecological resilience. 2. Plant functional group composition is more important in influencing ecosystem functioning than diversity. 3. Ecosystem resilience at a given level is related to the biomass of dominant PFG, which is determined by a balanced shift between dominant species biomass. The relatively even ecosystem resilience along the grazing gradient is attributed to the compensatory interactions of dominant species in their biomass variations

  6. Fall-grown oat to extend the fall grazing season for replacement dairy heifers.

    Coblentz, W K; Brink, G E; Hoffman, P C; Esser, N M; Bertram, M G

    2014-03-01

    Our objective was to assess the pasture productivity and forage characteristics of 2 fall-grown oat (Avena sativa L.) cultivars, specifically for extending the grazing season and reducing reliance on harvested forages by replacement dairy heifers. A total of 160 gravid Holstein heifers (80 heifers/yr) were stratified by weight, and assigned to 1 of 10 identical research pens (8 heifers/pen). Initial body weights were 480 ± 43.5 kg in 2011 and 509 ± 39.4 kg in 2012. During both years of the trial, four 1.0-ha pasture replicates were seeded in August with Ogle oat (Schumitsch Seed Inc., Antigo, WI), and 4 separate, but similarly configured, pasture replicates were seeded with Forage Plus oat (Kratz Farms, Slinger, WI). Heifer groups were maintained as units, assigned to specific pastures, and then allowed to graze fall-oat pastures for 6h daily before returning to the barn, where they were offered a forage-based basal total mixed ration. Two heifer groups were retained in confinement (without grazing) as controls and offered the identical total mixed ration as pasture groups. During 2011, available forage mass increased with strong linear and quadratic effects for both cultivars, peaking at almost 9 Mg/ha on October 31. In contrast, forage mass was not affected by evaluation date in 2012, remaining ≤ 2,639 kg/ha across all dates because of droughty climatic conditions. During 2012, Ogle exhibited greater forage mass than Forage Plus across all sampling dates (2,678 vs. 1,856 kg/ha), largely because of its more rapid maturation rate and greater canopy height. Estimates of energy density for oat forage ranged from 59.6 to 69.1% during 2011, and ranged narrowly from 68.4 to 70.4% during 2012. For 2011, responses for both cultivars had strong quadratic character, in which the most energy-dense forages occurred in mid November, largely due to accumulation of water-soluble carbohydrates that reached maximum concentrations of 18.2 and 15.1% for Forage Plus and Ogle

  7. Effect of Supplemental Corn Dried Distillers Grains with Solubles Fed to Beef Steers Grazing Native Rangeland during the Forage Dormant Season.

    Murillo, M; Herrera, E; Ruiz, O; Reyes, O; Carrete, F O; Gutierrez, H

    2016-05-01

    Two experiments were conducted to evaluate the effects of the level of corn dry distillers grains with solubles (CDDGS) supplementation on growing performance, blood metabolites, digestion characteristics and ruminal fermentation patterns in steers grazing dormant forage. In Exp. 1, of growth performance, 120 steers (204±5 kg initial body weight [BW]) were distributed randomly into 3 groups (each of 40 steers), which were provided with the following levels of CDDGS supplement: 0%, 0.25%, or 0.50% BW. All groups of steers were grazed for 30 days in each of 3 grazing periods (March, April, and May). Approximately 1,000 ha of the land was divided with electric fencing into 3 equally sized pastures (333 ha in size). Blood samples were collected monthly from 20 steers in each grazing group for analysis of glucose (G), urea-nitrogen (UN) and non-esterified fatty acids. Final BW, average daily gain (ADG) and supplement conversion (CDDGS-C) increased with increasing levels of CDDGS supplementation (p<0.05).The CDDGS supplementation also increased the plasma G and UN concentrations (p<0.05). In Exp. 2, of digestive metabolism, 9 ruminally cannulated steers (BW = 350±3 kg) were distributed, following a completely randomized design, into groups of three in each pasture. The ruminally cannulated steers were provided the same levels of CDDGS supplementation as in the growing performance study (0%, 0.25%, and 0.50% BW), and they grazed along with the other 40 steers throughout the grazing periods. The dry matter intake, crude protein intake, neutral detergent fiber intake (NDFI), apparent digestibility of dry matter (ADDM), crude protein (ADCP) and neutral detergent fiber (ADNDF) increased with increasing levels of CDDGS supplementation (p<0.05). The ruminal degradation rates of CP (kdCP), NDF (kdNDF) and passage rate (kp) also increased with increasing levels of CDDGS supplementation (p<0.05). Ruminal ammonia nitrogen (NH3-N) and propionate concentrations also increased with

  8. Effect of Supplemental Corn Dried Distillers Grains with Solubles Fed to Beef Steers Grazing Native Rangeland during the Forage Dormant Season

    M. Murillo

    2016-05-01

    Full Text Available Two experiments were conducted to evaluate the effects of the level of corn dry distillers grains with solubles (CDDGS supplementation on growing performance, blood metabolites, digestion characteristics and ruminal fermentation patterns in steers grazing dormant forage. In Exp. 1, of growth performance, 120 steers (204±5 kg initial body weight [BW] were distributed randomly into 3 groups (each of 40 steers, which were provided with the following levels of CDDGS supplement: 0%, 0.25%, or 0.50% BW. All groups of steers were grazed for 30 days in each of 3 grazing periods (March, April, and May. Approximately 1,000 ha of the land was divided with electric fencing into 3 equally sized pastures (333 ha in size. Blood samples were collected monthly from 20 steers in each grazing group for analysis of glucose (G, urea-nitrogen (UN and non-esterified fatty acids. Final BW, average daily gain (ADG and supplement conversion (CDDGS-C increased with increasing levels of CDDGS supplementation (p<0.05.The CDDGS supplementation also increased the plasma G and UN concentrations (p<0.05. In Exp. 2, of digestive metabolism, 9 ruminally cannulated steers (BW = 350±3 kg were distributed, following a completely randomized design, into groups of three in each pasture. The ruminally cannulated steers were provided the same levels of CDDGS supplementation as in the growing performance study (0%, 0.25%, and 0.50% BW, and they grazed along with the other 40 steers throughout the grazing periods. The dry matter intake, crude protein intake, neutral detergent fiber intake (NDFI, apparent digestibility of dry matter (ADDM, crude protein (ADCP and neutral detergent fiber (ADNDF increased with increasing levels of CDDGS supplementation (p<0.05. The ruminal degradation rates of CP (kdCP, NDF (kdNDF and passage rate (kp also increased with increasing levels of CDDGS supplementation (p<0.05. Ruminal ammonia nitrogen (NH3-N and propionate concentrations also increased with

  9. Effect of Supplemental Corn Dried Distillers Grains with Solubles Fed to Beef Steers Grazing Native Rangeland during the Forage Dormant Season

    Murillo, M.; Herrera, E.; Ruiz, O.; Reyes, O.; Carrete, F. O.; Gutierrez, H.

    2016-01-01

    Two experiments were conducted to evaluate the effects of the level of corn dry distillers grains with solubles (CDDGS) supplementation on growing performance, blood metabolites, digestion characteristics and ruminal fermentation patterns in steers grazing dormant forage. In Exp. 1, of growth performance, 120 steers (204±5 kg initial body weight [BW]) were distributed randomly into 3 groups (each of 40 steers), which were provided with the following levels of CDDGS supplement: 0%, 0.25%, or 0.50% BW. All groups of steers were grazed for 30 days in each of 3 grazing periods (March, April, and May). Approximately 1,000 ha of the land was divided with electric fencing into 3 equally sized pastures (333 ha in size). Blood samples were collected monthly from 20 steers in each grazing group for analysis of glucose (G), urea-nitrogen (UN) and non-esterified fatty acids. Final BW, average daily gain (ADG) and supplement conversion (CDDGS-C) increased with increasing levels of CDDGS supplementation (p<0.05).The CDDGS supplementation also increased the plasma G and UN concentrations (p<0.05). In Exp. 2, of digestive metabolism, 9 ruminally cannulated steers (BW = 350±3 kg) were distributed, following a completely randomized design, into groups of three in each pasture. The ruminally cannulated steers were provided the same levels of CDDGS supplementation as in the growing performance study (0%, 0.25%, and 0.50% BW), and they grazed along with the other 40 steers throughout the grazing periods. The dry matter intake, crude protein intake, neutral detergent fiber intake (NDFI), apparent digestibility of dry matter (ADDM), crude protein (ADCP) and neutral detergent fiber (ADNDF) increased with increasing levels of CDDGS supplementation (p<0.05). The ruminal degradation rates of CP (kdCP), NDF (kdNDF) and passage rate (kp) also increased with increasing levels of CDDGS supplementation (p<0.05). Ruminal ammonia nitrogen (NH3-N) and propionate concentrations also increased with

  10. Nitrous oxide production and consumption by denitrification in a grassland: Effects of grazing and hydrology.

    Hu, Jing; Inglett, Kanika S; Clark, Mark W; Inglett, Patrick W; Ramesh Reddy, K

    2015-11-01

    Denitrification is generally recognized as a major mechanism contributing to nitrous oxide (N2O) production, and is the only known biological process for N2O consumption. Understanding factors controlling N2O production and consumption during denitrification will provide insights into N2O emission variability, and potentially predict capacity of soils to serve as sinks or sources of N2O. This study investigated the effects of hydrology and grazing on N2O production and consumption in a grassland based agricultural watershed. A batch incubation study was conducted on soils (0-10 cm) collected along a hydrological gradient representing isolated wetland (Center), transient zone (Edge) and pasture upland (Upland), from both grazed and ungrazed areas. Production and consumption potentials of N2O were quantified on soils under four treatments, including (i) ambient condition, and amended with (ii) NO3(-), (iii) glucose-C, and (iv) NO3(-) +glucose-C. The impacts of grazing on N2O production and consumption were not observed. Soils in hydrologically distinct zones responded differently to N2O production and consumption. Under ambient conditions, both production and consumption rates of Edge soils were higher than those observed for Center and Upland soils. Results of amended incubations suggested NO3(-) was a key factor limiting N2O production and consumption rates in all hydrological zones. Over 5-d incubation with NO3(-) amendment, cumulative production and consumption of N2O for Center soils were 1.6 and 3.3 times higher than Edge soils, and 3.6 and 7.6 times higher than Upland soils, respectively. However, cumulative N2O net production for Edge soils was the highest, with 2 to 3 times higher than Upland and Center soils. Our results suggest that the transient areas between wetland and upland are likely to be "hot spots" of N2O emissions in this ecosystem. Wetlands within agricultural landscapes can potentially function to reduce both NO3(-) leaching and N2O emissions

  11. In situ feeding rates of plantonic copepods: A comparison of four methods

    Kiørboe, Thomas; Møhlenberg, Flemming; Riisgård, Hans Ulrik

    1985-01-01

    into estimates of in situ algal grazing rates by means of independently estimated gut turnover times, and were compared with chlorophyll and particle-volume grazing rates of animals sampled simultaneously and incubated in water from the collection depth. In addition, egg-production rates of adult females were...... problems of the different methods are discussed, and it is concluded that they all approach representative (although minimum) estimates of in situ feeding rates....

  12. Grazing reduces soil greenhouse gas fluxes in global grasslands: a meta-analysis

    Tang, Shiming; Tian, Dashuan; Niu, Shuli

    2017-04-01

    Grazing causes a worldwide degradation in grassland and likely alters soil greenhouse gas fluxes (GHGs). However, the general patterns of grazing-induced changes in grassland soil GHGs and the underlying mechanisms remain unclear. Thus, we synthesized 63 independent experiments in global grasslands that examined grazing impacts on soil GHGs (CO2, CH4 and N2O). We found that grazing with light or moderate intensity did not significantly influence soil GHGs, but consistently depressed them under heavy grazing, reducing CO2 emission by 10.55%, CH4 uptake by 19.24% and N2O emission by 28.04%. The reduction in soil CO2 was mainly due to decreased activity in roots and microbes (soil respiration per unit root and microbial biomass), which was suppressed by less water availability due to higher soil temperature induced by lower community cover under heavy grazing. N2O emission decreased with grazing-caused decline in soil total N. The inhibitory effect on methanotroph activities by water stress is responsible for the decreased CH4 uptake. Furthermore, grazing duration and precipitation also influenced the direction and magnitude of responses in GHGs fluxes. Overall, our results indicate that the reduction in soil CO2 and N2O emission under heavy grazing is partially compensated by the decrease in CH4 uptake, which is mainly regulated by variations in soil moisture.

  13. Nitrogen fertilization of grass/clover swards under cutting or grazing by dairy cows

    Søegaard, Karen

    2009-01-01

    farms over a period of three years. Nitrogen was applied at four rates (0, 75, 150, and 225 kg N year-1) with cutting or grazing regime in Year 1 and Year 2, after establishment. A spring-only application of 150 kg N was compared with four applications during the season, which was the fertilization...... affected. The results indicate different possibilities for strategic fertilization both at farm and field level, and in swards with a high clover content it demonstrates how the clover content can be used as a buffer both for maximizing the N-response and for manipulating the production profile.......Intensively managed perennial ryegrass/white clover (Lolium perenne L. and Trifolium repens L.) swards receive relatively high levels of fertilizer N, and high N surpluses can subsequently be found. The N-fertilization effects on growth, yield, and herbage quality were therefore examined on three...

  14. Using digital photography to examine grazing in montane meadows

    McIlroy, Susan K.; Allen-Diaz, Barbara H.; Berg, Alexander C.

    2011-01-01

    Cattle (Bos taurus) numbers on national forests are allocated based on allotment grazing capacity, but spatial patterns of timing and density at smaller scales are difficult to assess. However, it is often in meadows or riparian areas that grazing may affect hydrology, biodiversity, and other important ecosystem characteristics. To explore real-time animal presence in montane meadows we distributed 18 digital cameras across nine sites in the Sierra National Forest, California. Our objectives were to document seasonal and diurnal presence of both cattle and mule deer (Odocoileus hemionus), identify the effects of three fencing treatments on animal distribution, and test digital photography as a tool for documenting cattle presence. We recorded 409 399 images during daylight hours for two grazing seasons, and we identified 5 084 and 24 482 cattle "marks" (instances of animal occurrence) in 2006 and 2007, respectively. Deer presence was much lower, with 331 marks in 2006 and 598 in 2007. Morning cattle presence was highest before 0800 hours both years (13.7% and 15.4% of total marks for 2006 and 2007, respectively). Marks decreased until 1100 hours and then increased around 1400 hours and remained relatively stable until 1900 hours. Marks then rose precipitously, with >20% of total marks recorded after 1900 hours both years. Deer presence was less than 10% per hour until 1800 hours, when >20% of total marks were recorded after this time both years. Among treatments, cattle marks were highest outside fences at partially fenced meadows, and deer were highest within completely fenced meadows. Our experience suggests that cameras are not viable tools for meadow monitoring due to variation captured within meadows and the time and effort involved in image processing and review.

  15. Seroepidemiological study of Q fever in domestic ruminants in semi-extensive grazing systems

    Atxaerandio Raquel

    2010-01-01

    Full Text Available Abstract Background Q fever, a worldwide zoonotic disease caused by Coxiella burnetii, is endemic in northern Spain where it has been reported as responsible for large series of human pneumonia cases and domestic ruminants' reproductive disorders. To investigate pathogen exposure among domestic ruminants in semi-extensive grazing systems in northern Spain, a serosurvey was carried out in 1,379 sheep (42 flocks, 626 beef cattle (46 herds and 115 goats (11 herds. Serum antibodies were analysed by ELISA and positive samples were retested by Complement Fixation test (CFT to detect recent infections. Results ELISA anti-C. burnetii antibody prevalence was slightly higher in sheep (11.8 ± 2.0% than in goats (8.7 ± 5.9% and beef cattle (6.7 ± 2.0%. Herd prevalence was 74% for ovine, 45% for goat and 43% for bovine. Twenty-one percent of sheep flocks, 27% of goat and 14% of cattle herds had a C. burnetii seroprevalence ≥ 20%. Only 15 out of 214 ELISA-positive animals reacted positive by CFT. Age-associated seroprevalence differed between ruminant species with a general increasing pattern with age. No evidence of correlation between abortion history and seroprevalence rates was observed despite the known abortifacient nature of C. burnetii in domestic ruminants. Conclusions Results reported herein showed that sheep had the highest contact rate with C. burnetii in the region but also that cattle and goats should not be neglected as part of the domestic cycle of C. burnetii. This work reports basic epidemiologic patterns of C. burnetii in semi-extensive grazed domestic ruminants which, together with the relevant role of C. burnetii as a zoonotic and abortifacient agent, makes these results to concern both Public and Animal Health Authorities.

  16. Seroepidemiological study of Q fever in domestic ruminants in semi-extensive grazing systems.

    Ruiz-Fons, Francisco; Astobiza, Ianire; Barandika, Jesús F; Hurtado, Ana; Atxaerandio, Raquel; Juste, Ramón A; García-Pérez, Ana L

    2010-01-20

    Q fever, a worldwide zoonotic disease caused by Coxiella burnetii, is endemic in northern Spain where it has been reported as responsible for large series of human pneumonia cases and domestic ruminants' reproductive disorders. To investigate pathogen exposure among domestic ruminants in semi-extensive grazing systems in northern Spain, a serosurvey was carried out in 1,379 sheep (42 flocks), 626 beef cattle (46 herds) and 115 goats (11 herds). Serum antibodies were analysed by ELISA and positive samples were retested by Complement Fixation test (CFT) to detect recent infections. ELISA anti-C. burnetii antibody prevalence was slightly higher in sheep (11.8 +/- 2.0%) than in goats (8.7 +/- 5.9%) and beef cattle (6.7 +/- 2.0%). Herd prevalence was 74% for ovine, 45% for goat and 43% for bovine. Twenty-one percent of sheep flocks, 27% of goat and 14% of cattle herds had a C. burnetii seroprevalence >or= 20%. Only 15 out of 214 ELISA-positive animals reacted positive by CFT. Age-associated seroprevalence differed between ruminant species with a general increasing pattern with age. No evidence of correlation between abortion history and seroprevalence rates was observed despite the known abortifacient nature of C. burnetii in domestic ruminants. Results reported herein showed that sheep had the highest contact rate with C. burnetii in the region but also that cattle and goats should not be neglected as part of the domestic cycle of C. burnetii. This work reports basic epidemiologic patterns of C. burnetii in semi-extensive grazed domestic ruminants which, together with the relevant role of C. burnetii as a zoonotic and abortifacient agent, makes these results to concern both Public and Animal Health Authorities.

  17. Mesozooplankton production, grazing and respiration in the Bay of Bengal: Implications for net heterotrophy

    Fernandes, Veronica; Ramaiah, N.

    2016-03-01

    Mesozooplankton samples were collected from the mixed layer along a central (along 88°E) and a western transect in the Bay of Bengal during four seasons covered between 2001 and 2006 in order to investigate spatio-temporal variability in their biomass. At these stations, grazing and respiration rates were measured from live zooplankton hauled in from the surface during December 2005. Akin to the mesozooplankton "paradox" in the central and eastern Arabian Sea, biomass in the mixed layer was more or less invariant in the central and western Bay of Bengal, even as the chl a showed marginal temporal variation. By empirical equation, the mesozooplankton production rate calculated to be 70-246 mg C m- 2 d- 1 is on par with the Arabian Sea. Contrary to the conventional belief, mesozooplankton grazing impact was up to 83% on primary production (PP). Low PP coupled with very high zooplankton production (70% of PP) along with abundant bacterial production (50% of the PP; Ramaiah et al., 2009) is likely to render the Bay of Bengal net heterotrophic, especially during the spring intermonsoon. Greater estimates of fecal pellet-carbon egestion by mesozooplankton compared to the average particulate organic carbon flux in sediment traps, implies that much of the matter is recycled by heterotrophic communities in the mixed layer facilitating nutrient regeneration for phytoplankton growth. We also calculated that over a third of the primary production is channelized for basin-wide zooplankton respiration that accounts for 52 Mt C annually. In the current scenario of global warming, if low (primary) productive warm pools like the Bay of Bengal continue to be net heterotrophic, negative implications like enhanced emission of CO2 to the atmosphere, increased particulate flux to the deeper waters and greater utilization of dissolved oxygen resulting in expansion of the existing oxygen minimum zone are imminent.

  18. Review of grazing studies on plutonium-contaminated rangelands

    Smith, D.D.

    1977-01-01

    Literature is cited that has provided data on tissue actinide concentrations in grazing animals when the actinide dosages resulted from artificial administration or from periodic exposure. Only one long-term study is known where a reproducing beef herd was restricted to a plutonium-contaminated environment. Highlights of this study that are reviewed and discussed include: relationship of ingesta concentrations to food habits; tissue concentration related to length of exposure and level of exposure; and the concentration range in various tissues. Emphasis is given to the gonadal concentration which is approximately 25 times that of muscle and blood. Future study plans are also discussed

  19. Vegetation and Grazing in the St. Katherine Protectorate, South ...

    5. Grazing pressure. 1. 2. 3. 4. 5. P lant health. Unk . La bita e. Le gu m ino s a e. Co m p o sita e. A m ara nthac ea e. B ora gin ace ae. C h en opo dia c e ae. E u ph orb iac ea e. S cro ph ula ria cea e. A sc lep id ac e ae. C a ry o phy lla cea e. R ese dace ae. C a pp arace ae. Cuc urb ita cea e. Cruc ife rae. Gram inae. U m be.

  20. An Evaluation of Grazing-Incidence Optics for Neutron Imaging

    Gubarev, M. V.

    2007-01-01

    The refractive index for most materials is slightly less than unity, which opens an opportunity to develop the grazing incidence neutron imaging optics. The ideal material for the optics would be natural nickel and its isotopes. Marshall Space Flight Center (MSFC) has active development program on the nickel replicated optics for use in x-ray astronomy. Brief status report on the program is presented. The results of the neutron focusing optic test carried by the MSFC team at National Institute of Standards and Technology (NIST) are also presented. Possible applications of the optics are briefly discussed.

  1. Optical design of grazing incidence toroidal grating monochromator

    Pouey, M.; Howells, M.R.; Takacs, P.Z.

    1982-01-01

    Design rules using geometrical optics and physical optics associated with the phase balancing method are discussed for stigmatic toroidal grazing incidence monochromators. To determine the optical performance of devices involving mirrirs and/or gratings, ray tracing programs using exact geometry are quite widely used. It is then desirable to have some way to infer the practical performance of an instrument from a spot diagram created by tracing a limited number of rays. We propose a first approach to this problem involving an estimation of the geometrical intensity distribution in the image plane and the corresponding line spread function. (orig.)

  2. Ionization by ion impact at grazing incidence on insulator surface

    Martiarena, M L

    2003-01-01

    We have calculated the energy distribution of electrons produced by ionization of the ionic crystal electrons in grazing fast ion-insulator surface collision. The ionized electrons originate in the 2p F sup - orbital. We observe that the binary peak appears as a double change in the slope of the spectra, in the high energy region. The form of the peak is determined by the initial electron distribution and its position will be affected by the binding energy of the 2p F sup - electron in the crystal. This BEP in insulator surfaces will appear slightly shifted to the low energy side with respect the ion-atom one.

  3. Forage accumulation in brachiaria grass under continuous grazing with single or variable height during the seasons of the year

    Manoel Eduardo Rozalino Santos

    2013-05-01

    Full Text Available The objective of this study was to evaluate grazing management strategies of Brachiaria decumbens cv. Basilisk managed with different heights under continuous grazing with cattle. Two grazing management strategies were evaluated: maintenance of pasture with an average height of 25 cm throughout the experimental period and maintenance of pasture on the average of 15 cm in height during winter, up to 25 cm from the beginning of spring. The split-plot scheme and the randomized block design with four replications were adopted. The grazing management strategies corresponded to the primary factor, while the seasons (winter, spring and summer corresponded to secondary factor. The reduction of the average sward height to 15 cm in the winter resulted, when compared with pasture maintained at 25 cm, in overall higher growth rates (95 kg/ha.day DM and leaf blade (66.1 kg/ha.day DM, as well as higher rates of total accumulation (81.5 kg/ha.day DM and leaf blade (52.6 kg/ha.day DM. The accumulated forage production (from winter to summer was higher in the pasture lowered to 15 cm in winter (25.6 t/ha DM compared with that managed with an average height of 25 cm (22.2 t/ha DM. Regarding the seasons of the year, in the winter, there were lower rates of overall growth (6.4 kg/ha.day DM, leaf blade (5.6 kg/ha.day DM and pseudostem (0.8 kg/ha.day DM, and also lower total (-6.6 kg/ha.day DM and leaf blade (-7.5 kg/ha.day DM accumulation rates. In the spring there was a higher rate of leaf senescence (22.4 kg/ha.day DM. The accumulation of forage is incremented when the pasture of B. decumbens is lowered to 15 cm during the winter, and in the spring and summer, its average height is increased to 25 cm.

  4. Productive and Economic Responses in Grazing Dairy Cows to Grain Supplementation on Family Farms in the South of Brazil

    Luiz Carlos Pinheiro Machado Filho

    2014-07-01

    Full Text Available Pasture-based dairy production has been a major source of income for most family farms in the south of Brazil. Increasing milk prices have spurred an increase in grain supplementation, which has been poorly implemented, resulting in low levels of efficiency. To evaluate the consequences of supplementation on milk production and composition, grazing behavior and economic return, the widely used grain management system (CC-commercial concentrate, containing 21% CP, offered at 1 kg per 3.7 L of milk was compared with an energy supplement (GC-ground corn, with 9.5% CP, offered at 0.4% of live weight. Ten Holstein cows were paired into two groups, and subjected to the two treatments in a crossover design. The cows remained in the same grazing group, and the grain supplement was offered individually at milking time and consumed completely. Each experimental period lasted 14 days, with 10 days for diet adaptation and four days for data collection; individual milk production and samples were collected to determine levels of fat, protein, lactose, carotenoids, vitamin A and N-urea. Grazing behavior was observed (scans every 5 min in the first 4 h after the morning milking, and chemical composition of hand plucked samples of forage were measured. The cost of the supplement and profitability per treatment were calculated. Cows supplemented with GC consumed herbage with higher crude protein (CP: 16.23 vs. 14.62%; p < 0.05, had higher biting rate (44.21 vs. 39.54 bites/min; p < 0.03 and grazing time (22.20 vs. 20.55 scans; p < 0.05 than when receiving CC. There were no differences in milk composition between treatments (p > 0.05. However, higher concentrations of β-carotene and total carotenoids were detected in the milk of cows at 70–164 days of lactation, compared to <70 days of lactation (p < 0.05. Milk production was higher (13.19 vs. 11.59 kg/day; p < 0.05 when cows consumed CC, but resulted in lower profitability compared to GC (US$ 4.39 vs. US$ 4

  5. Genetic strain and diet effects on grazing behavior, pasture intake, and milk production.

    Sheahan, A J; Kolver, E S; Roche, J R

    2011-07-01

    Understanding how dairy cows adjust their grazing behavior in response to feed supplements is important for the development of management strategies that optimize profit from supplementation. New Zealand Holstein-Friesian (HF) cows have been selected for milk production on a predominantly pasture-based diet; in comparison, HF cows of North American (NA) ancestry have been selected almost exclusively for milk yield and fed diets high in nonfiber carbohydrates (NFC). We hypothesized, therefore, that supplementation would have differing effects on grazing behavior, pasture dry matter intake (DMI), and milk production in these genetic strains at peak, mid, and late lactation. A study was conducted over 2 consecutive lactations, with NA and NZ cows randomly allocated at calving to 0, 3, or 6 kg of dry matter/day concentrate plus unrestricted access to pasture. Pasture DMI, milk production, and grazing behavior were recorded at peak, mid, and late lactation. Concentrates were fed in equal amounts at morning and afternoon milking. The NA cows produced more milk and milk components, and had a greater pasture DMI, despite spending less time grazing. Declines in time spent grazing and pasture DMI were associated with increasing concentrate DMI. Grazing behavior following morning supplementation was different from that recorded following afternoon supplementation. Grazing ceased following morning supplementation before rumen fill could be a limiting factor, and the length of the grazing interval was inversely proportional to the amount of concentrate offered; these results suggest that physiological rather than physical stimuli were responsible for grazing cessation. The decrease in time spent grazing with increasing concentrate DMI is consistent with changes in neuroendocrine factors secreted in response to the presence of food in the digestive tract or with circulating products of digestion. After afternoon supplementation, sunset signaled the end of grazing irrespective of

  6. Synergistic Interactions within a Multispecies Biofilm Enhance Individual Species Protection against Grazing by a Pelagic Protozoan

    Prem K. Raghupathi

    2018-01-01

    Full Text Available Biofilm formation has been shown to confer protection against grazing, but little information is available on the effect of grazing on biofilm formation and protection in multispecies consortia. With most biofilms in nature being composed of multiple bacterial species, the interactions and dynamics of a multispecies bacterial biofilm subject to grazing by a pelagic protozoan predator were investigated. To this end, a mono and multispecies biofilms of four bacterial soil isolates, namely Xanthomonas retroflexus, Stenotrophomonas rhizophila, Microbacterium oxydans and Paenibacillus amylolyticus, were constructed and subjected to grazing by the ciliate Tetrahymena pyriformis. In monocultures, grazing strongly reduced planktonic cell numbers in P. amylolyticus and S. rhizophila and also X. retroflexus. At the same time, cell numbers in the underlying biofilms increased in S. rhizophila and X. retroflexus, but not in P. amylolyticus. This may be due to the fact that while grazing enhanced biofilm formation in the former two species, no biofilm was formed by P. amylolyticus in monoculture, either with or without grazing. In four-species biofilms, biofilm formation was higher than in the best monoculture, a strong biodiversity effect that was even more pronounced in the presence of grazing. While cell numbers of X. retroflexus, S. rhizophila, and P. amylolyticus in the planktonic fraction were greatly reduced in the presence of grazers, cell numbers of all three species strongly increased in the biofilm. Our results show that synergistic interactions between the four-species were important to induce biofilm formation, and suggest that bacterial members that produce more biofilm when exposed to the grazer not only protect themselves but also supported other members which are sensitive to grazing, thereby providing a “shared grazing protection” within the four-species biofilm model. Hence, complex interactions shape the dynamics of the biofilm and

  7. Aridity and grazing as convergent selective forces: an experiment with an Arid Chaco bunchgrass.

    Quiroga, R Emiliano; Golluscio, Rodolfo A; Blanco, Lisandro J; Fernández, Roberto J

    2010-10-01

    It has been proposed that aridity and grazing are convergent selective forces: each one selects for traits conferring resistance to both. However, this conceptual model has not yet been experimentally validated. The aim of this work was to experimentally evaluate the effect of aridity and grazing, as selective forces, on drought and grazing resistance of populations of Trichloris crinita, a native perennial forage grass of the Argentinean Arid Chaco region. We collected seeds in sites with four different combinations of aridity and grazing history (semiarid/ subhumid x heavily grazed/lightly grazed), established them in pots in a common garden, and subjected the resulting plants to different combinations of drought and defoliation. Our results agreed with the convergence model. Aridity has selected T. crinita genotypes that respond better to drought and defoliation in terms of sexual reproduction and leaf growth, and that can evade grazing due to a lower shoot: root ratio and a higher resource allocation to reserves (starch) in stem bases. Similarly, grazing has selected genotypes that respond better to drought and defoliation in terms of sexual reproduction and that can evade grazing due to a lower digestibility of leaf blades. These results allow us to extend concepts of previous models in plant adaptation to herbivory to models on plant adaptation to drought. The only variable in which we obtained a result opposite to predictions was plant height, as plants from semiarid sites were taller (and with more erect tillers) than plants from subhumid sites; we hypothesize that this result might have been a consequence of the selection exerted by the high solar radiation and soil temperatures of semiarid sites. In addition, our work allows for the prediction of the effects of dry or wet growing seasons on the performance of T. crinita plants. Our results suggest that we can rely on dry environments for selecting grazing-resistant genotypes and on high grazing pressure

  8. Physiological responses to variations in grazing and light conditions in native and invasive fucoids.

    Olabarria, Celia; Arenas, Francisco; Fernández, Ángela; Troncoso, Jesús S; Martínez, Brezo

    2018-08-01

    Poor physiological acclimatization to climate change has led to shifts in the distributional ranges of various species and to biodiversity loss. However, evidence also suggests the relevance of non-climatic physical factors, such as light, and biotic factors, which may act in interactive or additive way. We used a mechanistic approach to evaluate the ecophysiological responses of four seaweed species (three dominant intertidal fucoids, Fucus serratus, Ascophyllum nodosum, Bifurcaria bifurcata, and the invasive Sargassum muticum) to different conditions of grazing, light irradiance and ultraviolet (UV) radiation. We performed a large-scale mesocosm experiment with a total of 800 individual thalli of macroalgae. The factorial experimental design included major algal traits, photoacclimation, nutrient stoichiometry and chemical defence as response variables. Few significant effects of the factors acting alone or in combination were observed, suggesting a good capacity for acclimatization in all four species. The significant effects were generally additive and there were no potentially deleterious synergistic effects between factors. Fucus serratus, a species currently undergoing a drastic contraction of its southern distribution limit in Europe, was the most strongly affected species, showing overall lower photosynthetic efficiency than the other species. The growth rate of F. serratus decreased when UV radiation was filtered out, but only in the presence of grazers. Moreover, more individuals of this species tended to reach maturity in the absence of grazers, and the nitrogen content of tissues decreased under full-spectrum light. Only the phlorotannin content of tissues of B. bifurcata and of exudates of A. nodosum, both slow-growing species, were positively affected by respectively removal of UVB radiation and the presence of grazers. The findings for S. muticum, a well-established invasive seaweed across European coasts, suggested similar physiological response of

  9. The Marshall Grazing Incidence X-ray Spectrometer

    Kobayashi, Ken; Winebarger, Amy R.; Savage, Sabrina; Champey, Patrick; Cheimets, Peter N.; Hertz, Edward; Bruccoleri, Alexander R.; Golub, Leon; Ramsey, Brian; Ranganathan, Jaganathan; Marquez, Vanessa; Allured, Ryan; Parker, Theodore; Heilmann, Ralf K.; Schattenburg, Mark L.

    2017-08-01

    The Marshall Grazing Incidence X-ray Spectrometer (MaGIXS) is a NASA sounding rocket instrument designed to obtain spatially resolved soft X-ray spectra of the solar atmosphere in the 6-24 Å (0.5-2.0 keV) range. The instrument consists of a single shell Wolter Type-I telescope, a slit, and a spectrometer comprising a matched pair of grazing incidence parabolic mirrors and a planar varied-line space diffraction grating. The instrument is designed to achieve a 50 mÅ spectral resolution and 5 arcsecond spatial resolution along a +/-4-arcminute long slit, and launch is planned for 2019. We report on the status and our approaches for fabrication and alignment for this novel optical system. The telescope and spectrometer mirrors are replicated nickel shells, and are currently being fabricated at the NASA Marshall Space Flight Center. The diffraction grating is currently under development by the Massachusetts Institute of Technology (MIT); because of the strong line spacing variation across the grating, it will be fabricated through e-beam lithography.

  10. Governing Grazing and Mobility in the Samburu Lowlands, Kenya

    Annemiek Pas

    2018-03-01

    Full Text Available Pastoral mobility is seen as the most effective strategy to make use of constantly shifting resources. However, mobile pastoralism as a highly-valued strategy to manage grazing areas and exploit resource variability is becoming more complex, due to recurrent droughts, loss of forage, government-led settlement schemes, and enclosure of land for community conservation, among other reasons. Yet knowledge of how Samburu pastoralists perceive these changes, and govern and innovate in their mobility patterns and resource use, has received limited attention. This paper seeks to understand how Samburu pastoralists in the drylands of northern Kenya use and govern natural resources, how livestock grazing and mobility is planned for, and how boundaries and territory are constructed and performed both within and beyond the context of (nongovernmental projects. Fieldwork for this paper was conducted in Sesia, Samburu East, and consisted of interviews, focus group discussions, and participatory observation. Findings show that livestock mobility involves longer periods and more complex distances due to a shrinking resource base and new rules of access. Although access was previously generated based on the value of reciprocity, the creation of new forms of resource management results in conditional processes of inclusion and exclusion. Policy and project implementation has historically been driven by the imperative to secure land tenure and improve pasture in bounded areas. Opportunities to support institutions that promote mobility have been given insufficient attention.

  11. Subacute ruminal acidosis (SARA) in grazing Irish dairy cows.

    O'Grady, Luke; Doherty, Michael L; Mulligan, Finbar J

    2008-04-01

    Subacute ruminal acidosis (SARA) is a significant production disease of dairy cattle. Previous concerns have been raised over the occurrence of SARA in pasture-fed dairy cattle and the potential consequences of laminitis and lameness. Highly digestible perennial rye grass contains high concentrations of rapidly fermentable carbohydrate and low concentrations of physical effective fibre that may result in SARA. This study conducted a point prevalence survey of rumen health status in grazing Irish dairy cattle fed predominantly perennial rye grass-based pasture. The survey assessed rumen fluid, animal health status, milk production data and pasture composition. A total of 144 cows between 80 and 150 days in milk were sampled on 12 farms. Eleven percent of cows were classified as affected with SARA (pH 5.8). The study showed that low rumen pH is prevalent in grazing Irish dairy cattle consuming perennial rye grass-based pasture and raises concerns regarding effective pasture utilisation and possible consequences for animal health.

  12. Reducing supplementation frequency for Nellore beef steers grazing tropical pastures

    Roberta Carrilho Canesin

    2014-04-01

    Full Text Available Reduced supplementation frequency is a broadly applied management practice. Ruminants consuming low quality forages/pastures, supplemented less than once daily are able to maintain body weight gain (BWG, efficiency of use of dry matter, nitrogen and other nutrients, as compared with animals supplemented once daily. We evaluated the feeding behavior, dry matter intake (DMI, dry matter and organic matter digestibility (DMD and OMD, BWG, Longissimus muscle area and backfat depth of Nellore steers raised on Brachiaria brizantha cv. Marandu pastures during the dry season, with different supplementation patterns. Thirty six animals (338 ± 40.7 kg were distributed over nine paddocks according to a completely randomized design. Treatments were based on supplementation frequency: once daily (OD, once daily except Saturdays and Sundays (SS, or on alternate days (AD, at 1.0 %, 1.4 % and 2.0 % BW, respectively. Average total DMI accounted for 1.6 % BW day-1, with no effect of supplementation frequency. Supplementation frequency had no effect on BWG or grazing time during the day. There was no difference in Longissimus muscle area animals supplemented daily, SS and AD. The backfat depth was thinner in animals supplemented AD, but even in this case, it was within the standards considered satisfactory for a finishing steer. Reducing supplementation frequency seems a good option to lower labor costs without affecting feed efficiency or carcass quality in beef cattle grazing tropical pastures.

  13. The nitrogen, carbon and greenhouse gas budget of a grazed, cut and fertilised temperate grassland

    Jones, Stephanie K.; Helfter, Carole; Anderson, Margaret; Coyle, Mhairi; Campbell, Claire; Famulari, Daniela; Di Marco, Chiara; van Dijk, Netty; Sim Tang, Y.; Topp, Cairistiona F. E.; Kiese, Ralf; Kindler, Reimo; Siemens, Jan; Schrumpf, Marion; Kaiser, Klaus; Nemitz, Eiko; Levy, Peter E.; Rees, Robert M.; Sutton, Mark A.; Skiba, Ute M.

    2017-04-01

    Intensively managed grazed grasslands in temperate climates are globally important environments for the exchange of the greenhouse gases (GHGs) carbon dioxide (CO2), nitrous oxide (N2O) and methane (CH4). We assessed the N and C budget of a mostly grazed and occasionally cut and fertilised grassland in SE Scotland by measuring or modelling all relevant imports and exports to the field as well as changes in soil C and N stocks over time. The N budget was dominated by import from inorganic and organic fertilisers (21.9 g N m-2 a-1) and losses from leaching (5.3 g N m-2 a-1), N2 emissions (2.9 g N m-2 a-1), and NOx and NH3 volatilisation (3.9 g N m-2 a-1), while N2O emission was only 0.6 g N m-2 a-1. The efficiency of N use by animal products (meat and wool) averaged 9.9 % of total N input over only-grazed years (2004-2010). On average over 9 years (2002-2010), the balance of N fluxes suggested that 6.0 ± 5.9 g N m-2 a-1 (mean ± confidence interval at p > 0.95) were stored in the soil. The largest component of the C budget was the net ecosystem exchange of CO2 (NEE), at an average uptake rate of 218 ± 155 g C m-2 a-1 over the 9 years. This sink strength was offset by carbon export from the field mainly as grass offtake for silage (48.9 g C m-2 a-1) and leaching (16.4 g C m-2 a-1). The other export terms, CH4 emissions from the soil, manure applications and enteric fermentation, were negligible and only contributed to 0.02-4.2 % of the total C losses. Only a small fraction of C was incorporated into the body of the grazing animals. Inclusion of these C losses in the budget resulted in a C sink strength of 163 ± 140 g C m-2 a-1. By contrast, soil stock measurements taken in May 2004 and May 2011 indicated that the grassland sequestered N in the 0-60 cm soil layer at 4.51 ± 2.64 g N m-2 a-1 and lost C at a rate of 29.08 ± 38.19 g C m-2 a-1. Potential reasons for the discrepancy between these estimates are probably an underestimation of C losses, especially from

  14. Trends in grazing emission x-ray analysis techniques

    Grieken, R. van; Tsuji, K.; Injuk, J.

    2000-01-01

    In grazing-emission x-ray fluorescence (GEXRF) spectrometry, XRF is made surface-sensitive, not by grazing incidence of the exciting radiation as in total reflection XRF (TXRF), but by detecting only that part of fluorescence radiation that is emitted at grazing angles above a polished sample carrier or above a flat wafer. In case of GEXRF, and contrary to TXRF, wavelength-dispersive (WD) detection can be used. Applications are, in principle, similar to those of (variable angle) TXRF. At the laboratory scale, only prototype instruments are available, and the GEXRF unit can be an accessory to a commercial WD-XRF instrument. The detection limits of GEXRF are in the higher pg range, corresponding to a concentration of between 0.4-3 μg/l, if a sample volume of 100 μl is examined. Because of the WD detection, GEXRF also lends itself for the analysis of low-Z elements, from Z > 5; this is an advantage over conventional TXRF (but similar to TXRF using a thin-window energy-dispersive detector). Since the GEXRF prototype is a sequential rather than a simultaneous instrument, the analysis time is long when many elements have to be determined. Moreover, because the soft characteristic radiation is more strongly absorbed in its longer path through the matrix than in TXRF, the linear response for trace analysis using GEXRF is limited; this was proven by calculating the fluorescence intensities as a function of layer thickness and composition. The specimens are very limited in thickness. The sample preparation procedure for liquid or other samples to be analyzed with the GEXRF unit is thus very problematic. Results for water samples, bio-materials and pigment and aerosol samples have indeed shown that the quantitative nature of GEXRF for trace analysis is poor. The most promising features of GEXRF are in the field of surface and thin-layer analysis. Trace contaminations on silicon wafers can be determined and depth profiling can characterize stratified near-surface layers. But

  15. Vegetation selection by Angus crossbred vs. Raramuri Criollo nursing cows grazing Chihuauan Desert rangeland in summer

    We examined vegetation selection patterns of nursing Angus X Hereford crossbred (AH) and Raramuri Criollo (RC) cows grazing Chihuahuan Desert vegetation during the growing season. Eleven cows of each group grazed separately in two large pastures (1190ha, 1165ha) from mid-July until mid-August 2015 (...

  16. Competition between two grass species with and without grazing over a productivity gradient

    Kuijper, D.P.J.; Dubbeld, J.; Bakker, J.P.

    2005-01-01

    Soil nutrient-level and herbivory are predicted to have opposing effects on the allocation pattern of the competitive dominant plant species. Lower stem and higher leaf allocation are favoured when plants are grazed, whereas a higher stem allocation is favoured at high nutrient levels. Grazing by

  17. Dairy cattle on Norwegian alpine rangelands – grazing preferences and milk quality

    Sickel, H; Abrahamsen, R K; Eldegard, K; Lunnan, T; Norderhaug, A; Petersen, M.A.; Sickel, M.; Steenhuisen, F.; Ohlson, M.

    2014-01-01

    The results from the study ‘Effects of vegetation and grazing preferences on the quality of alpine dairy products’ will be presented. The main objective of the project was to investigate the connections bet - ween alpine rangeland vegetation, landscape use and grazing preferences of free ranging

  18. 36 CFR 222.3 - Issuance of grazing and livestock use permits.

    2010-07-01

    ... livestock use permits. 222.3 Section 222.3 Parks, Forests, and Public Property FOREST SERVICE, DEPARTMENT OF AGRICULTURE RANGE MANAGEMENT Grazing and Livestock Use on the National Forest System § 222.3 Issuance of grazing and livestock use permits. (a) Unless otherwise specified by the Chief, Forest Service, all...

  19. Long-term effects of grazing management and buffer strips on soil erosion from pastures

    High grazing pressure can lead to soil erosion in pastures by compacting soil and increasing runoff and sediment delivery to waterways. Limited information exists on the effects of grazing management and best management practices (BMPs), such as buffer strips, on soil erosion from pastures. The obje...

  20. Effects of grazing intensity on small mammal population ecology in wet meadows

    Schmidt, Niels Martin; Olsen, Henrik; Bildsøe, Mogens

    2005-01-01

    Livestock grazing is common management practice in wet grasslands. However, knowledge of its effects on small mammals is limited. We studied the influence of grazing intensity on small mammals in general and field voles Microtus agrestis in particular in two Danish wet meadows, 1998-2000. General...

  1. Root Characteristics of Perennial Warm-Season Grasslands Managed for Grazing and Biomass Production

    Rattan Lal

    2013-07-01

    Full Text Available Minirhizotrons were used to study root growth characteristics in recently established fields dominated by perennial C4-grasses that were managed either for cattle grazing or biomass production for bioenergy in Virginia, USA. Measurements over a 13-month period showed that grazing resulted in smaller total root volumes and root diameters. Under biomass management, root volume was 40% higher (49 vs. 35 mm3 and diameters were 20% larger (0.29 vs. 0.24 mm compared to grazing. While total root length did not differ between grazed and biomass treatments, root distribution was shallower under grazed areas, with 50% of total root length in the top 7 cm of soil, compared to 41% in ungrazed exclosures. These changes (i.e., longer roots and greater root volume in the top 10 cm of soil under grazing but the reverse at 17–28 cm soil depths were likely caused by a shift in plant species composition as grazing reduced C4 grass biomass and allowed invasion of annual unsown species. The data suggest that management of perennial C4 grasslands for either grazing or biomass production can affect root growth in different ways and this, in turn, may have implications for the subsequent carbon sequestration potential of these grasslands.

  2. Case study: dairies utilizing ultra-high stocking density grazing in Pennsylvania and New York

    Ultra-high stocking density (UHSD) grazing has gained interest in the forage industry. Proponents of UHSD emphasize increased forage use efficiency and soil improvement by grazing mature forage with stocking densities up to 560,425 kg ha**-1 of beef cattle on small paddocks with rest periods of up t...

  3. Effects of livestock grazing on neotropical migratory landbirds in western North America

    Carl E. Bock; Victoria A. Saab; Terrell D. Rich; David S. Dobkin

    1993-01-01

    Livestock grazing is a widespread and important influence on neotropical migratory birds in four major ecosystems in western North America: grasslands of the Great Plains and Southwest, riparian woodlands, Intermountain shrubsteppe, and open coniferous forests. We have reviewed available literature on avian responses to grazing in these habitats. Among 35 plains...

  4. Cattle grazing and fish recovery on US federal lands: can social-ecological systems science help?

    Susan Charnley; Hannah Gosnell; Kendra L Wendel; Mary M Rowland; Michael J Wisdom

    2018-01-01

    In the western US, grazing management on federal lands containing habitat for fish species listed under the US Endangered Species Act (ESA) has sparked social conflict and litigation for decades. To date, the problem has been addressed through a top-down environmental governance system, but rangeland managers and grazing permittees now believe there is a need for more...

  5. Grasshopper responses to fire and postfire grazing in the northern Great Plains vary among species

    Rangeland management practices such as burning and grazing management may affect grasshopper populations by impacting development, survival and reproduction. Experiments are lacking in the northern Great Plains examining the effects of fire and grazing intensity on grasshoppers. As part of a larger ...

  6. Some effects of winter grazing of Dohne sour veld | PF | African ...

    The utilisation of spared sour veld poses practical problems. As a result of the development of high level protein or nitrogen supplements it has however become possible to efficiently graze spared veld. Results of experiments during three winters where spared sour veld was grazed off either by sheep or by cattle are given.

  7. Physical impact of grazing by sheep on the dynamics of Nama ...

    UFS

    Physical impact of sheep grazing on arid Karoo subshrub/grass rangeland,. South Africa ... sustainability of rangeland resources, soil and vegetation responses to various grazing systems (Teague &. Dowhower .... The only significant decrease (F3,4 = 18.14, P <0.01) in basal cover of the total herbaceous layer for the 1995 ...

  8. Grazing management, resilience and the dynamics of a fire driven rangeland system

    Anderies, J.M.; Janssen, M.A.; Walker, B.H.

    2002-01-01

    We developed a stylized mathematical model to explore the effects of physical, ecological, and economic factors on the resilience of a managed fire-driven rangeland system. Depending on grazing pressure, the model exhibits one of three distinct configurations: a fire-dominated, grazing-dominated, or

  9. Using NDVI to estimate carbon fluxes from small rotationally grazed pastures

    Satellite-based Normalized Difference Vegetation Index (NDVI) data have been extensively used for estimating gross primary productivity (GPP) and yield of grazing lands throughout the world. However, the usefulness of satellite-based images for monitoring rotationally-grazed pastures in the northea...

  10. Habitat preference of geese is affected by livestock grazing : Seasonal variation in an experimental field evaluation

    Mandema, Freek S.; Tinbergen, Joost M.; Stahl, Julia; Esselink, Peter; Bakker, Jan P.

    The number of staging geese in northwestern Europe has increased dramatically. Growing goose numbers put strong grazing pressure on agricultural pastures. Damage to agricultural land may be mitigated by managing nature reserves in order to optimally accommodate large numbers of grazing geese.

  11. Food supply and demand, a simulation model of the functional response of grazing ruminants

    Smallegange, I.M.; Brunsting, A.M.H.

    2002-01-01

    A dynamic model of the functional response is a first prerequisite to be able to bridge the gap between local feeding ecology and grazing rules that pertain to larger scales. A mechanistic model is presented that simulates the functional response, growth and grazing time of ruminants. It is based on

  12. The effect of seasonal grazing on the infiltration capacity of soils in a ...

    The infiltration measurements were determined by means of a flood type concentric ring infiltrometer. The results showed that grazing during any one of the seasons reduced the infiltration capacity of the soils. The detrimental effects of summer and autumn grazing were, however, larger titan those of winter and spring ...

  13. Sierra Nevada grasslands: interactions between livestock grazing and ecosystem structure and function

    Barbara H. Allen-Diaz

    2004-01-01

    Livestock grazing plays an integral role in the grass-dominated ecosystems of the Sierra Nevada. Grazing has been asserted to influence such key ecological characteristics as water quality, net primary productivity, nutrient cycling, plant and animal diversity, wildlife habitat availability, and oak regeneration (Belsky and others 1999, Kauffmann and Krueger 1984)....

  14. X-ray diffraction study of surface-layer structure in parallel grazing rays

    Shtypulyak, N.I.; Yakimov, I.I.; Litvintsev, V.V.

    1989-01-01

    An x-ray diffraction method is described for study of thin polycrystalline and amorphous films and surface layers in an extremely asymmetrical diffraction system in parallel grazing rays using a DRON-3.0 diffractometer. The minimum grazing angles correspond to diffraction under conditions of total external reflection and a layer depth of ∼ 2.5-8 nm

  15. Impact of grazing on range plant community components under arid Mediterranean climate in northern Syria

    Niane, A.A.

    2013-01-01

    Keywords: Rotational grazing, full protection, continuous grazing species richness,

    species diversity, soil seed bank, Bayesian methods, Salsola vermiculata, seed

    longevity, rangeland management, Syria.

    Rangelands represent 70% of the semi-arid and arid

  16. Comparison of techniques for estimating herbage intake by grazing dairy cows

    Smit, H.J.; Taweel, H.Z.; Tas, B.M.; Tamminga, S.; Elgersma, A.

    2005-01-01

    For estimating herbage intake during grazing, the traditional sward cutting technique was compared in grazing experiments in 2002 and 2003 with the recently developed n-alkanes technique and with the net energy method. The first method estimates herbage intake by the difference between the herbage

  17. Tree-shrub associations in grazed woodlands: First rodents, then cattle?

    Smit, C.; Verwijmeren, M.

    2011-01-01

    Spatial associations of tree saplings with spiny or toxic plants in grazed woodlands are generally explained by associational resistance, i. e., protection against grazing via a well-defended neighbor. In this study, we tested whether directed seed dispersal and post-dispersal seed removal by wood

  18. Effects of buffer strips and grazing management on soil loss from pastures

    Intensive grazing pressure can cause soil erosion from pastures causing increased sediment loading to aquatic systems. The objectives of this work were to determine the long-term effects of grazing management and buffer strips on soil erosion from pastures fertilized with broiler litter. Field stud...

  19. Voluntary automatic milking in combination with grazing of dairy cows : Milking frequency and effects on behaviour

    Ketelaar-de Lauwere, C.C.; Ipema, A.H.; Ouwerkerk, van E.N.J.; Hendriks, M.M.W.B.; Metz, J.H.M.; Noordhuizen, J.P.T.M.; Schouten, W.G.P.

    1999-01-01

    Automatic milking systems (AMS) enable cows to be milked without human interference. Such systems are more acceptable to consumers and from the animal welfare point of view if they can be combined with grazing in the summer season. In this study, grazing was combined with fully automatic milking for

  20. Gradients in fracture force and grazing resistance across canopy layers in seven tropical grass species

    Jacobs, A.A.A.; Scheper, J.A.; Benvenutti, M.A.; Gordon, I.J.; Poppi, D.P.; Elgersma, A.

    2013-01-01

    In reproductive swards, stems can act as a barrier that affects the grazing behaviour of ruminant livestock. The barrier effect of stems is closely associated with both the force required to fracture the stems and the density of these stems (in combination, these make up grazing resistance), and

  1. Does grazing management matter for soil carbon sequestration in shortgrass steppe?

    Considerable uncertainty remains regarding the potential of grazing management on semiarid rangelands to sequester soil carbon. Short-term (less than 1 decade) studies have determined that grazing management potentially influences fluxes of carbon, but such studies are strongly influenced by prevail...

  2. Acoustic monitoring system to quantify ingestive behavior of free-grazing cattle

    Methods to estimate intake in grazing livestock include using markers, visual observation, mechanical sensors that respond to jaw movement and acoustic recording. In most of the acoustic monitoring studies, the microphone is inverted on the forehead of the grazing livestock and the skull is utilize...

  3. Effect of urea-molasses block supplementation on grazing weaner goats naturally infected with gastrointestinal nematodes

    R.M. Waruiru

    2004-11-01

    Full Text Available The influence of feeding urea-molasses blocks (UMB on growth and gastrointestinal (GI nematode parasitism of weaner goats grazing the same pasture was investigated on a farm in Nyandarua District, Kenya. Thirty female Small East African goat kids at an average age of 5 months were initially treated with albendazole orally (5 mg kg-1 body mass and randomly assigned into one of two groups: group I were fed UMB prepared using a cold process and group II kids (controls received no block supplementation (NBS. The UMB were given in the evening when the animals returned from grazing and were consumed during the night at a rate of 95.0 g head-1 day-1. Supplementation was undertaken for 3 consecutive months from July to September 2001 and January to March 2002. Body mass of the kids and faecal egg counts were measured monthly and larval cultures were performed on positive faecal samples of kids of each group. Five goats from each group were randomly selected for slaughter and total counts and identification of worms at the end of June 2002. Significant differences (P < 0.05 were found in cumulative mass gains of kids in group I from September compared with those in group II. On termination of the study kids in group I had gained an average of (+ SD 20.4 ± 1.4 kg while those in group II had gained 11.8 + 1.1 kg. From January 2002, faecal egg counts of the kids in the UMB group differed significantly (P < 0.05 from those of the NBS group and at slaughter, the mean (+ SD worm counts for the UMB group was 482 + 299 while that of the NBS group was 1 302 + 410. In all the goats, Haemonchus contortus was the predominant nematode recovered. These results indicate that UMB had significant effects in the control of GI nematode parasitism and enhanced growth of the young goats.

  4. Grazing experiments and model simulations of the role of zooplankton in Phaeocystis food webs

    Verity, P. G.

    2000-08-01

    A combined empirical and modelling study was conducted to further examine the potential importance of grazing by zooplankton in pelagic food webs in which Phaeocystis is a significant or dominant component. Laboratory experiments were designed to measure ingestion of Phaeocystis and other potential prey items which co-occur with Phaeocystis. Grazers included copepods and ciliates, and prey included Phaeocystis colonies and solitary cells, diatoms, ciliates, bacteria, and detritus. These data were expressed in the model currency of nitrogen units, and fit to hyperbolic tangent equations which included minimum prey thresholds. These equations and literature data were used to constrain a food web model whose purpose was to investigate trophic interactions rather than to mimic actual events. Nevertheless, the model output was similar to the general pattern and magnitude of development of Phaeocystis-diatom communities in some environments where they occur, e.g. north Norwegian waters. The model included three forms of nitrogen, three phytoplankton groups, bacteria, two zooplankton groups, and detritus, with detailed flows between compartments. An important component of the model was inclusion of variable prey preferences for zooplankton. The experiments and model simulations suggest several salient conclusions. Phaeocystis globosa colonies were eaten by a medium-sized copepod species, but ingestion appeared to be strongly dependent upon a proper size match between grazer and prey. If not, colonies were eaten little if at all. Phaeocystis solitary cells were ingested rapidly by ciliate microzooplankton, in agreement with prior literature observations. In contrast, detritus was eaten comparatively slowly by both ciliates and copepods. Both types of zooplankton exhibited apparent minimum prey thresholds below which grazing did not occur or was inconsequential. Model simulations implied that transitions between life cycle stages of Phaeocystis may potentially be important

  5. Revealing livestock effects on bunchgrass vegetation with Landsat ETM+ data across a grazing season

    Jansen, Vincent S.

    Remote sensing provides monitoring solutions for more informed grazing management. To investigate the ability to detect the effects of cattle grazing on bunchgrass vegetation with Landsat Enhanced Thematic Mapper Plus (ETM+) data, we conducted a study on the Zumwalt Prairie in northeastern Oregon across a gradient of grazing intensities. Biophysical vegetation data was collected on vertical structure, biomass, and cover at three different time periods during the grazing season: June, August, and October 2012. To relate these measures to the remotely sensed Landsat ETM+ data, Pearson's correlations and multiple regression models were computed. Using the best models, predicted vegetation metrics were then mapped across the study area. Results indicated that models using common vegetation indices had the ability to discern different levels of grazing across the study area. Results can be distributed to land managers to help guide grassland conservation by improving monitoring of bunchgrass vegetation for sustainable livestock management.

  6. Changes in semi-arid plant species associations along a livestock grazing gradient.

    Hugo Saiz

    Full Text Available In semi-arid ecosystems, vegetation is heterogeneously distributed, with plant species often associating in patches. These associations between species are not constant, but depend on the particular response of each species to environmental factors. Here, we investigated how plant species associations change in response to livestock grazing in a semi-arid ecosystem, Cabo de Gata-Níjar Natural Park in South East Spain. We established linear point-intercept transects at four sites with different grazing intensity, and recorded all species at each point. We investigated plant associations by comparing the number of times that each pair of species occurred at the same spatial point (co-occurrences, with the expected number of times based on species abundances. We also assessed associations for each shrub and grass species by considering all their pairs of associations and for the whole plant community by considering all pairs of associations on each site. At all sites, the plant community had a negative pattern of association, with fewer co-occurrences than expected. Negative association in the plant community increased at maximum grazing intensity. Most species associated as expected, particularly grass species, and positive associations were most important at intermediate grazing intensities. No species changed its type of association along the grazing gradient. We conclude that in the present plant community, grazing-resistant species compete among themselves and segregate in space. Some shrub species act as refuges for grazing-sensitive species that benefit from being spatially associated with shrub species, particularly at intermediate grazing intensities where positive associations were highest. At high grazing intensity, these shrubs can no longer persist and positive associations decrease due to the disappearance of refuges. Spatial associations between plant species and their response to grazing help identify the factors that organize

  7. Bison grazing increases arthropod abundance and diversity in a tallgrass prairie.

    Moran, Matthew D

    2014-10-01

    How grazing-induced ecosystem changes by ungulates indirectly affect other consumers is a question of great interest. I investigated the effect of grazing by American Bison (Bos bison L.) on an arthropod community in tallgrass prairie. Grazing increased the abundance of arthropods, an increase that was present in both herbivorous and carnivorous assemblages, but not in detritivores. The increase in herbivores and reduction in plant biomass from grazing resulted in an arthropod herbivore load almost three times higher in grazed plots compared with controls. Among herbivores, the sap-feeding insect guild was dramatically more abundant, while chewing herbivores were not affected. Herbivorous and carnivorous arthropod richness was higher in grazed plots, although the response was strongest among herbivores. Arthropod abundance on individual grasses and forbs was significantly higher in grazed areas, while plant type had no effect on abundance, indicating that the change was ecosystem-wide and not simply in response to a reduction in grass biomass from grazing. The response of arthropods to grazing was strongest in the early part of the growing season. Published research shows that ungulate grazing, although decreasing available biomass to other consumers, enhances plant quality by increasing nitrogen level in plants. The arthropod results of this study suggest higher plant quality outweighs the potential negative competitive effects of plant biomass removal, although other activities of bison could not be ruled out as the causative mechanism. Because arthropods are extremely abundant organisms in grasslands and a food source for other consumers, bison may represent valuable management tools for maintaining biodiversity.

  8. Grazing alters net ecosystem C fluxes and the global warming potential of a subtropical pasture.

    Gomez-Casanovas, Nuria; DeLucia, Nicholas J; Bernacchi, Carl J; Boughton, Elizabeth H; Sparks, Jed P; Chamberlain, Samuel D; DeLucia, Evan H

    2018-03-01

    The impact of grazing on C fluxes from pastures in subtropical and tropical regions and on the environment is uncertain, although these systems account for a substantial portion of global C storage. We investigated how cattle grazing influences net ecosystem CO 2 and CH 4 exchange in subtropical pastures using the eddy covariance technique. Measurements were made over several wet-dry seasonal cycles in a grazed pasture, and in an adjacent pasture during the first three years of grazer exclusion. Grazing increased soil wetness but did not affect soil temperature. By removing aboveground biomass, grazing decreased ecosystem respiration (R eco ) and gross primary productivity (GPP). As the decrease in R eco was larger than the reduction in GPP, grazing consistently increased the net CO 2 sink strength of subtropical pastures (55, 219 and 187 more C/m 2 in 2013, 2014, and 2015). Enteric ruminant fermentation and increased soil wetness due to grazers, increased total net ecosystem CH 4 emissions in grazed relative to ungrazed pasture (27-80%). Unlike temperate, arid, and semiarid pastures, where differences in CH 4 emissions between grazed and ungrazed pastures are mainly driven by enteric ruminant fermentation, our results showed that the effect of grazing on soil CH 4 emissions can be greater than CH 4 produced by cattle. Thus, our results suggest that the interactions between grazers and soil hydrology affecting soil CH 4 emissions play an important role in determining the environmental impacts of this management practice in a subtropical pasture. Although grazing increased total net ecosystem CH 4 emissions and removed aboveground biomass, it increased the net storage of C and decreased the global warming potential associated with C fluxes of pasture by increasing its net CO 2 sink strength. © 2017 by the Ecological Society of America.

  9. Surface damage through grazing incidence ions investigated by scanning tunneling microscopy

    Redinger, Alex

    2009-01-01

    function of the ion fluence. This method is also applicable under less grazing angles of incidence. The investigations show that the sputtering yield at step edges depends on the azimuthal orientation of the impinging ions with respect to the surface. This change is attributed to the orientation dependence of subsurface channeling. The step edge sputtering yield at small adatom clusters is measured. In this case, the topmost layer (which forms the step edge) has a small lateral extension in ion beam direction. The evaluation shows that the step edge yield is, compared to step edges with a long upper terrace, decreased by a factor of three. The physical reason can be traced back to subsurface channeling. The ions are able to pass underneath the cluster and exit the crystal without a large scattering event. Little energy is transfered to the crystal which results in a low sputtering yield. The influence of adsorbates on sputtering and surface damage in grazing incidence ion erosion is studied for the case of oxygen and carbon monoxide. A partial surface coverage with adsorbates causes an enhancement of the erosion rate (the amount of removed material per ion fluence) by a factor of up to 40 compared to the clean case. The study is performed for 5 keV Ar + ions for various grazing angles between 81 and 87 and temperatures ranging from 400 K to 550 K. Finally, coarsening of ion beam induced ripple patterns is analyzed. For surface temperatures of 450 K or below coarsening is athermal and kinetic, unrelated to diffusion and surface free energy. Similar to the situation of sand dunes, coarsening takes place through annihilation reactions of mobile defects in the pattern. The defect velocity derived on the basis of a simple model agrees quantitatively with the velocity of monoatomic steps illuminated by the ion beam. (orig.)

  10. Surface damage through grazing incidence ions investigated by scanning tunneling microscopy

    Redinger, Alex

    2009-07-10

    of material as a function of the ion fluence. This method is also applicable under less grazing angles of incidence. The investigations show that the sputtering yield at step edges depends on the azimuthal orientation of the impinging ions with respect to the surface. This change is attributed to the orientation dependence of subsurface channeling. The step edge sputtering yield at small adatom clusters is measured. In this case, the topmost layer (which forms the step edge) has a small lateral extension in ion beam direction. The evaluation shows that the step edge yield is, compared to step edges with a long upper terrace, decreased by a factor of three. The physical reason can be traced back to subsurface channeling. The ions are able to pass underneath the cluster and exit the crystal without a large scattering event. Little energy is transfered to the crystal which results in a low sputtering yield. The influence of adsorbates on sputtering and surface damage in grazing incidence ion erosion is studied for the case of oxygen and carbon monoxide. A partial surface coverage with adsorbates causes an enhancement of the erosion rate (the amount of removed material per ion fluence) by a factor of up to 40 compared to the clean case. The study is performed for 5 keV Ar{sup +} ions for various grazing angles between 81 and 87 and temperatures ranging from 400 K to 550 K. Finally, coarsening of ion beam induced ripple patterns is analyzed. For surface temperatures of 450 K or below coarsening is athermal and kinetic, unrelated to diffusion and surface free energy. Similar to the situation of sand dunes, coarsening takes place through annihilation reactions of mobile defects in the pattern. The defect velocity derived on the basis of a simple model agrees quantitatively with the velocity of monoatomic steps illuminated by the ion beam. (orig.)

  11. Short-term winter wheat (Triticum aestivum L.) cover crop grazing influence on calf growth, grain yield, and soil properties

    Winter cover cropping has many agronomic benefits and can provide forages base for spring livestock grazing. Winter cover crop grazing has shown immediate economic benefits through increased animal production. Winter wheat pasture grazing is common in beef cow-calf production and stocker operations....

  12. Non-traditional Forages in a Managed Grazing System for Control of Gastrointestinal Parasites in Sheep: Preliminary Work

    This project compared lambs grazing forage chicory (Cichorium intybus L.) with lambs grazing brown mid-rib forage sorghum (Sorghum bicolor (L.) Moench.) x sudangrass (Sorghum sudanense Piper) hybrid (BMR) to determine if anti-parasitic effects of chicory could be demonstrated. Lambs grazed these fo...

  13. Image processing for grazing incidence fast atom diffraction

    Debiossac, Maxime; Roncin, Philippe, E-mail: philippe.roncin@u-psud.fr

    2016-09-01

    Grazing incidence fast atom diffraction (GIFAD, or FAD) has developed as a surface sensitive technique. Compared with thermal energies helium diffraction (TEAS or HAS), GIFAD is less sensitive to thermal decoherence but also more demanding in terms of surface coherence, the mean distance between defects. Such high quality surfaces can be obtained from freshly cleaved crystals or in a molecular beam epitaxy (MBE) chamber where a GIFAD setup has been installed allowing in situ operation. Based on recent publications by Atkinson et al. (2014) and Debiossac et al. (2014), the paper describes in detail the basic steps needed to measure the relative intensities of the diffraction spots. Care is taken to outline the underlying physical assumptions.

  14. GRAZING BEHAVIOUR OF DAIRY COWS ON MOUNTAIN FARM

    J. VOŘÍŠKOVÁ

    2009-10-01

    Full Text Available The etological observation was provided on a dairy herd (65 Czech Fleckvieh and 51 Holstein cows on a low-input mountain farm during the pasture season (April – October 2008. The milking was provided two-times a day in the stalls. The 24-hours observations were made four-times: in June, July, September and October, in 10- minutes intervals. The cows spent 25 to 38 % of a day on average by feeding and 18 to 22 % on average by moving (stalls – pasture movements took about half of this period. The resting time consisting of chewing was found unsufficient and took 29 % to 40 % of a day on average. Better comfort of cows given by an improved milking technology and a more effective grazing management connected with longer time spent by resting is suggested to achieve higher milk yields on the farm.

  15. Goats on alpine grazing: study on metabolic and hematologic profiles

    A. Gaviraghi

    2011-03-01

    Full Text Available Summering on alpine pastures from June to October has long been the traditional management of goat flocks in the mountain areas of Lombardy. At present most of the 50.000 goats farmed in Lombardy are still summered, even though only a few thousands - belonging to local breed - are regularly milked. For these goats summering appears to be fundamental not only to allow milk production but also to restore body reserves. The increasing interest in commercial goat milk production in Lombardy involves mainly intensive farming with zero or minimum grazing. However, semi-extensive goat milk production, including summering, could respond to social and environmental goals (Citterio et al., 2002 being able to exploit some economic opportunities...

  16. Actinide concentrations in tissues from cattle grazing a contaminated range

    Smith, D.D.; Bernhardt, D.E.

    1977-01-01

    Actinide concentrations in the tissues of beef animals periodically sacrificed and sampled during a 3-year grazing study on a plutonium-contaminated range of the Nevada Test Site are discussed. Actinide concentrations in the skeletons of the cows originally introduced into the study areas showed little increase with increased time of exposure, while those of animals born in the study areas showed a continued upward trend with time. Plutonium-239/americium-241 ratios in tissues and ingesta suggest little differentiation in the uptake of these radionuclides. However, the plutonium-239/plutonium-238 ratios indicate that plutonium-238 is more readily absorbed. The gonadal concentrations of the actinides were significantly higher than those of blood and muscle and approached those of bone. These data indicate that consideration should be given to the plutonium-239 dose to gonads as well as that to bone, liver, and lungs of man

  17. Active Micro structured Optical Arrays of Grazing Incidence Reflectors

    Willingale, R.; Feldman, Ch.; Michette, A.; Hart, D.; McFaul, Ch; Morrison, G.R.; Pfauntsch, S.; Powell, A.K.; Sahraei, Sh.; Shand, M.T.; Button, T.; Rodriguez-Sanmartin, D.; Zhang, D.; Dunare, C.; Parkes, W.; Stevenson, T.; Folkard, M.; Vojnovic, B.; Vojnovic, B.

    2011-01-01

    The UK Smart X-Ray Optics (SXO) programme is developing active/adaptive optics for terrestrial applications. One of the technologies proposed is micro structured optical arrays (MOAs), which focus X-rays using grazing incidence reflection through consecutive aligned arrays of microscopic channels. Although such arrays are similar in concept to poly capillary and microchannel plate optics, they can be bent and adjusted using piezoelectric actuators providing control over the focusing and inherent aberrations. Custom configurations can be designed, using ray tracing and finite element analysis, for applications from sub-keV to several-keV X-rays, and the channels of appropriate aspect ratios can be made using deep silicon etching. An exemplar application will be in the micro probing of biological cells and tissue samples using Ti Ka radiation (4.5?keV) in studies related to radiation-induced cancers. This paper discusses the optical design, modelling, and manufacture of such optics

  18. Grazing intensity affects the environmental impact of dairy systems.

    Aguirre-Villegas, H A; Passos-Fonseca, T H; Reinemann, D J; Larson, R

    2017-08-01

    Dairy products are major components of the human diet but are also important contributors to global environmental impacts. This study evaluated greenhouse gas (GHG) emissions, net energy intensity (NEI), and land use of confined dairy systems with increasing levels of pasture in the diet. A Wisconsin farm was modeled to represent practices adopted by dairy operations in a humid continental climate typical in the Great Lakes region and other climates that have large differences in seasonal temperatures. Five grazing scenarios (all of which contained some portion of confinement) were modeled based on different concentrations of dry matter intake from pasture and feed supplementation from corn grain, corn silage, and soybean meal. Scenarios that incorporate grazing consisted of 5 mo of pasture feeding from May to September and 7 mo of confined feeding from October to April. Environmental impacts were compared within the 5 scenarios that incorporate grazing and across 2 entirely confined scenarios with and without on-farm electricity production through anaerobic digestion (AD). To conduct a fair comparison, all scenarios were evaluated based on the same total amount of milk produced per day where resource inputs were adjusted according to the characteristics of each scenario. A cradle-to-farm gate life cycle assessment evaluated the environmental burdens that were partitioned by allocation between milk and meat and by system expansion when biogas-based electricity was produced. Overall, results for all scenarios were comparable. Enteric methane was the greatest contributor to GHG emissions, and the production of crops was the most energy-intense process. For the confined scenario without AD, GHG emissions were 0.87 kg of CO 2 equivalents, NEI was 1.59 MJ, and land use was 1.59 m 2 /kg of fat- and protein-corrected milk (FPCM). Anaerobic digestion significantly reduced emissions to 0.28 kg of CO 2 equivalents/kg of FPCM and reduced NEI to -1.26 MJ/kg of FPCM, indicating

  19. Sustainability, arid grasslands and grazing: New applications for technology

    Pregenzer, A.L.; Parmenter, R.; Passell, H.D.; Budge, T.; Vande Caste, J.

    1999-12-08

    The study of ecology is taking on increasing global importance as the value of well-functioning ecosystems to human well-being becomes better understood. However, the use of technological systems for the study of ecology lags behind the use of technologies in the study of other disciplines important to human well-being, such as medicine, chemistry and physics. The authors outline four different kinds of large-scale data needs required by land managers for the development of sustainable land use strategies, and which can be obtained with current or future technological systems. They then outline a hypothetical resource management scenario in which data on all those needs are collected using remote and in situ technologies, transmitted to a central location, analyzed, and then disseminated for regional use in maintaining sustainable grazing systems. They conclude by highlighting various data-collection systems and data-sharing networks already in operation.

  20. A model of ammonia volatilization from a grazing livestock farm

    Hutchings, N. J.; Sommer, S. G.; Jarvis, S. C.

    A dynamic model was developed to predict the ammonia volatilization from grazing livestock farms and to allow potential control measures to be evaluated. The relationships within the model were based on the underlying physical and chemical processes but empirically based factors were used to reduce the demand for input data and where the understanding of the underlying processes was inadequate. On a daily basis, the model simulates the partitioning of dietary nitrogen into dung and urine and its subsequent fate within the pasture or the slurry handling system. The fate of dry matter and water added in dung, urine and from other sources is also predicted. The model illustrates the indirect interactions between ammonia sources, highlights the influence of slurry management on ammonia losses, stresses the need for integrated, whole farm measurements and demonstrates that assessments of the impact of control measures may be misleading unless considered at the scale of the whole farm.

  1. Beef heifer growth and reproductive performance following two levels of pasture allowance during the fall grazing period.

    Bailey, B L; Griggs, T C; Rayburn, E B; Krause, K M

    2014-08-01

    The objective of this study was to compare heifer growth and reproductive performance following 2 levels of stockpiled fall forage allowance of orchardgrass (30.5%) and tall fescue (14.1%). Spring-born heifers (n = 203 and BW = 246 ± 28.9 kg) of primarily Angus background were allocated to 2 grazing treatments during the fall period (November 12 to December 17 in yr 1, November 7 to January 4 in yr 2, and November 7 to January 14 in yr 3) each replicated 3 times per year for 3 yr. Treatments consisted of daily pasture DM allowance of 3.5% of BW (LO) or daily pasture DM allowance of 7.0% of BW (HI) under strip-grazing management. Throughout the winter feeding period, mixed grass-legume haylage and soybean hulls were fed. Heifers were grazed as 1 group under continuous stocking after the winter period. Heifers in the LO group gained less than heifers in the HI group during the fall grazing period (0.12 vs. 0.40 kg/d; P < 0.0001). For each 1 10 g increase in NDF/kg fall pasture (DM basis), fall ADG decreased 0.14 kg (P = 0.01). During winter feeding, ADG was 0.30 and 0.39 kg/d for LO vs. HI heifers, respectively (P = 0.0008). During the spring grazing period (April 16 to May 24 in yr 1, April 22 to May 26 in yr 2, and April 5 to May 16 in yr 3), LO heifers had numerically greater ADG than HI heifers (1.38 vs. 1.30 kg/d; P = 0.64). Hip height (122.7 vs. 121.4 cm; P = 0.0055), BCS (5.8 vs. 5.6; P = 0.0057), and BW (356 vs. 335 kg; P < 0.0001) at the end of spring grazing was greater for HI than LO heifers. Heifers in the LO group compensated with greater summer ADG than heifers in the HI group (0.74 vs. 0.66 kg/d; P = 0.03). Total ADG from treatment initiation (November) through pregnancy diagnosis (August) was greater for HI than LO heifers (0.61 vs. 0.55 kg/d; P < 0.001) as was BW at pregnancy diagnosis (415 vs. 402 kg; P = 0.0055). Percentage of heifers reaching puberty by the time of AI was 34% for both groups (P = 0.93). Percentage of heifers becoming pregnant to

  2. Sympatric cattle grazing and desert bighorn sheep foraging

    Garrison, Kyle R.; Cain, James W.; Rominger, Eric M.; Goldstein, Elise J.

    2015-01-01

    Foraging behavior affects animal fitness and is largely dictated by the resources available to an animal. Understanding factors that affect forage resources is important for conservation and management of wildlife. Cattle sympatry is proposed to limit desert bighorn population performance, but few studies have quantified the effect of cattle foraging on bighorn forage resources or foraging behavior by desert bighorn. We estimated forage biomass for desert bighorn sheep in 2 mountain ranges: the cattle-grazed Caballo Mountains and the ungrazed San Andres Mountains, New Mexico. We recorded foraging bout efficiency of adult females by recording feeding time/step while foraging, and activity budgets of 3 age-sex classes (i.e., adult males, adult females, yearlings). We also estimated forage biomass at sites where bighorn were observed foraging. We expected lower forage biomass in the cattle-grazed Caballo range than in the ungrazed San Andres range and lower biomass at cattle-accessible versus inaccessible areas within the Caballo range. We predicted bighorn would be less efficient foragers in the Caballo range. Groundcover forage biomass was low in both ranges throughout the study (Jun 2012–Nov 2013). Browse biomass, however, was 4.7 times lower in the Caballo range versus the San Andres range. Bighorn in the Caballo range exhibited greater overall daily travel time, presumably to locate areas of higher forage abundance. By selecting areas with greater forage abundance, adult females in the Caballo range exhibited foraging bout efficiency similar to their San Andres counterparts but lower overall daily browsing time. We did not find a significant reduction in forage biomass at cattle-accessible areas in the Caballo range. Only the most rugged areas in the Caballo range had abundant forage, potentially a result of intensive historical livestock use in less rugged areas. Forage conditions in the Caballo range apparently force bighorn to increase foraging effort by

  3. Effect of livestock grazing in the partitions of a semiarid plant-plant spatial signed network

    Saiz, Hugo; Alados, Concepción L.

    2014-08-01

    In recent times, network theory has become a useful tool to study the structure of the interactions in ecological communities. However, typically, these approaches focus on a particular kind of interaction while neglecting other possible interactions present in the ecosystem. Here, we present an ecological network for plant communities that consider simultaneously positive and negative interactions, which were derived from the spatial association and segregation between plant species. We employed this network to study the structure and the association strategies in a semiarid plant community of Cabo de Gata-Níjar Natural Park, SE Spain, and how they changed in 4 sites that differed in stocking rate. Association strategies were obtained from the partitions of the network, built based on a relaxed structural balance criterion. We found that grazing simplified the structure of the plant community. With increasing stocking rate species with no significant associations became dominant and the number of partitions decreased in the plant community. Independently of stocking rate, many species presented an associative strategy in the plant community because they benefit from the association to certain ‘nurse’ plants. These ‘nurses’ together with species that developed a segregating strategy, intervened in most of the interactions in the community. Ecological networks that combine links with different signs provide a new insight to analyze the structure of natural communities and identify the species which play a central role in them.

  4. Effect of Grazing Behavior on Weight Regain Post-Bariatric Surgery: A Systematic Review

    Nathalia Pizato

    2017-12-01

    Full Text Available Grazing, a type of maladaptive eating behavior, has been associated with poor weight outcomes in bariatric patients. The purpose of this study was to conduct a systematic review of the association between grazing behavior and weight regain post-bariatric surgery. Literature searches, study selection, design of the method, and quality appraisal were carried out by two independent authors. The search strategy was performed until October 2017 in Medline, Embase, Cochrane, Lilacs, Scopus, Web of Science, Google Scholar, ProQuest Dissertation & Theses, and Open Grey. Of a total of 3764 articles, five papers met the inclusion criteria (four original articles and one thesis, comprising 994 subjects, mostly women. The prevalence of grazing behavior ranged from 16.6 to 46.6%, and the highest prevalence of significant weight regain was 47%. The association between grazing and weight regain was observed in four of the five evaluated studies. Our findings support an association between grazing behavior and weight regain after bariatric surgery, regardless of surgery type and contextual concept of grazing. Further studies are needed to confirm the clarity of the real prevalence and interfering factors related to grazing behavior and weight outcomes.

  5. Effects of livestock grazing on grasshopper abundance on a native rangeland in Montana.

    O'Neill, Kevin M; Olson, Bret E; Wallander, Roseann; Rolston, Marni G; Seibert, Catherine E

    2010-06-01

    Livestock grazing can affect habitat quality for grasshoppers through effects on food and oviposition site availability, microclimate, and other factors. Because of this, some authors have suggested that grazing programs can be used to help manage pest grasshopper populations. In a 6-yr study, we controlled access of cattle to replicated experimental plots on an Agropyron spicatum/Poa sandbergii pasture to create consistent year-to-year differences in postgrazing plant cover, with resultant affects on microclimate. After sampling grasshoppers multiple times after grazing treatments each summer, we found evidence of between-treatment differences in grasshopper abundance for the entire assemblage during 4 of the 6 yr. Some species, including Melanoplus sanguinipes (perhaps the worse rangeland grasshopper pest in the western United States), tended to be more abundant on ungrazed plots, whereas Melanoplus gladstoni often had greater densities on heavily-grazed plots. The effect of grazing on grasshopper densities in this study was lower in magnitude and less consistent among years than in a study we conducted simultaneously at a nearby site where the vegetation was dominated by the exotic species crested wheatgrass (Agropyron cristatum). Our results generally support proposals that grazing could be used to reduce pest grasshopper densities, although the effectiveness of a particular grazing scheme may vary among sites, years, and grasshopper and vegetation assemblages.

  6. Grazing impact on desert plants and soil seed banks: Implications for seed-eating animals

    Pol, Rodrigo G.; Sagario, M. Cecilia; Marone, Luis

    2014-02-01

    We assess whether the knowledge of livestock diet helps to link grazing effects with changes in plant cover and soil seed bank size, aiming at inferring the consequences of grazing on seed-eating animals. Specifically, we test whether continuous and heavy grazing reduce the cover, number of reproductive structures and seed reserves of the same grass species whose seeds are selected and preferred by granivorous animals in the central Monte desert, Argentina. Grass cover and the number of grass spikes usually diminished under grazing conditions in the two localities studied (Telteca and Ñacuñán), and soil seed bank was consistently reduced in all three years evaluated owing to a decline of perennial grass and forb seeds. In particular, the abundance of those seeds selected and preferred by birds and ants (in all cases grass species) declined 70-92% in Ñacuñán, and 52-72% in Telteca. Reduction of perennial grass cover and spike number in grazed sites reinforced the causal link between livestock grazing and the decline of grass soil seed reserves throughout failed plant reproduction. Grass seed bank depletion suggests that grazing may trigger a "cascade" of mechanisms that affect the abundance and persistence of valuable fodder species as well as the availability of seed resources for granivorous animals.

  7. Concentrate Supplement Modifies the Feeding Behavior of Simmental Cows Grazing in Two High Mountain Pastures.

    Romanzin, Alberto; Corazzin, Mirco; Piasentier, Edi; Bovolenta, Stefano

    2018-05-16

    During grazing on Alpine pastures, the use of concentrates in dairy cows' diet leads to a reduction of the environmental sustainability of farms, and influences the selective pressure on some plant species. In order to minimize the use of concentrates, it is imperative to obtain data on the grazing behavior of cows. The aim of this study was to assess the effect of concentrate levels on the behavior of dairy cows during grazing. One hundred and ten lactating Italian Simmental cows, that sequentially grazed two pastures characterized by Poion alpinae (Poion) and Seslerion caeruleae (Seslerion) alliance, were considered. For each pasture, eight cows were selected and assigned to two groups: High and Low, supplemented with 4 kg/head/d, and 1 kg/head/d of concentrate respectively. Cows were equipped with a noseband pressure sensor and a pedometer (RumiWatch system, ITIN-HOCH GmbH) to assess grazing, ruminating, and walking behavior. In addition, the plant selection of the animals was assessed. On Poion, increased supplement intake caused a more intense selection of legumes, without affecting feeding and walking times. On Seslerion, grazing time was higher in Low than High. Grazing management in alpine region must take into account the great variability of pastures that largely differ from a floristic and nutritional point of view.

  8. Concentrate Supplement Modifies the Feeding Behavior of Simmental Cows Grazing in Two High Mountain Pastures

    Alberto Romanzin

    2018-05-01

    Full Text Available During grazing on Alpine pastures, the use of concentrates in dairy cows’ diet leads to a reduction of the environmental sustainability of farms, and influences the selective pressure on some plant species. In order to minimize the use of concentrates, it is imperative to obtain data on the grazing behavior of cows. The aim of this study was to assess the effect of concentrate levels on the behavior of dairy cows during grazing. One hundred and ten lactating Italian Simmental cows, that sequentially grazed two pastures characterized by Poion alpinae (Poion and Seslerion caeruleae (Seslerion alliance, were considered. For each pasture, eight cows were selected and assigned to two groups: High and Low, supplemented with 4 kg/head/d, and 1 kg/head/d of concentrate respectively. Cows were equipped with a noseband pressure sensor and a pedometer (RumiWatch system, ITIN-HOCH GmbH to assess grazing, ruminating, and walking behavior. In addition, the plant selection of the animals was assessed. On Poion, increased supplement intake caused a more intense selection of legumes, without affecting feeding and walking times. On Seslerion, grazing time was higher in Low than High. Grazing management in alpine region must take into account the great variability of pastures that largely differ from a floristic and nutritional point of view.

  9. [Community structure and diversity of soil arthropods in naturally restored sandy grasslands after grazing].

    Liu, Ren-tao; Zhao, Ha-lin; Zhao, Xue-yong

    2010-11-01

    Taking the Naiman Desertification Research Station under Chinese Academy of Sciences as a base, an investigation was conducted on the community structure of soil arthropods in the naturally restored sandy grasslands after different intensity grazing disturbance, with the effects of vegetation and soil on this community structure approached. In the non-grazing grassland, soil arthropods were rich in species and more in individuals, and had the highest diversity. In the restored grassland after light grazing, soil arthropods had the lowest evenness and diversity. In the restored grassland after moderate grazing, the individuals of soil arthropods were lesser but the major groups were more, and the evenness and diversity were higher. In the restored grassland after heavy grazing, the individuals of soil arthropods were more but the major groups were lesser, and the diversity was higher. Plant individuals' number, vegetation height and coverage, and soil alkalinity were the main factors affecting the soil arthropod community in naturally restored grasslands after different intensity grazing disturbance. It was implied that after 12-year exclosure of grassland, soil arthropod community could be recovered to some degree, while grazing disturbance had long-term negative effects on the arthropod community.

  10. Effect of water-soluble carbohydrate content in orchardgrass pasture on grazing time and rumen fermentation in dairy cows.

    Ueda, Koichiro; Mitani, Tomohiro; Kondo, Seiji

    2016-09-01

    Two experiments were conducted to clarify the effect of water-soluble carbohydrate (WSC) content in orchardgrass pasture on the diurnal distribution of grazing time. Six ruminally cannulated, non-lactating dairy cows were grazed on either of two pastures with different orchardgrass cultivars containing low WSC (LWSC; cultivar: 'Hokkai 28') or high WSC (HWSC; cultivar: 'Harunemidori'). The cows were grazed in morning and evening sessions in experiment 1, whereas the cows were grazed throughout the day in experiment 2. In experiment 1, grazing time of the cows on HWSC was longer than that of the cows on LWSC (P content. © 2015 Japanese Society of Animal Science.

  11. Modelling parasite transmission in a grazing system: the importance of host behaviour and immunity.

    Naomi J Fox

    Full Text Available Parasitic helminths present one of the most pervasive challenges to grazing herbivores. Many macro-parasite transmission models focus on host physiological defence strategies, omitting more complex interactions between hosts and their environments. This work represents the first model that integrates both the behavioural and physiological elements of gastro-intestinal nematode transmission dynamics in a managed grazing system. A spatially explicit, individual-based, stochastic model is developed, that incorporates both the hosts' immunological responses to parasitism, and key grazing behaviours including faecal avoidance. The results demonstrate that grazing behaviour affects both the timing and intensity of parasite outbreaks, through generating spatial heterogeneity in parasite risk and nutritional resources, and changing the timing of exposure to the parasites' free-living stages. The influence of grazing behaviour varies with the host-parasite combination, dependent on the development times of different parasite species and variations in host immune response. Our outputs include the counterintuitive finding that under certain conditions perceived parasite avoidance behaviours (faecal avoidance can increase parasite risk, for certain host-parasite combinations. Through incorporating the two-way interaction between infection dynamics and grazing behaviour, the potential benefits of parasite-induced anorexia are also demonstrated. Hosts with phenotypic plasticity in grazing behaviour, that make grazing decisions dependent on current parasite burden, can reduce infection with minimal loss of intake over the grazing season. This paper explores how both host behaviours and immunity influence macro-parasite transmission in a spatially and temporally heterogeneous environment. The magnitude and timing of parasite outbreaks is influenced by host immunity and behaviour, and the interactions between them; the incorporation of both regulatory processes

  12. Grazing intensity on the plant diversity of alpine meadow in the eastern Tibetan plateau

    Wu Ning

    2004-04-01

    Full Text Available Because ofthe remoteness and harsh conditions of the high-altitude rangelands on the eastern Tibetan Plateau, the relationship between yak grazing and plant diversity has not been so clear although livestock increase was thought as the main issue leading to the degradation of rangeland. In the debate of rangeland degradation, biodiversity loss has been assumed as one of the indicators in the last two decades. In this paper authors measured the effects of different grazing intensities on the plant diversity and the structure of Kobresia pygmaea community in the case-study area, northwestern Sichuan. The results indicated that plant diversity of alpine meadow has different changing trends respectively with the change of grazing intensity and seasons. In June the highest plant diversity occurred in the intensively grazed (HG plots, but in July and September species biodiversity index of slightly grazed (LG plots is higher than other experimental treatments. In August the intermediate grazed (IG plots has the highest biodiversity index. Moreover, it was found that intensively grazing always leads to the increase of plant density, but meanwhile the decrease of community height, coverage and biomass. Over-grazing can change the community structure and lead to the succession from Kobresia pygmaea dominated community to Poa pratensis dominated. Analyzing results comprehensively, it can be suggested that the relationship between grazing intensity and plant diversity is not linear, i.e. diversity index is not as good as other characteristics of community structure to evaluate rangeland degradation on the high altitude situation. The change of biodiversity is so complicated that it can not be explained with the simple corresponding causality.

  13. Interannual and seasonal variability in short-term grazing impact of Euphausia superba in nearshore and offshore waters west of the Antarctic Peninsula

    Ross, R. M.; Quetin, L. B.; Haberman, K. L.

    1998-11-01

    Our focus in this paper is the interaction between macrozooplanktonic grazers and primary producers, and the interannual and seasonal variability in the Palmer Long-Term Ecological Research (Palmer LTER) study region from Anvers Island to Adelaide Island. Short-term grazing estimates are calculated by integrating (1) theoretical and experimental estimates of ingestion rates in response to the standing stock of phytoplankton, and (2) field measurements of phytoplankton standing stock and grazer biomass. Field data come from three austral summer cruises (January/February of 1993, 1994, and 1995) and one sequence of seasonal cruises (summer, fall and winter 1993). The relative and absolute abundance of the dominant macrozooplankton grazers, Euphausia superba and Salpa thompsoni, varied by at least an order of magnitude on the spatial and temporal scales observed. Mean grazing rates ranged from 0.4 to 9.0 μg chlorophyll m -2 h -1 for the Antarctic krill and salp populations over the three summer cruises. This leads to variability in the flow of carbon from the primary producers through the grazers on the same scales. Temporal and spatial variability in grazing impact and faecal pellet production are high.

  14. Seasonal and size-dependent variations in the phytoplankton growth and microzooplankton grazing in the southern South China Sea under the influence of the East Asian monsoon

    Zhou, L.; Tan, Y.; Huang, L.; Hu, Z.; Ke, Z.

    2015-11-01

    To examine seasonal and size-dependent variations in the phytoplankton growth and microzooplankton grazing in oligotrophic tropical waters under the influence of seasonal reversing monsoon, dilution experiments were conducted during the summer of 2009 (21 May to 9 June) and winter 2010 (9 to 18 November) in the southern South China Sea (SSCS). The results showed that environmental variables, phytoplankton biomass, phytoplankton growth rate (μ), microzooplankton grazing rate (m), and correlationship (coupling) between the μ and m, rather than the microzooplankton grazing impact on phytoplankton (m/μ) significantly varied between the two seasons. Higher relative preference index (RPI) for the larger-sized (> 3 μm) phytoplankton than pico-phytoplankton (intermittent arrivals of the northeast winter monsoon could lead to the low μ and m, and the decoupling between the μ and m in the SSCS, through influencing nutrient supply to the surface water, and inducing surface seawater salinity decrease. The low m/μ (waters such as that of the SSCS.

  15. The influence of grazing intensity on soil properties and degradation processes in Mediterranean rangelands (Extremadura, SW Spain)

    Pulido-Fernández, Manuel; Schnabel, Susanne; Francisco Lavado-Contador, Joaquín

    2014-05-01

    Rangelands cover vast extensions of land in Spain (>90,000 km2), where a total amount of 13 millions of domestic animals graze extensively their pastures. By clear-cutting shrubs, removing selected trees and by cultivation, these rangelands were created from former Mediterranean oak forests, mainly composed by holm oak and cork oak (Quercus ilex rotundifolia and Q. suber) as tree species, Nowadays this land system is exploited economically in large farms (>100 ha), most of them held on private ownership (80% of total) and dedicated to extensive ranching. Overgrazing is common and the excessive stocking rates may deteriorate soil quality, causing economic losses and environmental damage. Many studies have been developed on the effects of livestock grazing over soil properties and degradation processes, most of them by only comparing extreme cases (e.g. ungrazed vs. grazed or overgrazed areas). The main goal of this study is to contribute to the understanding on how animal grazing affects soil properties and degradation processes. The study is particularly focused on soil compaction and sheet erosion as related to the reduction of vegetation cover by defoliation. Soil properties were analysed from 119 environmental units selected from 56 farms distributed throughout the region of Extremadura (SW Spain). The units are representative of different rangeland types, i.e. scrublands of Retama sphaerocarpa, dehesas (wooded rangelands) and treeless grasslands. Soil surface cover was determined along transects in September 2010 (antecedent rainfall: 413-923 mm) considering the following classes: bare ground, grasses, mosses, litter, stones (<2 mm) and rock outcrops. Farmer interviews were also conducted in order to quantify stocking rates and to assess land management in 12 out of 56 farms. In the farms where transects and farmer interviews could not be carried out, bare soil surface and livestock densities were estimated. Bare soil surface was determined by classifying

  16. Effect of grazing intensity and applied fertilizers on pasture production and animal gain

    Sigurbjoernsson, B.; Gudmundsson, O.; Arnalds, A.; Thorsteinsson, I.; Eiriksson, T.

    1983-01-01

    A 5-year study was conducted to determine the effect of grazing intensity and fertilizers on the production of twin lambs in Iceland. Three sites were selected: dry highland, dry lowland and lowland bog. Although increasing the stocking rate reduced the daily gain and carcass weight per lamb, these factors were markedly increased per unit area. Tritiated water was used to establish the body composition and water turnover rates in the lambs. The criteria for optimum use of a pasture could best be established by considering the condition of the sward. Fertilizer (78 to 92 kg N/ha and 18 to 80 kg P/ha) increased the carcass weight by a factor of three on the lowland bog, but by a factor of ten on the less productive highlands. Fertilizer increased standing vegetation by a factor of 11 to 18 and also increased forage quality by markedly increasing the protein and phosphorus content and the digestibility. Fertilizer restored and improved the species composition of the pasture in addition to its productivity. (author)

  17. Social interactions among grazing reef fish drive material flux in a coral reef ecosystem.

    Gil, Michael A; Hein, Andrew M

    2017-05-02

    In human financial and social systems, exchanges of information among individuals cause speculative bubbles, behavioral cascades, and other correlated actions that profoundly influence system-level function. Exchanges of information are also widespread in ecological systems, but their effects on ecosystem-level processes are largely unknown. Herbivory is a critical ecological process in coral reefs, where diverse assemblages of fish maintain reef health by controlling the abundance of algae. Here, we show that social interactions have a major effect on fish grazing rates in a reef ecosystem. We combined a system for observing and manipulating large foraging areas in a coral reef with a class of dynamical decision-making models to reveal that reef fish use information about the density and actions of nearby fish to decide when to feed on algae and when to flee foraging areas. This "behavioral coupling" causes bursts of feeding activity that account for up to 68% of the fish community's consumption of algae. Moreover, correlations in fish behavior induce a feedback, whereby each fish spends less time feeding when fewer fish are present, suggesting that reducing fish stocks may not only reduce total algal consumption but could decrease the amount of algae each remaining fish consumes. Our results demonstrate that social interactions among consumers can have a dominant effect on the flux of energy and materials through ecosystems, and our methodology paves the way for rigorous in situ measurements of the behavioral rules that underlie ecological rates in other natural systems.

  18. Parrotfish grazing ability: interspecific differences in relation to jaw-lever mechanics and relative weight of adductor mandibulae on an Okinawan coral reef.

    Nanami, Atsushi

    2016-01-01

    Parrotfishes (family Labridae: Scarini) are regarded to have important roles for maintaining the ecosystem balance in coral reefs due to their removal of organic matter and calcic substrates by grazing. The purpose of the present study was to clarify the interspecific differences in grazing ability of five parrotfish species (Chlorurus sordidus, C. bowersi, Scarus rivulatus, S. niger and S. forsteni) in relation to interspecific differences in jaw-lever mechanics and the relative weight of the adductor mandibulae (muscles operating jaw closing). The grazing ability was calculated by using stomach contents (CaCO3 weight/organic matter weight) defined as the grazing ability index (GAI). There were significant interspecific differences in GAI (C. sordidus = C. bowersi > S. rivulatus > S. niger = S. forsteni). Teeth of C. sordidus and C. bowersi were protrusive-shape whereas teeth of S. rivulatus, S. niger and S. forsteni were flat-shape. C. sordidus and C. bowersihave jaw-lever mechanics producing a greater biting force and have a larger weight of adductor mandibulae. S. rivulatus has jaw-lever mechanics producing a greater biting force but a smaller weight of adductor mandibulae that produce an intermediate biting force. In contrast, S. niger and S. forsteni have jaw-lever mechanics producing a lesser biting force and have a smaller weight of adductor mandibulae. Feeding rates and foray size of S. rivulatus, S. niger and S. forsteni were greater than C. sordidus and C. bowersi. The degree in bioerosion (GAI × feeding rate) was the largest for S. rivulatusand the smallest for S. forsteni. The degree in bioerosion for C. sordidus was larger than S. niger whereas relatively equal between C. bowersi and S. niger. These results suggest that interspecific difference in GAI was explained by interspecific differences in teeth shape, jaw-lever mechanics and relative weight of adductor mandibulae. The interspecific difference in the degree of bioerosion suggests the

  19. Bulls grazing Kentucky 31 tall fescue exhibit impaired growth, semen quality, and decreased semen freezing potential

    Serum prolactin (PRL) and testosterone concentrations, body weight, body composition, semen quality, and semen freezing potential for bulls grazing the toxic tall fescue (Lolium arundinaceum [Schreb.] Darbysh. ¼ Schedonorous arundinaceum [Schreb.] Dumort.) cultivar Kentucky 31 (E+) compared with a n...

  20. Modeling the influence from ocean transport, mixing and grazing on phytoplankton diversity

    Adjou, Mohamed; Bendtsen, Jørgen; Richardson, Katherine

    2012-01-01

    Phytoplankton diversity, whether defined on the basis of functional groups or on the basis of numbers of individual species, is known to be heterogeneous throughout the global ocean. The factors regulating this diversity are generally poorly understood, although access to limiting nutrients...... in generating and maintaining diversity, we apply the model to quantify the potential role of zooplankton grazing and ocean transport for the coexistence of competing species and phytoplankton diversity. We analyze the sensitivity of phytoplankton biomass distributions to different types of grazing functional...... responses and show that preferential grazing on abundant species, for example as formulated by the Holling type III grazing function, is a key factor for maintaining species’ coexistence. Mixing and large-scale advection are shown to potentially have a significant impact on the distribution of phytoplankton...

  1. Insect herbivory and vertebrate grazing impact food limitation and grasshopper populations during a severe outbreak

    Interspecific competition between distantly related herbivores, as well as between large vertebrate herbivores and phytophagous insects, has received little attention. Livestock grazing is the dominant land use in western North American grasslands, where phytophagous insects can be the dominant herb...

  2. Grazing incidence optics; Proceedings of the Meeting, Orlando, FL, Apr. 3, 4, 1986

    Osantowski, John F. (Editor); Van Speybroeck, Leon (Editor)

    1986-01-01

    Papers are presented on the diffraction-limited performance of grazing incidence optical systems; transverse ray aberrations of Wolter type 1 telescopes; hybrid X-ray telescope systems; surface characterization of grazing incidence optics in the extreme UV and X-ray regions; and the surface roughness properties of synchrotron radiation optics. Topics discussed include the simulation of free-abrasive grinding of grazing incidence mirrors with vertical-honing and flexible blades; mirrors for the Extreme Ultraviolet Explorer; the design and development of conical X-ray imaging mirrors; thermal loading considerations for synchrotron radiation mirrors; and grazing incidence optics for synchrotron radiation insertion-device beams. Consideration is given to the interpretation of glancing incidence scattering measurements; damage processes in short wavelength coated FEL optics; the replication of grain incidence optics; and the assembly and alignment of the Technology Mirror Assembly.

  3. Grazing effects on forage production and botanical composition in a Quercus ithaburensis subs. macrolepis silvopastoral system

    Pantera, A.; Papanastasis, V. P.

    2009-04-01

    Grazing is considered as a major factor affecting forage production as well as botanical composition of many silvopastoral systems. In order to study these effects, three pairs of grazed and protected plots were established in a Quercus ithaburensis subsp. macrolepis silvopastoral system. The experiment was carried out in western Greece, 15 km west of the city of Agrinion. Data were collected for two continuous years and included the determination of palatable and unpalatable to animals plant species as well as the botanical composition. The results suggest that heavy grazing decreased biomass production approximately threefold. Grazing also affected number of acorns, botanical composition as well as vegetation cover whereas had no effect on natural regeneration in the study period.

  4. Seasonal grazing and food preference of herbivores in a Posidonia oceanica meadow

    Andrea Peirano

    2001-12-01

    Full Text Available Seasonal grazing of the fish Sarpa salpa (L., the urchin Paracentrotus lividus Lamarck and the isopods Idotea spp. was compared with the C/N ratio of adult and intermediate leaves and epiphytes of Posidonia oceanica (L. Delile, collected at three different depths. Despite seasonal differences in grazing, herbivores showed preferences throughout the year for adult leaves with more epiphyte and higher N contents. The maximum grazing on adult and intermediate leaves was observed in September and in June for fish and in March for urchins, whereas it was irregular for isopods. Grazing by the three herbivores was not related to their preference for leaves or epiphytes, notwithstanding the seasonal differences in their C and N contents. We concluded that herbivores show no preference for food type throughout the year and that seasonal consumption of P. oceanica is related mainly to herbivore behaviour.

  5. Synergistic Interactions within a Multispecies Biofilm Enhance Individual Species Protection against Grazing by a Pelagic Protozoan

    Raghupathi, Prem Krishnan; Liu, Wenzheng; Sabbe, Koen

    2018-01-01

    of a multispecies bacterial biofilm subject to grazing by a pelagic protozoan predator were investigated. To this end, a mono and multispecies biofilms of four bacterial soil isolates, namely Xanthomonas retroflexus, Stenotrophomonas rhizophila, Microbacterium oxydans and Paenibacillus amylolyticus, were...

  6. The Development of a Differential Deposition Technique for Figure Correction in Grazing Incidence Optics

    National Aeronautics and Space Administration — We propose the development of a physical-vapor-deposition coating technique to correct residual figure errors in grazing-incidence optics. The process involves...

  7. Livestock grazing and trampling of birds' nests: An experiment using artificial nests

    Mandema, Freek S.; Tinbergen, Joost M.; Ens, Bruno J.; Bakker, Jan P.

    2013-01-01

    The purpose of this study is to experimentally determine the differences between four grazing treatments on the trampling of nests. Additionally, we examine to what extent the trampling probability of nests is higher close to a source of fresh water. We compare the trampling of artificial nests in five different grazing treatments in an experimental design. We use buried clay pigeon targets as artificial mimics of bird nests to obtain reliable estimates of trampling risk and compare these wit...

  8. Livestock grazing intensity affects abundance of Common shrews (Sorex araneus) in two meadows in Denmark

    Schmidt, Niels M; Olsen, Henrik; Leirs, Herwig

    2009-01-01

    Abstract Background Current nature conservation in semi-natural grasslands often includes grazing and hay cutting, as well as the abandonment of draining. Semi-natural grassland and in particular meadows constitute important habitat type for a large number of animal species in today's fragmented and intensively cultivated landscape of Europe. Here we focus on the population characteristics of Common shrews Sorex araneus in relation to livestock grazing intensity in two wet meadows in western ...

  9. Use of scanning electron microscopy to confirm the identity of lice infesting communally grazed goat herds

    P.J. Sebei; C.M.E. McCrindle; E.D. Green; M.L. Turner

    2004-01-01

    Lice have been described on goats in commercial farming systems in South Africa but not from flocks on communal grazing. During a longitudinal survey on the causes of goat kid mortality, conducted in Jericho district, North West Province, lice were collected from communally grazed indigenous goats. These lice were prepared for and viewed by scanning electron microscopy, and micromorphological taxonomic details are described. Three species of lice were found in the study area and identif...

  10. A model for analyzing influence of timber production on lichens for reindeer grazing

    Eriksson, Olof; Sandewall, Mats; Wilhelmsson, Erik

    1987-01-01

    A model for long-term analysis of the influence of timber production on lichens for reindeer grazing (Cladina, Alectoria, Bryoria spp and others) in Sweden is presented. The annual production of and demand for lichens are estimated and compared. Production of these lichens is presumed to set the upper limit for the reindeer population. Reindeer graze on both ground and tree lichens, which both must be accessible in sufficient amounts and at the right times of the year if reindeer husbandry is...

  11. Assessing the impacts of Acacia mearnsii on grazing provision and livestock production

    Yapi, T

    2012-10-01

    Full Text Available with selective grazing Others: grass invaders, forbs and serge Bare: refers to bare ground RESULTS: Grass species composition and basal cover 0 10 20 30 40 50 60 70 80 Uninvaded Cleared Light Dense Co ver (% ) A. mearnsii invasion status... Light Dense M o is tu re (% ) Acacia mearnsii invasion status P?0.05 CONCLUSIONS and RECOMMENDATIONS Conclusions ?High density invasions of A. mearnsii have negative effects on rangelands productivity ?Removal of A. mearnsii improves grazing...

  12. Effects of livestock species and stocking density on accretion rates in grazed salt marshes

    Nolte, Stefanie; Esselink, Peter; Bakker, Jan P.; Smit, Christian

    2015-01-01

    Coastal ecosystems, such as salt marshes, are threatened by accelerated sea-level rise (SLR). Salt marshes deliver valuable ecosystem services such as coastal protection and the provision of habitat for a unique flora and fauna. Whether salt marshes in the Wadden Sea area are able to survive

  13. Nickel, Cobalt, Chromium and Copper in agricultural and grazing land soils of Europe

    Albanese, Stefano; Sadeghi, Martiya; De Vivo, Benedetto; Lima, Annamaria; Cicchella, Domenico; Dinelli, Enrico

    2014-05-01

    In the framework of the GEMAS (Geochemical Mapping of Agricultural and Grazing Land Soils) project, concentrations of Ni, Co, Cu and Cr were determined for the whole available dataset (2218 samples of agricultural soil and 2127 samples of grazing land soil) covering a total area of 5.6 million sq km all over Europe. The distribution pattern of Ni in the European soils (both agricultural and grazing land soils) shows the highest concentrations in correspondence with the Mediterranean area (especially in Greece, the Balcan Peninsula and NW Italy) with average values generally ranging between 40 mg/kg and 140 mg/kg and anomalous areas characterized by peaks higher than 2400 mg/kg. Concentrations between 10 mg/kg and 40 mg/kg characterize Continental Europe north of Alps and, partly, the Scandinavian countries. Lower concentrations (agricultural and grazing land soils. The maximum concentration peaks of Cobalt and Cr rise up to respectively 126 mg/kg and 696 mg/kg in agricultural soils and up to 255 mg/kg and 577 mg/kg in grazing land soils. Copper distribution in the soils collected across Europe, although has a general correspondence with the patterns of Ni, Co, Cr, shows some peculiarities. Specifically, Cu is characterized by high concentration values (up to 395 mg/kg in agricultural soils and 373 mg/kg in Grazing land soils) also in correspondence with the Roman Comagmatic Province and the south western coast of France characterized by a wide spread of vineyards.

  14. Grazing-Activated Production of Dimethyl Sulfide (DMS) by two clones of Emiliania huxleyi

    Wolfe, Gordon V.; Steinke, Michael

    1996-01-01

    Emiliania huxleyi clones CCMP 370 and CCMP 373 produced similar amounts of dimethylsulfoniopropionate (DMSP) during axenic exponential growth, averaging 109 mM internal DMSP. Both clones had detectable DMSP lyase activity, as measured by production of dimethyl sulfide (DMS) during in vitro assays of crude cell preparations, but activities and conditions differed considerably between clones. Clone 373 had high activity; clone 370 had low activity and required chloride. For both strains, enzyme activity per cell was constant during exponential growth, but little DMS was produced by healthy cells. Rather, DMS production was activated when cells were subjected to physical or chemical stresses that caused cell lysis. We propose that DMSP lyase and DMSP are segregated within these cells and re-action only under conditions that result in cell stress or damage. Such activation occurs during microzooplankton grazing. When these clones were grazed by the dinoflagellate Oxyrrhis marina, DMS was produced; ungrazed cells, as well as those exposed to grazer exudates and associated bacteria, generated no DMS. Grazing of clone 373 produced much more DMS than grazing of clone 370, consistent with their relative in vitro DMSP lyase activities. DMS was only generated when cells were actually being grazed, indicating that ingested cells were responsible for the DMS formation. We suggest that even low levels of grazing can greatly accelerate DMS production.

  15. The effects of grazing intensity on soil processes in a Mediterranean protected area.

    Panayiotou, Evaggelia; Dimou, Maria; Monokrousos, Nikolaos

    2017-08-08

    We investigated the temporal and among-site differentiation of soil functionality properties in fields under different grazing intensities (heavy and light) and compared them to those found in their adjacent hedgerows, consisting either of wooden shrubs (Rubus canescens) or of high trees (Populus sp.), during the cold and humid seasons of the year. We hypothesized that greater intensity of grazing would result in higher degradation of the soil system. The grazing factor had a significant effect on soil organic C and N, microbial biomass C, microbial biomass N, microbial activity, and β-glucosidase, while acid phosphatase and urease activity were not found to differ significantly among the management systems. The intensity of grazing affected mostly the chemical properties of soil (organic C and N) and altered significantly the composition of the soil microbial community, as lower C:N ratio of the microbial biomass indicates the dominance of bacteria over fungi in the heavily grazed fields. All estimated biological variables presented higher values in the humid period, although the pattern of differentiation was similar at both sampling times, revealing that site-specific variations were more pronounced than the time-specific ones. Our results indicate that not all C, N, and P dynamics were equally affected by grazing. Management plans applied to pastures, in order to improve soil quality properties and accelerate passive reforestation, should aim at the improvement of soil parameters related primarily to C and secondly to N cycle.

  16. Grazing preference and utilization of soil fungi by Folsomia candida (Collembola)

    Hedenec, Petr; Frouz, Jan

    2016-04-01

    Soil fungi are important food resources for soil fauna. Here we ask whether the collembolan Folsomia candida shows selectivity in grazing between four saprophytic fungi (Penicillium chrysogenum, Penicillium expansum, Absidia glauca, and Cladosporium herbarum), whether grazing preference corresponds to effects on collembolan reproduction, and whether the effects of fungi on grazing and reproduction depends on the fungal substrate, which included three kinds of litter (Alnus glutinosa, Salix caprea, and Quercus robur) and one kind of agar (yeast extract). On agar, Cladosporium herbarum and Absidia glauca were the most preferred fungi and supported the highest collembolan reproduction. On fungal-colonized litter, grazing preference was more affected by litter type than by fungal species whereas collembolan reproduction was affected by both litter type and fungal species. On fungal-colonized litter, the litter type that was most preferred for grazing did not support the highest reproduction, i.e., there was an inconsistency between food preference and suitability. Alder and willow were preferred over oak for grazing, but alder supported the least reproduction.

  17. An agent-based model of cattle grazing toxic Geyer's larkspur.

    Jablonski, Kevin E; Boone, Randall B; Meiman, Paul J

    2018-01-01

    By killing cattle and otherwise complicating management, the many species of larkspur (Delphinium spp.) present a serious, intractable, and complex challenge to livestock grazing management in the western United States. Among the many obstacles to improving our understanding of cattle-larkspur dynamics has been the difficulty of testing different grazing management strategies in the field, as the risk of dead animals is too great. Agent-based models (ABMs) provide an effective method of testing alternate management strategies without risk to livestock. ABMs are especially useful for modeling complex systems such as livestock grazing management, and allow for realistic bottom-up encoding of cattle behavior. Here, we introduce a spatially-explicit, behavior-based ABM of cattle grazing in a pasture with a dangerous amount of Geyer's larkspur (D. geyeri). This model tests the role of herd cohesion and stocking density in larkspur intake, finds that both are key drivers of larkspur-induced toxicosis, and indicates that alteration of these factors within realistic bounds can mitigate risk. Crucially, the model points to herd cohesion, which has received little attention in the discipline, as playing an important role in lethal acute toxicosis. As the first ABM to model grazing behavior at realistic scales, this study also demonstrates the tremendous potential of ABMs to illuminate grazing management dynamics, including fundamental aspects of livestock behavior amidst ecological heterogeneity.

  18. Microbial quality of soil from the Pampa biome in response to different grazing pressures

    Rafael S. Vargas

    2015-06-01

    Full Text Available The aim of this study was to evaluate the impact of different grazing pressures on the activity and diversity of soil bacteria. We performed a long-term experiment in Eldorado do Sul, southern Brazil, that assessed three levels of grazing pressure: high pressure (HP, with 4% herbage allowance (HA, moderate pressure (MP, with 12% HA, and low pressure (LP, with 16% HA. Two reference areas were also assessed, one of never-grazed native vegetation (NG and another of regenerated vegetation after two years of grazing (RG. Soil samples were evaluated for microbial biomass and enzymatic (β-glucosidase, arylsulfatase and urease activities. The structure of the bacterial community and the population of diazotrophic bacteria were evaluated by RFLP of the 16S rRNA and nifH genes, respectively. The diversity of diazotrophic bacteria was assessed by partial sequencing of the 16S rDNA gene. The presence of grazing animals increased soil microbial biomass in MP and HP. The structures of the bacterial community and the populations of diazotrophic bacteria were altered by the different grazing managements, with a greater diversity of diazotrophic bacteria in the LP treatment. Based on the characteristics evaluated, the MP treatment was the most appropriate for animal production and conservation of the Pampa biome.

  19. Species Diversity and Botanical Composition of Permanent Grassland as a Response to Different Grazing Management Practices

    Marie Štýbnarová

    2015-01-01

    Full Text Available The effects of different levels of grazing utilization (two, three and four grazing cycles per year and mineral fertilization (nil-fertilization; N100P30K60 on the botanical composition of permanent grasslands were studied in the locality of Rapotín (Czech Republic, 332 m a.s.l. from 2003–2010. The vegetation of the experimental pasture was classified as Cynosurion. It was found that moderate treatment (three grazing cycles per year without mineral fertilization showed the highest value of diversity index (DI = 6.08, and maximum dominance of legumes (Dmax = 9.1%, particularly Trifolium repens. The highest dominance of grasses (Dmax = 77.7%, mainly Dactylis glomerata and Elytrigia repens, was achieved with the fertilized treatment utilized in two grazing cycles per year. Based on RDA results, tested management treatments explained 26% of species composition variability, where effect of number of grazing cycles per year was five-times higher than effect of fertilization. We recommend grassland utilization in three grazing cycles per year as the most suitable way from the objective of both species diversity and botanical composition of pastures in similar site conditions. Pasture fertilization should be more controlled by careful consideration of individual pasture goals, actual nutrient status of the soil and possible environmental risks.

  20. Ingestive behavior of supplemented Nellore heifers grazing palisadegrass pastures managed with different sward heights.

    Vieira, Bruno Ramalho; Azenha, Mariana Vieira; Casagrande, Daniel Rume; Costa, Diogo Fleury Azevedo; Ruggieri, Ana Cláudia; Berchielli, Telma Teresinha; Reis, Ricardo Andrade

    2017-04-01

    Three sward heights (15, 25 and 35 cm) and three supplement types (energy, energy-protein, and a mineral mix supplement) were evaluated in a 3 × 3 factorial arrangement distributed in a completely randomized design to study changes in forage search patterns in Nellore heifers in a continuous grazing system. Pasture data were collected using two replicates (paddocks) per treatment over four periods during the rainy season. The behavior assessments were made in the first and fourth grazing seasons. It was hypothesized that supplements and pasture management would modify ingestive behavior, considering that animals would require less time grazing if they had energy requirements met through higher digestibility of better managed paddocks, or use of supplements high in energy. Total and green forage masses along with green : dead material ratio were greater in treatments managed with higher sward heights. Sward managed with 35 cm height resulted in lower leaf : stem ratio compared with 15 cm sward height treatments. The animals on the 15 cm pastures spent more time grazing overall and during each meal, but there were no differences observed in meal numbers in comparison to 35 cm treatments. Heifers fed protein and/or energy supplements spent less time grazing in the early afternoon, but overall grazing time was the same for all animals. © 2016 Japanese Society of Animal Science.

  1. Increasing importance of precipitation variability on global livestock grazing lands

    Sloat, Lindsey L.; Gerber, James S.; Samberg, Leah H.; Smith, William K.; Herrero, Mario; Ferreira, Laerte G.; Godde, Cécile M.; West, Paul C.

    2018-03-01

    Pastures and rangelands underpin global meat and milk production and are a critical resource for millions of people dependent on livestock for food security1,2. Forage growth, which is highly climate dependent3,4, is potentially vulnerable to climate change, although precisely where and to what extent remains relatively unexplored. In this study, we assess climate-based threats to global pastures, with a specific focus on changes in within- and between-year precipitation variability (precipitation concentration index (PCI) and coefficient of variation of precipitation (CVP), respectively). Relating global satellite measures of vegetation greenness (such as the Normalized Difference Vegetation Index; NDVI) to key climatic factors reveals that CVP is a significant, yet often overlooked, constraint on vegetation productivity across global pastures. Using independent stocking data, we found that areas with high CVP support lower livestock densities than less-variable regions. Globally, pastures experience about a 25% greater year-to-year precipitation variation (CVP = 0.27) than the average global land surface area (0.21). Over the past century, CVP has generally increased across pasture areas, although both positive (49% of pasture area) and negative (31% of pasture area) trends exist. We identify regions in which livestock grazing is important for local food access and economies, and discuss the potential for pasture intensification in the context of long-term regional trends in precipitation variability.

  2. MYCOTOXINS CONTAMINATION IN EDIBLE LAND SNAIL AT GRAZING PADDOCK ENVIRONMENT

    Ime Ebenso

    2013-02-01

    Full Text Available Mycotoxins contamination of animal products is under reported. Juvenile edible land snails (Archachatina marginata were exposed as sentinels in bottomless metal drums for 1 week at abandoned, new and reference sites respectively at grazing paddock environment, to assess the presence of foodborne microbiological mycotoxins contamination during the dry season. Mycological analysis of A. marginata samples revealed high (p<0.05 contamination at all paddocks ranged from 1.2-1.3 x 105 cfu-g. Results revealed values that were found to be unacceptable by FAO/WHO standards. The presence of Aspergillus niger, A. fumigatus and Penicillum expansum were noted as potential toxicogenic mycoflora. Snails were tolerant to all levels of contamination with no clinical signs of infection or mortality. This finding could serve as basis for assessing pre-slaughter microbial contamination of livestock farm/field environment in order to establish data with comparative epidemiological value, which could highlight early warning signals of food safety risk and cross-contamination of mycotoxins in the food chain.

  3. The fabrication and characterization of replicated and lacquer coated grazing

    Ulmer, M.P.; Haidle, R.; Altkorn, R.; Georgeopolos, P.; Rodricks, B.; Takacs, P.Z.

    1992-01-01

    This paper reports on work done over the past two years in our laboratory to produce X-ray optics. We also report on tests that we have made to evaluate the performance of pieces that we have produced. As we progress towards the 21st century, there is a growing need to understand fabrication techniques for grazing incidence optics. To this end we report our results of fabricating, testing, and measuring both Wolter I optics and flats. We have used the techniques of lacquer coating. We have made flats to determine our ability to coat surfaces with lacquer and gold, as well as to demonstrate reflectivity up to 40 keV. We also produced Wolter I optics nickel optics with a gold coated optical surface. Here we report and interpret results from X-ray reflectivity and Wyko profiler optical measurements. We also describe our fabrication process and provide a critique of the process and describe how we hope to further improve upon the basic technique

  4. Grazing incidence EUV study of the Alcator tokamaks

    Castracane, J.

    1982-01-01

    The use of impurity radiation to examine plasma conditions is a well known technique. To gain access, however, to the hot, central portion of the plasma created in the present confinement machines it is necessary to be able to observe radiation from medium and heavy elements such as molybdenum and iron. These impurities radiate primarily in the extreme ultra violet region of the spectrum and can play a role in the power balance of the tokamak. Radiation from highly ionized molybdenum was examined on the Alcator A and C tokamaks using a photometrically calibrated one meter grazing incidence monochromator. On Alcator A, a pseudo-continuum of Mo emissions in the 60 to 100 A ranges were seen to comprise 17% of the radiative losses from the plasma. This value closely matched measurements by a broad band bolometer array. Following these preliminary measurements, the monochromator was transferred to Alcator C for a more thorough examination of EUV emissions. Deviations from predicted scaling laws for energy confinement time vs density were observed on this machine

  5. Vesper Sparrows and Western Meadowlarks Show a Mixed Response to Cattle Grazing in the Intermountain Region of British Columbia

    Megan L. Harrison

    2010-06-01

    Full Text Available Livestock grazing in the shortgrass steppe of the Intermountain region of British Columbia is predicted to have significant effects on grassland habitats and their associated ground-nesting bird communities. We tested whether grazed and ungrazed sites could be discriminated on the basis of their vegetation communities, whether the abundance of two ground-nesting bird species, Vesper Sparrow (Pooecetes gramineus and Western Meadowlark (Sturnella neglecta, differed between grazed and ungrazed sites, and whether vegetation variables found to differ between grazed and ungrazed plots could be used to predict the abundance of the two bird species at a fine scale. Grazed sites were easily distinguishable from a site that had been ungrazed for >30 years based on the structure and composition of their vegetation communities. However, more detailed grazing categories could not be distinguished on the basis of vegetation characteristics. Despite the existence of grazing effects on vegetation structure and composition, we found no consistent differences in abundance of Vesper Sparrows and Western Meadowlarks between the grazed and ungrazed sites. However, there was weak evidence that the abundance of both species was higher at fine-scale plots (100 m radius point count station with less bare ground and taller vegetation. Bare ground cover was lower on grazed plots, but vegetation was taller on ungrazed plots. Combined, our results suggest that low intensity grazing leads to grassland habitat change with both negative and positive effects on Vesper Sparrows and Western Meadowlarks, resulting in no net change in their broad-scale abundance.

  6. Marshall Grazing Incidence X-ray Spectrometer (MaGIXS) Slit-Jaw Imaging System

    Wilkerson, P.; Champey, P. R.; Winebarger, A. R.; Kobayashi, K.; Savage, S. L.

    2017-12-01

    The Marshall Grazing Incidence X-ray Spectrometer is a NASA sounding rocket payload providing a 0.6 - 2.5 nm spectrum with unprecedented spatial and spectral resolution. The instrument is comprised of a novel optical design, featuring a Wolter1 grazing incidence telescope, which produces a focused solar image on a slit plate, an identical pair of stigmatic optics, a planar diffraction grating and a low-noise detector. When MaGIXS flies on a suborbital launch in 2019, a slit-jaw camera system will reimage the focal plane of the telescope providing a reference for pointing the telescope on the solar disk and aligning the data to supporting observations from satellites and other rockets. The telescope focuses the X-ray and EUV image of the sun onto a plate covered with a phosphor coating that absorbs EUV photons, which then fluoresces in visible light. This 10-week REU project was aimed at optimizing an off-axis mounted camera with 600-line resolution NTSC video for extremely low light imaging of the slit plate. Radiometric calculations indicate an intensity of less than 1 lux at the slit jaw plane, which set the requirement for camera sensitivity. We selected a Watec 910DB EIA charge-coupled device (CCD) monochrome camera, which has a manufacturer quoted sensitivity of 0.0001 lux at F1.2. A high magnification and low distortion lens was then identified to image the slit jaw plane from a distance of approximately 10 cm. With the selected CCD camera, tests show that at extreme low-light levels, we achieve a higher resolution than expected, with only a moderate drop in frame rate. Based on sounding rocket flight heritage, the launch vehicle attitude control system is known to stabilize the instrument pointing such that jitter does not degrade video quality for context imaging. Future steps towards implementation of the imaging system will include ruggedizing the flight camera housing and mounting the selected camera and lens combination to the instrument structure.

  7. Size-selective microzooplankton grazing on the phytoplankton in the Curonian Lagoon (SE Baltic Sea

    Evelina Grinienė

    2016-10-01

    Full Text Available Dilution experiments were performed to estimate phytoplankton growth and microzooplankton grazing rates at two sites: freshwater (Nida and brackish water (Smiltyne in the Curonian Lagoon (SE Baltic Sea. Using the size-fractionation approach and dilution experiments, we found that the microzooplankton community was able to remove up to 78% of nanophytoplankton (2–20 μm standing stock and 130% of the total daily primary production in the brackish waters of the lagoon, and up to 83% of standing stock and 76% of the primary production of picophytoplankton (0.2–2 μm in the freshwater part. The observed differences were attributed to the changes in ciliate community size and trophic structure, with larger nano-filterers (30–60 μm dominating the brackish water assemblages and pico-nano filterers (<20 μm and 20–30 μm prevailing in the freshwater part of the lagoon.

  8. Postfledging survival of Grasshopper Sparrows in grasslands managed with fire and grazing

    Hovick, Torre J.; Miller, James R.; Koford, Rolf R.; Engle, David M.; Debinski, Diane M.

    2011-01-01

    More accurate estimates of survival after nestlings fledge are needed for population models to be parameterized and population dynamics to be understood during this vulnerable life stage. The period after fledging is the time when chicks learn to fly, forage, and hide from predators. We monitored postfledging survival, causespecific mortality, and movements of Grasshopper Sparrows (Ammodramus savannarum) in grassland managed with fire and grazing. In 2009, we attached radio transmitters to 50 nestlings from 50 different broods and modeled their survival in response to climatic, biological, and ecological variables. There was no effect of treatment on survival. The factor most influencing postfledging survival was age; no other variable was significant. The majority of chicks (74%) died within 3 days of radio-transmitter attachment. We attributed most mortality to mesopredators (48%) and exposure (28%). Fledglings' movements increased rapidly for the first 4 days after they left the nest and were relatively stable for the remaining 10 days we tracked them. On average, fledglings took flight for the first time 4 days after fledging and flew ≥10 m 9 days after fledging. Our data show that the Grasshopper Sparrow's survival rates may be less than most models relying on nest-success estimates predict, and we emphasize the importance of incorporating estimates of survival during the postfledging period in demographic models.

  9. Effects of nitrogen fertilization and grazing on the emission of nitrous oxide from grassland

    Velthof, G.L.; Oenema, O. [Nutrient Management Institute NMI, Wageningen Agricultural University, Wageningen (Netherlands)

    1995-12-31

    Nitrous oxide (N2O) is one of the trace gases that possibly contribute to the depletion of stratospheric ozone and to global warming. Soils are a major source of N2O. Thus far, the contribution of agricultural soils and practises in The Netherlands to the total N2O burden of the atmosphere is largely unknown, because in-situ field measurements are scarce. In the research project reported here, effects of nitrogen (N) fertilization, grazing animals and soil type on N2O emission from grassland in The Netherlands were investigated. The aim of these investigations was to provide insight into the major factors that contribute to N2O emission from managed grassland and to provide quantitative N2O emission rates, obtained from field measurements. The research programme was split in three parts. First, a monitoring study, in which fluxes of N2O were measured weekly at four contrasting grassland sites with three different management practices each, during a period of two years. Secondly, field and greenhouse studies, in which the temporal and spatial variability of N2O fluxes, the effects of type and level of N fertilizer application and the effect of groundwater level on N2O emissions from grassland were assessed in detail. Thirdly, model calculations in which the possibilities were assessed of the use of improved nutrient management as tool to reduce N2O losses from dairy farming systems in The Netherlands, using a whole-farm approach. figs., tabs., refs.

  10. Canopy characteristics, animal behavior and forage intake by goats grazing on Tanzania-grass pasture with different heights - doi: 10.4025/actascianimsci.v34i4.14544

    Maurílio Souza dos Santos

    2012-10-01

    Full Text Available This study evaluated the influence of Tanzania-grass sward height (30, 50, 70 and 90 cm on the morphological characteristics of the canopy, grazing behavior and forage intake by adult Anglo Nubian female goats. A completely randomized experimental design was employed, with two replicates in space and two replicates in time. Six animals were used to assess the grazing behavior, and four, the ingestion process. The rise in sward height increased the forage and leaf mass, the percentages of stem and dead material, and reduced the leaf stem-1 ratio. Above 50 cm there was an increase in grazing time and a decrease in leisure time. A positive linear correlation was detected between sward height and bite depth. The consumed forage mass, ingestion rate and daily intake were higher at 50 cm, indicating that the other heights reduced the intake process. The sward height was negatively correlated to the bite rate and positively to the bite time. The sward height of 50 cm presents the best combination of features, favoring the grazing and ingestive behavior of female adult goats.

  11. Milk from cows grazing on cool-season pastures provides an enhanced profile of bioactive fatty acids compared to those grazed on a monoculture of pearl millet.

    Bainbridge, Melissa L; Egolf, Emily; Barlow, John W; Alvez, Juan P; Roman, Joe; Kraft, Jana

    2017-02-15

    The demand for dairy products from grass-fed cows is driven, in part, by their more desirable fatty acid (FA) profile, containing more n-3 FA and conjugated linoleic acids (CLA) than conventionally produced dairy products. This study investigated the effects of pearl millet (PM) vs. cool-season pasture (CSP) on animal performance and milk FA in a grazing system. Eight Holstein dairy cows were used in a repeated measures design with four-week periods. Forage type had no effect on animal performance (estimated dry matter intake, milk production, fat, or protein). The contents of CLA and n-3 FA in a serving of whole milk (3.25% fat) increased when cows grazed CSP compared to PM. A serving of whole milk from cows grazing PM had a higher content of saturated FA and branched-chain FA. In conclusion, the contents of various bioactive FA were higher in milk fat of cows grazing a CSP compared to PM. Copyright © 2016 Elsevier Ltd. All rights reserved.

  12. Multiple exposure routes of a pesticide exacerbate effects on a grazing mayfly.

    Pristed, Mathias Joachim Skov; Bundschuh, Mirco; Rasmussen, Jes Jessen

    2016-09-01

    Hydrophobic pesticides such as pyrethroid insecticides tend to occur in their soluble form mainly as transient pulses in streams. In addition, they are regularly detected in significant quantities adsorbed to stream sediments and other organic in-stream structures. Consequently, stream biota is likely subjected to pesticide exposure via multiple routes. In this study we aimed at investigating the influence of exposure routes for the pyrethroid insecticide lambda-cyhalothrin on the grazing mayfly Heptagenia sulphurea. Therefore, H. sulphurea was exposed to lambda-cyhalothrin via single- (water or biofilm) or biphasic exposure (water and biofilm) at environmentally realistic concentrations (0, 0.1, 1μgL(-1)) and exposure duration (2h) in a full factorial design (n=5). Mortality, moulting frequency, and biofilm accrual (proxy for feeding rate) were recorded subsequent to a 7 d post exposure period. Mortality significantly increased and moulting frequency significantly decreased with increasing concentrations of lambda-cyhalothrin in the water phase whereas exposure via biofilm prompted no significant effects on these endpoints (α=0.05). Effect predictions systematically underestimated and overestimated effects for mortality and moulting frequency, respectively. Similarly, mayfly feeding rate was significantly reduced by water phase exposure whereas pre-exposed biofilm did not significantly affect this variable. However, we found a significant but non-systematic interaction between water phase and biofilm exposure on mayfly feeding rate. Our results show that exposure to the same pesticide via multiple exposure routes may increase the magnitude of effects beyond the level predicted from single phase exposures which has clear implications for the aquatic risk assessment of hydrophobic pesticides. However, our results additionally reveal that interactions between pesticide exposure routes may vary between selected dependent variables. We emphasize that unravelling the

  13. Radionuclides in sheep grazing near old uranium mines

    Carvalho, Fernando P.; Oliveira, Joao M.; Malta, M. [Instituto Superior Tecnico/Campus Tecnologico e Nuclear/ (IST/CTN), Universidade de Lisboa, Estrada Nacional 10 - ao km 139,7, - 2695-066 Bobadela LRS (Portugal); Lemos, M.E. [Servicos de Alimentacao e Veterinaria da Regiao Centro, Bairro Na Sra dos Remedios, 6300 Guarda (Portugal); Vala, H.; Esteves, F. [Escola Superior Agraria de Viseu, Quinta da Alagoa, Estrada de Nelas, Ranhados,3500-606 Viseu (Portugal)

    2014-07-01

    During the past century extensive uranium mining took place in Portugal for radium and uranium production. Many uranium deposits were mined as open pits and after ore extraction and transportation to milling facilities, mining wastes were left on site. One uranium ore mining site, Boco Mine, was extracted in the 1960's and 70's and mining waste and open pits were left uncovered and non-remediated since closure of uranium mining activities. During the nineties a quarry for sand extraction was operated in the same site and water from a local stream was extensively used in sand sieving. Downstream the mine areas, agriculture soils along the water course are currently used for cattle grazing. Water from this stream, and water wells, soil, pasture and sheep meat were analyzed for radionuclides of the uranium series. The U- series radionuclide {sup 226}Ra was generally the highest in concentrations especially in soil, pasture, and in internal organs of sheep. Ra-226 concentrations averaged 1093±96 Bq/kg (dry weight) in soil, 43±3 Bq/kg (dw) in pasture, and 0.76±0.41 Bq/kg (dw) in muscle tissue of sheep grown there. Other sheep internal organs displayed much higher {sup 226}Ra concentrations, such as the brain and kidneys with 7.7±2.3 Bq/kg (dw) and 28±29 Bq/kg (dw), respectively. Results of tissue sample analysis for sheep grown in a comparison area were 2 to 11 times lower, depending on the tissue. Absorbed radiation doses for internal organs of sheep were computed and may exceed 20 mSv/y in the kidney. Although elevated, this absorbed radiation dose still is below the threshold for biological effects on mammals. Nevertheless, enhanced environmental radioactive contamination mainly due to radium was observed in the area of influence of this legacy uranium mine and there is potential food chain transfer for humans (authors)

  14. Water Quality Conditions Associated with Cattle Grazing and Recreation on National Forest Lands.

    Leslie M Roche

    Full Text Available There is substantial concern that microbial and nutrient pollution by cattle on public lands degrades water quality, threatening human and ecological health. Given the importance of clean water on multiple-use landscapes, additional research is required to document and examine potential water quality issues across common resource use activities. During the 2011 grazing-recreation season, we conducted a cross sectional survey of water quality conditions associated with cattle grazing and/or recreation on 12 public lands grazing allotments in California. Our specific study objectives were to 1 quantify fecal indicator bacteria (FIB; fecal coliform and E. coli, total nitrogen, nitrate, ammonium, total phosphorus, and soluble-reactive phosphorus concentrations in surface waters; 2 compare results to a water quality regulatory benchmarks, b recommended maximum nutrient concentrations, and c estimates of nutrient background concentrations; and 3 examine relationships between water quality, environmental conditions, cattle grazing, and recreation. Nutrient concentrations observed throughout the grazing-recreation season were at least one order of magnitude below levels of ecological concern, and were similar to U.S. Environmental Protection Agency (USEPA estimates for background water quality conditions in the region. The relative percentage of FIB regulatory benchmark exceedances widely varied under individual regional and national water quality standards. Relative to USEPA's national E. coli FIB benchmarks-the most contemporary and relevant standards for this study-over 90% of the 743 samples collected were below recommended criteria values. FIB concentrations were significantly greater when stream flow was low or stagnant, water was turbid, and when cattle were actively observed at sampling. Recreation sites had the lowest mean FIB, total nitrogen, and soluble-reactive phosphorus concentrations, and there were no significant differences in FIB and

  15. Biological soil crusts across disturbance–recovery scenarios: effect of grazing regime on community dynamics.

    Concostrina-Zubiri, L; Huber-Sannwald, E; Martínez, I; Flores Flores, J L; Reyes-Agüero, J A; Escude, A; Belnap, J

    Grazing represents one of the most common disturbances in drylands worldwide, affecting both ecosystem structure and functioning. Despite the efforts to understand the nature and magnitude of grazing effects on ecosystem components and processes, contrasting results continue to arise. This is particularly remarkable for the biological soil crust (BSC) communities (i.e., cyanobacteria, lichens, and bryophytes), which play an important role in soil dynamics. Here we evaluated simultaneously the effect of grazing impact on BSC communities (resistance) and recovery after livestock exclusion (resilience) in a semiarid grassland of Central Mexico. In particular, we examined BSC species distribution, species richness, taxonomical group cover (i.e., cyanobacteria, lichen, bryophyte), and composition along a disturbance gradient with different grazing regimes (low, medium, high impact) and along a recovery gradient with differently aged livestock exclosures (short-, medium-, long-term exclusion). Differences in grazing impact and time of recovery from grazing both resulted in slight changes in species richness; however, there were pronounced shifts in species composition and group cover. We found we could distinguish four highly diverse and dynamic BSC species groups: (1) species with high resistance and resilience to grazing, (2) species with high resistance but low resilience, (3) species with low resistance but high resilience, and (4) species with low resistance and resilience. While disturbance resulted in a novel diversity configuration, which may profoundly affect ecosystem functioning, we observed that 10 years of disturbance removal did not lead to the ecosystem structure found after 27 years of recovery. These findings are an important contribution to our understanding of BCS dynamics from a species and community perspective placed in a land use change context.

  16. Biological soil crusts across disturbance-recovery scenarios: effect of grazing regime on community dynamics

    Concostrina-Zubiri, L.; Huber-Sannwald, E.; Martínez, I.; Flores Flores, J. L.; Reyes-Agüero, J. A.; Escudero, A.; Belnap, Jayne

    2014-01-01

    Grazing represents one of the most common disturbances in drylands worldwide, affecting both ecosystem structure and functioning. Despite the efforts to understand the nature and magnitude of grazing effects on ecosystem components and processes, contrasting results continue to arise. This is particularly remarkable for the biological soil crust (BSC) communities (i.e., cyanobacteria, lichens, and bryophytes), which play an important role in soil dynamics. Here we evaluated simultaneously the effect of grazing impact on BSC communities (resistance) and recovery after livestock exclusion (resilience) in a semiarid grassland of Central Mexico. In particular, we examined BSC species distribution, species richness, taxonomical group cover (i.e., cyanobacteria, lichen, bryophyte), and composition along a disturbance gradient with different grazing regimes (low, medium, high impact) and along a recovery gradient with differently aged livestock exclosures (short-, medium-, long-term exclusion). Differences in grazing impact and time of recovery from grazing both resulted in slight changes in species richness; however, there were pronounced shifts in species composition and group cover. We found we could distinguish four highly diverse and dynamic BSC species groups: (1) species with high resistance and resilience to grazing, (2) species with high resistance but low resilience, (3) species with low resistance but high resilience, and (4) species with low resistance and resilience. While disturbance resulted in a novel diversity configuration, which may profoundly affect ecosystem functioning, we observed that 10 years of disturbance removal did not lead to the ecosystem structure found after 27 years of recovery. These findings are an important contribution to our understanding of BCS dynamics from a species and community perspective placed in a land use change context.

  17. Interactions of Grazing History, Cattle Removal and Time since Rain Drive Divergent Short-Term Responses by Desert Biota

    Frank, Anke S. K.; Dickman, Chris R.; Wardle, Glenda M.; Greenville, Aaron C.

    2013-01-01

    Arid grasslands are used worldwide for grazing by domestic livestock, generating debate about how this pastoral enterprise may influence native desert biota. One approach to resolving this question is to experimentally reduce livestock numbers and measure the effects. However, a key challenge in doing this is that historical grazing impacts are likely to be cumulative and may therefore confound comparisons of the short-term responses of desert biota to changes in stocking levels. Arid areas are also subject to infrequent flooding rainfalls that drive productivity and dramatically alter abundances of flora and fauna. We took advantage of an opportunity to study the recent effects of a property-scale cattle removal on two properties with similarly varied grazing histories in central Australia. Following the removal of cattle in 2006 and before and after a significant rainfall event at the beginning of 2007, we sampled vegetation and small vertebrates on eight occasions until October 2008. Our results revealed significant interactions of time of survey with both grazing history and grazing removal for vascular plants, small mammals and reptiles. The mammals exhibited a three-way interaction of time, grazing history and grazing removal, thus highlighting the importance of careful sampling designs and timing for future monitoring. The strongest response to the cessation of grazing after two years was depressed reproductive output of plants in areas where cattle continued to graze. Our results confirm that neither vegetation nor small vertebrates necessarily respond immediately to the removal of livestock, but that rainfall events and cumulative grazing history are key determinants of floral and faunal performance in grassland landscapes with low and variable rainfall. We suggest that improved assessments could be made of the health of arid grazing environments if long-term monitoring were implemented to track the complex interactions that influence how native biota

  18. Non-bleached colonies of massive Porites may attract fishes for selective grazing during mass bleaching events

    Eri Ikeuchi

    2017-06-01

    Full Text Available In this study we investigated the variation in grazing scar densities between bleached and non-bleached colonies of massive Porites species in Sekisei Lagoon (Okinawa, southwestern Japan during a mass bleaching event in 2016. The grazing scar densities and bleaching susceptibility varied among neighboring colonies of massive Porites spp. However, non-bleached colonies had significantly more surface scars than bleached colonies. One explanation for these variations is that corallivorous fishes may selectively graze on non-bleached, thermally tolerant colonies. This is the first report of a relationship between grazing scars and the bleaching status of massive Porites spp. colonies during a mass bleaching event.

  19. 78 FR 66064 - Notice of Intent To Prepare a Livestock Grazing Monument Management Plan Amendment and Associated...

    2013-11-04

    ...-level decisions associated with livestock grazing, thereby amending the GSENM Management Plan. DATES..., archaeology, paleontology, wildlife and fisheries, hydrology, soils, sociology and economics, and public...

  20. The effects of potential changes in United States beef production on global grazing systems and greenhouse gas emissions

    Dumortier, Jerome; Hayes, Dermot J; Carriquiry, Miguel; Elobeid, Amani; Fabiosa, Jacinto F; Dong, Fengxia; Du Xiaodong; Martin, Pamela A; Mulik, Kranti

    2012-01-01

    We couple a global agricultural production and trade model with a greenhouse gas model to assess leakage associated with modified beef production in the United States. The effects on emissions from agricultural production (i.e., methane and nitrous oxide emissions from livestock and crop management) as well as from land-use change, especially grazing system, are assessed. We find that a reduction of US beef production induces net carbon emissions from global land-use change ranging from 37 to 85 kg CO 2 -equivalent per kg of beef annualized over 20 years. The increase in emissions is caused by an inelastic domestic demand as well as more land-intensive cattle production systems internationally. Changes in livestock production systems such as increasing stocking rate could partially offset emission increases from pasture expansion. In addition, net emissions from enteric fermentation increase because methane emissions per kilogram of beef tend to be higher globally. (letter)

  1. Parasitic Infections of West African Dwarf Goats and their Saanen Crosses in a Zero-Grazing Farming System in The Gambia

    S. Dhollander

    2005-01-01

    Full Text Available Twenty West African Dwarf goats (WADs and 15 Saanen x WAD crosses were managed in an intensified, zero-grazing farming system in an area with low to moderate tsetse challenge in The Gambia. During a period of one year, monthly samples were collected to monitor the helminth egg (EPG and coccidia oocyst outputs (OPG per gram of feces, the packed cell volume (PCV, and trypanosome parasitemia in the goats. High OPGs were found from September to December, resulting in a preweaning mortality rate of 20% in both breeds. The animals were moderately infested with helminths from the middle of the rainy season until early dry season. Trypanosome infections were not detected in WADs, neither were they in the crossbred goats using the buffy coat technique. The average birth weights of crossbred and WAD kids were 2.4 and 2.0 kg, respectively. The growth rate of crossbred kids was significantly higher than that of local kids. The preweaning growth rates of crossbred and WAD kids were 114.75 and 65.57 g/day, whereas the postweaning growth rates were 58.82 and 36.41 g/day, respectively. The fast growth rate of crossbred goats compared to WAD goats indicates that rearing Saanen x WAD crosses in a zero-grazing system can increase productivity. Strict hygiene in the goat sheds, however, is essential to avoid coccidiosis outbreaks.

  2. Sentinel model for influenza A virus monitoring in free-grazing ducks in Thailand.

    Boonyapisitsopa, Supanat; Chaiyawong, Supassama; Nonthabenjawan, Nutthawan; Jairak, Waleemas; Prakairungnamthip, Duangduean; Bunpapong, Napawan; Amonsin, Alongkorn

    2016-01-01

    Influenza A virus (IAV) can cause influenza in birds and mammals. In Thailand, free-grazing ducks are known IAV reservoirs and can spread viruses through frequent movements in habitats they share with wild birds. In this study, the sentinel model for IAV monitoring was conducted over 4 months in two free-grazing duck flocks. IAV subtypes H4N6 (n=1) and H3N8 (n=5) were isolated from sentinel ducks at the ages of 13 and 15 weeks. Clinical signs of depression and ocular discharge were observed in the infected ducks. Phylogenetic analysis and genetic characterization of the isolated IAVs indicated that all Thai IAVs were clustered in the Eurasian lineage and pose low pathogenic avian influenza characteristics. Serological analysis found that antibodies against IAVs could be detected in the ducks since 9-weeks-old. In summary, our results indicate that the sentinel model can be used for IAV monitoring in free-grazing duck flocks. Since free-grazing ducks are potential reservoirs and transmitters of IAVs, routine IAV surveillance in free-grazing duck flocks can be beneficial for influenza prevention and control strategies. Copyright © 2015 Elsevier B.V. All rights reserved.

  3. CHANGES IN THE MORPHOLOGY AND POLYSACCHARIDE CONTENT OF MICROCYSTIS AERUGINOSA (CYANOBACTERIA) DURING FLAGELLATE GRAZING(1).

    Yang, Zhou; Kong, Fanxiang; Shi, Xiaoli; Zhang, Min; Xing, Peng; Cao, Huansheng

    2008-06-01

    To investigate the changes in the morphology and polysaccharide content of Microcystis aeruginosa (Kütz.) Kütz. during flagellate grazing, cultures of M. aeruginosa were exposed to grazing Ochromonas sp. for a period of 9 d under controlled laboratory conditions. M. aeruginosa responded actively to flagellate grazing and formed colonies, most of which were made up of several or dozens of cells, suggesting that flagellate grazing may be one of the biotic factors responsible for colony formation in M. aeruginosa. When colonies were formed, the cell surface ultrastructure changed, and the polysaccharide layer on the surface of the cell wall became thicker. This change indicated that synthesis and secretion of extracellular polysaccharide (EPS) of M. aeruginosa cells increased under flagellate grazing pressure. The contents of soluble extracellular polysaccharide (sEPS), bound extracellular polysaccharide (bEPS), and total polysaccharide (TPS) in colonial cells of M. aeruginosa increased significantly compared with those in single cells. This finding suggested that the increased amount of EPS on the cell surface may play a role in keeping M. aeruginosa cells together to form colonies. © 2008 Phycological Society of America.

  4. Using Ecophysiology to Improve Farm Efficiency: Application in Temperate Dairy Grazing Systems

    David F. Chapman

    2016-04-01

    Full Text Available Information on the physiological ecology of grass-dominant pastures has made a substantial contribution to the development of practices that optimise the amount of feed harvested by grazing animals in temperate livestock systems. However, the contribution of ecophysiology is often under-stated, and the need for further research in this field is sometimes questioned. The challenge for ecophysiolgists, therefore, is to demonstrate how ecophysiological knowledge can help solve significant problems looming for grassland farming in temperate regions while also removing constraints to improved productivity from grazed pastures. To do this, ecophysiological research needs to align more closely with related disciplines, particularly genetics/genomics, agronomy, and farming systems, including systems modelling. This review considers how ecophysiological information has contributed to the development of grazing management practices in the New Zealand dairy industry, an industry that is generally regarded as a world leader in the efficiency with which pasture is grown and utilised for animal production. Even so, there are clear opportunities for further gains in pasture utilisation through the refinement of grazing management practices and the harnessing of those practices to improved pasture plant cultivars with phenotypes that facilitate greater grazing efficiency. Meanwhile, sub-optimal persistence of new pastures continues to constrain productivity in some environments. The underlying plant and population processes associated with this have not been clearly defined. Ecophysiological information, placed in the context of trait identification, grounded in well-designed agronomic studies and linked to plant improvements programmes, is required to address this.

  5. STRUCTURE AND NUTRITIVE VALUE OF DEFERRED PASTURE OF BRACHIARIA DECUMBENS CV. BASILISK DURING THE GRAZING PERIOD

    Manoel Eduardo Rozalino Santos

    2011-07-01

    Full Text Available The experiment aimed to understand the effect of grazing period on morphology and nutritive value of deferred Brachiaria decumbens cv. Basilisk pasture and on hand-plucking sample with cattle. Subdivided plots were used according to a randomized block design with two replicates. Four grazing periods (1, 31, 57 and 88 days and two forage samples (available in pasture (AP and obtained by hand-plucking (HP were studied. The live leaf laminae (LLL, potentially digestible neutral detergent fiber (PDNDF, potentially digestible dry matter (PDDM and crude protein (CP levels were higher and dead leaf laminae (DLL, and dead stem (DS, neutral detergent fiber (NDF and indigestible NDF percentages were lower in sample of HP in relation to forage AP. The grazing period decreased linearly the LLL, PDNDF, PDDM percentages, as well as increased linearly DS and indigestible NDF levels in forages. The potential selectivity indexes (PSI of LLL and indigestible NDF increased linearly with grazing period. The PSI of live stem was smaller and the PSI of CP was higher in interim periods of grazing. The reduction in deferring period results in B. decumbens with better morphological composition and nutritional value, which favors the animal selectivity.

  6. Re-visiting the nutrition of dairy sheep grazing Mediterranean pastures

    M. Decandia

    2010-04-01

    Full Text Available In the light of recent findings in sheep nutrition and behaviour, the diets of grazing dairy sheep should be based on forages encompassing a variety of complementary nutritional values and containing moderate levels of complementary plant secondary metabolites, until recently regarded as "anti-nutritional". In lactating sheep, pastures of tannin-containing legumes like sulla (Hedysarum coronarium and chicory (Cichorium intybus can be integrated with annual grasses for establishing sustainable artificial pastures under rainfed conditions. Diets based on these forages, while ensuring high milking performance, can mitigate the unbalance of CP to energy ratio of grazing sheep. By grazing sulla and annual or Italian ryegrass (50:50 by area as spatially conterminal monocultures or in timely sequence (complementary grazing sheep eat more and perform better than by grazing the ryegrass pasture only. Concentrate supplementation of lactating sheep should be preferably based on fibrous sources (soyhulls or beet pulps, particularly from mid-lactation onwards and when supplementation levels are high. Milk urea concentration is confirmedly a useful monitoring tool to balance protein nutrition and curb the waste of N at animal and system level.

  7. Regional livestock grazing, human demography and fire incidence in the Portuguese landscape

    Filipa Torres-Manso

    2014-04-01

    Full Text Available Aim of study:Wildfire incidence in Portugal is high in comparison with other Mediterranean Europe countries. Wildfire problems have been worsened by complex interactions between land use, livestock grazing and human population during the 20th century. In this study we try to understand these interactions and relationships.Area of study: Portugal country. Material and Methods: For the mainland Portuguese territory we present a statistical temporal analysis (1930-2001 based on the densities of livestock grazing and human inhabitants at the smallest administrative unit level, the parish. We compare these data with fire incidence descriptors (average area burned and average fire density between 1990 and 2007. Research highlights: We have identified clusters of parishes sharing common trends in the evolution of livestock and human inhabitant densities. A cause-effect relationship was not detected between livestock grazing density and fire incidence. However, the results point out clusters of parishes where conflicts between forest, fire and livestock grazing are important in the North, Centre and South regions of Portugal.Key Words: Livestock grazing; inhabitants; forest; fire; vegetation.

  8. Short-term spider community monitoring after cattle removal in grazed grassland

    Guilherme O. da Silva

    2017-10-01

    Full Text Available ABSTRACT. At the Pampa Biome, grazing, like others disturbances, affects fauna and flora, creating heterogeneity in the environment. Little is known about how the diversity and richness of arthropods change during this impact. To improve the knowledge of how spider diversity is affected by grazing, experiments were realized at Pampa. The hypothesis is that abundance of spider will be different when comparing grazed and ungrazed areas. A paired block, with two areas of one hectare each, was established in three areas in the Environmental Protection Area of Ibirapuitã (APA Ibirapuitã, state of Rio Grande do Sul, Brazil. One of these hectares was closed with fences, excluding the catle grazing, in August of 2012. Samplings were realized in November of 2011, 2012 and 2013 using Pitfall traps filled with formol 4% and disposed in an “X” format in each area. For statistical analyses, T test, ANOSIM, ANOVA and Rarefaction were performed. A total of 1,315 spiders were captured, comprising 77 species or morphospecies belonging to 20 families. The family most abundant was Lycosidae followed by Hahniidae, Linyphiidae and Theridiidae. Linyphiidae was the richest family with 14 species or morphospecies identified. All spiders, adults and juveniles, only adults in species and morphospecies, and most abundant species were used as models for statistics. These models revealed no significant difference between grazed and ungrazed areas after three and 15 months of cattle exclusion.

  9. Morphological Responses Explain Tolerance of the Bamboo Yushania microphylla to Grazing

    Kesang Wangchuk

    2014-01-01

    Full Text Available Mechanisms of tolerance of the bamboo Y. microphylla to ungulate herbivory were investigated by measuring above- and belowground morphogenetic traits and biomass allocation patterns of the bamboo Y. microphylla under grazed and ungrazed conditions in a Himalayan mixed conifer forest. Data were collected from 5 populations consisting of 10 ramets each in adjacent grazed and ungrazed plots. Compared with ungrazed ramets, the aboveground morphological modifications of grazed ramets were higher culm density, shorter and thinner culms, shorter internode, and shorter top leaf. The belowground morphological modifications for the grazed ramets were thinner rhizomes, lower rhizome biomass and dry matter, more nodes, and shorter internodes. Despite the lower biomass and dry matter, the root-to-shoot ratio was higher for grazed ramets. Results suggest that Y. microphylla subjected to herbivory shows aboveground overcompensation in terms of densification at the cost of belowground biomass, but at the same time maintains a higher proportion of belowground reserves, as compared to ungrazed conditions. These responses provide adequate evidence to conclude that Y. microphylla tolerates ungulate herbivory through above- and belowground morphological modifications.

  10. e-Dairy: a dynamic and stochastic whole-farm model that predicts biophysical and economic performance of grazing dairy systems.

    Baudracco, J; Lopez-Villalobos, N; Holmes, C W; Comeron, E A; Macdonald, K A; Barry, T N

    2013-05-01

    A whole-farm, stochastic and dynamic simulation model was developed to predict biophysical and economic performance of grazing dairy systems. Several whole-farm models simulate grazing dairy systems, but most of them work at a herd level. This model, named e-Dairy, differs from the few models that work at an animal level, because it allows stochastic behaviour of the genetic merit of individual cows for several traits, namely, yields of milk, fat and protein, live weight (LW) and body condition score (BCS) within a whole-farm model. This model accounts for genetic differences between cows, is sensitive to genotype × environment interactions at an animal level and allows pasture growth, milk and supplements price to behave stochastically. The model includes an energy-based animal module that predicts intake at grazing, mammary gland functioning and body lipid change. This whole-farm model simulates a 365-day period for individual cows within a herd, with cow parameters randomly generated on the basis of the mean parameter values, defined as input and variance and co-variances from experimental data sets. The main inputs of e-Dairy are farm area, use of land, type of pasture, type of crops, monthly pasture growth rate, supplements offered, nutritional quality of feeds, herd description including herd size, age structure, calving pattern, BCS and LW at calving, probabilities of pregnancy, average genetic merit and economic values for items of income and costs. The model allows to set management policies to define: dry-off cows (ceasing of lactation), target pre- and post-grazing herbage mass and feed supplementation. The main outputs are herbage dry matter intake, annual pasture utilisation, milk yield, changes in BCS and LW, economic farm profit and return on assets. The model showed satisfactory accuracy of prediction when validated against two data sets from farmlet system experiments. Relative prediction errors were <10% for all variables, and concordance

  11. Effect of supplementation on the performance of grazing Belgian Blue double-muscled heifers.

    Fiems, L O; De Boever, J L; Vanacker, J M

    2013-11-01

    Six experiments were conducted to investigate the effect of a feed supplement on the performance of grazing Belgian Blue double-muscled (BBDM) heifers with an initial weight and age of 195 ± 43 kg and 190 ± 52 days. Treatments included were: Exp. 1: supplementation with beet pulp (BP): 2 kg/day per head v. ad libitum intake; Exp. 2: supplementation ad libitum with BP v. a mixture of BP and soybean meal (SBM; BP/SBM ratio of 80/20; FW (fresh weight) basis); Exp. 3: supplementation with 4 kg/day per head of a mixture of BP/SBM (80/20; FW basis) v. BP/formaldehyde-treated SBM (BP/FSBM); Exp. 4: supplementation with 4 kg/day per head of a mixture with a similar protein content (125 g DVE per kg dry matter (DM)), consisting of 80/20 BP/SBM v. 92/8 BP/FSBM; Exp. 5: supplementation with 3 kg/day per head of a mixture of BP/SBM (80/20; FW basis) v. BP/DDGS (dried distillers grains and solubles; 70/30, FW basis); and Exp. 6: supplementation with 3 kg/day per head of 80/20 BP/SBM v. maize silage (MS) and SBM, on the basis of a similar protein concentration in the DM as the 80/20 BP/SBM supplement, and fed at a similar amount of DM as in the BP/SBM group. Supplementing BP ad libitum did not affect daily gain (0.54 v. 0.48 kg) and partial feed conversion (3.62 kg on average) compared with 2 kg/day. Supplying SBM besides BP increased growth rate compared with BP (0.87 v. 0.62 kg/day; P 0.10), but blood urea levels were reduced by FSBM (P < 0.05). DDGS tended to increase growth rate (0.77 v. 0.59 kg/day; P < 0.10) compared with BP/SBM, without effect on partial feed conversion. Replacing BP by MS did not affect daily gain, but partial feed conversion tended to be higher (3.21 v. 3.60 kg/kg body weight (BW) gain; P = 0.062). Increasing the supplement (80/20 BP/SBM) level from 3 to 4 kg daily, corresponding to 1.02% and 1.18% of the mean BW, respectively, resulted in a tendency (P = 0.121) for an increased growth rate. Grazing BBDM heifers of <1 year of age necessitate extra

  12. Eaten out of house and home: impacts of grazing on ground-dwelling reptiles in Australian grasslands and grassy woodlands.

    Howland, Brett; Stojanovic, Dejan; Gordon, Iain J; Manning, Adrian D; Fletcher, Don; Lindenmayer, David B

    2014-01-01

    Large mammalian grazers can alter the biotic and abiotic features of their environment through their impacts on vegetation. Grazing at moderate intensity has been recommended for biodiversity conservation. Few studies, however, have empirically tested the benefits of moderate grazing intensity in systems dominated by native grazers. Here we investigated the relationship between (1) density of native eastern grey kangaroos, Macropus giganteus, and grass structure, and (2) grass structure and reptiles (i.e. abundance, richness, diversity and occurrence) across 18 grassland and grassy Eucalyptus woodland properties in south-eastern Australia. There was a strong negative relationship between kangaroo density and grass structure after controlling for tree canopy cover. We therefore used grass structure as a surrogate for grazing intensity. Changes in grazing intensity (i.e. grass structure) significantly affected reptile abundance, reptile species richness, reptile species diversity, and the occurrence of several ground-dwelling reptiles. Reptile abundance, species richness and diversity were highest where grazing intensity was low. Importantly, no species of reptile was more likely to occur at high grazing intensities. Legless lizards (Delma impar, D. inornata) were more likely to be detected in areas subject to moderate grazing intensity, whereas one species (Hemiergis talbingoensis) was less likely to be detected in areas subject to intense grazing and three species (Menetia greyii, Morethia boulengeri, and Lampropholis delicata) did not appear to be affected by grazing intensity. Our data indicate that to maximize reptile abundance, species richness, species diversity, and occurrence of several individual species of reptile, managers will need to subject different areas of the landscape to moderate and low grazing intensities and limit the occurrence and extent of high grazing.

  13. Eaten out of house and home: impacts of grazing on ground-dwelling reptiles in Australian grasslands and grassy woodlands.

    Brett Howland

    Full Text Available Large mammalian grazers can alter the biotic and abiotic features of their environment through their impacts on vegetation. Grazing at moderate intensity has been recommended for biodiversity conservation. Few studies, however, have empirically tested the benefits of moderate grazing intensity in systems dominated by native grazers. Here we investigated the relationship between (1 density of native eastern grey kangaroos, Macropus giganteus, and grass structure, and (2 grass structure and reptiles (i.e. abundance, richness, diversity and occurrence across 18 grassland and grassy Eucalyptus woodland properties in south-eastern Australia. There was a strong negative relationship between kangaroo density and grass structure after controlling for tree canopy cover. We therefore used grass structure as a surrogate for grazing intensity. Changes in grazing intensity (i.e. grass structure significantly affected reptile abundance, reptile species richness, reptile species diversity, and the occurrence of several ground-dwelling reptiles. Reptile abundance, species richness and diversity were highest where grazing intensity was low. Importantly, no species of reptile was more likely to occur at high grazing intensities. Legless lizards (Delma impar, D. inornata were more likely to be detected in areas subject to moderate grazing intensity, whereas one species (Hemiergis talbingoensis was less likely to be detected in areas subject to intense grazing and three species (Menetia greyii, Morethia boulengeri, and Lampropholis delicata did not appear to be affected by grazing intensity. Our data indicate that to maximize reptile abundance, species richness, species diversity, and occurrence of several individual species of reptile, managers will need to subject different areas of the landscape to moderate and low grazing intensities and limit the occurrence and extent of high grazing.

  14. Successive sheep grazing reduces population density of Brandt's voles in steppe grassland by altering food resources: a large manipulative experiment.

    Li, Guoliang; Yin, Baofa; Wan, Xinrong; Wei, Wanhong; Wang, Guiming; Krebs, Charles J; Zhang, Zhibin

    2016-01-01

    Livestock grazing has shaped grassland ecosystems around the world. Previous studies indicated grazing showed various impacts on small rodents; however, most studies were conducted over 1-2 years without controlling for confounding factors such as immigration/emigration and predation in rodents. Brandt's voles (Lasiopodomys brandtii) are generally recognized as pests because of food overlap with domestic herbivores, but are also important for biodiversity conservation because they provide nests or food to many birds. Fully understanding the ecological relationship between domestic herbivores and small mammals is essential to making ecosystem management decisions. To address these needs, we carried out a field experiment during the period 2010-2013 to assess the effects of sheep grazing on vegetation and the population density of Brandt's voles along a gradient of three grazing intensities by using 12 large-scale enclosures. Responses of Brandt's voles to livestock grazing varied with grazing intensity and year. As compared to the control group, sheep grazing had no effect on vole abundance in the first year but an overall negative effect on vole abundance in the following 3 years. Successive grazing caused decreases in survival and male body mass of voles, but had no significant effect on fecundity. Negative effects of grazing were associated with a grazing-induced deterioration in both food quantity (reflected by biomass and cover of less-preferred plants), and food quality (measured by tannin and total phenol content). Our findings highlight the urgent need for more flexible management of yearly rotational grazing to optimize livestock production while maintaining species diversity and ecosystem health.

  15. Release and Consumption of DMSP from Emiliania Huxleyi during grazing by Oxyrrhis Marina

    Wolfe, Gordon V.; Sherr, Evelyn B.; Sherr, Barry F.

    1994-01-01

    Degradation and release to solution of intracellular dimethylsulfoniopropionate (DMSP) from Emiliania huxleyi 370 was observed during grazing by the heterotrophic dinoflagellate Oxyrrhis marina in 24 h bottle incubations. Between 30 and 70% of the lost algal DMSP was metabolized by the grazers without production of dimethylsulfide (DMS) when grazer densities were 150 to 450/ml. The rest was released to solution and about 30% was converted to DMS by bacteria associated with the grazer culture. These experiments demonstrate that grazing by herbivorous protists may be an important sink for DMSP in marine waters, removing a potential source of DMS. Microzooplankton grazing may also indirectly increase the production of DMS by transferring algal DMSP to the dissolved pool, making it available for bacterial metabolism.

  16. PRODUCTIVITY OF A SILVOPASTORAL SYSTEM UNDER INTENSIVE MIXED SPECIES GRAZING BY CATTLE AND SHEEP

    Leonor Yalid Manriquez-Mendoza

    2011-11-01

    Full Text Available The presence of forage trees in pastures enhances yield and nutritional quality of forage available for animal feeding. We assessed forage yield and nutritional quality, and weight gain of cattle and sheep foraging in a silvopastoral system containing Guazuma ulmifolia Lam. and the grasses Digitaria eriantha Stent (cv. Pangola, Brachiaria brizantha (Hochst. ex A. Rich. Stapf (cv. Insurgentes and Megathyrsus maximus (Jacq. B.K. Simon & S.W.L. Jacobs (cv. Tanzania, during three seasons (windy, dry and rainy in two grazing treatments: 1 mixed species grazing by four to five Criollo Lechero Tropical heifers and six female Pelibuey lambs, and 2 simple species grazing by 12 female Pelibuey lambs. Weight gain was greater (P

  17. Experiment and application of soft x-ray grazing incidence optical scattering phenomena

    Chen, Shuyan; Li, Cheng; Zhang, Yang; Su, Liping; Geng, Tao; Li, Kun

    2017-08-01

    For short wavelength imaging systems,surface scattering effects is one of important factors degrading imaging performance. Study of non-intuitive surface scatter effects resulting from practical optical fabrication tolerances is a necessary work for optical performance evaluation of high resolution short wavelength imaging systems. In this paper, Soft X-ray optical scattering distribution is measured by a soft X-ray reflectometer installed by my lab, for different sample mirrors、wavelength and grazing angle. Then aim at space solar telescope, combining these scattered light distributions, and surface scattering numerical model of grazing incidence imaging system, PSF and encircled energy of optical system of space solar telescope are computed. We can conclude that surface scattering severely degrade imaging performance of grazing incidence systems through analysis and computation.

  18. The role of grazing land on the buffalo population dynamics in Brebes regency

    Sumanto

    2017-04-01

    Brebes District is one of the centre of grazing buffalo in Indonesia that involve thousands of rearers usually kept as a family savings. This paper highlighted the availability of land and the role of the grazing land for the durability of the maintenance of buffalo in Brebes Regency. The information obtained is from interviewed the livestock facilitators in the sub-district (primary data) and from statistic of agriculture in Brebes Regency 2014 (secondary data). Generally the buffalo kept semi-intensively and commonly the buffaloes graze in the fields that are not used from morning until evening and during nights buffaloes are placed in the stalls. Rearers chose the semi-intensive system in rearing the buffalo because it is considered easy to manage and they do not need to provide fresh money to prepare the roughage for feed, because commonly the grazing buffalo are shepherd by herdman that will receive buffalo as their payment. The population density is very high (1.056 heads/km2), the buffalo ownership is between 2-4 head/households; generally the location of the grazing land is in the forest, rice fields fallow, and sleeping land, and estimated that greenfeed stock is still available abunandtly, on the other hand the urban land is less capacity of feed. The spread of buffalo is only in 125 villages from 297 villages in Brebes. The acceptance of buffalo business is around IDR 3.5 million to IDR 7.5 million/family/year. The availability of grazing land strongly influence the maintaining of buffalo farming by rearers.

  19. Grazing of particle-associated bacteria-an elimination of the non-viable fraction.

    Gonsalves, Maria-Judith; Fernandes, Sheryl Oliveira; Priya, Madasamy Lakshmi; LokaBharathi, Ponnapakkam Adikesavan

    Quantification of bacteria being grazed by microzooplankton is gaining importance since they serve as energy subsidies for higher trophic levels which consequently influence fish production. Hence, grazing pressure on viable and non-viable fraction of free and particle-associated bacteria in a tropical estuary controlled mainly by protist grazers was estimated using the seawater dilution technique. In vitro incubations over a period of 42h showed that at the end of 24h, growth coefficient (k) of particle-associated bacteria was 9 times higher at 0.546 than that of free forms. Further, 'k' value of viable cells on particles was double that of free forms at 0.016 and 0.007, respectively. While bacteria associated with particles were grazed (coefficient of removal (g)=0.564), the free forms were relatively less grazed indicating that particle-associated bacteria were exposed to grazers in these waters. Among the viable and non-viable forms, 'g' of non-viable fraction (particle-associated bacteria=0.615, Free=0.0086) was much greater than the viable fraction (particle-associated bacteria=0.056, Free=0.068). Thus, grazing on viable cells was relatively low in both the free and attached states. These observations suggest that non-viable forms of particle-associated bacteria were more prone to grazing and were weeded out leaving the viable cells to replenish the bacterial standing stock. Particle colonization could thus be a temporary refuge for the "persistent variants" where the viable fraction multiply and release their progeny. Copyright © 2016 Sociedade Brasileira de Microbiologia. Published by Elsevier Editora Ltda. All rights reserved.

  20. Monitoring of livestock grazing effects on Bureau of Land Management land

    Veblen, Kari E.; Pyke, David A.; Aldridge, Cameron L.; Casazza, Michael L.; Assal, Timothy J.; Farinha, Melissa A.

    2013-01-01

    Public land management agencies, such as the Bureau of Land Management (BLM), are charged with managing rangelands throughout the western United States for multiple uses, such as livestock grazing and conservation of sensitive species and their habitats. Monitoring of condition and trends of these rangelands, particularly with respect to effects of livestock grazing, provides critical information for effective management of these multiuse landscapes. We therefore investigated the availability of livestock grazing-related quantitative monitoring data and qualitative region-specific Land Health Standards (LHS) data across BLM grazing allotments in the western United States. We then queried university and federal rangeland science experts about how best to prioritize rangeland monitoring activities. We found that the most commonly available monitoring data were permittee-reported livestock numbers and season-of-use data (71% of allotments) followed by repeat photo points (58%), estimates of forage utilization (52%), and, finally, quantitative vegetation measurements (37%). Of the 57% of allotments in which LHS had been evaluated as of 2007, the BLM indicated 15% had failed to meet LHS due to livestock grazing. A full complement of all types of monitoring data, however, existed for only 27% of those 15%. Our data inspections, as well as conversations with rangeland experts, indicated a need for greater emphasis on collection of grazing-related monitoring data, particularly ground cover. Prioritization of where monitoring activities should be focused, along with creation of regional monitoring teams, may help improve monitoring. Overall, increased emphasis on monitoring of BLM rangelands will require commitment at multiple institutional levels.

  1. Effect of summer grazing on welfare of dairy cows reared in mountain tie-stall barns

    Simonetta Dovier

    2010-09-01

    Full Text Available Traditional mountain farms have an important economic, social and environmental role. The Alps management system for dairy cows consists of animals kept indoors from autumn to spring, mostly in tie-stalls, and moved to mountain pasture in summer. The aim of our study was to assess the effect of mountain summer grazing on the welfare of dairy cows housed in tie-stall barns. Twenty-four farms were considered. In twelve of them, animals were reared in tie-stalls and moved to mountain pasture for three months in summer; they were visited three times: (i four weeks before grazing during the indoor period in the stall; (ii about three weeks after the start of grazing; and (iii in the stall, in autumn, at least three weeks after returning from grazing. The other twelve farms kept the animals in tie-stalls all year; they were visited once in autumn. Data were collected following a protocol that considers animal-based measures and structure information on the basis of Quality Welfare Consortium® indications. Data allowed the calculation of both the Animal Needs Index score (ANI 35L and an overall assessment of the cows’ welfare obtained from three general aspects: housing, animal’s physical condition, and animal’s behaviour. Summer grazing had a significant positive effect on injuries, lameness and animal’s rising duration but a negative effect on faeces consistency. Moreover, a reduction of tongue playing was observed. The ANI 35L and the overall assessment did not show significant differences linked to summer grazing, which tended to have a positive but temporary effect on animal behaviour.

  2. Grazing of particle-associated bacteria-an elimination of the non-viable fraction

    Maria-Judith Gonsalves

    Full Text Available Abstract Quantification of bacteria being grazed by microzooplankton is gaining importance since they serve as energy subsidies for higher trophic levels which consequently influence fish production. Hence, grazing pressure on viable and non-viable fraction of free and particle-associated bacteria in a tropical estuary controlled mainly by protist grazers was estimated using the seawater dilution technique. In vitro incubations over a period of 42 h showed that at the end of 24 h, growth coefficient (k of particle-associated bacteria was 9 times higher at 0.546 than that of free forms. Further, ‘k’ value of viable cells on particles was double that of free forms at 0.016 and 0.007, respectively. While bacteria associated with particles were grazed (coefficient of removal (g = 0.564, the free forms were relatively less grazed indicating that particle-associated bacteria were exposed to grazers in these waters. Among the viable and non-viable forms, ‘g’ of non-viable fraction (particle-associated bacteria = 0.615, Free = 0.0086 was much greater than the viable fraction (particle-associated bacteria = 0.056, Free = 0.068. Thus, grazing on viable cells was relatively low in both the free and attached states. These observations suggest that non-viable forms of particle-associated bacteria were more prone to grazing and were weeded out leaving the viable cells to replenish the bacterial standing stock. Particle colonization could thus be a temporary refuge for the “persistent variants” where the viable fraction multiply and release their progeny.

  3. In situ provision of drinking water to grazing dairy cows improves milk production.

    Miglierina, M M; Bonadeo, N; Ornstein, A M; Becú-Villalobos, D; Lacau-Mengido, I M

    2018-01-01

    To determine the effect of providing water within the area grazed by dairy cows on milk yield and quality, compared to requiring cows to walk to a distant water trough, on a dairy farm in the Pampa region of Argentina during summer. Holstein dairy cows were allocated to two herds with similar parity, days in milk and milk production. They were grazed in one paddock that was divided in two, with a fixed water trough at one end. Cows were moved twice daily to grazing plots within the paddock. Control cows (n=66) could only access water from the fixed trough, whereas supplemented cows (n=67) also received water from a mobile trough within the grazing plot. Milk production of each cow, and water consumption of the two herds were measured daily over 62 days. Milk composition for each herd was determined weekly from Days 18 to 60 of the study, and grazing behaviour was observed between 08:00 and 16:00 hours on Days 11-15, 19-22 and 39-43. Over the 62 days of the study, supplemented cows produced 1.39 (SE 0.11) L/cow/day more milk than Control cows (p=0.027). Estimated mean daily water intake was 50.4 (SE 2.1) L/cow/day for supplemented cows and 58.2 (SE 2.7) L/cow/day for Control cows (p=0.004). Percentage total solids in milk was higher for supplemented (12.5 (SE 0.06)%) than Control (12.4 (SE 0.04)%) cows (p=0.047). During the periods of behavioural observation, a higher percentage of cows in the water supplemented than the Control herd were observed in the grazing area (p=0.012). This preliminary study demonstrated that provision of water to dairy cows within the grazing plot was beneficial for milk production and composition, and may be associated with longer periods spent within the grazing area, during hot weather in the Pampa region of Argentina.

  4. Selective grazing from protist over enteric bacteria in an aquatic system

    Dominguez, M. S.; Escalante, A. H.; Folabella, A. M.; Zamora, A. S.

    2009-07-01

    Its very clear that the grazing from protozoan can be an important source of mortality for the suspended bacteria, both in marine and freshwater environments. Considering that the presence of fecal contamination its a frequent phenomenon in this environments, and that Escherichia coli and members of Enterococcus genera are indicators of microbiology water quality, we analyze the effect of grazing from protozoan over E. coli and Enterococcus faecalis in de Los Padres Lagoon waters (Buenos Aires, Argentina) 37 degree centigrade 56'30'' S, 57 degree centigrade 44'30'' W). (Author)

  5. The impact of sheep grazing on the carbon balance of a peatland

    Worrall, Fred, E-mail: Fred.Worrall@durham.ac.uk; Clay, Gareth D.

    2012-11-01

    Estimates of the greenhouse gas (GHG) fluxes resulting from sheep grazing upon upland peat soils have never been fully quantified. Previous studies have been limited to individual flux pathways or to comparing the presence to the absence of sheep grazing. Therefore, this study combines a model of the physical impact of grazing with models of: biomass production; energy usage in sheep; and peat accumulation. These combined modelling approaches enabled this study to consider the indirect and direct impacts of sheep upon the carbon and greenhouse gas balance of a peatland at different grazing intensities as well as the changes between grazing intensities. The study considered four vegetation scenarios (Calluna sp., Molinia sp.; reseeded grasses, and Agrostis-Festuca grassland) and a mixed vegetation scenario based upon the vegetation typical of upland peat ecosystems in northern England. Each scenario was considered for altitudes between 350 and 900 m above sea level and for grazing intensities between 0.1 and 2 ewes/ha. The study can show that the total GHG flux at the vegetative carrying capacity tended to decline with increasing altitude for all vegetation scenarios considered except for Molinia sp. The average total GHG flux for all scenarios was 1505 kg CO{sub 2}eq/ha/yr/(ewe/ha), and on average 89% of the fluxes were directly from the sheep and not from the soil, and are therefore not unique to a peat soil environment. The study suggests that emission factors for upland sheep have been greatly underestimated. By comparing the total flux due to grazers to the flux to or from the soil that allows the study to define a GHG carry capacity, i.e. the grazing intensity at which the flux due to grazing is equal to the sink represented by the peat soils, this GHG carrying capacity varies between 0.2 and 1.7 ewes/ha with this capacity declining with increasing altitude for all model scenarios. -- Highlights: Black-Right-Pointing-Pointer Vegetative carrying capacity was

  6. Population fluctuations, losses to grazing, and reproductive success of Dactylorhiza sambucina on Bornholm, Denmark

    Sonne, Mette Nordvig; Hauser, Thure Pavlo

    2014-01-01

    generally increased in the early 1990s but declined after that. We could find no effect of vegetation management, neither were the fluctuations related to suggested climatic factors. High proportions of plants were lost to grazing in the study year; same could be deduced for previous years when more than...... one census was available. Grazing in spring and early summer may therefore contribute to the decline of D. sambucina, as suggested by others. Populations seemed not to be affected by lack of pollination or population inbreeding, as fruit set and reproductive size was as high as in large...

  7. Selective grazing from protist over enteric bacteria in an aquatic system

    Dominguez, M. S.; Escalante, A. H.; Folabella, A. M.; Zamora, A. S.

    2009-01-01

    Its very clear that the grazing from protozoan can be an important source of mortality for the suspended bacteria, both in marine and freshwater environments. Considering that the presence of fecal contamination its a frequent phenomenon in this environments, and that Escherichia coli and members of Enterococcus genera are indicators of microbiology water quality, we analyze the effect of grazing from protozoan over E. coli and Enterococcus faecalis in de Los Padres Lagoon waters (Buenos Aires, Argentina) 37 degree centigrade 56'30'' S, 57 degree centigrade 44'30'' W). (Author)

  8. Spatio-temporal optimization of sampling for bluetongue vectors (Culicoides) near grazing livestock

    Kirkeby, Carsten; Stockmarr, Anders; Bødker, Rene

    2013-01-01

    BACKGROUND: Estimating the abundance of Culicoides using light traps is influenced by a large variation in abundance in time and place. This study investigates the optimal trapping strategy to estimate the abundance or presence/absence of Culicoides on a field with grazing animals. We used 45 light...... absence of vectors on the field. The variation in the estimated abundance decreased steeply when using up to six traps, and was less pronounced when using more traps, although no clear cutoff was found. CONCLUSIONS: Despite spatial clustering in vector abundance, we found no effect of increasing...... monitoring programmes on fields with grazing animals....

  9. Forage intake and wastage by ewes in pea/hay barley swath grazing and bale feeding systems

    Harvested feed costs, particularly during the winter, are traditionally the highest input associated with a ruminant livestock operation. Although swath grazing has been practiced for over 100 years and literature exists for cattle use of swath grazing, no published results are available on use of s...

  10. Nest Success and Cause-Specific Nest Failure of Grassland Passerines Breeding in Prairie Grazed by Livestock

    This manuscript describes two years of field research on ground-nesting songbird species at Zumwalt Prairie Reserve, northeastern Oregon, USA. Cattle-grazing has long been suspected in declines of ground-nesting songbirds in grazed grassland, primarily due to increased trampling...

  11. Grazing moderates increases in C3 grass abundance over seven decades across a soil texture gradient in shortgrass steppe

    Questions: How does long-term grazing exclusion influence plant community composition in a semiarid grassland? Can spatial variation in the effects of grazing exclusion be explained by variation in soil texture? Location: The shortgrass steppe of northeastern Colorado, USA, located in the North Amer...

  12. An experimental analysis of grasshopper community responses to fire and livestock grazing in a northern mixed-grass prairie.

    Branson, David H; Sword, Gregory A

    2010-10-01

    The outcomes of grasshopper responses to both vertebrate grazing and fire vary across grassland ecosystems, and are strongly influenced by local climactic factors. Thus, the possible application of grazing and fire as components of an ecologically based grasshopper management strategy must be investigated in regional studies. In this study, we examined the effects of grazing and fire on grasshopper population density and community composition in a northern Great Plains mixed-grass prairie. We employed a large-scale, replicated, and fully-factorial manipulative experimental design across 4 yr to examine the separate and interactive effects of three grazing systems in burned and unburned habitats. Grasshopper densities were low throughout the 4-yr study and 1 yr of pretreatment sampling. There was a significant fire by grazing interaction effect on cumulative density and community composition, resulting from burned season long grazing pastures having higher densities than unburned pastures. Shannon diversity and grasshopper species richness were significantly higher with twice-over rotational livestock grazing. The ability to draw strong conclusions regarding the nature of species composition shifts and population changes in the presence of fire and grazing is complicated by the large site differences and low grasshopper densities. The results reinforce the importance of long-term research to examine the effects of habitat manipulation on grasshopper population dynamics.

  13. Equine Grazing in Managed Subalpine Wetlands: Effects on Arthropods and Plant Structure as a Function of Habitat

    Holmquist, Jeffrey G.; Schmidt-Gengenbach, Jutta; Haultain, Sylvia A.

    2013-12-01

    Grazing management necessarily emphasizes the most spatially extensive vegetation assemblages, but landscapes are mosaics, often with more mesic vegetation types embedded within a matrix of drier vegetation. Our primary objective was to contrast effects of equine grazing on both subalpine vegetation structure and associated arthropods in a drier reed grass ( Calamagrostis muiriana) dominated habitat versus a wetter, more productive sedge habitat ( Carex utriculata). A second objective was to compare reed grass and sedge as habitats for fauna, irrespective of grazing. All work was done in Sequoia National Park (CA, USA), where detailed, long-term records of stock management were available. We sampled paired grazed and control wet meadows that contained both habitats. There were moderate negative effects of grazing on vegetation, and effects were greater in sedge than in reed grass. Conversely, negative grazing effects on arthropods, albeit limited, were greater in the drier reed grass, possibly due to microhabitat differences. The differing effects on plants and animals as a function of habitat emphasize the importance of considering both flora and fauna, as well as multiple habitat types, when making management decisions. Sedge supported twice the overall arthropod abundance of reed grass as well as greater diversity; hemipteran and dipteran taxa were particularly abundant in sedge. Given the greater grazing effects on sedge vegetation, greater habitat provision for terrestrial arthropods, and value as aquatic arthropod habitat, the wetter sedge assemblage is worthy of additional consideration by managers when planning for grazing and other aspects of land usage.

  14. Landscape management of fire and grazing regimes alters the fine-scale habitat utilisation by feral cats.

    McGregor, Hugh W; Legge, Sarah; Jones, Menna E; Johnson, Christopher N

    2014-01-01

    Intensification of fires and grazing by large herbivores has caused population declines in small vertebrates in many ecosystems worldwide. Impacts are rarely direct, and usually appear driven via indirect pathways, such as changes to predator-prey dynamics. Fire events and grazing may improve habitat and/or hunting success for the predators of small mammals, however, such impacts have not been documented. To test for such an interaction, we investigated fine-scale habitat selection by feral cats in relation to fire, grazing and small-mammal abundance. Our study was conducted in north-western Australia, where small mammal populations are sensitive to changes in fire and grazing management. We deployed GPS collars on 32 cats in landscapes with contrasting fire and grazing treatments. Fine-scale habitat selection was determined using discrete choice modelling of cat movements. We found that cats selected areas with open grass cover, including heavily-grazed areas. They strongly selected for areas recently burnt by intense fires, but only in habitats that typically support high abundance of small mammals. Intense fires and grazing by introduced herbivores created conditions that are favoured by cats, probably because their hunting success is improved. This mechanism could explain why, in northern Australia, impacts of feral cats on small mammals might have increased. Our results suggest the impact of feral cats could be reduced in most ecosystems by maximising grass cover, minimising the incidence of intense fires, and reducing grazing by large herbivores.

  15. Landscape management of fire and grazing regimes alters the fine-scale habitat utilisation by feral cats.

    Hugh W McGregor

    Full Text Available Intensification of fires and grazing by large herbivores has caused population declines in small vertebrates in many ecosystems worldwide. Impacts are rarely direct, and usually appear driven via indirect pathways, such as changes to predator-prey dynamics. Fire events and grazing may improve habitat and/or hunting success for the predators of small mammals, however, such impacts have not been documented. To test for such an interaction, we investigated fine-scale habitat selection by feral cats in relation to fire, grazing and small-mammal abundance. Our study was conducted in north-western Australia, where small mammal populations are sensitive to changes in fire and grazing management. We deployed GPS collars on 32 cats in landscapes with contrasting fire and grazing treatments. Fine-scale habitat selection was determined using discrete choice modelling of cat movements. We found that cats selected areas with open grass cover, including heavily-grazed areas. They strongly selected for areas recently burnt by intense fires, but only in habitats that typically support high abundance of small mammals. Intense fires and grazing by introduced herbivores created conditions that are favoured by cats, probably because their hunting success is improved. This mechanism could explain why, in northern Australia, impacts of feral cats on small mammals might have increased. Our results suggest the impact of feral cats could be reduced in most ecosystems by maximising grass cover, minimising the incidence of intense fires, and reducing grazing by large herbivores.

  16. 75 FR 22617 - Notice of Intent To Prepare an Environmental Assessment for Domestic Sheep Grazing on the Dog...

    2010-04-29

    ... Intent To Prepare an Environmental Assessment for Domestic Sheep Grazing on the Dog Creek and Green Creek... that will evaluate a range of alternatives for grazing domestic sheep on the Dog Creek and Green Creek... to the Bishop RMP, and would therefore require a plan amendment. The Dog Creek allotment consists of...

  17. EFFECTS OF FERTILIZER TYPE (CHICKEN LITTER VS. INORGANIC FERTILIZER) AND CATTLE GRAZING ON THE SOIL MICROBIAL COMMUNITY

    Pasture plots included unharvested, hayed, light and heavy cattle grazing pressure, fertilized with either inorganic N-P-K or broiler litter. Total phospholipid fatty acids (PLFAs) followed a seasonal trend and were higher in grazed plots than hayed & unharvested plots. Fungi a...

  18. Spatial diversity in canopy height at Redshank and Oystercatcher nest-sites in relation to livestock grazing

    Mandema, Freek S.; Tinbergen, Joost M.; Ens, Bruno J.; Bakker, Jan P.

    2013-01-01

    In this study we examined the effect of different livestock grazing treatments on breeding bird densities in a salt marsh habitat. To avoid an experiment on the large scale needed to directly measure grazing effects on bird densities, we followed a two-step approach. First, we measured vegetation

  19. Variability in carbon dioxide fluxes among six winter wheat paddocks managed under different tillage and grazing practices

    Carbon dioxide (CO2) fluxes from six winter wheat (Triticum aestivum L.) paddocks (grain only, graze-grain, and graze-out) managed under conventional till (CT) and no-till (NT) systems were synthesized for the 2016-2017 growing season to compare the magnitudes and seasonal dynamics of CO2 fluxes and...

  20. Rangeland dynamics in South Omo Zone of Southern Ethiopia: Assessment of rangeland condition in relation to altitude and Grazing types

    Terefe, A.; Ebro, A.; Tessema, Z.K.

    2010-01-01

    A study was undertaken in Hamer and Benna-Tsemay districts of the Southern Ethiopia with the objective to determine the condition of the rangelands for grazing animals as influenced by altitude and grazing types. The rangelands in each of the study districts were stratified based on altitude and

  1. Alterations in serotonin receptor-induced contractility of bovine lateral saphenous vein in cattle grazing endophyte-infected tall fescue

    As part of a large 2-year study documenting the physiologic impact of grazing endophyte-infected tall fescue on growing cattle, 2 experiments were conducted to characterize and evaluate the effects of grazing 2 levels of toxic endophyte-infected tall fescue pastures on vascular contractility and ser...

  2. Moderate livestock grazing of salt, and brackish marshes benefits breeding birds along the mainland coast of the Wadden Sea

    Mandema, Freek S.; Tinbergen, Joost M.; Ens, Bruno J.; Koffijberg, Kees; Dijkema, Kees S.; Bakker, Jan P.

    Our study investigated how bird species richness and abundance was related to livestock grazing on salt, and brackish marshes, with an emphasis on songbirds, and shorebirds. Survey areas with a high percentage cover of tall vegetation were assumed to have experienced lower livestock grazing

  3. Moderate livestock grazing of salt, and brackish marshes benefits breeding birds along the mainland coast of the Wadden Sea

    Mandema, F.S.; Tinbergen, J.M.; Ens, B.J.; Koffijberg, K.; Dijkema, K.S.; Bakker, J.P.

    2015-01-01

    Our study investigated how bird species richness and abundance was related to livestock grazing on salt, and brackish marshes, with an emphasis on songbirds, and shorebirds. Survey areas with a high percentage cover of tall vegetation were assumed to have experienced lower livestock grazing

  4. A note on the effects of paddock size on the white clover content of swards grazed by sheep

    Wolf, de P.L.; Schulte, R.P.O.; Lantinga, E.A.

    2004-01-01

    The maintenance of a high white clover content in mixed swards under sheep grazing has been a challenge to date. This paper presents the results of an experiment in which the effect of the length of a grazing period on the botanical composition of a mixed sward was studied. Paddocks ranging in size

  5. Evaluation of Meat and Egg Traits of Beijing-you Chickens Rotationally Grazing on Chicory Pasture in a Chestnut Forest

    L Meng

    Full Text Available ABSTRACT Barn and cage-fed chickens have presented several problems, such as high rates of infectious disease and consequent antibiotic abuse, poorer chicken health and welfare, and often poorer meat and egg quality compared with free-range chickens. The poultry agroforestry system is becoming increasingly popular in many poultry farms nowadays. In this study, to evaluate the contribution of poultry agroforestry system to enhance some meat and egg traits of Beijing-you chickens, some indexes of meat and egg qualities, some indexes of slaughter traits, and the feed conversion efficiency were investigated in rotational grazing Beijing-you chickens on chicory (Cichorium intybus L. pasture (CGRG group and only free-ranging chickens on bare land without forage (control group in chestnut forest. Results showed that the live body weight, the dressing weight, the thigh muscle weight, and the breast muscle weight were increased (p<0.05 based on the decrease of 15% feed concentration in the CGRG group relative to the control. Furthermore, compared with the control, the crude ash, the essential amino acid content, and the inosinic acid content were increased (p<0.05, and the crude fat contents were decreased (p<0.05 in the thigh and breast muscles, while the yolk cholesterol and the feed conversion ratio were significantly decreased (p<0.05 in the CGRG group. This study would provide a scientific basis and technological support for the large-scale demonstration and application of rotational grazing chickens on the artificial pasture in forest.

  6. An investigation into the causes of low calving percentage in communally grazed cattle in Jericho, North West Province

    E. Mokantla

    2004-06-01

    Full Text Available The communal grazing system is generally understood to have a low input, low output type of management. However, the actual inputs and outputs of the farmers are not well known and the farmers are often unaware of their problems. Although the causes of low calving percentage are well understood in commercial beef farming enterprises in South Africa, the same is not true for communal farming systems. The aim of this study was to determine the reproductive performance of beef cattle on a communal farming system in Jericho, NorthWest Province. Ten farmers from five villages with a total of 265 cows and 13 bulls were purposively selected. The selection criteria were that each farmer had to have a minimum of 10 breeding cows and a bull and be willing to participate in the study. This was followed by a 12-month longitudinal study with monthly herd visits where cows were examined rectally and bulls (n = 13 were subjected to a single breeding soundness evaluation. The calving percentage was found to be 37.7 %. This is lower than the recorded percentages for commercial beef cattle on extensive grazing. The factors playing a role in low calving percentage were ranked using field data. From this it appeared that failure of cows to become pregnant was the main cause of poor calving percentage as opposed of loss of calves through abortion or resorption. Sub-fertility of the bulls was found to be of great significance and it is proposed that this be included in extension messages and that bulls be fertility tested routinely. Poor body condition score of cows, mainly caused by poor management, was also considered to play a major role in reducing pregnancy rates. Infectious diseases like trichomonosis, campylobacteriosis and brucellosis played a much leser role than anticipated.

  7. Determinants of permanent first incisor eruption in grazing Australian Angora goats.

    McGregor, B A; Butler, K L

    2011-12-01

    To investigate the effects of live weight, sex and other factors on deciduous (first incisor) loss and permanent first incisor development in Angora goats. Goats were part of a pen study on the effects of energy intake in Angora does during pregnancy and lactation on kid growth and development. The design was three levels of nutrition in mid-pregnancy × two levels of postnatal nutrition in 17 randomised blocks. Conception times were calculated by using artificial insemination, with ultrasound examination 43 days after insemination. Does were fed different amounts of a formulated diet in their pens. After weaning, goats were grazed in sex groups. Deciduous first incisor loss and permanent first incisor development were recorded at 11 time points from 14 to 20 months of age. For each sex, the time for visible eruption and full development of permanent first incisor declined linearly with increased live weight by 5.9 and 5.4 days/kg live weight, respectively. The time to reach similar development stages for first permanent incisors eruption was 3 months longer for the lightest animals compared with the heaviest animals. Date of birth, birth weight, doe age, growth rates, mid-pregnancy and postnatal nutrition, parity, day of weaning and weaning weight had no detectable effect. The results explain much of the substantial range in reported first permanent incisor eruption dates for small ruminants and have application in ageing of goats, marketing of kids for meat, in the selection of animals for breeding flocks and in educational material. © 2011 The Authors. Australian Veterinary Journal © 2011 Australian Veterinary Association.

  8. Multiyear nutrient removal performance of three constructed wetlands intercepting tile drain flows from grazed pastures.

    Tanner, Chris C; Sukias, James P S

    2011-01-01

    Subsurface tile drain flows can be a major s ource of nurient loss from agricultural landscapes. This study quantifies flows and nitrogen and phosphorus yields from tile drains at three intensively grazed dairy pasture sites over 3- to 5-yr periods and evaluates the capacity of constructed wetlands occupying 0.66 to 1.6% of the drained catchments too reduce nutrient loads. Continuous flow records are combined with automated flow-proportional sampling of nutrient concentrations to calculate tile drain nutrient yields and wetland mass removal rates. Annual drainage water yields rangedfrom 193 to 564 mm (16-51% of rainfall) at two rain-fed sites and from 827 to 853 mm (43-51% of rainfall + irrigation) at an irrigated site. Annually, the tile drains exported 14 to 109 kg ha(-1) of total N (TN), of which 58 to 90% was nitrate-N. Constructed wetlands intercepting these flows removed 30 to 369 gTN m(-2) (7-63%) of influent loadings annually. Seasonal percentage nitrate-N and TN removal were negatively associated with wetland N mass loadings. Wetland P removal was poor in all wetlands, with 12 to 115% more total P exported annually overall than received. Annually, the tile drains exported 0.12 to 1.38 kg ha of total P, of which 15 to 93% was dissolved reactive P. Additional measures are required to reduce these losses or provide supplementary P removal. Wetland N removal performance could be improved by modifying drainage systems to release flows more gradually and improving irrigation practices to reduce drainage losses.

  9. Leaf economics spectrum-productivity relationships in intensively grazed pastures depend on dominant species identity.

    Mason, Norman W H; Orwin, Kate; Lambie, Suzanne; Woodward, Sharon L; McCready, Tiffany; Mudge, Paul

    2016-05-01

    Plant functional traits are thought to drive variation in primary productivity. However, there is a lack of work examining how dominant species identity affects trait-productivity relationships. The productivity of 12 pasture mixtures was determined in a 3-year field experiment. The mixtures were based on either the winter-active ryegrass (Lolium perenne) or winter-dormant tall fescue (Festuca arundinacea). Different mixtures were obtained by adding forb, legume, and grass species that differ in key leaf economics spectrum (LES) traits to the basic two-species dominant grass-white clover (Trifolium repens) mixtures. We tested for correlations between community-weighted mean (CWM) trait values, functional diversity, and productivity across all plots and within those based on either ryegrass or tall fescue. The winter-dormant forb species (chicory and plantain) had leaf traits consistent with high relative growth rates both per unit leaf area (high leaf thickness) and per unit leaf dry weight (low leaf dry matter content). Together, the two forb species achieved reasonable abundance when grown with either base grass (means of 36% and 53% of total biomass, respectively, with ryegrass tall fescue), but they competed much more strongly with tall fescue than with ryegrass. Consequently, they had a net negative impact on productivity when grown with tall fescue, and a net positive effect when grown with ryegrass. Strongly significant relationships between productivity and CWM values for LES traits were observed across ryegrass-based mixtures, but not across tall fescue-based mixtures. Functional diversity did not have a significant positive effect on productivity for any of the traits. The results show dominant species identity can strongly modify trait-productivity relationships in intensively grazed pastures. This was due to differences in the intensity of competition between dominant species and additional species, suggesting that resource-use complementarity is a

  10. Diet and cooling interactions on physiological responses of grazing dairy cows, milk production and composition

    Gallardo, M. R.; Valtorta, S. E.; Leva, P. E.; Gaggiotti, M. C.; Conti, G. A.; Gregoret, R. F.

    2005-11-01

    The objective of this trial was to evaluate the effects of diet and cooling in the holding pen before milking on rectal temperature, respiration rate and milk production and composition. Fifty-eight lactating Holstein cows were used in a factorial split-plot design, at Rafaela Experimental Station from 12 January to 3 March 2003. The treatments were combinations of two diets: control (CD) and balanced (BD) with two levels of cooling before milking: none (NSF) and a sprinkler and fans (SF). Forage:concentrate ratios for CD and BD were 81:19 and 68:32, respectively. Cows were milked twice daily. Milk production was recorded daily, and milk composition (fat, protein, lactose and urea) was analysed twice a week. The physiological data were recorded once a week, before the cattle entered the holding pen and after milking, in the afternoon. Average maximum weekly temperature humidity index was 75.4 and ranged from 61.4 to 83. There were highly significant effects of cooling on physiological responses. Milk production was affected by diet and cooling, with no interaction; the highest and lowest production of milk was 22.42 and 20.07 l/cow per day, for BD+SF and CD+NSF, respectively. Protein was affected by diet, and was higher for BD (3.17 vs. 3.08%). There were interaction effects on milk fat at the 8% level, the highest concentration being 3.65% for BD+NFS. It was concluded that under grazing conditions, cooling by sprinkler and fans before milking improves the comfort of dairy cows, and that the effects on milk production and composition are enhanced when diets are specially formulated for heat-stress periods.

  11. Optimum stocking rate for goat production on improved highland ...

    The effects of four stocking rates (SR; 7.5, 15, 30 and 45 goats ha-1) on goat performance and herbage productivity were examined on the perennial pastures. The experiment was applied by grazing 65 six-months old Chinese Yunling black goat wethers for two years. Significant year × SR interactions were observed on ...

  12. Effects of cultivar and grazing initiation date on fall-grown oat for replacement dairy heifers.

    Coblentz, W K; Brink, G E; Esser, N M; Cavadini, J S

    2015-09-01

    Fall-grown oat has shown promise for extending the grazing season in Wisconsin, but the optimum date for initiating grazing has not been evaluated. Our objectives for this project were (1) to assess the pasture productivity and nutritive value of 2 oat cultivars [Ogle and ForagePlus (OG and FP, respectively)] with late-September (EG) or mid-October (LG) grazing initiation dates; and (2) to evaluate growth performance by heifers grazing these oat forages compared with heifers reared in confinement (CON). A total of 160 gravid Holstein heifers (80 heifers/yr) were assigned to 10 research groups (8 heifers/group). Mean initial body weight was 509±40.5 kg in 2013 and 517±30.2 kg in 2014. Heifer groups were assigned to specific pastures arranged as a 2×2 factorial of oat cultivars and grazing initiation dates. Grazing heifer groups were allowed to strip-graze oat pastures for 6 h daily before returning to the barn, where they were offered a forage-based basal total mixed ration. Main effects of oat cultivar and sampling date interacted for forage characteristics in 2013, but not in 2014. During 2013, oat forage mass increased until early November before declining in response to freezing weather conditions, thereby exhibiting linear and quadratic effects of sampling date, regardless of oat cultivar. Similar trends over time were observed in 2014. For 2013, the maximum forage mass was 5,329 and 5,046 kg/ha for FP and OG, respectively, whereas the mean maximum forage mass for 2014 was 4,806 kg/ha. ForagePlus did not reach the boot stage of growth during either year of the trial; OG matured more rapidly, reaching the late-heading stage during 2013, but exhibited only minor maturity differences from FP in 2014. For 2013, average daily gain for CON did not differ from grazing heifer groups (overall mean=0.63 kg/d); however, average daily gain from FP was greater than OG (0.68 vs. 0.57 kg/d), and greater from EG compared with LG (0.82 vs. 0.43 kg/d). For 2013, advantages in

  13. Study of Plant Species Richness in Habitats with Different Grazing Intensities at Golestan National Park and Surrounding Area

    A. Bagheri

    2016-12-01

    Full Text Available Considering the importance of plant diversity and to evaluate the effect of grazing pressure on species richness and structure of plant communities, this experiment was conducted at Golestan National Park and its surrounding areas in the north east of Iran. Sampling was conducted in intact and abandoned habitats and habitats under seasonal and heavy grazing, using Modified Whitaker Plot in 1, 10,100 and 1000 m2 spatial scales. Results showed that the composition of plant species from different habitats was different. In addition the increasing intensity of grazing increased the importance of therophytes and decreased the role of hemicryptophytes and phanerophytes and also decreasd the amount of species richness. Mean species richness of studied habitat showed a significant difference in all four sampling spatial scales. The results showed that plant species richness decreased in the areas affected by heavy grazing and conservation against grazing plays an important role in maintaining species richness.

  14. How does grazing relate to body mass index, self-compassion, mindfulness and mindful eating in a student population?

    Mantzios, Michail; Egan, Helen; Bahia, Henna; Hussain, Misba; Keyte, Rebecca

    2018-01-01

    Contemporary research investigating obesity has focused on grazing (i.e. an uncontrolled and repetitive consumption of small amounts of food). Meanwhile, constructs such as mindfulness, mindful eating and self-compassion have received much attention in assisting individuals with eating behaviours and weight regulation. The association between those constructs and grazing, however, has not been explored. In a cross-sectional study, university students ( n  = 261) were recruited to explore the relationship of mindfulness, mindful eating and self-compassion with current weight and grazing. Results indicated that all constructs were negatively related to grazing, but only mindful eating related negatively to current weight. In addition, mindful eating mediated the relationship between grazing and current weight. Possible explanations and future directions are discussed further with an emphasis on the need for more empirical work.

  15. Increase in plasma total antioxidant capacity of grazing Japanese Black heifers and cows in forestland in Japan.

    Haga, Satoshi; Ishizaki, Hiroshi; Nakano, Miwa; Nakao, Seiji; Hirano, Kiyoshi; Yamamoto, Yoshito; Kitagawa, Miya; Sasaki, Hiroyuki; Kariya, Yoshihiro

    2014-02-01

    Blood total antioxidant capacity (TAC) has become a key bio-marker for animal health. Forest-grazing cattle are known to forage various native plants that have high TAC. This study evaluated differences of plasma TAC between forest-grazing (FG) and pasture-grazing cattle (PG). Experiment 1 monitored the plasma TAC levels of 32 Japanese Black cattle. The level in PG did not change throughout the grazing period. However, that in FG, which increased from summer, was significantly higher than that in PG through fall (P trees consumed by FG were higher than those in pasture grasses. Results of this study show that plasma TAC of grazing Japanese Black cattle in forestland increase from summer through fall. © 2013 Japanese Society of Animal Science.

  16. Grazing and climatic variability in Sajama National Park, Bolivia

    Yager, K.

    2008-12-01

    Full Text Available Sajama National Park, the first protected area in Bolivia, includes five indigenous communities with a primary production base of pastoralism. The semi-arid region of the Central Andes is one of the most extreme areas of human occupation at 4200 meters altitude and affected by high climatic variability. This paper studies the relations between climate variability, resilience, biodiversity of pastures and pastoral production in Sajama National Park. We present a botanical study of palatable pasture herbs between two years, one humid (2006 and the other dry (2007. Thirty vascular plants were recorded. The number of species and the cover of iro (Festuca ortophylla peak in areas of intermediate disturbance; areas that are at a medium distance from camelid corrals. On the other hand, the cover of ephemeral plants between tussocks increases in high disturbance areas. This is interpreted as a result of the tradeoff between the damage of grazing and the benefit of the fertilization produced by the herding animals. The local people clearly perceive strong impacts of climate change, combined with changes in management and human pressures. The social dynamics and production management, combined with climate warming, water reduction, and the increasing variability of surface water regimes create potential risks for the local sustainability of pastoralism.

    El Parque Nacional Sajama, la primer área protegida de Bolivia, incluye a cinco comunidades indígenas con una base de producción principalmente de ganadería. Esta región semi-árida de los Andes Centrales es una de las áreas más extremas de ocupación humana a 4200 metros de altura y es afectada por una alta variabilidad climática. Este trabajo considera las relaciones entre la variabilidad climática, resiliencia, biodiversidad de pastos y la producción ganadera en el Parque Nacional Sajama. Presentamos un estudio botánico de las comunidades de hierbas palatables a lo largo de dos a

  17. A Review of Protist Grazing Below the Photic Zone Emphasizing Studies of Oxygen-Depleted Water Columns and Recent Applications of In situ Approaches

    Virginia P. Edgcomb

    2017-04-01

    Full Text Available Little is still known of the impacts of protist grazing on bacterioplankton communities in the dark ocean. Furthermore, the accuracy of assessments of in situ microbial activities, including protist grazing, can be affected by sampling artifacts introduced during sample retrieval and downstream manipulations. Potential artifacts may be increased when working with deep-sea samples or samples from chemically unique water columns such as oxygen minimum zones (OMZs. OMZs are oxygen-depleted regions in the ocean, where oxygen concentrations can drop to <20 μM. These regions are typically located near eastern boundary upwelling systems and currently occur in waters occupying below about 8% of total ocean surface area, representing ~1% of the ocean's volume. OMZs have a profound impact not only on the distribution of marine Metazoa, but also on the composition and activities of microbial communities at the base of marine food webs. Here we present an overview of current knowledge of protist phagotrophy below the photic zone, emphasizing studies of oxygen-depleted waters and presenting results of the first attempt to implement new technology for conducting these incubation studies completely in situ (the Microbial Sampling- Submersible Incubation Device, MS-SID. We performed 24-h incubation experiments in the Eastern Tropical South Pacific (ETSP OMZ. This preliminary study shows that up to 28% of bacterial biomass may be consumed by protists in waters where oxygen concentrations were down to ~4.8 μM and up to 13% at a station with nitrite accumulation where oxygen concentrations were undetectable. Results also show that shipboard measurements of grazing rates were lower than rates measured from the same water using the MS-SID, suggesting that in situ experiments help to minimize artifacts that may be introduced when conducting incubation studies using waters collected from below the photic zone, particularly from oxygen-depleted regions of the water

  18. Allelopathic cover crop prior to seeding is more important than subsequent grazing/mowing in grassland establishment

    Milchunas, Daniel G.; Vandever, Mark W.; Ball, Leonard O.; Hyberg, Skip

    2011-01-01

    The effects of grazing, mowing, and type of cover crop were evaluated in a previous winter wheat–fallow cropland seeded to grassland under the Conservation Reserve Program in eastern Colorado. Prior to seeding, the fallow strips were planted to forage sorghum or wheat in alternating strips (cover crops), with no grazing, moderate to heavy grazing, and mowing (grazing treatments) superimposed 4 yr after planting and studied for 3 yr. Plots previously in wheat had more annual and exotic species than sorghum plots. Concomitantly, there were much greater abundances of perennial native grass and all native species in sorghum than wheat cropped areas. The competitive advantage gained by seeded species in sorghum plots resulted in large increases in rhizomatous western wheatgrass. Sorghum is known to be allelopathic and is used in crop agriculture rotations to suppress weeds and increase crop yields, consistent with the responses of weed and desired native species in this study. Grazing treatment had relatively minor effects on basal and canopy cover composition of annual or exotic species versus perennial native grass or native species. Although grazing treatment never was a significant main effect, it occasionally modified cover crop or year effects. Opportunistic grazing reduced exotic cheatgrass by year 3 but also decreased the native palatable western wheatgrass. Mowing was a less effective weed control practice than grazing. Vegetative basal cover and aboveground primary production varied primarily with year. Common management practices for revegetation/restoration currently use herbicides and mowing as weed control practices and restrict grazing in all stages of development. Results suggest that allelopathic cover crop selection and opportunistic grazing can be effective alternative grass establishment and weed control practices. Susceptibility, resistance, and interactions of weed and seeded species to allelopathic cover species/cultivars may be a fruitful area

  19. Signal grass structure at different sites of the same pasture under three grazing intensities - doi: 10.4025/actascianimsci.v35i1.11801

    Ronan Lopes Albino

    2013-01-01

    Full Text Available The experiment was conducted to evaluate Brachiaria decumbens cv. Basilisk at different sites of the same pasture featuring varying grazing intensities (under grazed, properly grazed and overgrazed. The pasture was managed under continuous stocking using 200-kg cattle and grass height kept at about 25 cm. The randomized block design was used, with three replications. Sward height (38.0 cm and extended plant height (85.2 cm were greater at the under grazed site. The falling index was lower at the properly grazed site (1.28. At the under grazed site, the masses of green leaf blade (3442 kg ha-1 DM, green stem (8370 kg ha-1 DM, green forage (11812 kg ha-1 DM and total forage (14137 kg ha-1 DM were higher when compared to the overgrazed and properly grazed sites. Dead material mass was higher at the properly grazed (3422 kg ha-1 DM and under grazed (2324 kg ha-1 DM sites. At the under grazed sites, there was a higher occurrence of tillers taller than 40 cm. Tillers with sizes between 10 and 30 cm predominated in properly grazed sites. In overgrazed site there was a higher share of tillers with sizes smaller than 20 cm. There is spatial variability of vegetation in the same pasture of Brachiaria decumbens cv. Basilisk due to uneven grazing by cattle.

  20. Linking sheep density and grazing frequency to persistence of herb species in an alpine environment

    Lanta, V.; Austrheim, G.; Evju, M.; Klimešová, Jitka; Mysterud, A.

    2014-01-01

    Roč. 29, č. 3 (2014), s. 411-420 ISSN 0912-3814 R&D Projects: GA ČR GA526/09/0963 Institutional support: RVO:67985939 Keywords : sheep grazing * alpine pastures * Norway Subject RIV: EH - Ecology, Behaviour Impact factor: 1.296, year: 2014

  1. supplementation of energy and/or protein to steers grazing summer ...

    Some aspects of the effect of supplementary energy and/or protein, strategically ptovided to steers on summer veld, were investi gated. 40 Friesland steers in the age ... was posed whether the strategic provision of energy and or protein to steers grazing .... Definitions and abbreviotions was determined after cooling for 24 h ...

  2. Cattle grazing in semiarid forestlands: Habitat selection during periods of drought

    C. L. Roever; T. DelCurto; M. Rowland; M. Vavra; M. Wisdom

    2015-01-01

    Climate change models are predicting increased frequency and severity of droughts in arid and semiarid environments, and these areas are responsible for much of the world’s livestock production. Because cattle (Bos Taurus) grazing can impact the abundance, distribution, and ecological function of native plant and animal communities, it is important...

  3. Taxonomical and functional diversity turnover in Mediterranean grasslands: interactions between grazing, habitat type and rainfall

    Carmona, C. P.; Azcárate, F. M.; de Bello, Francesco; Ollero, H. S.; Lepš, Jan; Peco, B.

    2012-01-01

    Roč. 49, č. 5 (2012), 1084-1093 ISSN 0021-8901 Institutional research plan: CEZ:AV0Z60050516; CEZ:AV0Z50070508 Institutional support: RVO:67985939 ; RVO:60077344 Keywords : Dehesa * diversity partitioning * functional redundancy * grazing management Subject RIV: EH - Ecology, Behaviour Impact factor: 4.740, year: 2012

  4. Technical Note: Daily variation in intake of a salt-limited supplement by grazing steers

    The objective of this research was to develop and test an automated supplement intake measurement system (SmartFeed, SF) in grazing trials. The SF was developed by C-lock Inc., (Rapid City, SD), and was designed using a stainless steel feed bin with load cells and an radio frequency identification ...

  5. Comparative aspects of ruminants and camels grazing on a thornbush savannah pasture

    Engelhardt, W. von; Rutagwenda, T.; Lechner-Doll, M.; Kaske, M.; Schultka, W.

    1989-01-01

    A factor limiting animal production in a savannah pasture is the ability of the animals to adapt and survive during the harsh dry season. Survival strategies for the various species are different. Compared to cattle and sheep, camels, and to a lesser extent goats, have the advantage of being able to select high quality plant species. Camels and goats compete very little for forage that is predominantly grazed by cattle, donkeys and sheep. As a result, camels and goats are less subject to the grazing pressures experienced by other animals. During the harsh dry season, cattle, and also sheep, eat mostly low quality forage. When doing this, they are able to increase the retention time of feed particles in the forestomach by increasing forestomach volume. This strategy allows the digestion of poor quality, fibre rich diets to be improved. Camels are superior because they are able to use two different strategies. When fed a very poor quality diet they selectively retain feed particles in the forestomach for a considerable length of time. When grazing in the thornbush savannah, on the other hand, they select medium or high quality plants, which are not used by cattle, donkeys and sheep and are only partly used by goats. A multispecies grazing system may help to improve livestock productivity on a semiarid pasture because the available plant biomass is utilized more efficiently. At the same time overgrazing and its consequences are diminished. (author). 11 refs

  6. Grazing supplementation and crop diversification on beef farm simulations in southern Brazil: a case study

    Economics and environmental footprints of beef cattle raised on natural pasture or combined with soybean in specific biomes are still not well evaluated. The objective of this research was to simulate and evaluate the economics of three common pastured beef grazing systems in southern Brazil along w...

  7. Nest survival of American Coots relative to grazing, burning, and water depths

    Austin, Jane E.; Buhl, Deborah A.

    2011-01-01

    Water and emergent vegetation are key features influencing nest site selection and success for many marsh-nesting waterbirds. Wetland management practices such as grazing, burning, and water-level manipulations directly affect these features and can influence nest survival. We used model selection and before-after-control-impact approaches to evaluate the effects of water depth and four common land-management practices or treatments, i.e., summer grazing, fall grazing, fall burning, and idle (no active treatment) on nest survival of American coots (Fulica americana) nesting at Grays Lake, a large montane wetland in southeast Idaho. The best model included the variables year × treatment, and quadratic functions of date, water depth, and nest age; height of vegetation at the nest did not improve the best model. However, results from the before-after-control-impact analysis indicate that management practices affected nest success via vegetation and involved interactions of hydrology, residual vegetation, and habitat composition. Nest success in idled fields changed little between pre- and post-treatment periods, whereas nest success declined in fields that were grazed or burned, with the most dramatic declines the year following treatments. The importance of water depth may be amplified in this wetland system because of rapid water-level withdrawal during the nesting season. Water and land-use values for area ranchers, management for nesting waterbirds, and long-term wetland function are important considerations in management of water levels and vegetation.

  8. Practices to Reduce Milk Carbon Footprint on Grazing Dairy Farms in Southern Uruguay: Case Studies.

    Carbon footprint (CF) is an increasingly relevant indicator to estimate the impact of a product on climate change. This study followed international guidelines to quantify the CF of milk produced on 24 dairy farms in Uruguay. Cows were grazed all year and supplemented with concentrate feeds. These d...

  9. Perennial ryegrass for dairy cows: effects of cultivar on herbage intake during grazing

    Smit, H.J.

    2005-01-01

    Keywords:Perennial ryegrass, Lolium perenne , sward morphology, sward cutting, n-alkanes, herbage intake, selection, preference.Perennial ryegrass ( Lolium perenne L.) is the most important species for feeding dairy cows. The majority of the farmers in the Netherlands graze their

  10. Regional Standards for Rangeland Health and Guidelines for Livestock Grazing Management ... A Progress Report

    1996-01-01

    In August 1995, new BLM regulations for rangeland administration went into effect. The new regulations require BLM to establish regional standards for rangeland health and guidelines for grazing management. This publication is a report on the alternatives being considered for the Montana/Dakotas Rangeland Health Standards and Guidelines process.

  11. Soil quality parameters for row-crop and grazed pasture systems with agroforestry buffers

    Incorporation of trees and establishment of buffers are practices that can improve soil quality. Soil enzyme activities and water stable aggregates are sensitive indices for assessing soil quality by detecting early changes in soil management. However, studies comparing grazed pasture and row crop...

  12. Grasshopper fecundity responses to grazing and fire in a tallgrass prairie.

    Laws, Angela N; Joern, Anthony

    2011-10-01

    Grasshopper abundance and diversity vary with management practices such as fire and grazing. Understanding how grasshopper life history traits such as fecundity respond to management practices is key to predicting grasshopper population dynamics in heterogeneous environments. Landscape-level experimental fire and bison grazing treatments at the Konza Prairie Biological Station (Manhattan, KS) provide an opportunity to examine how management affects grasshopper fecundity. Here we report on grasshopper fecundity for nine common species at Konza Prairie. From 2007 to 2009, adult female grasshoppers were collected every 3 wk from eight watersheds that varied in fire and grazing treatments. Fecundity was measured by examining female reproductive tracts, which contain a record of past and current reproductive activity. Body size was a poor predictor of fecundity for all species. Despite large differences in vegetation structure and composition with management regime (grazing and fire interval), we observed little effect of management on grasshopper fecundity. Habitat characteristics (grasshopper density, vegetation biomass, and vegetation quality; measured in 2008 and 2009) were better predictors of past fecundity than current fecundity, with species-specific responses. Fecundity increased throughout the summer, indicating that grasshoppers were able to acquire sufficient nutritional resources for egg production in the early fall when vegetation quality is generally low. Because fecundity did not vary across management treatments, population stage structure may be more important for determining population level reproduction than management regime at Konza Prairie.

  13. Milk urea concentration as an indicator of ammonia emission from dairy cow barn under restricted grazing

    Duinkerken, van G.; Smits, M.C.J.; Andre, G.; Sebek, L.B.J.; Dijkstra, J.

    2011-01-01

    Bulk milk urea concentration was evaluated to assess its potential as an indicator of ammonia emission from a dairy cow barn in a situation with restricted grazing. An experiment was carried out with a herd of, on average, 52 Holstein-Friesian dairy cows. The cows were housed in a naturally

  14. Evapotranspiration in winter wheat under different grazing and tillage practices in the southern Great Plains

    Precipitation in the Southern Great Plains (SGP) is highly variable both spatially and temporally with recurring periods of severe drought. Winter wheat (Triticum aestivum L.) – summer fallow system with conventional tillage is the principal dryland cropping system in this region for both grazing an...

  15. Simulating runoff from small grazed pasture watersheds located at North Appalachian Experimental Watershed in Ohio

    Runoff from grazing pasture lands can impact water quality in receiving streams if not well managed. Management consists of conservation practices to reduce runoff and pollutants transport. Simulation models have been effectively used to design and implement these conservation practices. The Agricul...

  16. Comparative Assessment of Goods and Services Provided by Grazing Regulation and Reforestation in Degraded Mediterranean Rangelands

    Papanastasis, Vasilios P.; Bautista, Susana; Chouvardas, Dimitrios; Mantzanas, Konstantinos; Papadimitriou, Maria; Garcia Mayor, Angeles; Koukioumi, Polina; Papaioannou, Athanasios; Vallejo, Ramon V.

    2017-01-01

    Several management actions are applied to restore ecosystem services in degraded Mediterranean rangelands, which range from adjusting the grazing pressure to the removal of grazers and pine plantations. Four such actions were assessed in Quercus coccifera L. shrublands in northern Greece: (i)

  17. Mesozooplankton production, grazing and respiration in the Bay of Bengal: Implications for net heterotrophy

    Fernandes, V.; Ramaiah, N.

    with the Arabian Sea. Contrary to the conventional belief, mesozooplankton grazing impact was up to 83% on primary production (PP). Low PP coupled with very high zooplankton production (70% of PP) along with abundant bacterial production (50% of the PP; Ramaiah et...

  18. Analysis of factors affecting milk yield of Ankole cows grazed on ...

    Effects of seasonal rainfall (RF) and maximum temperature (Tm) variations on milk yield of Ankole cows grazed solely on range pastures were investigated. The resulting changes in herbage growth (HG), herbage yields (HY), herbage crude protein CPh) and neutral detergent fibre (NDF), as well as body condition score ...

  19. Effects of herbivore grazing on the physiognomy of the coralline alga ...

    Effects of herbivore grazing on the physiognomy of the coralline alga Spongites yendoi and on associated competitive interactions. ... overlapping distributions between strongly interacting species along a broad geographical gradient is not just a significant feature of the ecology of terrestrial, but also of marine ecosystems.

  20. Effect of Grazing on Forage Quality and Quantity for Ungulates of ...

    This study examined the effect of grazing as simulated by clipping on forage quality and quantity in terms of above ground biomass, live, total production and nutrients content of forages utilized by ungulates of Kainji Lake National Park. Three 2.5m by 2.5m plots were constructed in the three main vegetation communities in ...