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Sample records for previous grazing experience

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

    African Journals Online (AJOL)

    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 ...

  2. Successive sheep grazing reduces population density of Brandt's voles in steppe grassland by altering food resources: a large manipulative experiment.

    Science.gov (United States)

    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.

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

    Science.gov (United States)

    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.

  4. Monitoring grazing intensity: an experiment with canopy spectra applied to satellite remote sensing

    Science.gov (United States)

    Li, Fei; Zhao, Ying; Zheng, Jiajia; Luo, Juhua; Zhang, Xiaoqiang

    2016-04-01

    The quantification of grassland grazing intensity (GI) and its detailed spatial distribution are important for grassland management and ecological protection. Remote sensing has great potential in these areas, but its use is still limited. This study analyzed the impacts of grazing on biophysical properties of vegetation and suggested using biomass to quantify GI because of its stability and interpretability. In comparison to a single spectral index, such as the red edge index (REI), combining REI and a cellulose absorption ratio index calculated from hyperspectral data performs better for biomass estimation. Further, an auxiliary spectral index, called the grazing monitoring index (GMI), was developed based on differences in spectral reflectance in the infrared range. Experiments in a grazing area of the Inner Mongolia grassland indicated that GMI can identify GI, with three range intervals (GMI blocks in the experimental grazing area. Overall, our study provides inspiration and ideas for using satellite remote sensing for evaluating plant production, standing biomass, and livestock impacts.

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

    DEFF Research Database (Denmark)

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

    2010-01-01

    sensors placed on the head of the cows, bite frequency was registered manually by noting the rip off sound during a specified time bout. Sward registrations comprised grass length measurement by rising plate meter , grass quality by laboratory analysis of hand harvested grass simulating the cows grazing...

  6. Multi-paddock grazing on rangelands: why the perceptual dichotomy between research results and rancher experience?

    Science.gov (United States)

    Teague, Richard; Provenza, Fred; Kreuter, Urs; Steffens, Tim; Barnes, Matt

    2013-10-15

    results reported by successful grazing managers; we highlight the shortcomings of most of the previously conducted grazing systems research for providing information relevant for rangeland managers who aim to achieve desired environmental and economic goals. Finally, we outline knowledge gaps and present testable hypotheses to broaden our understanding of how planned multi-paddock grazing management can be used at the ranching enterprise scale to facilitate the adaptive management of rangelands under dynamic environmental conditions. Copyright © 2013 Elsevier Ltd. All rights reserved.

  7. Specific Previous Experience Affects Perception of Harmony and Meter

    Science.gov (United States)

    Creel, Sarah C.

    2011-01-01

    Prior knowledge shapes our experiences, but which prior knowledge shapes which experiences? This question is addressed in the domain of music perception. Three experiments were used to determine whether listeners activate specific musical memories during music listening. Each experiment provided listeners with one of two musical contexts that was…

  8. The SSRL ultrahigh vacuum grazing incidence monochromator: design considerations and operating experience

    International Nuclear Information System (INIS)

    Brown, F.C.; Bachrach, R.Z.; Lien, N.

    1978-01-01

    Considerable experience has now accumulated with the 'grasshopper' monochromator installed on the four degree line at the Stanford Synchrotron Radiation Laboratory. This is one of the first bakeable high vacuum instruments for use with a storage ring source in the photon energy range 25 to 1000 eV. The unique features of this instrument will be discussed from a general point of view, including the source emittance and the transforming properties of the beam line plus monochromator. Actual performance figures will be given in order to better appraise the limits of focusing optics and gratings at two degree grazing incidence. Improvements such as post-monochromator optics, isolation valves and provisions for adjustment will be briefly discussed. (Auth.)

  9. Response of ecosystem CO2fluxes to grazing intensities - a five-year experiment in the Hulunber meadow steppe of China.

    Science.gov (United States)

    Yan, R R; Tang, H J; Lv, S H; Jin, D Y; Xin, X P; Chen, B R; Zhang, B H; Yan, Y C; Wang, X; Murray, Philip J; Yang, G X; Xu, L J; Li, L H; Zhao, S

    2017-08-25

    Grazing is the primary land use in the Hulunber meadow steppe. However, the quantitative effects of grazing on ecosystem carbon dioxide (CO 2 ) fluxes in this zone remain unclear. A controlled experiment was conducted from 2010 to 2014 to study the effects of six stocking rates on CO 2 flux, and the results showed that there were significant differences in CO 2 fluxes by year, treatment, and month. The effects of light and intermediate grazing remained relatively constant with grazing year, whereas the effects of heavy grazing increased substantially with grazing duration. CO 2 flux significantly decreased with increasing grazing intensity and duration, and it was significantly positively correlated with rainfall, soil moisture (SM), the carbon to nitrogen ratio (C/N ratio), soil available phosphorus (SAP), soil NH 4 + -N, soil NO 3 - N, aboveground biomass (AGB), coverage, height, and litter and negatively correlated with air temperature, total soil N (TN) and microbial biomass N (MBN). A correspondence analysis showed that the main factors influencing changes in CO 2 emissions under grazing were AGB, height, coverage, SM, NH 4 + -N and NO 3 - N. Increased rainfall and reduced grazing resulted in greater CO 2 emissions. Our study provides important information to improve our understanding of the role of livestock grazing in GHG emissions.

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

    Directory of Open Access Journals (Sweden)

    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.

  11. Carbon sink activity is stronger under grazing than under mowing: results from a paired eddy flux towers experiment

    Science.gov (United States)

    Pintér, Krisztina; Balogh, János; Koncz, Péter; Hidy, Dóra; Cserhalmi, Dóra; Papp, Marianna; Fóti, Szilvia; Nagy, Zoltán

    2014-05-01

    Effect of grazing vs. mowing on carbon balance of a grassland was investigated by a paired eddy towers (one of them measuring the grazed, the another the mowed treatment) experiment at the Bugacpuszta sandy grassland site (HU-Bug, 46.69° N, 19.6° E, 114m asl, 10.4 ° C annual mean temperature, 562 mm annual precipitation sum) located in the Hungarian Plain. Eddy covariance measurements started in July, 2002. The area of the mowed treatment is 1 ha, it is located within the grazed treatment (500 ha). Electric fence was set up around the selected area in spring of 2011. Study years include 2011, 2012 and 2013. The pasture is managed extensively (average grazing pressure of 0.5 cattle per hectare), the cattle herd regularly took several kilometres during a grazing day. Annual net ecosystem exchange (NEE) of the grassland is strongly limited by precipitation, there were 2 source years within the 11 years (2003-2013) of measurements, during which the average annual balance was -109 gCm-2year-1 with standard deviation of 106 gCm-2year-1. Carbon sink activity of the grassland was stronger in the grazed treatment than in the mowed treatment during the three year study period (paired t-test, P=0.058). In the grazed treatment the average sink strength was -142.8 ±40 gCm-2year-1, while in the mowed treatment the average sink strength was -61.5 ±46.5 gCm-2year-1. Differences of carbon balances between the treatments were positively correlated to the annual sum of evapotranspiration (ET), while ETs of the treatments were almost identical (differences within a 10mm year-1 range) in each study year. Water use efficiency in the mowed treatment was 44% of that in the grazed treatment (P=0.045) as a result of the differences in sink capacity. The higher sensitivity to drought by the mowed treatment manifested in decreased sink capacity during summer and in decreased regeneration capacity during autumn rains as shown by the cumulative NEE in the different years. Minor but

  12. Livestock grazing and trampling of birds' nests: An experiment using artificial nests

    OpenAIRE

    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...

  13. Phytoplankton growth and microzooplankton grazing dynamics across vertical environmental gradients determined by transplantin situdilution experiments.

    Science.gov (United States)

    Gutiérrez-Rodríguez, Andrés; Selph, Karen E; Landry, Michael R

    2016-03-01

    The Costa Rica Dome (CRD) represents a classic case of the bloom-forming capacity of small phytoplankton. Unlike other upwelling systems, autotrophic biomass in the CRD is dominated by picocyanobacteria and small eukaryotes that outcompete larger diatoms and reach extremely high biomass levels. We investigated responses of the subsurface phytoplankton community of the CRD to changes associated with vertical displacement of water masses, coupling in situ transplanted dilution experiments with flow cytometry and epifluorescence microscopy to assess group-specific dynamics. Growth rates of Synechococcus (SYN) and photosynthetic picoeukaryotes (PEUK) were positively correlated with light ( R pearson_SYN = 0.602 and R pearson_PEUK = 0.588, P grazing and growth rates were closely coupled in all picophytoplankton groups ( R spearman_PRO = 0.572, R spearman_SYN = 0.588, R spearman_PEUK = 0.624), and net growth rates remained close to zero. Conversely, the abundance and biomass of larger phytoplankton, mainly diatoms, increased more than 10-fold in shallower transplant incubations indicating that, in addition to trace-metal chemistry, light also plays a significant role in controlling microphytoplankton populations in the CRD.

  14. Spatial relationship with the grazing pressure and alpine grassland degradation base on the GPS tracing experiment: a case study in the source region of Yellow River

    Science.gov (United States)

    Liu, L.; Zhang, Y.

    2014-12-01

    It is hard to distinguish the affects from the human activities and climate change on the grassland degradation, especially to quantification the human activities. Grazing is the main kind of human activities on the alpine grassland. To investigate the relationship of the grazing activities and grassland degradation will help the understanding of the effects of human impacts. A GPS tracing experiment was designed to tracing the activities of the Yaks. The spatial distribution of the grazing pressure was simulated under Geographic Information System. The biomass distribution and grazing pressure was compared to judge the distribution of overgrazing. The main research results are: (1) The tracing experiment could record the track of the Yaks very well, and it could be a good tool for the quantification research of grazing pressure. (2) The grazing activities have good relationship with vegetation, residents and landform. The worse vegetation is, the grazing time is longer and the radius is bigger. The closer to the residents, the grazing intensive is higher. The grazing route is influenced by the landform. Usually the herds would like to choose the least cost way. And the grazing intensive is higher in sunny slope. (3) The grazing probability is higher while the elevation is lower and the vegetation is better. The numbers of livestock of different villages determine the spatial distribution of the grazing pressure but it has very big heterogeneity in the same village. It seems the forage is enough in the research area since the available biomass is about 1190058t and the total demand is only 603700t. But because of the heterogeneity of the grazing pressure, there are still overgrazing in some villages. The area of overgrazing is 6 percent in the winter rangeland and 11 percent in summer rangeland. It is important to take care of the spatial heterogeneity of the grazing pressure and grass production in the management of the grassland ecosystem. It should improve the

  15. Livestock grazing and trampling of birds' nests : An experiment using artificial nests

    NARCIS (Netherlands)

    Mandema, Freek S.; Tinbergen, Joost M.; Ens, Bruno J.; Bakker, Jan P.

    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

  16. Plant compensation to grazing and soil carbon dynamics in a tropical grassland.

    Science.gov (United States)

    Ritchie, Mark E

    2014-01-01

    The effects of grazing on soil organic carbon (SOC) dynamics, particularly in the tropics, are still poorly understood. Plant compensation to grazing, whereby plants maintain leaf area (C input capacity) despite consumption (C removal) by grazers, has been demonstrated in tropical grasslands but its influence on SOC is largely unexplored. Here, the effect of grazing on plant leaf area index (LAI) was measured in a field experiment in Serengeti National Park, Tanzania. LAI changed little for grazing intensities up to 70%. The response curve of LAI versus grazing intensity was used in a mass balance model, called SNAP, of SOC dynamics based on previous data from the Serengeti. The model predicted SOC to increase at intermediate grazing intensity, but then to decline rapidly at the highest grazing intensities. The SNAP model predictions were compared with observed SOC stocks in the 24 grazed plots of a 10-year grazing exclosure experiment at eight sites across the park that varied in mean annual rainfall, soil texture, grazing intensity and plant lignin and cellulose. The model predicted current SOC stocks very well (R (2) > 0.75), and suggests that compensatory plant responses to grazing are an important means of how herbivores might maintain or increase SOC in tropical grasslands.

  17. Analysis of previous perceptual and motor experience in breaststroke kick learning

    Directory of Open Access Journals (Sweden)

    Ried Bettina

    2015-12-01

    Full Text Available One of the variables that influence motor learning is the learner’s previous experience, which may provide perceptual and motor elements to be transferred to a novel motor skill. For swimming skills, several motor experiences may prove effective. Purpose. The aim was to analyse the influence of previous experience in playing in water, swimming lessons, and music or dance lessons on learning the breaststroke kick. Methods. The study involved 39 Physical Education students possessing basic swimming skills, but not the breaststroke, who performed 400 acquisition trials followed by 50 retention and 50 transfer trials, during which stroke index as well as rhythmic and spatial configuration indices were mapped, and answered a yes/no questionnaire regarding previous experience. Data were analysed by ANOVA (p = 0.05 and the effect size (Cohen’s d ≥0.8 indicating large effect size. Results. The whole sample improved their stroke index and spatial configuration index, but not their rhythmic configuration index. Although differences between groups were not significant, two types of experience showed large practical effects on learning: childhood water playing experience only showed major practically relevant positive effects, and no experience in any of the three fields hampered the learning process. Conclusions. The results point towards diverse impact of previous experience regarding rhythmic activities, swimming lessons, and especially with playing in water during childhood, on learning the breaststroke kick.

  18. Do emotional intelligence and previous caring experience influence student nurse performance? A comparative analysis.

    Science.gov (United States)

    Stenhouse, Rosie; Snowden, Austyn; Young, Jenny; Carver, Fiona; Carver, Hannah; Brown, Norrie

    2016-08-01

    Reports of poor nursing care have focused attention on values based selection of candidates onto nursing programmes. Values based selection lacks clarity and valid measures. Previous caring experience might lead to better care. Emotional intelligence (EI) might be associated with performance, is conceptualised and measurable. To examine the impact of 1) previous caring experience, 2) emotional intelligence 3) social connection scores on performance and retention in a cohort of first year nursing and midwifery students in Scotland. A longitudinal, quasi experimental design. Adult and mental health nursing, and midwifery programmes in a Scottish University. Adult, mental health and midwifery students (n=598) completed the Trait Emotional Intelligence Questionnaire-short form and Schutte's Emotional Intelligence Scale on entry to their programmes at a Scottish University, alongside demographic and previous caring experience data. Social connection was calculated from a subset of questions identified within the TEIQue-SF in a prior factor and Rasch analysis. Student performance was calculated as the mean mark across the year. Withdrawal data were gathered. 598 students completed baseline measures. 315 students declared previous caring experience, 277 not. An independent-samples t-test identified that those without previous caring experience scored higher on performance (57.33±11.38) than those with previous caring experience (54.87±11.19), a statistically significant difference of 2.47 (95% CI, 0.54 to 4.38), t(533)=2.52, p=.012. Emotional intelligence scores were not associated with performance. Social connection scores for those withdrawing (mean rank=249) and those remaining (mean rank=304.75) were statistically significantly different, U=15,300, z=-2.61, p$_amp_$lt;0.009. Previous caring experience led to worse performance in this cohort. Emotional intelligence was not a useful indicator of performance. Lower scores on the social connection factor were associated

  19. New tools for grazing incidence neutron scattering experiments open perspectives to study nano-scale tribology mechanisms

    Science.gov (United States)

    Frielinghaus, H.; Gvaramia, M.; Mangiapia, G.; Jaksch, S.; Ganeva, M.; Koutsioubas, A.; Mattauch, S.; Ohl, M.; Monkenbusch, M.; Holderer, O.

    2017-11-01

    Using grazing incidence scattering methods allows for depth profiling near surface structures very efficiently Dosch (1986). In parallel, layered structures have been used as resonators to enhance the wave field Kozhevnikov et al. (2007), Khaydukov et al. (2011), Kozhevnikov et al. (2011) and Nesnidal and Walker (1996) that directly increases the scattered intensity too. Third, the combination of these methods with neutron spin echo spectroscopy allows for near surface studies of dynamics Jaksch et al. (2015) and Frielinghaus et al. (2012) that can be correlated to tribological effects on the molecular level. This field of science, the tribology, - so far - has been driven mainly by the surface force balance that measures the macroscopic response of the system (latest research employs also AFM) Raviv et al. (2003) [1], Chung et al. (2016) [2] and Mocny and Klok (2016) [3]. The progress of this method was to reach the nano-scale distances that were necessary to obtain information about the friction of the nano-structures. The proposed method of grazing incidence neutron spin echo spectroscopy gives access to much more detailed information of molecular response to confinement by one or two hard walls, and therefore would pave the way for very rich and precise tribological comparisons of theory with experiments.

  20. Long- term effects of previous experience determine nutrient discrimination abilities in birds

    Directory of Open Access Journals (Sweden)

    Spitzer Kathrin

    2008-02-01

    Full Text Available Abstract Background Foraging behaviour is an essential ecological process linking different trophic levels. A central assumption of foraging theory is that food selection maximises the fitness of the consumer. It remains unknown, however, whether animals use innate or learned behaviour to discriminate food rewards. While many studies demonstrated that previous experience is a strong determinant of complex food choices such as diet mixing, the response to simple nutritional stimuli, such as sugar concentrations, is often believed to be innate. Results Here we show that previous experience determines the ability to track changes in sugar composition in same-aged individuals of a short-lived migratory songbird, the garden warbler (Sylvia borin. Although birds received identical foods for seven months prior to the experiment, wild-caught birds achieved higher sugar intake rates than hand-raised birds when confronted with alternative, differently coloured, novel food types. Hand-raised and wild birds did not differ in their initial colour selection or overall food intake, but wild birds were quicker to adjust food choice to varying sugar intake. Conclusion Over a period of at least seven months, broader previous experience translates into a higher plasticity of food choice leading to higher nutrient intake. Our results thus highlight the need to address previous long-term experience in foraging experiments. Furthermore, they show that hand-raised animals are often poor surrogates for testing the foraging behaviour of wild animals.

  1. Effects of cattle grazing on small mammal communities in the Hulunber meadow steppe.

    Science.gov (United States)

    Cao, Chan; Shuai, Ling-Ying; Xin, Xiao-Ping; Liu, Zhi-Tao; Song, Yan-Ling; Zeng, Zhi-Gao

    2016-01-01

    Small mammals play important roles in many ecosystems, and understanding their response to disturbances such as cattle grazing is fundamental for developing sustainable land use strategies. However, how small mammals respond to cattle grazing remains controversial. A potential cause is that most of previous studies adopt rather simple experimental designs based solely on the presence/absence of grazing, and are thus unable to detect any complex relationships between diversity and grazing intensity. In this study, we conducted manipulated experiments in the Hulunber meadow steppe to survey small mammal community structures under four levels of grazing intensities. We found dramatic changes in species composition in native small mammal communities when grazing intensity reached intermediate levels (0.46 animal unit/ha). As grazing intensity increased, Spermophilus dauricus gradually became the single dominant species. Species richness and diversity of small mammals in ungrazed and lightly grazed (0.23 animal unit/ha) area were much higher than in intermediately and heavily grazed area. We did not detect a humped relationship between small mammal diversity and disturbance levels predicted by the intermediate disturbance hypothesis (IDH). Our study highlighted the necessity of conducting manipulated experiments under multiple grazing intensities.

  2. Impact of vocational interests, previous academic experience, gender and age on Situational Judgement Test performance

    NARCIS (Netherlands)

    Schripsema, Nienke R.; Trigt, van Anke M.; Borleffs, Jan C. C.; Cohen-Schotanus, Janke

    Situational Judgement Tests (SJTs) are increasingly implemented in medical school admissions. In this paper, we investigate the effects of vocational interests, previous academic experience, gender and age on SJT performance. The SJT was part of the selection process for the Bachelor's degree

  3. Impact of Vocational Interests, Previous Academic Experience, Gender and Age on Situational Judgement Test Performance

    Science.gov (United States)

    Schripsema, Nienke R.; van Trigt, Anke M.; Borleffs, Jan C. C.; Cohen-Schotanus, Janke

    2017-01-01

    Situational Judgement Tests (SJTs) are increasingly implemented in medical school admissions. In this paper, we investigate the effects of vocational interests, previous academic experience, gender and age on SJT performance. The SJT was part of the selection process for the Bachelor's degree programme in Medicine at University of Groningen, the…

  4. Simulatedin vivoElectrophysiology Experiments Provide Previously Inaccessible Insights into Visual Physiology.

    Science.gov (United States)

    Quiroga, Maria; Price, Nicholas SC

    2016-01-01

    Lecture content and practical laboratory classes are ideally complementary. However, the types of experiments that have led to our detailed understanding of sensory neuroscience are often not amenable to classroom experimentation as they require expensive equipment, time-consuming surgeries, specialized experimental techniques, and the use of animals. While sometimes feasible in small group teaching, these experiments are not suitable for large cohorts of students. Previous attempts to expose students to sensory neuroscience experiments include: the use of electrophysiology preparations in invertebrates, data-driven simulations that do not replicate the experience of conducting an experiment, or simply observing an experiment in a research laboratory. We developed an online simulation of a visual neuroscience experiment in which extracellular recordings are made from a motion sensitive neuron. Students have control over stimulation parameters (direction and contrast) and can see and hear the action potential responses to stimuli as they are presented. The simulation provides an intuitive way for students to gain insight into neurophysiology, including experimental design, data collection and data analysis. Our simulation allows large cohorts of students to cost-effectively "experience" the results of animal research without ethical concerns, to be exposed to realistic data variability, and to develop their understanding of how sensory neuroscience experiments are conducted.

  5. Impact of Previous Pharmacy Work Experience on Pharmacy School Academic Performance

    Science.gov (United States)

    Mar, Ellena; T-L Tang, Terrill; Sasaki-Hill, Debra; Kuperberg, James R.; Knapp, Katherine

    2010-01-01

    Objectives To determine whether students' previous pharmacy-related work experience was associated with their pharmacy school performance (academic and clinical). Methods The following measures of student academic performance were examined: pharmacy grade point average (GPA), scores on cumulative high-stakes examinations, and advanced pharmacy practice experience (APPE) grades. The quantity and type of pharmacy-related work experience each student performed prior to matriculation was solicited through a student survey instrument. Survey responses were correlated with academic measures, and demographic-based stratified analyses were conducted. Results No significant difference in academic or clinical performance between those students with prior pharmacy experience and those without was identified. Subanalyses by work setting, position type, and substantial pharmacy work experience did not reveal any association with student performance. A relationship was found, however, between age and work experience, ie, older students tended to have more work experience than younger students. Conclusions Prior pharmacy work experience did not affect students' overall academic or clinical performance in pharmacy school. The lack of significant findings may have been due to the inherent practice limitations of nonpharmacist positions, changes in pharmacy education, and the limitations of survey responses. PMID:20498735

  6. Stress and blood donation: effects of music and previous donation experience.

    Science.gov (United States)

    Ferguson, E; Singh, A P; Cunningham-Snell, N

    1997-05-01

    Making a blood donation, especially for first-time donors, can be a stressful experience. These feelings of stress may inhibit donors from returning. This paper applies stress theory to this particular problem. The effects of a stress management intervention (the provision of music) and previous donor experience were examined in relation to pre- and post-donation mood, environmental appraisals and coping behaviour. Results indicated that the provision of music had detrimental effects on environmental appraisals for those who have donated up to two times previously, but beneficial effects for those who had donated three times before. These effects were, to an extent, moderated by coping processes but not perceived control. It is recommended that the provision of music is not used as a stress management technique in the context of blood donation.

  7. Important biological information uncovered in previously unaligned reads from chromatin immunoprecipitation experiments (ChIP-Seq)

    Science.gov (United States)

    Ouma, Wilberforce Zachary; Mejia-Guerra, Maria Katherine; Yilmaz, Alper; Pareja-Tobes, Pablo; Li, Wei; Doseff, Andrea I.; Grotewold, Erich

    2015-01-01

    Establishing the architecture of gene regulatory networks (GRNs) relies on chromatin immunoprecipitation followed by massively parallel sequencing (ChIP-Seq) methods that provide genome-wide transcription factor binding sites (TFBSs). ChIP-Seq furnishes millions of short reads that, after alignment, describe the genome-wide binding sites of a particular TF. However, in all organisms investigated an average of 40% of reads fail to align to the corresponding genome, with some datasets having as much as 80% of reads failing to align. We describe here the provenance of previously unaligned reads in ChIP-Seq experiments from animals and plants. We show that a substantial portion corresponds to sequences of bacterial and metazoan origin, irrespective of the ChIP-Seq chromatin source. Unforeseen was the finding that 30%–40% of unaligned reads were actually alignable. To validate these observations, we investigated the characteristics of the previously unaligned reads corresponding to TAL1, a human TF involved in lineage specification of hemopoietic cells. We show that, while unmapped ChIP-Seq read datasets contain foreign DNA sequences, additional TFBSs can be identified from the previously unaligned ChIP-Seq reads. Our results indicate that the re-evaluation of previously unaligned reads from ChIP-Seq experiments will significantly contribute to TF target identification and determination of emerging properties of GRNs. PMID:25727450

  8. Impact of vocational interests, previous academic experience, gender and age on Situational Judgement Test performance.

    Science.gov (United States)

    Schripsema, Nienke R; van Trigt, Anke M; Borleffs, Jan C C; Cohen-Schotanus, Janke

    2017-05-01

    Situational Judgement Tests (SJTs) are increasingly implemented in medical school admissions. In this paper, we investigate the effects of vocational interests, previous academic experience, gender and age on SJT performance. The SJT was part of the selection process for the Bachelor's degree programme in Medicine at University of Groningen, the Netherlands. All applicants for the academic year 2015-2016 were included and had to choose between learning communities Global Health (n = 126), Sustainable Care (n = 149), Intramural Care (n = 225), or Molecular Medicine (n = 116). This choice was used as a proxy for vocational interest. In addition, all graduate-entry applicants for academic year 2015-2016 (n = 213) were included to examine the effect of previous academic experience on performance. We used MANCOVA analyses with Bonferroni post hoc multiple comparisons tests for applicant performance on a six-scenario SJT. The MANCOVA analyses showed that for all scenarios, the independent variables were significantly related to performance (Pillai's Trace: 0.02-0.47, p performance on three scenarios (p performance on two scenarios (p performance, as was previous academic experience. Gender and age were related to performance on SJT scenarios in different settings. Especially the first effect might be helpful in selecting appropriate candidates for areas of health care in which more professionals are needed.

  9. "My math and me": Nursing students' previous experiences in learning mathematics.

    Science.gov (United States)

    Røykenes, Kari

    2016-01-01

    In this paper, 11 narratives about former experiences in learning of mathematics written by nursing students are thematically analyzed. Most students had a positive relationship with the subject in primary school, when they found mathematics fun and were able to master the subject. For some, a change occurred in the transition to lower secondary school. The reasons for this change was found in the subject (increased difficulty), the teachers (movement of teachers, numerous substitute teachers), the class environment and size (many pupils, noise), and the student him- or herself (silent and anonymous pupil). This change was also found in the transition from lower to higher secondary school. By contrast, some students had experienced changes that were positive, and their mathematics teacher was a significant factor in this positive change. The paper emphasizes the importance of previous experiences in learning mathematics to nursing students when learning about drug calculation. Copyright © 2015. Published by Elsevier Ltd.

  10. Patterns of plant selection by grazing cattle in two savanna ...

    African Journals Online (AJOL)

    Patterns of plant selection by grazing cattle in two savanna grasslands: A plant's eye view. ... African Journal of Range and Forage Science ... had been previously grazed generally had a greater influence on the amount a tuft was grazed during an individual grazing event than species identity, location or moribund material.

  11. Grazing damage to plants and gastropod and grasshopper densities in a CO 2-enrichment experiment on calcareous grassland

    Science.gov (United States)

    Ledergerber, Stephan; Thommen, G. Heinrich; Baur, Bruno

    Plant-herbivore interactions may change as atmospheric CO 2 concentrations continue to rise. We examined the effects of elevated atmospheric CO 2 and CO 2-exposure chambers on the grazing damage to plants, and on the abundances of potential herbivores (terrestrial gastropods and grasshoppers) in a calcareous grassland in the Jura mountains of Switzerland (village of Nenzlingen). Individuals of most plant species examined showed slight grazing damage. However, plots with CO 2 enrichment and plots with ambient atmosphere did not differ in the extent of grazing damage. Similarly, plots with CO 2 enrichment and plots with ambient atmosphere did not differ in either gastropod or grasshopper density. Experimental plots with and without chambers did not differ in the number of gastropods. However, the densities of gastropods and grasshoppers and extent of grazing damage to plants were generally lower in the experimental area than in the grassland outside the experimental field.

  12. Differences between previously married and never married 'gay' men: family background, childhood experiences and current attitudes.

    Science.gov (United States)

    Higgins, Daryl J

    2004-01-01

    Despite a large body of literature on the development of sexual orientation, little is known about why some gay men have been (or remain) married to a woman. In the current study, a self-selected sample of 43 never married gay men ('never married') and 26 gay men who were married to a woman ('previously married') completed a self-report questionnaire. Hypotheses were based on five possible explanations for gay men's marriages: (a) differences in sexual orientation (i.e., bisexuality); (b) internalized homophobia; (c) religious intolerance; (d) confusion created because of childhood/adolescent sexual experiences; and/or (e) poor psychological adjustment. Previously married described their families' religious beliefs as more fundamentalist than never married. No differences were found between married' and never married' ratings of their sexual orientation and identity, and levels of homophobia and self-depreciation. Family adaptability and family cohesion and the degree to which respondents reported having experienced child maltreatment did not distinguish between previously married and never married. The results highlight how little is understood of the reasons why gay men marry, and the need to develop an adequate theoretical model.

  13. Reciprocity, culture and human cooperation: previous insights and a new cross-cultural experiment.

    Science.gov (United States)

    Gächter, Simon; Herrmann, Benedikt

    2009-03-27

    Understanding the proximate and ultimate sources of human cooperation is a fundamental issue in all behavioural sciences. In this paper, we review the experimental evidence on how people solve cooperation problems. Existing studies show without doubt that direct and indirect reciprocity are important determinants of successful cooperation. We also discuss the insights from a large literature on the role of peer punishment in sustaining cooperation. The experiments demonstrate that many people are 'strong reciprocators' who are willing to cooperate and punish others even if there are no gains from future cooperation or any other reputational gains. We document this in new one-shot experiments, which we conducted in four cities in Russia and Switzerland. Our cross-cultural approach allows us furthermore to investigate how the cultural background influences strong reciprocity. Our results show that culture has a strong influence on positive and in especially strong negative reciprocity. In particular, we find large cross-cultural differences in 'antisocial punishment' of pro-social cooperators. Further cross-cultural research and experiments involving different socio-demographic groups document that the antisocial punishment is much more widespread than previously assumed. Understanding antisocial punishment is an important task for future research because antisocial punishment is a strong inhibitor of cooperation.

  14. The relationship of previous training and experience of journal peer reviewers to subsequent review quality.

    Directory of Open Access Journals (Sweden)

    Michael L Callaham

    2007-01-01

    Full Text Available BACKGROUND: Peer review is considered crucial to the selection and publication of quality science, but very little is known about the previous experiences and training that might identify high-quality peer reviewers. The reviewer selection processes of most journals, and thus the qualifications of their reviewers, are ill defined. More objective selection of peer reviewers might improve the journal peer review process and thus the quality of published science. METHODS AND FINDINGS: 306 experienced reviewers (71% of all those associated with a specialty journal completed a survey of past training and experiences postulated to improve peer review skills. Reviewers performed 2,856 reviews of 1,484 separate manuscripts during a four-year study period, all prospectively rated on a standardized quality scale by editors. Multivariable analysis revealed that most variables, including academic rank, formal training in critical appraisal or statistics, or status as principal investigator of a grant, failed to predict performance of higher-quality reviews. The only significant predictors of quality were working in a university-operated hospital versus other teaching environment and relative youth (under ten years of experience after finishing training. Being on an editorial board and doing formal grant (study section review were each predictors for only one of our two comparisons. However, the predictive power of all variables was weak. CONCLUSIONS: Our study confirms that there are no easily identifiable types of formal training or experience that predict reviewer performance. Skill in scientific peer review may be as ill defined and hard to impart as is "common sense." Without a better understanding of those skills, it seems unlikely journals and editors will be successful in systematically improving their selection of reviewers. This inability to predict performance makes it imperative that all but the smallest journals implement routine review ratings

  15. The Importance of Business Model Factors for Cloud Computing Adoption: Role of Previous Experiences

    Directory of Open Access Journals (Sweden)

    Bogataj Habjan Kristina

    2017-08-01

    Full Text Available Background and Purpose: Bringing several opportunities for more effective and efficient IT governance and service exploitation, cloud computing is expected to impact the European and global economies significantly. Market data show that despite many advantages and promised benefits the adoption of cloud computing is not as fast and widespread as foreseen. This situation shows the need for further exploration of the potentials of cloud computing and its implementation on the market. The purpose of this research was to identify individual business model factors with the highest impact on cloud computing adoption. In addition, the aim was to identify the differences in opinion regarding the importance of business model factors on cloud computing adoption according to companies’ previous experiences with cloud computing services.

  16. Sexual Liberalism-Conservatism: the effect of human values, gender, and previous sexual experience.

    Science.gov (United States)

    Guerra, Valeschka M; Gouveia, Valdiney V; Sousa, Deliane M; Lima, Tiago J; Freires, Leogildo A

    2012-08-01

    Despite theoretical associations, there is a lack of empirical studies on the axiological basis of sexual liberalism-conservatism. Two studies demonstrated important associations between these constructs for young adults. In Study 1, participants were 353 undergraduate students with a mean age of 20.13 (SD = 1.84), who completed the Sexual Liberalism-Conservatism Scale and the Basic Values Survey. In Study 2, participants were 269 undergraduate students, with a mean age of 20.3 (SD = 1.82), who completed a social desirability scale in addition to Study 1 instruments. Results showed how values can predict sexual liberalism-conservatism after controlling for social desirability. Attitudes towards one's own sexual behavior were more conservative whereas attitudes towards other's sexual behavior were more liberal. Gender was not a significant predictor of sexual attitudes whereas previous sexual experience showed a significant association to this construct. In general, results corroborated previous findings, showing that participants with a tendency to present socially desirable answers also tended to present themselves as sexually conservative.

  17. Decomposing experience-driven attention: opposite attentional effects of previously predictive cues

    Science.gov (United States)

    Lin, Zhicheng; Lu, Zhong-Lin; He, Sheng

    2016-01-01

    A central function of the brain is to track the dynamic statistical regularities in the environment—such as what predicts what over time. How does this statistical learning process alter sensory and attentional processes? Drawing upon animal conditioning and predictive coding, we developed a learning procedure that revealed two distinct components through which prior learning-experience controls attention. During learning, a visual search task was used in which the target randomly appeared at one of several locations but always inside an encloser of a particular color—the learned color served to direct attention to the target location. During test, the color no longer predicted the target location. When the same search task was used in the subsequent test, we found that the learned color continued to attract attention despite the behavior being counterproductive for the task and despite the presence of a completely predictive cue. However, when tested with a flanker task that had minimal location uncertainty—the target was at the fixation surrounded by a distractor—participants were better at ignoring distractors in the learned color than other colors. Evidently, previously predictive cues capture attention in the same search task but can be better suppressed in a flanker task. These results demonstrate opposing components—capture and inhibition—in experience-driven attention, with their manifestations crucially dependent on task context. We conclude that associative learning enhances context-sensitive top-down modulation while reduces bottom-up sensory drive and facilitates suppression, supporting a learning-based predictive coding account. PMID:27068051

  18. Do previous sports experiences influence the effect of an enrichment programme in basketball skills?

    Science.gov (United States)

    Santos, Sara; Mateus, Nuno; Sampaio, Jaime; Leite, Nuno

    2017-09-01

    The aim of this study was to examine the effect of an enrichment programme in motor, technical and tactical basketball skills, when accounting for the age of youth sport specialisation. Seventy-six college students (age: M = 20.4, SD = 1.9) were allocated according to three different paths: (i) non-structured (n = 14), (ii) early specialisation (n = 34), and (iii) late specialisation (n = 28), according to information previously provided by the participants about the quantity and type of sporting activities performed throughout their sporting careers. Then, the participants of each path were randomly distributed across control and experimental groups. Variables under study included agility, technical skills circuit, as well as tactical actions performed in a 4-on-4 full-court basketball game. The results indicated improvements in the early and late specialisation paths namely in the experimental training groups. However, the late specialisation path revealed larger benefits, in contrast with the non-structured path, which showed less sensitivity to the enrichment programme, mostly sustained in physical literacy and differential learning. Higher improvements were observed in agility, and also in reducing the number of unsuccessful actions performed during the game. Overall, this study provided evidence of how early sports experiences affect basketball skill acquisition and contribute to adapt to new contexts with motor and technical-tactical challenges. In addition, a path supported by late specialisation might present several advantages in sport performance achievement.

  19. TU-CD-BRD-01: Making Incident Learning Practical and Useful: Challenges and Previous Experiences

    International Nuclear Information System (INIS)

    Ezzell, G.

    2015-01-01

    It has long been standard practice in radiation oncology to report internally when a patient’s treatment has not gone as planned and to report events to regulatory agencies when legally required. Most potential errors are caught early and never affect the patient. Quality assurance steps routinely prevent errors from reaching the patient, and these “near misses” are much more frequent than treatment errors. A growing number of radiation oncology facilities have implemented incident learning systems to report and analyze both errors and near misses. Using the term “incident learning” instead of “event reporting” emphasizes the need to use these experiences to change the practice and make future errors less likely and promote an educational, non-punitive environment. There are challenges in making such a system practical and effective. Speakers from institutions of different sizes and practice environments will share their experiences on how to make such a system work and what benefits their clinics have accrued. Questions that will be addressed include: How to create a system that is easy for front line staff to access How to motivate staff to report How to promote the system as positive and educational and not punitive or demeaning How to organize the team for reviewing and responding to reports How to prioritize which reports to discuss in depth How not to dismiss the rest How to identify underlying causes How to design corrective actions and implement change How to develop useful statistics and analysis tools How to coordinate a departmental system with a larger risk management system How to do this without a dedicated quality manager Some speakers’ experience is with in-house systems and some will share experience with the AAPM/ASTRO national Radiation Oncology Incident Learning System (RO-ILS). Reports intended to be of value nationally need to be comprehensible to outsiders; examples of useful reports will be shown. There will be ample time set

  20. Effect of slug grazing on biomass production of a plant community during a short-term biodiversity experiment

    Czech Academy of Sciences Publication Activity Database

    Lanta, Vojtěch

    2007-01-01

    Roč. 32, - (2007), s. 145-151 ISSN 1146-609X R&D Projects: GA ČR GD206/03/H034 Institutional research plan: CEZ:AV0Z60050516 Keywords : biodiverzity * preference grazing * slug s Subject RIV: EF - Botanics Impact factor: 1.306, year: 2007

  1. Previous experience of family violence and intimate partner violence in pregnancy

    Directory of Open Access Journals (Sweden)

    Ana Bernarda Ludermir

    2017-09-01

    Full Text Available ABSTRACT OBJECTIVE To estimate differential associations between the exposure to violence in the family of origin and victimization and perpetration of intimate partner violence in pregnancy. METHODS A nested case-control study was carried out within a cohort study with 1,120 pregnant women aged 18–49 years old, who were registered in the Family Health Strategy of the city of Recife, State of Pernambuco, Brazil, between 2005 and 2006. The cases were the 233 women who reported intimate partner violence in pregnancy and the controls were the 499 women who did not report it. Partner violence in pregnancy and previous experiences of violence committed by parents or other family members were assessed with a standardized questionnaire. Multivariate logistic regression analyses were modeled to identify differential associations between the exposure to violence in the family of origin and victimization and perpetration of intimate partner violence in pregnancy. RESULTS Having seen the mother suffer intimate partner violence was associated with physical violence in childhood (OR = 2.62; 95%CI 1.89–3.63 and in adolescence (OR = 1.47; 95%CI 1.01–2.13, sexual violence in childhood (OR = 3.28; 95%CI 1.68–6.38 and intimate partner violence during pregnancy (OR = 1.47; 95% CI 1.01 – 2.12. The intimate partner violence during pregnancy was frequent in women who reported more episodes of physical violence in childhood (OR = 2.08; 95%CI 1.43–3.02 and adolescence (OR = 1.63; 95%CI 1.07–2.47, who suffered sexual violence in childhood (OR = 3.92; 95%CI 1.86–8.27, and who perpetrated violence against the partner (OR = 8.67; 95%CI 4.57–16.45. CONCLUSIONS Experiences of violence committed by parents or other family members emerge as strong risk factors for intimate partner violence in pregnancy. Identifying and understanding protective and risk factors for the emergence of intimate partner violence in pregnancy and its maintenance may help

  2. Previous experience of family violence and intimate partner violence in pregnancy.

    Science.gov (United States)

    Ludermir, Ana Bernarda; Araújo, Thália Velho Barreto de; Valongueiro, Sandra Alves; Muniz, Maria Luísa Corrêa; Silva, Elisabete Pereira

    2017-01-01

    To estimate differential associations between the exposure to violence in the family of origin and victimization and perpetration of intimate partner violence in pregnancy. A nested case-control study was carried out within a cohort study with 1,120 pregnant women aged 18-49 years old, who were registered in the Family Health Strategy of the city of Recife, State of Pernambuco, Brazil, between 2005 and 2006. The cases were the 233 women who reported intimate partner violence in pregnancy and the controls were the 499 women who did not report it. Partner violence in pregnancy and previous experiences of violence committed by parents or other family members were assessed with a standardized questionnaire. Multivariate logistic regression analyses were modeled to identify differential associations between the exposure to violence in the family of origin and victimization and perpetration of intimate partner violence in pregnancy. Having seen the mother suffer intimate partner violence was associated with physical violence in childhood (OR = 2.62; 95%CI 1.89-3.63) and in adolescence (OR = 1.47; 95%CI 1.01-2.13), sexual violence in childhood (OR = 3.28; 95%CI 1.68-6.38) and intimate partner violence during pregnancy (OR = 1.47; 95% CI 1.01 - 2.12). The intimate partner violence during pregnancy was frequent in women who reported more episodes of physical violence in childhood (OR = 2.08; 95%CI 1.43-3.02) and adolescence (OR = 1.63; 95%CI 1.07-2.47), who suffered sexual violence in childhood (OR = 3.92; 95%CI 1.86-8.27), and who perpetrated violence against the partner (OR = 8.67; 95%CI 4.57-16.45). Experiences of violence committed by parents or other family members emerge as strong risk factors for intimate partner violence in pregnancy. Identifying and understanding protective and risk factors for the emergence of intimate partner violence in pregnancy and its maintenance may help policymakers and health service managers to develop intervention strategies.

  3. The Impact of an International Cultural Experience on Previously Held Stereotypes by American Student Nurses.

    Science.gov (United States)

    Heuer, Loretta; Bengiamin, Marlene; Downey, Vicki Wessman

    2001-01-01

    Examined stereotypes held by U.S. student nurses before and after participating in an educational experience in Russia. The experience was intended to prepare them to be effective nurses in multicultural health care settings. Data from student interviews indicated that the experience changed students' stereotyped attitudes about Russian culture…

  4. Previous Experiences with Epilepsy and Effectiveness of Information to Change Public Perception of Epilepsy

    NARCIS (Netherlands)

    Gutteling, Jan M.; Seydel, E.R.; Wiegman, O.

    1986-01-01

    Differences with regard to the effectiveness of health information and attitude change are suggested between people with direct, behavioral experiences with a health topic and people with indirect, nonbehavioral experiences. The effects of three different methods of health education about epilepsy,

  5. Study of some physical aspects previous to design of an exponential experiment

    International Nuclear Information System (INIS)

    Caro, R.; Francisco, J. L. de

    1961-01-01

    This report presents the theoretical study of some physical aspects previous to the design of an exponential facility. The are: Fast and slow flux distribution in the multiplicative medium and in the thermal column, slowing down in the thermal column, geometrical distribution and minimum needed intensity of sources access channels and perturbations produced by possible variations in its position and intensity. (Author) 4 refs

  6. The Role of Previous Experience and Attitudes toward Statistics in Statistics Assessment Outcomes among Undergraduate Psychology Students

    Science.gov (United States)

    Dempster, Martin; McCorry, Noleen K.

    2009-01-01

    Previous research has demonstrated that students' cognitions about statistics are related to their performance in statistics assessments. The purpose of this research is to examine the nature of the relationships between undergraduate psychology students' previous experiences of maths, statistics and computing; their attitudes toward statistics;…

  7. Bevacizumab plus chemotherapy in elderly patients with previously untreated metastatic colorectal cancer: single center experience

    Directory of Open Access Journals (Sweden)

    Ocvirk Janja

    2016-06-01

    Full Text Available Metastatic colorectal cancer (mCRC is mainly a disease of elderly, however, geriatric population is underrepresented in clinical trials. Patient registries represent a tool to assess and follow treatment outcomes in this patient population. The aim of the study was with the help of the patients’ register to determine the safety and efficacy of bevacizumab plus chemotherapy in elderly patients who had previously untreated metastatic colorectal cancer.

  8. The Impact of Previous Online Course Experience RN Students' Perceptions of Quality

    Science.gov (United States)

    Hixon, Emily; Barczyk, Casimir; Ralston-Berg, Penny; Buckenmeyer, Janet

    2016-01-01

    The purpose of this paper is to explore whether experienced online students (who have completed seven or more online courses) perceive the quality of their courses differently than novice online students (who have completed three or fewer online courses) or students with an intermediate level of online course experience (those who have completed…

  9. Is the ability to perform transurethral resection of the prostate influenced by the surgeon's previous experience?

    Directory of Open Access Journals (Sweden)

    José Cury

    2008-01-01

    Full Text Available PURPOSE: To evaluate the influence of the urologist's experience on the surgical results and complications of transurethral resection of the prostate (TURP. PATIENTS AND METHODS: Sixty-seven patients undergoing transurethral resection of the prostate without the use of a video camera were randomly allocated into three groups according to the urologist's experience: a urologist having done 25 transurethral resections of the prostate (Group I - 24 patients; a urologist having done 50 transurethral resections of the prostate (Group II - 24 patients; a senior urologist with vast transurethral resection of the prostate experience (Group III - 19 patients. The following were recorded: the weight of resected tissue, the duration of the resection procedure, the volume of irrigation used, the amount of irrigation absorbed and the hemoglobin and sodium levels in the serum during the procedure. RESULTS: There were no differences between the groups in the amount of irrigation fluid used per operation, the amount of irrigation fluid absorbed or hematocrit and hemoglobin variation during the procedure. The weight of resected tissue per minute was approximately four times higher in group III than in groups I and II. The mean absorbed irrigation fluid was similar between the groups, with no statistical difference between them (p=0.24. Four patients (6% presented with TUR syndrome, without a significant difference between the groups. CONCLUSION: The senior urologist was capable of resecting four times more tissue per time unit than the more inexperienced surgeons. Therefore, a surgeon's experience may be important to reduce the risk of secondary TURP due to recurring adenomas or adenomas that were incompletely resected. However, the incidence of complications was the same between the three groups.

  10. [A brief history of resuscitation - the influence of previous experience on modern techniques and methods].

    Science.gov (United States)

    Kucmin, Tomasz; Płowaś-Goral, Małgorzata; Nogalski, Adam

    2015-02-01

    Cardiopulmonary resuscitation (CPR) is relatively novel branch of medical science, however first descriptions of mouth-to-mouth ventilation are to be found in the Bible and literature is full of descriptions of different resuscitation methods - from flagellation and ventilation with bellows through hanging the victims upside down and compressing the chest in order to stimulate ventilation to rectal fumigation with tobacco smoke. The modern history of CPR starts with Kouwenhoven et al. who in 1960 published a paper regarding heart massage through chest compressions. Shortly after that in 1961Peter Safar presented a paradigm promoting opening the airway, performing rescue breaths and chest compressions. First CPR guidelines were published in 1966. Since that time guidelines were modified and improved numerously by two leading world expert organizations ERC (European Resuscitation Council) and AHA (American Heart Association) and published in a new version every 5 years. Currently 2010 guidelines should be obliged. In this paper authors made an attempt to present history of development of resuscitation techniques and methods and assess the influence of previous lifesaving methods on nowadays technologies, equipment and guidelines which allow to help those women and men whose life is in danger due to sudden cardiac arrest. © 2015 MEDPRESS.

  11. Quantification of radular marks as a method for estimating grazing of intertidal gastropods on rocky shores.

    Science.gov (United States)

    Forrest, R E.; Chapman, M G.; Underwood, A J.

    2001-04-15

    Wax discs have been used previously on intertidal rocky shores to record the grazing activity of gastropods. This study has evaluated this methodology for recording grazing of four common intertidal microalgal grazers on intertidal shores in New South Wales, Australia. In the laboratory, the four species examined-the patellid limpet, Cellana tramoserica (Sowerby), the trochid, Austrocochlea porcata (A. Adams), the neritid, Nerita atramentosa Reeve and the littorinid, Bembicium nanum (Lamarck)-made distinctive marks in the wax. These allowed identification of each species or combinations of species grazing over the different discs. Field experiments showed that the intensity of grazing, as indicated by the mean number of scratches per disc, was positively related to the number of gastropods in the surrounding area during low tide for C. tramoserica. The number of scratches per disc in any area was correlated with the percentage of discs scratched. The relationship for C. tramoserica was found at two scales-in sites (approximately 3x3 m) and also in plots (50x50 cm) within sites. Therefore, densities that were measured when these limpets were inactive during low tide provided good estimates of grazing activity during high tide. This is largely because these limpets do not move far between where they rest and where they feed. The amount of microalgal food in the vicinity was not correlated with density, nor with grazing intensity. No relationship between density and grazing intensity was found for N. atramentosa, although experiments were only done in the field at one spatial scale (in sites, 3x3 m). Results obtained in the laboratory and in the field show that wax discs are useful to distinguish grazing by different species of gastropods on Australian rocky shores and allow tests of hypotheses about grazing activity at different spatial scales.

  12. The role of previous experience and attitudes toward statistics in statistics assessment outcomes among undergraduate psychology students

    OpenAIRE

    Dempster, Martin; McCorry, Noleen

    2009-01-01

    Previous research has demonstrated that students’ cognitions about statistics are related to their performance in statistics assessments. The purpose of this research is to examine the nature of the relationships between undergraduate psychology students’ previous experiences of maths, statistics and computing; their attitudes toward statistics; and assessment on a statistics course. Of the variables examined, the strongest predictor of assessment outcome was students’ attitude about their in...

  13. Bevacizumab plus chemotherapy in elderly patients with previously untreated metastatic colorectal cancer: single center experience

    International Nuclear Information System (INIS)

    Ocvirk, Janja; Moltara, Maja Ebert; Mesti, Tanja; Boc, Marko; Rebersek, Martina; Volk, Neva; Benedik, Jernej; Hlebanja, Zvezdana

    2016-01-01

    Metastatic colorectal cancer (mCRC) is mainly a disease of elderly, however, geriatric population is underrepresented in clinical trials. Patient registries represent a tool to assess and follow treatment outcomes in this patient population. The aim of the study was with the help of the patients’ register to determine the safety and efficacy of bevacizumab plus chemotherapy in elderly patients who had previously untreated metastatic colorectal cancer. The registry of patients with mCRC was designed to prospectively evaluate the safety and efficacy of bevacizumab-containing chemotherapy as well as selection of patients in routine clinical practice. Patient baseline clinical characteristics, pre-specified bevacizumab-related adverse events, and efficacy data were collected, evaluated and compared according to the age categories. Between January 2008 and December 2010, 210 patients with mCRC (median age 63, male 61.4%) started bevacizumab-containing therapy in the 1 st line setting. Majority of the 210 patients received irinotecan-based chemotherapy (68%) as 1 st line treatment and 105 patients (50%) received bevacizumab maintenance therapy. Elderly (≥ 70 years) patients presented 22.9% of all patients and they had worse performance status (PS 1/2, 62.4%) than patients in < 70 years group (PS 1/2, 35.8%). Difference in disease control rate was mainly due to inability to assess response in elderly group (64.6% in elderly and 77.8% in < 70 years group, p = 0.066). The median progression free survival was 10.2 (95% CI, 6.7–16.2) and 11.3 (95% CI, 10.2–12.6) months in elderly and < 70 years group, respectively (p = 0.58). The median overall survival was 18.5 (95% CI, 12.4–28.9) and 27.4 (95% CI, 22.7–31.9) months for elderly and < 70 years group, respectively (p = 0.03). Three-year survival rate was 26% and 37.6% in elderly vs. < 70 years group (p = 0.03). Overall rates of bevacizumab-related adverse events were similar in both groups: proteinuria 21

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

    African Journals Online (AJOL)

    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 ...

  15. The relationship between emotional intelligence, previous caring experience and successful completion of a pre-registration nursing/midwifery degree.

    Science.gov (United States)

    Snowden, Austyn; Stenhouse, Rosie; Duers, Lorraine; Marshall, Sarah; Carver, Fiona; Brown, Norrie; Young, Jenny

    2018-02-01

    To examine the relationship between baseline emotional intelligence and prior caring experience with completion of pre-registration nurse and midwifery education. Selection and retention of nursing students is a global challenge. Emotional intelligence is well-conceptualized, measurable and an intuitive prerequisite to nursing values and so might be a useful selection criterion. Previous caring experience may also be associated with successful completion of nurse training. Prospective longitudinal study. Self-report trait and ability emotional intelligence scores were obtained from 876 student nurses from two Scottish Universities before they began training in 2013. Data on previous caring experience were recorded. Relationships between these metrics and successful completion of the course were calculated in SPSS version 23. Nurses completing their programme scored significantly higher on trait emotional intelligence than those that did not complete their programme. Nurses completing their programme also scored significantly higher on social connection scores than those that did not. There was no relationship between "ability" emotional intelligence and completion. Previous caring experience was not statistically significantly related to completion. Students with higher baseline trait emotional intelligence scores were statistically more likely to complete training than those with lower scores. This relationship also held using "Social connection" scores. At best, previous caring experience made no difference to students' chances of completing training. Caution is urged when interpreting these results because the headline findings mask considerable heterogeneity. Neither previous caring experience or global emotional intelligence measures should be used in isolation to recruit nurses. © 2017 The Authors. Journal of Advanced Nursing Published by John Wiley & Sons Ltd.

  16. Previous International Experience, Cross-Cultural Training, and Expatriates' Cross-Cultural Adjustment: Effects of Cultural Intelligence and Goal Orientation

    Science.gov (United States)

    Koo Moon, Hyoung; Kwon Choi, Byoung; Shik Jung, Jae

    2012-01-01

    Although various antecedents of expatriates' cross-cultural adjustment have been addressed, previous international experience, predeparture cross-cultural training, and cultural intelligence (CQ) have been most frequently examined. However, there are few attempts that explore the effects of these antecedents simultaneously or consider the possible…

  17. Pain related to mandibular block injections and its relationship with anxiety and previous experiences with dental anesthetics

    NARCIS (Netherlands)

    van Wijk, A.; Lindeboom, J.A.; de Jongh, A.; Tuk, J.G.; Hoogstraten, J.

    2012-01-01

    Objective. Anesthetic injections should reassure patients with the prospect of painless treatment, but for some patients it is the main source of their fear. We investigated pain resulting from mandibular block injections in relation to anxiety and previous experience with receiving injections.

  18. The Effect of Previous Co-Worker Experience on the Survival of Knowledge Intensive Start-Ups

    DEFF Research Database (Denmark)

    Timmermans, Bram

    The aim of the paper is to investigate the effect of previous co-worker experience on the survival of knowledge intensive start-ups. For the empirical analysis I use the Danish Integrated Database of Labor Market Research (IDA). This longitudinal employer-employee database allows me to identify co-worker...... experience among all members of the firm. In addition, I will make a distinction between ordinary start-ups and entrepreneurial spin-offs. The results show that previous co-worker experience has a positive effect on new firm survival. This effect appears to be valid predominantly for ordinary start-ups than...

  19. The relationship between emotional intelligence, previous caring experience and mindfulness in student nurses and midwives: a cross sectional analysis.

    Science.gov (United States)

    Snowden, Austyn; Stenhouse, Rosie; Young, Jenny; Carver, Hannah; Carver, Fiona; Brown, Norrie

    2015-01-01

    Emotional Intelligence (EI), previous caring experience and mindfulness training may have a positive impact on nurse education. More evidence is needed to support the use of these variables in nurse recruitment and retention. To explore the relationship between EI, gender, age, programme of study, previous caring experience and mindfulness training. Cross sectional element of longitudinal study. 938year one nursing, midwifery and computing students at two Scottish Higher Education Institutes (HEIs) who entered their programme in September 2013. Participants completed a measure of 'trait' EI: Trait Emotional Intelligence Questionnaire Short Form (TEIQue-SF); and 'ability' EI: Schutte's et al. (1998) Emotional Intelligence Scale (SEIS). Demographics, previous caring experience and previous training in mindfulness were recorded. Relationships between variables were tested using non-parametric tests. Emotional intelligence increased with age on both measures of EI [TEIQ-SF H(5)=15.157 p=0.001; SEIS H(5)=11.388, p=0.044]. Females (n=786) scored higher than males (n=149) on both measures [TEIQ-SF, U=44,931, z=-4.509, pintelligence. Mindfulness training was associated with higher 'ability' emotional intelligence. Implications for recruitment, retention and further research are explored. Copyright © 2014. Published by Elsevier Ltd.

  20. Previous experiences and emotional baggage as barriers to lifestyle change - a qualitative study of Norwegian Healthy Life Centre participants.

    Science.gov (United States)

    Følling, Ingrid S; Solbjør, Marit; Helvik, Anne-S

    2015-06-23

    Changing lifestyle is challenging and difficult. The Norwegian Directorate of Health recommends that all municipalities establish Healthy Life Centres targeted to people with lifestyle issues. Little is known about the background, experiences and reflections of participants. More information is needed about participants to shape effective lifestyle interventions with lasting effect. This study explores how participants in a lifestyle intervention programme describe previous life experiences in relation to changing lifestyle. Semi-structured qualitative in-depth interviews were performed with 23 participants (16 women and 7 men) aged 18 - 70 years. The data were analysed using systematic text condensation searching for issues describing participants' responses, and looking for the essence, aiming to share the basis of life-world experiences as valid knowledge. Participants identified two main themes: being stuck in old habits, and being burdened with emotional baggage from their previous negative experiences. Participants expressed a wish to change their lifestyles, but were unable to act in accordance with the health knowledge they possessed. Previous experiences with lifestyle change kept them from initiating attempts without professional assistance. Participants also described being burdened by an emotional baggage with problems from childhood and/or with family, work and social life issues. Respondents said that they felt that emotional baggage was an important explanation for why they were stuck in old habits and that conversely, being stuck in old habits added load to their already emotional baggage and made it heavier. Behavioural change can be hard to perform as psychological distress from life baggage can influence the ability to change. The study participants' experience of being stuck in old habits and having substantial emotional baggage raises questions as to whether or not Healthy Life Centres are able to help participants who need to make a lifestyle

  1. Grazing and grazing management terminology in Southern Africa ...

    African Journals Online (AJOL)

    The former group includes veld, fynbos, karoo, grassveld, bushveld, sourveld. sweetveld, pastures, leys, permanent pastures, cultivated pastures, introduced pastures, species selective grazing, area selective grazing, grazing capacity, current grazing capacity and potential grazing capacity. Some of these terms are well ...

  2. Relationship between premature loss of primary teeth with oral hygiene, consumption of soft drinks, dental care, and previous caries experience.

    Science.gov (United States)

    López-Gómez, Sandra Aremy; Villalobos-Rodelo, Juan José; Ávila-Burgos, Leticia; Casanova-Rosado, Juan Fernando; Vallejos-Sánchez, Ana Alicia; Lucas-Rincón, Salvador Eduardo; Patiño-Marín, Nuria; Medina-Solís, Carlo Eduardo

    2016-02-26

    We determine the relationship between premature loss of primary teeth and oral hygiene, consumption of soft drinks, dental care and previous caries experience. This study focused on 833 Mexican schoolchildren aged 6-7. We performed an oral examination to determine caries experience and the simplified oral hygiene index. The dependent variable was the prevalence of at least one missing tooth (or indicated for extraction) of the primary dentition; this variable was coded as 0 = no loss of teeth and 1 = at least one lost primary tooth. The prevalence of at least one missing tooth was 24.7% (n = 206) (95% CI = 21.8-27.7). The variables that were associated with the prevalence of tooth loss (p oral hygiene (OR = 3.24), a lower frequency of brushing (OR = 1.60), an increased consumption of soda (OR = 1.89) and use of dental care (curative: OR = 2.83, preventive: OR = 1.93). This study suggests that the premature loss of teeth in the primary dentition is associated with oral hygiene, consumption of soft drinks, dental care and previous caries experience in Mexican schoolchildren. These data provide relevant information for the design of preventive dentistry programs.

  3. A 20-year experience with liver transplantation for polycystic liver disease: does previous palliative surgical intervention affect outcomes?

    Science.gov (United States)

    Baber, John T; Hiatt, Jonathan R; Busuttil, Ronald W; Agopian, Vatche G

    2014-10-01

    Although it is the only curative treatment for polycystic liver disease (PLD), orthotopic liver transplantation (OLT) has been reserved for severely symptomatic, malnourished, or refractory patients who are not candidates for palliative disease-directed interventions (DDI). Data on the effect of previous DDIs on post-transplant morbidity and mortality are scarce. We analyzed the outcomes after OLT for PLD recipients, and determined the effects of previous palliative surgical intervention on post-transplantation morbidity and mortality. We performed a retrospective analysis of factors affecting perioperative outcomes after OLT for PLD between 1992 and 2013, including comparisons of recipients with previous major open DDIs (Open DDI, n = 12) with recipients with minimally invasive or no previous DDIs (minimal DDI, n = 16). Over the 20-year period, 28 recipients underwent OLT for PLD, with overall 30-day, 1-, and 5-year graft and patient survivals of 96%, 89%, 75%, and 96%, 93%, 79%, respectively. Compared with the minimal DDI group, open DDI recipients accounted for all 5 deaths, had inferior 90-day and 1- and 5-year survivals (83%, 83%, and 48% vs 100%, 100%, 100%; p = 0.009), and greater intraoperative (42% vs 0%; p = 0.003), total (58% vs 19%; p = 0.031), and Clavien grade IV or greater (50% vs 6%; p = 0.007) postoperative complications, more unplanned reoperations (50% vs 13%; p = 0.003), and longer total hospital (27 days vs 17 days; p = 0.035) and ICU (10 days vs 4 days; p = 0.045) stays. In one of the largest single-institution experiences of OLT for PLD, we report excellent long-term graft and patient survival. Previous open DDIs are associated with increased risks of perioperative morbidity and mortality. Improved identification of PLD patients bound for OLT may mitigate perioperative complications and potentially improve post-transplantation outcomes. Copyright © 2014 American College of Surgeons. Published by Elsevier Inc. All rights reserved.

  4. Effect of alternate and simultaneous grazing on endoparasite infection in sheep and cattle

    OpenAIRE

    Brito, Daiana Lima; Dallago, Bruno Stéfano Lima; Louvandini, Helder; Santos, Viviane Rodrigues Verdolin dos; Torres, Sonia Emília Figueirêdo de Araújo; Gomes, Edgard Franco; Amarante, Alessandro Francisco Talamini do; Melo, Cristiano Barros de; McManus, Concepta Margaret

    2013-01-01

    This experiment was carried out on 8 ha of Panicum maximum cv. Tanzania pastures, with rotational grazing consisting of 7 days of occupation and 21 days of rest. Four treatments were evaluated: cattle grazing alone (BOV), sheep grazing alone (OVI), cattle and sheep grazing simultaneously (SIM) and cattle grazing followed by sheep (alternate - ALT). Twenty heifers and 30 male Santa Inês lambs were used. Fecal egg count (FEC) and fecal cultures were carried out. Blood was also collected to exam...

  5. Birds bias offspring sex ratio in response to livestock grazing.

    Science.gov (United States)

    Prior, Gina L; Evans, Darren M; Redpath, Stephen; Thirgood, Simon J; Monaghan, Pat

    2011-12-23

    Livestock grazing, which has a large influence on habitat structure, is associated with the widespread decline of various bird species across the world, yet there are few experimental studies that investigate how grazing pressure influences avian reproduction. We manipulated grazing pressure using a replicated field experiment, and found that the offspring sex ratio of a common upland passerine, the meadow pipit Anthus pratensis, varied significantly between grazing treatments. The proportion of sons was lowest in the ungrazed and intensively grazed treatments and highest in treatments grazed at low intensity (by sheep, or a mixture of sheep and cattle). This response was not related to maternal body condition. These results demonstrate the sensitivity of avian reproductive biology to variation in local conditions, and support growing evidence that too much grazing, or the complete removal of livestock from upland areas, is detrimental for common breeding birds.

  6. Does Previous Experience of Floods Stimulate the Adoption of Coping Strategies? Evidence from Cross Sectional Surveys in Nigeria and Tanzania

    Directory of Open Access Journals (Sweden)

    Sheila A. Boamah

    2015-11-01

    Full Text Available In sub-Saharan Africa, hydro-meteorological related disasters, such as floods, account for the majority of the total number of natural disasters. Over the past century, floods have affected 38 million people, claimed several lives and caused substantial economic losses in the region. The goal of this paper is to examine how personality disposition, social network, and socio-demographic factors mitigate the complex relationship between stressful life experiences of floods and ocean surges and the adoption of coping strategies among coastal communities in Nigeria and Tanzania. Generalized linear models (GLM were fitted to cross-sectional survey data on 1003 and 1253 individuals in three contiguous coastal areas in Nigeria and Tanzania, respectively. Marked differences in the type of coping strategies were observed across the two countries. In Tanzania, the zero-order relationships between adoption of coping strategies and age, employment and income disappeared at the multivariate level. Only experience of floods in the past year and social network resources were significant predictors of participants’ adoption of coping strategies, unlike in Nigeria, where a plethora of factors such as experience of ocean surges in the past one year, personality disposition, age, education, experience of flood in the past one year, ethnicity, income, housing quality and employment status were still statistically significant at the multivariate level. Our findings suggest that influence of previous experience on adoption of coping strategies is spatially ubiquitous. Consequently, context-specific policies aimed at encouraging the adoption of flood-related coping strategies in vulnerable locations should be designed based on local needs and orientation.

  7. Grazing Impact Oscillations

    NARCIS (Netherlands)

    Weger, J.G.; Water, van de W.; Molenaar, J.

    2000-01-01

    An impact oscillator is a periodically driven system that hits a wall when its amplitude exceeds a critical value. We study impact oscillations where collisions with the wall are with near-zero velocity (grazing impacts). A characteristic feature of grazing impact dynamics is a geometrically

  8. Application of a finite element method for computing grazing incidence wave structure in an impedance tube - Comparison with experiment. [for duct liner aeroacoustic design

    Science.gov (United States)

    Lester, H. C.; Parrott, T. L.

    1979-01-01

    The acoustic performance of a liner specimen, in a grazing incidence impedance tube, is analyzed using a finite element method. The liner specimen was designed to be a locally reacting, two-degree-of-freedom type with the resistance and reactance provided by perforated facesheets and compartmented cavities. Measured and calculated wave structures are compared for both normal and grazing incidence from 0.3 to 1.2 kHz. A finite element algorithm was incorporated into an optimization loop in order to predict liner grazing incidence impedance from measured SWR and null position data. Results suggest that extended reaction effects may have been responsible for differences between normal and grazing incidence impedance estimates.

  9. The Impact of Previous Action on Bargaining—An Experiment on the Emergence of Preferences for Fairness Norms

    Directory of Open Access Journals (Sweden)

    Thomas Neumann

    2017-08-01

    Full Text Available The communication of participants to identify an acceptable bargaining outcome in the Nash bargaining game is all about fairness norms. Participants introduce fairness norms which yield a better outcome for themselves in order to convince the other participant of their bargaining proposal. Typically, these fairness norms are in line with theoretical predictions, which support a wide variety of different but fair outcomes the participants can choose from. In this experiment, we play two treatments of the Nash bargaining game: in one treatment, the participants play a dictator game prior to bargaining, and in the other treatment they do not. We find that participants who have not played the dictator game intensively discuss the outcome of the game and come to solutions closer to the equal split of the pie the longer they chat. This effect vanishes as soon as the participants have previous experience from a dictator game: instead of chatting, they establish the fairness norm introduced in the dictator game. Remarkably, if the dictator is unfair in the dictator game, he also gets a higher share of the pie in the Nash bargaining game.

  10. Grazing weakens temporal stabilizing effects of diversity in the Eurasian steppe.

    Science.gov (United States)

    Ren, Haiyan; Taube, Friedhelm; Stein, Claudia; Zhang, Yingjun; Bai, Yongfei; Hu, Shuijin

    2018-01-01

    Many biodiversity experiments have demonstrated that plant diversity can stabilize productivity in experimental grasslands. However, less is known about how diversity-stability relationships are mediated by grazing. Grazing is known for causing species losses, but its effects on plant functional groups (PFGs) composition and species asynchrony, which are closely correlated with ecosystem stability, remain unclear. We conducted a six-year grazing experiment in a semi-arid steppe, using seven levels of grazing intensity (0, 1.5, 3.0, 4.5, 6.0, 7.5, and 9.0 sheep per hectare) and two grazing systems (i.e., a traditional, continuous grazing system during the growing period (TGS), and a mixed one rotating grazing and mowing annually (MGS)), to examine the effects of grazing system and grazing intensity on the abundance and composition of PFGs and diversity-stability relationships. Ecosystem stability was similar between mixed and continuous grazing treatments. However, within the two grazing systems, stability was maintained through different pathways, that is, along with grazing intensity, persistence biomass variations in MGS, and compensatory interactions of PFGs in their biomass variations in TGS. Ecosystem temporal stability was not decreased by species loss but rather remain unchanged by the strong compensatory effects between PFGs, or a higher grazing-induced decrease in species asynchrony at higher diversity, and a higher grazing-induced increase in the temporal variation of productivity in diverse communities. Ecosystem stability of aboveground net primary production was not related to species richness in both grazing systems. High grazing intensity weakened the temporal stabilizing effects of diversity in this semi-arid grassland. Our results demonstrate that the productivity of dominant PFGs is more important than species richness for maximizing stability in this system. This study distinguishes grazing intensity and grazing system from diversity effects on

  11. Identifying qualitative effects of different grazing types on below-ground communities and function in a long-term field experiment

    DEFF Research Database (Denmark)

    Macdonald, Catriona A.; Crawley, Michael J.; Wright, Denis J.

    2015-01-01

    for ecosystem functions. The mechanism behind these impacts are likely to be driven by both direct effects of grazing altering the pattern of nutrient inputs and by indirect effects through changes in plant species composition. However, we could not entirely discount that the pesticide used to exclude...... invertebrates may have affected some microbial community measures. Nevertheless, our work illustrates that human activity that affects grazing intensity may affect ecosystem functioning and sustainability, as regulated by multi-trophic interactions between above- and below-ground communities....

  12. The effects of timing of grazing on plant and arthropod communities in high-elevation grasslands.

    Science.gov (United States)

    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.

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

    African Journals Online (AJOL)

    The invasive Leymus racemosus species is mainly established by ramets (or clonal seedling). A field 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 ...

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

    African Journals Online (AJOL)

    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.

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

    DEFF Research Database (Denmark)

    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...

  16. Ingestive behaviour, herbage intake and grazing efficiency of beef cattle steers on Tanzania guineagrass subjected to rotational stocking managements

    OpenAIRE

    Difante,Gelson dos Santos; Euclides,Valéria Pacheco Batista; Nascimento Júnior,Domicio do; Silva,Sila Carneiro da; Torres Júnior,Roberto Augusto de Almeida; Sarmento,Daniel Oliveira de Lucena

    2009-01-01

    The objective of this experiment was to evaluate the ingestive behaviour, herbage intake and grazing efficiency of beef cattle steers grazing on Panicum maximum Jacq. cv. Tanzania subjected to different rotational stocking intensities. Treatments corresponded to two post-grazing conditions (residues of 25 and 50 cm) associated with a pre-grazing condition of 95% sward canopy light interception during regrowth (LI). The grazing time increased linearly with the duration of the occupation period...

  17. The quantification of grazing capacity from grazing — and ...

    African Journals Online (AJOL)

    The relation between rangeland condition and grazing capacity was determined along a degradation gradient. In studying agronomic values of forage species, the average production per tuft was combined with its grazing preferences, to link grazing values for species in the semi-arid grasslands of southern Africa.

  18. The Grazing Capacity and Stocking Rate of the Gongoshi Grazing ...

    African Journals Online (AJOL)

    This study assessed the grazing capacity and stocking rate of the Gongoshi grazing reserve in Adamawa State, Nigeria. Determination of the grazing capacity was carried out by assessing the forage yield, while forage yield was assessed by clipping of desirable herbage within a series of quadrants (1m2 in size) distributed ...

  19. Grazing Incidence Optics Technology

    Science.gov (United States)

    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.

  20. Dietary selection of sheep grazing the semi-arid grasslands of Inner Mongolia, China at different grazing intensities.

    Science.gov (United States)

    Schiborra, A; Gierus, M; Wan, H W; Glindemann, T; Wang, C J; Susenbeth, A; Taube, F

    2010-08-01

    The objective of this study was to investigate dietary selection of sheep grazing semi-arid grassland in Inner Mongolia, China, using the difference in organic matter digestibility (OMD) of herbage ingested and herbage on offer as indicator for selection. Faecal N was used as digestibility index for herbage ingested (FOMD), while OMD of herbage on offer (GOMD) was estimated from gas production obtained by the Hohenheim gas test. It was hypothesized that the difference between FOMD and GOMD is high, when grazing animals select against low quality herbage provided that herbage is abundant. In a grazing experiment, six grazing intensities (1.5, 3.0, 4.5, 6.0, 7.5 and 9.0 sheep/ha), representing light to very heavy grazing intensity for the semi-arid grassland, were compared. The amount of herbage on offer decreased with increasing grazing intensity. Independent statistical analysis of FOMD and GOMD showed that the differences between grazing intensities for both OMD determinations (FOMD: 54.0-57.3%, GOMD: 55.2-57.5%) were not significant (p > 0.05). The difference between FOMD and GOMD was not significant for grazing intensities, but varied between sampling periods from -4 to 1 percentage units. In conclusion, the lack of significance for the difference between FOMD and GOMD suggests that for the semi-arid grassland of Inner Mongolia, China, sheep did not select their feed due to a homogeneous nutritional composition of herbage on offer in 2005, regardless of grazing intensity.

  1. The Impact of Previous Schooling Experiences on a Quaker High School's Graduating Students' College Entrance Exam Scores, Parents' Expectations, and College Acceptance Outcomes

    Science.gov (United States)

    Galusha, Debbie K.

    2010-01-01

    The purpose of the study is to determine the impact of previous private, public, home, or international schooling experiences on a Quaker high school's graduating students' college entrance composite exam scores, parents' expectations, and college attendance outcomes. The study's results suggest that regardless of previous private, public, home,…

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

    Directory of Open Access Journals (Sweden)

    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.

  3. Community responses of arthropods to a range of traditional and manipulated grazing in shortgrass steppe.

    Science.gov (United States)

    Newbold, T A Scott; Stapp, Paul; Levensailor, Katherine E; Derner, Justin D; Lauenroth, William K

    2014-06-01

    Responses of plants to grazing are better understood, and more predictable, than those of consumers in North American grasslands. In 2003, we began a large-scale, replicated experiment that examined the effects of grazing on three important arthropod groups-beetles, spiders, and grasshoppers-in shortgrass steppe of north-central Colorado. We investigated whether modifications of the intensity and seasonality of livestock grazing alter the structure and diversity of macroarthropod communities compared with traditional grazing practices. Treatments represented a gradient of grazing intensity by cattle and native herbivores: long-term grazing exclosures; moderate summer grazing (the traditional regime); intensive spring grazing; intensive summer grazing; and moderately summer-grazed pastures also inhabited by black-tailed prairie dogs (Cynomys ludovicianus Ord). Beetles and spiders were the most common groups captured, comprising 60% and 21%, respectively, of 4,378 total pitfall captures. Grasshopper counts were generally low, with 3,799 individuals observed and densities grazing treatments, responding not only to long-term grazing conditions, but also to the short-term, more-intensive grazing manipulations. In response, arthropods were, in general, relatively insensitive to these grazing-induced structural changes. However, species-level analyses of one group (Tenebrionidae) revealed both positive and negative effects of grazing treatments on beetle richness and activity-density. Importantly, these responses to grazing were more pronounced in a year when spring-summer rainfall was low, suggesting that both grazing and precipitation-which together may create the greatest heterogeneity in vegetation structure-are drivers of consumer responses in this system.

  4. Influence of Previous Crop on Durum Wheat Yield and Yield Stability in a Long-term Experiment

    Directory of Open Access Journals (Sweden)

    Anna Maria Stellacci

    2011-02-01

    Full Text Available Long-term experiments are leading indicators of sustainability and serve as an early warning system to detect problems that may compromise future productivity. So the stability of yield is an important parameter to be considered when judging the value of a cropping system relative to others. In a long-term rotation experiment set up in 1972 the influence of different crop sequences on the yields and on yield stability of durum wheat (Triticum durum Desf. was studied. The complete field experiment is a split-split plot in a randomized complete block design with two replications; the whole experiment considers three crop sequences: 1 three-year crop rotation: sugar-beet, wheat + catch crop, wheat; 2 one-year crop rotation: wheat + catch crop; 3 wheat continuous crop; the split treatments are two different crop residue managements; the split-split plot treatments are 18 different fertilization formulas. Each phase of every crop rotation occurred every year. In this paper only one crop residue management and only one fertilization treatment have been analized. Wheat crops in different rotations are coded as follows: F1: wheat after sugar-beet in three-year crop rotation; F2: wheat after wheat in three-year crop rotation; Fc+i: wheat in wheat + catch crop rotation; Fc: continuous wheat. The following two variables were analysed: grain yield and hectolitre weight. Repeated measures analyses of variance and stability analyses have been perfomed for the two variables. The stability analysis was conducted using: three variance methods, namely the coefficient of variability of Francis and Kannenberg, the ecovalence index of Wricke and the stability variance index of Shukla; the regression method of Eberhart and Russell; a method, proposed by Piepho, that computes the probability of one system outperforming another system. It has turned out that each of the stability methods used has enriched of information the simple variance analysis. The Piepho

  5. Ipilimumab in the real world: the UK expanded access programme experience in previously treated advanced melanoma patients.

    Science.gov (United States)

    Ahmad, Saif S; Qian, Wendi; Ellis, Sarah; Mason, Elaine; Khattak, Muhammad A; Gupta, Avinash; Shaw, Heather; Quinton, Amy; Kovarikova, Jarmila; Thillai, Kiruthikah; Rao, Ankit; Board, Ruth; Nobes, Jenny; Dalgleish, Angus; Grumett, Simon; Maraveyas, Anthony; Danson, Sarah; Talbot, Toby; Harries, Mark; Marples, Maria; Plummer, Ruth; Kumar, Satish; Nathan, Paul; Middleton, Mark R; Larkin, James; Lorigan, Paul; Wheater, Matthew; Ottensmeier, Christian H; Corrie, Pippa G

    2015-10-01

    Before licensing, ipilimumab was first made available to previously treated advanced melanoma patients through an expanded access programme (EAP) across Europe. We interrogated data from UK EAP patients to inform future clinical practice. Clinicians registered in the UK EAP provided anonymized patient data using a prespecified variable fields datasheet. Data collected were baseline patient characteristics, treatment delivered, toxicity, response, progression-free survival and overall survival (OS). Data were received for 193 previously treated metastatic melanoma patients, whose primary sites were cutaneous (82%), uveal (8%), mucosal (2%), acral (3%) or unknown (5%). At baseline, 88% of patients had a performance status (PS) of 0-1 and 20% had brain metastases. Of the patients, 53% received all four planned cycles of ipilimumab; the most common reason for stopping early was disease progression, including death from melanoma. Toxicity was recorded for 171 patients, 30% of whom experienced an adverse event of grade 3 or higher, the most common being diarrhoea (13%) and fatigue (9%). At a median follow-up of 23 months, the median progression-free survival and OS were 2.8 and 6.1 months, respectively; the 1-year and 2-year OS rates were 31 and 14.8%, respectively. The 2-year OS was significantly lower for patients with poorer PS (P<0.0001), low albumin concentrations (P<0.0001), the presence of brain metastases (P=0.007) and lactate dehydrogenase levels more than two times the upper limit of normal (P<0.0001) at baseline. These baseline characteristics are negative predictors of benefit from ipilimumab and should be taken into consideration before prescription.

  6. The Impact of Previous Athletic Experience on Current Physical Fitness in Former Collegiate Athletes and Noncollegiate Athletes.

    Science.gov (United States)

    Simon, Janet E; Docherty, Carrie L

    Physical activity performed at moderate intensity is associated with reduced risk of mortality, cardiovascular disease, hypertension, and some types of cancers. However, vigorous physical activity during participation in college athletics may increase the risk of injury, which might limit future physical activity levels. To evaluate differences in current physical fitness levels between former Division I athletes and noncollegiate athletes. Cross-sectional study. Level 3. The sample was recruited from a large midwestern university alumni database and consisted of 2 cohorts: (1) former Division I athletes (n = 100; mean age, 53.1 ± 7.4 years) and (2) nonathletes who were active in college (n = 100; age, 51.4 ± 7.3 years). Individuals answered a demographics questionnaire and completed a physical fitness assessment consisting of 7 measures: percent body fat, 1-mile walk, sit-to-stand test, push-up, half sit-up test, sit and reach test, and back scratch test. Performance was significantly worse for former Division I athletes compared with nonathletes for percent body fat (mean difference, 7.58%; F (1, 198) = 59.91; P sit-to-stand test (mean difference, 4.3 repetitions; F (1, 198) = 6.59; P = 0.01), and push-up test (mean difference, 8.9 repetitions; F (1, 198) = 7.35; P = 0.01). Former Division I athletes may be limited because of previous injury, inhibiting their ability to stay active later in life. It is imperative that clinicians, coaches, and strength and conditioning specialists understand the possible future repercussions from competing at the Division I level.

  7. Mixed grazing with heifers and pregnant sows

    OpenAIRE

    Soegaard, Karen; Sehested, Jakob; Danielsen, Viggo

    2000-01-01

    In 1999, a mixed grazing system with heifers and pregnant soews was compared with grazing systems with heifers and sows alone. Normally, herbage quality used for sow grazing is not optimal for high herbage intake and it was therefore examined whether mixed grazing with heifers could improve the grazing system. Herbage quality and botanical composition of the sward was best where heifers grazed alone, followed by swards with mixed grazing and the poorest quality and composition were in swards ...

  8. Hippopotamus and livestock grazing : Influences on riparian vegetation and facilitation of other herbivores in the Mara Region of Kenya

    NARCIS (Netherlands)

    Kanga, Erustus M.; Ogutu, Joseph O.; Piepho, Hans-Peter; Olff, Han

    Riparian savanna habitats grazed by hippopotamus or livestock experience seasonal ecological stresses through the depletion of herbaceous vegetation, and are often points of contacts and conflicts between herbivores, humans and their livestock. We investigated how hippopotamus and livestock grazing

  9. Mixed Grazing Systems Benefit both Upland Biodiversity and Livestock Production

    Science.gov (United States)

    Fraser, Mariecia D.; Moorby, Jon M.; Vale, James E.; Evans, Darren M.

    2014-01-01

    Background 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 21st 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. Methods 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. Results, Conclusion and Significance 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

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

    Directory of Open Access Journals (Sweden)

    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

  11. Management and Yield Prediction of Kunugi (Quercus acutissima) Grazing Forests

    OpenAIRE

    Mitsuo, Matsumoto; Kenjirou, Honda; Juuro, Kurogi; Forest Management Division, Forestry and Forest Products Research Institute; Formerly Kyushu Research Center, Forestry and Forest Products Research Institute; Formerly Kyushu Research Center, Forestry and Forest Products Research Institute

    1999-01-01

    This study deals with grazing in kunugi (Quercus acutissima) forests in the Aso district of Kyushu Island in southwest Japan. These forests are managed for production of bed-logs for shiitake mushrooms and cow-calf farming. One of their characteristics is short-term rotation such as 10-15 years for bed-logs and a year for calf production. A forest grazing experiment was begun in Minamioguni to look at forest growth, vegetation change and grazing intensity. Stem densities dropped in a few year...

  12. Effects of post-grazing forage mass on a beef cattle grazing system on Tanzânia grass pastures

    Directory of Open Access Journals (Sweden)

    Marco Antonio Penati

    2014-06-01

    Full Text Available The objective of this study was to evaluate the effect of grazing intensity on herbage accumulation, animal performance, and total system yield on irrigated Tanzania grass pastures under rotational stocking. The experiment was conducted from October 1999 to January 2001, in a complete randomized block design with four replications. Treatments consisted of three grazing intensities, represented by the following quantities of green forage dry mass remaining after grazing: 1,000 (high intensity, 2,500 (intermediate intensity and 4,000 (low intensity kg ha−1. Grazing cycles were of 36 days (33 rest and 3 grazing. The values observed at the end of the experiment for post grazing forage mass were close to the proposed values. Forage yield was 25,278, 36,850, and 34,144 kg DM ha−1, whereas animal performance was 0.398, 0.541, and 0.564 kg BW day−1for high, intermediate and low intensities, respectively. Grazing intensity was positive related to the stocking rate (6.5, 5.2 and 4.1 AU ha−1 at high, intermediate and low intensities, respectively. Total system yield was not affected by treatments, ranging between 1,518 and 1,287 kg BW ha−1 year−1.

  13. Positive short-term effects of sheep grazing on the alpine avifauna.

    Science.gov (United States)

    Loe, Leif Egil; Mysterud, Atle; Stien, Audun; Steen, Harald; Evans, Darren M; Austrheim, Gunnar

    2007-02-22

    Grazing by large herbivores may negatively affect bird populations. This is of great conservation concern in areas with intensive sheep grazing. Sheep management varies substantially between regions, but no study has been performed in less intensively grazed systems. In a fully replicated, landscape scale experiment with three levels of sheep grazing, we tested whether the abundance and diversity of an assemblage of mountain birds were negatively affected by grazing or if grazing facilitated the bird assemblage. Density of birds was higher at high sheep density compared with low sheep density or no sheep by the fourth grazing season, while there was no clear effect on bird diversity. Thus, agricultural traditions and land use politics determining sheep density may change the density of avifauna in either positive or negative directions.

  14. Ammonia emissions of a rotational grazing system

    Science.gov (United States)

    Voglmeier, Karl; Häni, Christoph; Jocher, Markus; Ammann, Christof

    2017-04-01

    Intensive agricultural livestock production is the main source of air pollution by ammonia (NH3). Grazing is considered to reduce emissions significantly. However, ammonia emissions measurements on pastures are very rare and most emission models base their emissions factors for grazing on studies from the 1990s, which report a large emission range from 2.7% to 13.6% of the applied total ammonia nitrogen (TAN). We present first results of the Posieux pasture experiment in 2016 where NH3 concentration and fluxes were measured during the grazing season. The applied methods include an eddy covariance system with a two channel reactive nitrogen (Nr) converter measuring in parallel the sum of oxidized Nr species and the sum of the total Nr species. The difference of the two channels corresponds to the sum of reduced Nr species. Furthermore four MiniDOAS instruments for line integrated concentration measurements without an inlet system were used. The fluxes were estimated by applying a backward Lagrangian stochastic model (bLS) to the concentration difference of paired MiniDOAS up- and downwind of a sub-plot of the field. Monitoring of dung (visual survey) and urine patch locations (with soil electrical conductivity sensor) was carried out after each grazing rotation on selected sub-plots. It helped to compute statistics of the dung/urine patch distribution on the pasture. The experimental setup and the environmental conditions resulted in high temporal and spatial dynamics of NH3 concentrations and fluxes. The calculated fluxes were used to estimate the total net emission during the grazing period. Based on the average dung/urine patch distribution on the field an emission factor for the pasture was computed and compared to results from the literature. We discuss the applicability and limitations of the two measurement systems, reconsider the main emission drivers and explain differences in the results.

  15. Bivalve grazing can shape phytoplankton communities

    Science.gov (United States)

    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.

  16. Grazing weakens temporal stabilizing effects of diversity in the Eurasian steppe

    OpenAIRE

    Ren, Haiyan; Taube, Friedhelm; Stein, Claudia; Zhang, Yingjun; Bai, Yongfei; Hu, Shuijin

    2017-01-01

    Abstract Many biodiversity experiments have demonstrated that plant diversity can stabilize productivity in experimental grasslands. However, less is known about how diversity–stability relationships are mediated by grazing. Grazing is known for causing species losses, but its effects on plant functional groups (PFGs) composition and species asynchrony, which are closely correlated with ecosystem stability, remain unclear. We conducted a six‐year grazing experiment in a semi‐arid steppe, usin...

  17. Analysis of current research addressing complementary use of life-cycle assessment and risk assessment for engineered nanomaterials: have lessons been learned from previous experience with chemicals?

    DEFF Research Database (Denmark)

    Grieger, Khara Deanne; Laurent, Alexis; Miseljic, Mirko

    2012-01-01

    While it is generally agreed that successful strategies to address the health and environmental impacts of engineered nanomaterials (NM) should consider the well-established frameworks for conducting life-cycle assessment (LCA) and risk assessment (RA), scientific research, and specific guidance...... on how to practically apply these methods are still very much under development. This paper evaluates how research efforts have applied LCA and RA together for NM, particularly reflecting on previous experiences with applying these methods to chemicals. Through a literature review and a separate analysis...... of research focused on applying LCA and RA together for NM, it appears that current research efforts have taken into account some key ‘‘lessons learned’’ from previous experience with chemicals while many key challenges remain for practically applying these methods to NM. We identified two main approaches...

  18. Assessment of the Relationship between Recurrent High-risk Pregnancy and Mothers’ Previous Experience of Having an Infant Admitted to a Neonatal Intensive Care Unit

    Directory of Open Access Journals (Sweden)

    Sedigheh Hantoosh Zadeh

    2015-01-01

    Full Text Available Background & aim:  High-risk pregnancies increase the risk of Intensive Care Unit (ICU and Neonatal Intensive Care Unit (NICU admission in mothers and their newborns. In this study, we aimed to identify the association between the recurrence of high-risk pregnancy and mothers’ previous experience of having an infant admitted to NICU. Methods:We performed a cohort, retrospective study to compare subsequent pregnancy outcomes among 232 control subjects and 200 female cases with a previous experience of having a newborn requiring NICU admission due to intrauterine growth retardation, preeclampsia, preterm birth, premature rupture of membranes, and asphyxia. The information about the prevalence of subsequent high-risk pregnancies was gathered via phone calls. Results: As the results indicated, heparin, progesterone, and aspirin were more frequently administered in the case group during subsequent pregnancies, compared to the control group (P

  19. Patient's anxiety and fear of anesthesia: effect of gender, age, education, and previous experience of anesthesia. A survey of 400 patients.

    Science.gov (United States)

    Mavridou, Paraskevi; Dimitriou, Varvara; Manataki, Adamantia; Arnaoutoglou, Elena; Papadopoulos, Georgios

    2013-02-01

    Patients express high anxiety preoperatively, because of fears related to anesthesia and its implications. The purpose of this survey was to gain insight into these fears and to study whether they are affected by patients' sex, age, education, or previous experience of anesthesia. Questionnaires with fixed questions were distributed to consenting, consecutive surgical patients before the pre-anesthetic visit. The questionnaires included patients' demographics and questions related to their fears about anesthesia. Four-hundred questionnaires were collected and analyzed. Eighty-one percent of patients experience preoperative anxiety. The main sources of their anxiety were fear of postoperative pain (84 %), of not waking up after surgery (64.8 %), of being nauseous or vomiting (60.2 %), and of drains and needles (59.5 %). Patients are less concerned about being paralyzed because of anesthesia (33.5 %) or of revealing personal issues (18.8 %). Gender seems to affect patients fears, with women being more afraid (85.3 vs. 75.6 % of men, p = 0.014). The effects of patients' age, level of education, and previous experience of anesthesia are minor, except for individual questions. Sixty-three percent of our patients (mostly women 67.4 vs. 57.4 % of men, p = 0.039) talk about these fears with their relatives, although a vast majority of 95.5 % would prefer to talk with the anesthesiologist and be reassured by him. All patients, mostly women, express fears about anesthesia; this fear leads to preoperative anxiety. Slight differences are observed for some individual questions among patients of different sex, education level, and previous experience of anesthesia.

  20. Grazing incidence beam expander

    Energy Technology Data Exchange (ETDEWEB)

    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.

  1. Evaluation of gastro-intestinal nematode parasite control strategies for first-season grazing cattle in Sweden.

    Science.gov (United States)

    Dimander, Sten-Olof; Höglund, Johan; Uggla, Arvid; Spörndly, Eva; Waller, Peter J

    2003-02-13

    A three-year grazing experiment (1998-2000) was conducted with first-season grazing cattle (FSGC) on improved pastures in central-eastern Sweden. Comparison was made between five groups with 10 calves in each group where four of these were set stocked and either (1) untreated, (2) ivermectin bolus treated, (3) subjected to biological control with the nematophagous fungus Duddingtonia flagrans, or (4) treated with a copper wire particle bolus. The fifth treatment was an evasive grazing strategy, whereby untreated calves were turned out onto pasture used by older cattle the previous year and then these calves were moved to silage aftermath in mid-July. To introduce low-levels of parasite infection to the experiment, each animal received a 'priming dose' of approximately 5,000 Ostertagia ostertagi and 5,000 Cooperia oncophora infective third stage larvae immediately prior to the start of the first grazing year of the trial. Results showed that efficient and sustainable parasite control of FSGC was possible to achieve without the use of anthelmintics by using turnout pastures that the previous year had been grazed by older cattle, in combination with a mid-July move to aftermath leys. Biological control also proved beneficial but the efficacy was impaired if high faecal egg counts coincided with rapid dung pat degradation due to heavy rainfall. No indication of parasite control was observed with the copper wire particle bolus. It was also demonstrated that the impact of gastrointestinal (GI) parasitism varied between years and that the level of overwintering contamination is important but likewise, is unpredictable. Although faecal egg counts in 1999 were low, due both to a delayed turnout and drought for the major part of the grazing season, deposited eggs successfully developed to infective larvae and overwintered in large numbers. The population of overwintered infective larvae at the time of turnout in early May played an important role in the course of infection

  2. Effect of different grazing pressure by lambs grazing Lolium perenne ...

    African Journals Online (AJOL)

    high (HGP), medium (MGP) and low (LGP), corresponding to 30, 50 and 75 g available DM/kg BW/day, respectively] on the quality of herbage consumed by lambs grazing Lolium perenne and Dactylis glomerata pastures in spring.

  3. Explaining infant feeding: The role of previous personal and vicarious experience on attitudes, subjective norms, self-efficacy, and breastfeeding outcomes.

    Science.gov (United States)

    Bartle, Naomi C; Harvey, Kate

    2017-11-01

    Breastfeeding confers important health benefits to both infants and their mothers, but rates are low in the United Kingdom and other developed countries despite widespread promotion. This study examined the relationships between personal and vicarious experience of infant feeding, self-efficacy, the theory of planned behaviour variables of attitudes and subjective norm, and the likelihood of breastfeeding at 6-8 weeks post-natally. A prospective questionnaire study of both first-time mothers (n = 77) and experienced breastfeeders (n = 72) recruited at an antenatal clinic in South East England. Participants completed a questionnaire at 32 weeks pregnant assessing personal and vicarious experience of infant feeding (breastfeeding, formula-feeding, and maternal grandmother's experience of breastfeeding), perceived control, self-efficacy, intentions, attitudes (to breastfeeding and formula-feeding), and subjective norm. Infant feeding behaviour was recorded at 6-8 weeks post-natally. Multiple linear regression modelled the influence of vicarious experience on attitudes, subjective norm, and self-efficacy (but not perceived control) and modelled the influence of attitude, subjective norm, self-efficacy, and past experience on intentions to breastfeed. Logistic regression modelled the likelihood of breastfeeding at 6-8 weeks. Previous experience (particularly personal experience of breastfeeding) explained a significant amount of variance in attitudes, subjective norm, and self-efficacy. Intentions to breastfeed were predicted by subjective norm and attitude to formula-feeding and, in experienced mothers, self-efficacy. Breastfeeding at 6 weeks was predicted by intentions and vicarious experience of formula-feeding. Vicarious experience, particularly of formula-feeding, has been shown to influence the behaviour of first-time and experienced mothers both directly and indirectly via attitudes and subjective norm. Interventions that reduce exposure to formula

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

    Science.gov (United States)

    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

  5. 25 CFR 167.8 - Grazing rights.

    Science.gov (United States)

    2010-04-01

    ... 25 Indians 1 2010-04-01 2010-04-01 false Grazing rights. 167.8 Section 167.8 Indians BUREAU OF... rights. (a) The Superintendent shall determine grazing rights of bona fide live-stock owners based on recommendations of District Grazing Committees. Grazing rights shall be recognized for those permittees having...

  6. Heterotrophic nanoflagellate grazing facilitates subarctic Atlantic bloom development

    DEFF Research Database (Denmark)

    Paulsen, Maria Lund; Riisgaard, Karen; St. John, Michael

    2017-01-01

    and was substantially higher than the growth of the larger microzooplankton (MZP), i.e. ciliates and dinoflagellates. During the first experiment, small phytoplankton dominated and overall protist grazing (HNF + MZP) was low. In the later experiments, MZP grazing on HNF became evident; however, MZP were not able......-down control of small-sized phytoplankton, thus paving the way for a diatomdominated spring bloom. To assess the trophic role of protist grazers during the winter to spring transition, 3 experiments were performed using size-fractionated surface water from the Iceland Basin (March−April 2012......). These experiments demonstrated heterotrophic nanoflagellates (HNF) grazing of picophytoplankton to be a key pathway, even though these are rarely considered as important phytoplankton grazers in high-latitude systems. The growth rate of HNF was significantly correlated to the biomass of picophytoplankton...

  7. Technical note: utilization of sainfoin by grazing steers and a method for predicting daily gain from small-plot grazing data.

    Science.gov (United States)

    Mowrey, D P; Matches, A G; Preston, R L

    1992-07-01

    Sainfoin (Onobrychis viciaefolia Scop.) is adapted to the calcareous soils of the southern Great Plains and can provide early season forage that does not induce bloating; however, little is known about performance by ruminants grazing sainfoin. Our objective was to determine the effect of plant growth stage and grazing pressures on potential animal production from sainfoin as predicted from energy intake as a multiple of maintenance. Nitrogen-fertilized (100 kg of N/ha) Renumex sainfoin was grown under irrigation on a Pullman clay loam (fine, mixed, thermic Torretic Paleustoll) near Lubbock, TX. Light (L), medium (M), and heavy (H) grazing pressures were applied with steers grazing sainfoin that was at the bud (B), flower (F), and seed shatter (S) stages of growth. The L, M, and H pressures were grazed to remove 50, 75, and 90% of the standing plant height. Across growth stages, L, M, and H grazing pressures averaged 52, 69, and 87% removal of pregrazed herbage mass. Dry matter intake as a percentage of BW of steers averaged 3.9, 2.8, and 1.7 for L, M, and H grazing pressures. Across growth stages, predicted live weight gain for L, M, and H grazing pressures averaged .86, .67, and .03 kg/d. Our findings indicate that the multiple of maintenance method may be useful for evaluating treatments from small-plot grazing experiments.

  8. Analysis of current research addressing complementary use of life-cycle assessment and risk assessment for engineered nanomaterials: have lessons been learned from previous experience with chemicals?

    International Nuclear Information System (INIS)

    Grieger, Khara D.; Laurent, Alexis; Miseljic, Mirko; Christensen, Frans; Baun, Anders; Olsen, Stig I.

    2012-01-01

    While it is generally agreed that successful strategies to address the health and environmental impacts of engineered nanomaterials (NM) should consider the well-established frameworks for conducting life-cycle assessment (LCA) and risk assessment (RA), scientific research, and specific guidance on how to practically apply these methods are still very much under development. This paper evaluates how research efforts have applied LCA and RA together for NM, particularly reflecting on previous experiences with applying these methods to chemicals. Through a literature review and a separate analysis of research focused on applying LCA and RA together for NM, it appears that current research efforts have taken into account some key “lessons learned” from previous experience with chemicals while many key challenges remain for practically applying these methods to NM. We identified two main approaches for using these methods together for NM: “LC-based RA” (traditional RA applied in a life-cycle perspective) and “RA-complemented LCA” (conventional LCA supplemented by RA in specific life-cycle steps). Hence, the latter is the only identified approach which genuinely combines LC- and RA-based methods for NM-risk research efforts to date as the former is rather a continuation of normal RA according to standard assessment procedures (e.g., REACH). Both these approaches along with recommendations for using LCA and RA together for NM are similar to those made previously for chemicals, and thus, there does not appear to be much progress made specific for NM. We have identified one issue in particular that may be specific for NM when applying LCA and RA at this time: the need to establish proper dose metrics within both methods.

  9. The effect of past grazing intensity on the vigour of Themeda triandra ...

    African Journals Online (AJOL)

    , during a full season's rest, of tufts of Themeda triandra Forssk. and Tristachya leucothrix Nees, which (1) had not been grazed, (2) had been leniently, or (3) had been severely grazed during the previous two growing seasons. A sequential ...

  10. Increase in plasma total antioxidant capacity of grazing Japanese Black heifers and cows in forestland in Japan.

    Science.gov (United States)

    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 grazing Japanese Black cattle in forestland increase from summer through fall. © 2013 Japanese Society of Animal Science.

  11. Investigations on the effect of grazing intensity on the transfer of radionuclides to cow's milk

    International Nuclear Information System (INIS)

    Voigt, G.; Schotola, C.; Crout, N.M.J.; Absalom, J.

    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)

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

    African Journals Online (AJOL)

    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.

  13. Plant community responses to livestock grazing: An assessment of alternative management practices in a semiarid grassland

    Science.gov (United States)

    Matthew R. Loeser; Thomas D. Sisk; Timothy E. Crews

    2001-01-01

    One of the most prevalent land-use practices in the American Southwest, and one of the most contentious issues among land-use policymakers, is the grazing of domestic livestock. In an effort to contribute scientific understanding to this debate, we have designed experiments comparing the effects of alternative grazing regimes on plant communities. In a semiarid...

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

    NARCIS (Netherlands)

    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

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

    Science.gov (United States)

    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 ...

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

    Science.gov (United States)

    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

  17. Effect of allowed grazing time, inert rumen bulk and length of starvation before grazing on the weight, composition and dermentative end-products of the rumen contents of lactating dairy cows

    NARCIS (Netherlands)

    Chilibroste, P.; Tamminga, S.; Bruchem, van J.; Togt, van der P.L.

    1998-01-01

    The effect of length of the allowed grazing time (Experiment 1), length of starvation time and placement in the rumen of inert bulk material before grazing (Experiment 2) on liquid and particulate rumen pool sizes, composition and fermentability was investigated. In Experiment 1, four lengths of

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

    Science.gov (United States)

    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.

  19. Effect of alternate and simultaneous grazing on endoparasite infection in sheep and cattle

    Directory of Open Access Journals (Sweden)

    Daiana Lima Brito

    Full Text Available This experiment was carried out on 8 ha of Panicum maximum cv. Tanzania pastures, with rotational grazing consisting of 7 days of occupation and 21 days of rest. Four treatments were evaluated: cattle grazing alone (BOV, sheep grazing alone (OVI, cattle and sheep grazing simultaneously (SIM and cattle grazing followed by sheep (alternate - ALT. Twenty heifers and 30 male Santa Inês lambs were used. Fecal egg count (FEC and fecal cultures were carried out. Blood was also collected to examine red and white cell series, total plasma protein (TPP, albumin and hemoglobin. FEC and estimated nematode pathogenicity index in sheep were lower in the SIM treatment. The Haemonchus spp. proportion was higher in isolated grazing systems. For sheep, mixed grazing was shown to reduce endoparasite infection, and SIM was better than ALT. For cattle, no difference between grazing systems was seen. Therefore, simultaneous grazing (sheep and cattle may be a tool for reducing the need for anthelmintic treatments in sheep.

  20. [Effect of grazing on the temperature sensitivity of soil respiration in Hulunber meadow steppe].

    Science.gov (United States)

    Wang, Xu; Yan, Rui-Rui; Deng, Yu; Yan, Yu-Chun; Xin, Xiao-Ping

    2014-05-01

    Grazing is one of the major human activities which lead to disturbance on grassland ecosystem. Quantifying the effect of grazing on the temperature sensitivity of soil respiration ( Q10 ) is essential for accurate assessment of carbon budget in grassland ecosystem. This study was conducted on the grazing gradients experiment platform in Hulunber meadow steppe. Soil respiration was measured by a dynamic closed chamber method (equipped with Li 6400-09, Lincoln, NE, USA) during the growing season in 2011. The results showed that soil respiration had significant seasonal variation and the maximum occurred in July, which was mainly dominated by temperature. The order of average soil respiration during the period from May to September in different treatments was G1 > GO > G2 > G3 > G4 > G5. Comparing with non-grazing treatment, Q10 under heavy grazing conditions (0. 92 Au hm-2) was reduced by about 10% , and was increased a little under light grazing conditions (0. 23 Au hm-2). There was a significant negative correlation between Q15 and grazing intensities (r = 0. 944, P temperature sensitivity of soil respiration to different degrees. The Q10 under different grazing gradients had positive linear regression relationships with aboveground biomass, belowground biomass, soil organic carbon and soil moisture. They could explain 71.0%-85.2% variations of Q10. It was suggested that the variation of Q10 was mainly determined by the change of biotic and environmental factors due to grazing.

  1. Research Note Effects of previous cultivation on regeneration of ...

    African Journals Online (AJOL)

    Research Note Effects of previous cultivation on regeneration of Julbernadia globiflora and Brachystegia spiciformis in grazing areas of Mupfurudzi ... Plant attributes for Julbernadia globiflora and Brachystegia spiciformis were measured in previously cultivated and uncultivated sites making up rangelands of the scheme.

  2. A non-diatom plankton bloom controlled by copepod grazing and amphipod predation: Preliminary results from the LOHAFEX iron-fertilisation experiment

    Digital Repository Service at National Institute of Oceanography (India)

    Mazzocchi, M.G.; Gonzalez, H.E.; Vandromme, P.; Borrione, I.; deAlcala, M.R.; Gauns, M.; Assmy, P.; Fuchs, B.; Klaas, C.; Martin, P.; Montresor, M.; Ramaiah, N.; Naqvi, S.W.A.; Smetacek, V.

    .E. González). 6 GLOBEC INTERNATIONAL NEWSLETTER OCTOBER 2009 7 GLOBEC INTERNATIONAL NEWSLETTER OCTOBER 2009 Macrozooplankton was dominated by the swarm - forming, hyperiid amphipod Themisto gaudichaudii, an active, aggressive, indiscriminate carnivore which... - fold higher inside (24 ind. 100 m - 3 ) than outside the patch (12 ind. 100 m - 3 ). This was confirmed by a transect of four trawls conducted from outside to inside the patch at the end of the experiment (Fig. 8). What attracted swarms...

  3. Effect of different grazing pressures by lambs grazing Lolium ...

    African Journals Online (AJOL)

    high (HGP), medium (MGP) and low (LGP), corresponding to 30, 50 and 75 g available DM/kg BW/day, respectively] on the performance of lambs grazing Lolium perenne and Dactylis glomerata pastures in spring. Feed intakes and average ...

  4. The influence of urine and dung deposition on patch grazing ...

    African Journals Online (AJOL)

    Urine deposition may consequently be an important factor in patch initiation and patch development. Keywords: cattle; deposition; dung; grazing frequency; grazing intensity; grazing pattern; grazing patterns; herbage; patch grazing; sheep; sheep grazing; south africa; southern tall grassveld; ukulinga research station; urine

  5. Livestock grazing, wildlife habitat, and rangeland values

    Science.gov (United States)

    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...

  6. 25 CFR 173.6 - Stock grazing.

    Science.gov (United States)

    2010-04-01

    ... 25 Indians 1 2010-04-01 2010-04-01 false Stock grazing. 173.6 Section 173.6 Indians BUREAU OF... WITHDRAWN OR ACQUIRED IN CONNECTION WITH INDIAN IRRIGATION PROJECTS § 173.6 Stock grazing. Permittees may graze upon lands covered by such permits, such stock as may be required in connection with the purposes...

  7. 25 CFR 168.5 - Grazing capacity.

    Science.gov (United States)

    2010-04-01

    ... 25 Indians 1 2010-04-01 2010-04-01 false Grazing capacity. 168.5 Section 168.5 Indians BUREAU OF INDIAN AFFAIRS, DEPARTMENT OF THE INTERIOR LAND AND WATER GRAZING REGULATIONS FOR THE HOPI PARTITIONED LANDS AREA § 168.5 Grazing capacity. (a) The Area Director shall prescribe the maximum number of each...

  8. High motility reduces grazing mortality of planktonic bacteria

    DEFF Research Database (Denmark)

    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...... that the number of predator-prey contacts increased with bacterial swimming speed, but ingestion rates dropped at speeds of >25 mum s(-1) as a result of handling problems with highly motile cells. Comparative studies of a moderately motile strain (45 mum s-1) further revealed changes in the bacterial swimming...... speed distribution due to speed-selective flagellate grazing. Better long-term survival of the highly motile strain was indicated by fourfold-higher bacterial numbers in the presence of grazing compared to the moderately motile strain. Putative constraints of maintaining high swimming speeds were tested...

  9. Cold season soil respiration in response to grazing and warming in the High Arctic Svalbard

    DEFF Research Database (Denmark)

    Strebel, Ditte; Elberling, Bo; Morgner, Elke

    2010-01-01

    of Arctic Goose Habitat: Impacts of Land Use, Conservation and Elevated Temperatures). New measurements of soil CO2 effluxes, temperatures and water contents were regularly made from July to November 2007. SOC stocks were quantified, and the reactivity and composition measured by basal soil respiration (BSR...... in significantly higher CO2 effluxes. Different grazing intensities had no significant effects on observed soil respiration, but BSR rates at the mesic site (13-23 mu g CO2 g soil-C-1 h-1) were highest with moderate grazing and lowest in the absence of grazing. A limited effect of grazing on microbial respiration......The influence of goose grazing intensity and open-topped chambers (OTCs) on near-surface quantities and qualities of soil organic carbon (SOC) was evaluated in wet and mesic ecosystems in Svalbard. This study followed up a field experiment carried out in 2003-05 (part of the project Fragility...

  10. Ecology of grazing lawns in Africa.

    Science.gov (United States)

    Hempson, Gareth P; Archibald, Sally; Bond, William J; Ellis, Roger P; Grant, Cornelia C; Kruger, Fred J; Kruger, Laurence M; Moxley, Courtney; Owen-Smith, Norman; Peel, Mike J S; Smit, Izak P J; Vickers, Karen J

    2015-08-01

    Grazing lawns are a distinct grassland community type, characterised by short-stature and with their persistence and spread promoted by grazing. In Africa, they reveal a long co-evolutionary history of grasses and large mammal grazers. The attractiveness to grazers of a low-biomass sward lies in the relatively high quality of forage, largely due to the low proportion of stem material in the sward; this encourages repeat grazing that concomitantly suppresses tall-grass growth forms that would 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 to grazing lawn existence, can also cause these systems to be highly dynamic. Here we identify differences in growth form among grazing lawn grass species, and assess how compositional differences among lawn types, as well as environmental variables, influence their maintenance requirements (i.e. grazing frequency) and vulnerability to degradation. We also make a clear distinction between the processes of lawn establishment and lawn maintenance. Rainfall, soil nutrient status, grazer community composition and fire regime have strong and interactive influences on both processes. However, factors that concentrate grazing pressure (e.g. nutrient hotspots and sodic sites) have more bearing on where lawns establish. Similarly, we discuss the relevance of enhanced rates of nitrogen cycling and of sodium levels to lawn maintenance. Grazer community composition and density has considerable significance to grazing lawn dynamics; not all grazers are adapted to foraging on short-grass swards, and differences in body size and relative mouth dimensions determine which species are able to convert tall-grass swards into grazing lawns under different conditions. Hence, we evaluate the roles of different grazers in lawn dynamics, as well as the

  11. Use of Intracervical Foley Catheter for Induction of Labour in Cases of Previous Caesarean Section: Experience of a single tertiary centre in Oman.

    Science.gov (United States)

    Gonsalves, Hazel; Al-Riyami, Nihal; Al-Dughaishi, Tamima; Gowri, Vaidayanathan; Al-Azri, Mohammed; Salahuddin, Ayesha

    2016-11-01

    This study aimed to evaluate rates of success and perinatal complications of labour induction using an intracervical Foley catheter among women with a previous Caesarean delivery at a tertiary centre in Oman. This retrospective cohort study included 68 pregnant women with a history of a previous Caesarean section who were admitted for induction via Foley catheter between January 2011 and December 2013 to the Sultan Qaboos University Hospital, Muscat, Oman. Patient data were collected from electronic and delivery ward records. Most women were 25-35 years old (76.5%) and 20 women had had one previous vaginal delivery (29.4%). The most common indication for induction of labour was intrauterine growth restriction with oligohydramnios (27.9%). Most women delivered after 40 gestational weeks (48.5%) and there were no neonatal admissions or complications. The majority experienced no complications during the induction period (85.3%), although a few had vaginal bleeding (5.9%), intrapartum fever (4.4%), rupture of the membranes (2.9%) and cord prolapse shortly after insertion of the Foley catheter (1.5%). However, no cases of uterine rupture or scar dehiscence were noted. Overall, the success rate of vaginal birth after a previous Caesarean delivery was 69.1%, with the remaining patients undergoing an emergency Caesarean section (30.9%). The use of a Foley catheter in the induction of labour in women with a previous Caesarean delivery appears a safe option with a good success rate and few maternal and fetal complications.

  12. Research Note Effects of previous cultivation on regeneration of ...

    African Journals Online (AJOL)

    We investigated the effects of previous cultivation on regeneration potential under miombo woodlands in a resettlement area, a spatial product of Zimbabwe's land reforms. We predicted that cultivation would affect population structure, regeneration, recruitment and potential grazing capacity of rangelands. Plant attributes ...

  13. Methane uptake and emissions in a typical steppe grazing system during the grazing season

    Science.gov (United States)

    Wang, Xiaoya; Zhang, Yingjun; Huang, Ding; Li, Zhiqiang; Zhang, Xiaoqing

    2015-03-01

    This study investigated the effects of livestock grazing on CH4 emissions by testing six grazing conditions at Guyuan State Key Monitoring and Research Station of Grassland Ecosystem (China) in 2011 and 2012. Under all grazing systems, steppe soils were measured to be CH4 sinks. The uptake of CH4 by grassland was primarily determined by topsoil (7 cm) temperature and soil (0-7 cm) moisture in grassland at short-term grazing and non-grazing. The cumulative uptake of CH4 during the grazing period for all conditions was 0.88-3.23 kg hm-2 CH4, and the highest level was observed in the continuously moderate grazing condition. Reducing grazing stocking in the short-term did not significantly change the uptake of CH4 when compared with continuously heavy grazing condition. Enteric CH4 emissions were not significantly affected by the grazing period or conditions. The uptake of CH4 by grassland soil offset 3.1-8.6% of the CH4 emissions from the grazing sheep and was most effective at the continuously moderate grazing condition. These findings imply that continuously moderate grazing is the best approach considered here for optimizing the soil as a sink for atmospheric CH4.

  14. Thermal balance of cattle grazing winter range: model application.

    Science.gov (United States)

    Keren, E N; Olson, B E

    2006-05-01

    Beef cattle grazing semiarid foothill rangeland of the Northern Rockies during winter may be exposed to cold temperatures and high winds while grazing pastures with low nutritional value. Cattle can physiologically and behaviorally respond to the changing environment to lower their metabolic requirements and reduce the effects of cold exposure. Requirements of grazing cattle may be overpredicted with models developed in controlled settings that do not account for energy-conserving behaviors. We refined a simple thermal balance equation to model heat exchange of free-ranging cattle. We accounted for the complex interactions between animal behavior and the changing natural environment by applying the insulation characteristics of the cattle's tissue and coat to a simple geometric shape of an asymmetric ellipsoid at different orientations to the sun and wind. We compared the model predictions with heat production measured in 3 studies, and in all cases the model predictions were similar to those reported. Model simulations indicate behaviors, such as lying and orientation to the sun, mitigated the effects of extreme weather. For many combinations of winter weather variables, metabolic requirements increased only slightly due to cold exposure of mature beef cattle in a near-maintenance state. The results indicate that solar radiation contributes strongly to the thermal balance of a cow. Thus, previous models that do not account for the irradiative environment may overestimate metabolic requirements of cattle acclimated to grazing winter range.

  15. Assessing the impact of previous experience, and attitudes towards technology, on levels of engagement in a virtual reality based occupational therapy intervention for spinal cord injury rehabilitation

    LENUS (Irish Health Repository)

    McCaughey, Manus Dr.

    2007-01-01

    The aim of the current research project was to determine if there were significant differences between patients with higher or lower levels of experience with technology in terms of their level of engagement with virtual reality (VR) in occupational therapy, their future uptake of VR technology in therapy, and their attitudes towards technology. Patients’ experience of technology was also examined in relation to demographic characteristics such as age and education level.\\r\

  16. Signal grass structure at different sites of the same pasture under three grazing intensities - doi: 10.4025/actascianimsci.v35i1.11801

    Directory of Open Access Journals (Sweden)

    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.

  17. Study of some physical aspects previous to design of an exponential experiment; Estudio de algunos aspectos fisicos previos al diseno de una experiencia exponencial

    Energy Technology Data Exchange (ETDEWEB)

    Caro, R.; Francisco, J. L. de

    1961-07-01

    This report presents the theoretical study of some physical aspects previous to the design of an exponential facility. The are: Fast and slow flux distribution in the multiplicative medium and in the thermal column, slowing down in the thermal column, geometrical distribution and minimum needed intensity of sources access channels and perturbations produced by possible variations in its position and intensity. (Author) 4 refs.

  18. Use of Intracervical Foley Catheter for Induction of Labour in Cases of Previous Caesarean Section; Experience of a single tertiary centre in Oman

    Directory of Open Access Journals (Sweden)

    Hazel Gonsalves

    2016-11-01

    Full Text Available Objectives: This study aimed to evaluate rates of success and perinatal complications of labour induction using an intracervical Foley catheter among women with a previous Caesarean delivery at a tertiary centre in Oman. Methods: This retrospective cohort study included 68 pregnant women with a history of a previous Caesarean section who were admitted for induction via Foley catheter between January 2011 and December 2013 to the Sultan Qaboos University Hospital, Muscat, Oman. Patient data were collected from electronic and delivery ward records. Results: Most women were 25–35 years old (76.5% and 20 women had had one previous vaginal delivery (29.4%. The most common indication for induction of labour was intrauterine growth restriction with oligohydramnios (27.9%. Most women delivered after 40 gestational weeks (48.5% and there were no neonatal admissions or complications. The majority experienced no complications during the induction period (85.3%, although a few had vaginal bleeding (5.9%, intrapartum fever (4.4%, rupture of the membranes (2.9% and cord prolapse shortly after insertion of the Foley catheter (1.5%. However, no cases of uterine rupture or scar dehiscence were noted. Overall, the success rate of vaginal birth after a previous Caesarean delivery was 69.1%, with the remaining patients undergoing an emergency Caesarean section (30.9%. Conclusion: The use of a Foley catheter in the induction of labour in women with a previous Caesarean delivery appears a safe option with a good success rate and few maternal and fetal complications.

  19. The Role of Cell Morphotype in Protist Grazing on the Model Diatom Phaeodactylum tricornutum

    Science.gov (United States)

    Beaudoin, D.; Johnson, M. D.; Tirichine, L.; Rastogi, A.; Bowler, C.

    2016-02-01

    Microzooplankton grazing is the single greatest loss to daily primary production in the oceans. Factors such as prey quality, chemical defense, and morphology are known to play important roles in mediating interactions with protist grazers. However, for most phytoplankton species we lack a mechanistic understanding of variables that modulate grazing and their relative importance. Here we test the hypothesis that morphological complexity acts to decrease grazing rates of microzooplankton predators, using strains of Phaeodactylum tricornutum with distinct morphotypes (oval, fusiform, and triradiate). Specifically we expected to find lower grazing on the triradiate morphotype. In experiments with predominantly uniform morphotypes, our results demonstrate that grazing by the heterotrophic dinoflagellate Oxyrrhis marina was surprisingly greatest on triradiate P. tricornutum, while oval and fusiform morphotypes revealed lower rates. Furthermore, the triradiate morphotype also supported higher growth rates of O. marina. We are currently investigating the role of grazing on morphotype frequency in P. tricornutum strains with mixed phenotypes. Chemical factors, such as prey nutritional content, and oxylipin profiles are also being investigated. Collectively, these experiments will help to determine the role of intraspecific phenotypes in predator-prey interactions, and how grazing helps to shape morphotype frequency in prey populations.

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

    African Journals Online (AJOL)

    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.

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

    African Journals Online (AJOL)

    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 ...

  2. Livestock grazing affects the egg size of an insectivorous passerine.

    Science.gov (United States)

    Evans, Darren M; Redpath, Stephen M; Evans, Sharon A; Elston, David A; Dennis, Peter

    2005-09-22

    Livestock grazing is a major driver of ecosystem change, and has been associated with significant declines in various bird species worldwide. In Britain, there is particular concern that severe grazing pressure is deleteriously affecting vegetation and birds in upland regions. However, the mechanism by which grazing affects birds is unclear. Here, we report for the first time, to our knowledge, that sheep grazing pressure affects the egg size of a common upland passerine: the meadow pipit Anthus pratensis. We manipulated sheep stocking densities in a replicated field experiment, and found that plots with the highest stocking density contained nests with the smallest eggs, and that plots with low stocking density contained nests with the largest eggs. However, eggs laid in ungrazed plots were also small, suggesting that either too many sheep or their removal from upland areas might have a detrimental effect on pipit egg size. We found no significant effect on fledging success but the reduced post-fledging survival of young from smaller eggs, as seen in other studies, could partly explain declines in upland birds.

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

    Science.gov (United States)

    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

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

    Directory of Open Access Journals (Sweden)

    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.

  5. A grazing clock for measurement of time spent grazing by cattle ...

    African Journals Online (AJOL)

    To date, time spent grazing has been measured most successfully using an electronic grazing clock. Difficulties experienced with this clock however, were that temperature and stage in the life of the batteries affected the readings. Further, periods of grazing shorter than the units of time registered by the clock could not be ...

  6. The grazing capacity of sweetveld: 1 A technique to record grazing ...

    African Journals Online (AJOL)

    A technique is proposed for measuring the grazing capacity of sweet grassveld. The suggested procedure is to record the parameter on plots simulating individual camps in rotational grazing systems. This allows considerably smaller experimental areas to be used than in conventional stocking rate trials. Grazing capacity is ...

  7. Spatial diversity in canopy height at Redshank and Oystercatcher nest-sites in relation to livestock grazing

    NARCIS (Netherlands)

    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

  8. Alterations in serotonin receptor-induced contractility of bovine lateral saphenous vein in cattle grazing endophyte-infected tall fescue

    Science.gov (United States)

    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...

  9. A note on the effects of paddock size on the white clover content of swards grazed by sheep

    NARCIS (Netherlands)

    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

  10. Grazing incidence diffraction : A review

    Energy Technology Data Exchange (ETDEWEB)

    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.

  11. Calcium and Magnesium Released from Residues in an Integrated Crop-Livestock System under Different Grazing Intensities

    Directory of Open Access Journals (Sweden)

    Joice Mari Assmann

    Full Text Available ABSTRACT Under integrated crop-livestock production systems (ICLS, plant and animal residues are important nutrient stocks for plant growth. Grazing management, by affecting the numbers of both plants and animals and the quality of residues, will influence nutrient release rates. The objective of this study was to evaluate the impact of grazing intensity on Ca and Mg release from pasture, dung, and soybean residues in a long-term no-till integrated soybean-cattle system. The experiment was established in May 2001 in a Latossolo Vermelho Distroférrico (Rhodic Hapludox. Treatments were a gradient of grazing intensity, determined by managing a black oat + Italian ryegrass pasture at 10, 20, 30, and 40 cm grazing height and no-grazing (NG, followed by soybean cropping. Ca and Mg release rates were determined in two entire cycles (2009/11. Moderate grazing (20 and 30 cm sward height led to greater Ca and Mg release rates from pasture and dung residues, with low average half-life values (13 and 3 days for Ca and 16 and 6 days for Mg for pasture and dung, respectively. Grazing compared with NG resulted in greater Ca and Mg release from pasture and dung residues. Grazing intensity did not affect Ca and Mg release rates or amounts from soybean residues, but Ca and Mg release rates were greater from soybean leaves than from stems. Although moderate grazing intensities produce higher quality residues and higher calcium and magnesium release rates, a higher total nutrient amount is released by light grazing intensity and no-grazing, determined by higher residue production. Grazing intensity is, then, important for nutrient dynamics in the soil-plant-animal continuum.

  12. Performance and parasitosis in heifers grazing mixed with sows

    OpenAIRE

    Sehested, Jakob; Monrad, J.; Søegaard, Karen; Danielsen, Viggo

    2000-01-01

    The aim of the study was to investigate the effect of mixed grazing with first season heifers and pregnant sows on animal performance, gastro-intestinal helminths, pasture quality and sward structure during three grazing seasons. This presentation will focus on results from 1999, primarily regarding performance and parasitosis in heifers. There have been no earlier reports on such mixed grazing systems. Three grazing systems were studied in replicate: 1) Heifers grazing alone; 2) sows grazing...

  13. The influence of reindeer grazing and trampling on newly seeded fields in Finnmark, Norway

    OpenAIRE

    Lin, Wenjiao

    2011-01-01

    In recent years, conflicts between reindeer herdsmen and resident farmers have increased in Finnmark, northern Norway. The causes of these conflicts vary, but one of the major causes is reindeer grazing and trampling on newly seeded fields in spring and early summer. I studied the effect reindeer have on the production of grass at harvesting time as a result of their grazing and trampling on newly seeded fields in early summer. Field experiments were conducted between June and September 2009 ...

  14. Performance of sheep grazing Brachiaria decumbens, Panicum ...

    African Journals Online (AJOL)

    Performance of sheep grazing Brachiaria decumbens, Panicum maximum and Pennisetum purpureum in combination with gliricidia sepium. ... The animals weregrazed continuously for 28 days in the sub plots. Sheep grazing the Gliricidia/Panicum plot had a higher (P < 001) growth rate (38 g d-1) than those animals ...

  15. Herbage intake by grazing dairy cows

    NARCIS (Netherlands)

    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

  16. 75 FR 29572 - Information Collection; Grazing Management

    Science.gov (United States)

    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...

  17. Prescription of oral anticoagulation for patients with atrial fibrillation and previous hospitalization in a cardiology department. Experience in actual practice in a tertiary hospital.

    Science.gov (United States)

    Fabregat-Andrés, Ó; Cubillos-Arango, A; Chacón-Hernández, N; Montagud, V; Morell, S; Fácila, L

    2015-01-01

    Atrial fibrillation is the main reason for oral anticoagulation in our community. New oral anticoagulants (NOACs) overcome the disadvantages of vitamin K antagonists (VKAs), although there are scarce data on its use in our community. The aim of our study was to assess the use of NOACs and anticoagulation control using VKA as measured by the time within the therapeutic range (TTR) in an actual clinical scenario. A retrospective cohort analysis was conducted of 816 patients admitted to cardiology over a period of 3 years, with a diagnosis of atrial fibrillation and anticoagulant treatment at discharge. We assessed the percentage of patients prescribed NOACs and the TTR with VKA. We compared safety and efficacy events during the 15-month follow-up among the patients prescribed NOAC, those prescribed VKA with a good TTR and those with a poor TTR. The percentage of patients prescribed NOAC was 7.6%. Serial INR measurements found that 71.3% of patients had a poor TTR. Although the groups were not comparable, a higher incidence of the combined event was observed in those treated with VKA and a poor TTR compared with those prescribed NOAC (p=.01). For patients with a previous hospitalization in cardiology in a tertiary hospital and a diagnosis of atrial fibrillation, the rate of NOAC prescription is low, and the TTR with VKA was poor. Copyright © 2015 Elsevier España, S.L.U. y Sociedad Española de Medicina Interna (SEMI). All rights reserved.

  18. Grazing Pressure of Cattle on Mixed Pastures at Coal Mine Land Reclamation

    Directory of Open Access Journals (Sweden)

    T. P. Daru

    2012-04-01

    Full Text Available The objective of the research was to determine the grazing pressure in mix pasture of signal grass (Brachiaria decumbens and puero (Pueraria phaseoloides at coal mining reclamation. The experiment was arranged by randomized block design consisted of 5 stocking rate treatments, those were 12.56, 19.63, 28.26, 38.47, and 50.24 m2.animal-1.d-1 which were equal to length of tether rope of 2.0, 2.5, 3.0, 3.5, and 4.0 m, respectively. The rotation system was applied by modifying the tether. Each rotation period was 30 d of three-rotation period. Result of this experiment showed that average daily gain (ADG was different (P<0.05 with different grazing pressure. Highest total gain has achieved at length of tether rope 2.0 m or grazing area 12.56 m2.animal-1.d-1 and decreased linearly with increasing length of rope from 254.29 to 100.17 kg.ha-1. Maximum dry matter consumption was achieved at length of tether rope of 3.32 m or grazing area 34.61 m2.animal-1.d-1. Average dry matter yield in this experiment was 235.39 g.m-2.d-1 or 2.35 ton.ha-1.mo-1. Botanical composition of signal grass, puero, and weeds before and after grazing was change with grazing pressure.

  19. PREVIOUS SECOND TRIMESTER ABORTION

    African Journals Online (AJOL)

    PNLC

    PREVIOUS SECOND TRIMESTER ABORTION: A risk factor for third trimester uterine rupture in three ... for accurate diagnosis of uterine rupture. KEY WORDS: Induced second trimester abortion - Previous uterine surgery - Uterine rupture. ..... scarred uterus during second trimester misoprostol- induced labour for a missed ...

  20. Remote sensing of grazing effects on vegetation in northern Senegal using MODIS time series

    Science.gov (United States)

    Olsen, J. L.; Miehe, S.; Ceccato, P.; Fensholt, R.

    2013-12-01

    The effect of grazing on vegetation development in the Sahel is a much debated and researched issue. For monitoring grazing intensity remote sensing could be a powerful tool, providing ways to fill some of the unavoidable gaps in information for research in this field. Especially as instruments with moderate spatial resolution capabilities onboard polar orbiting platforms, such as the Moderate Resolution Imaging Spectroradiometer (MODIS), are providing time series of data which are now long enough to allow statistically valid per-pixel examinations. A key issue for proper application of remote sensing observations is an in depth understanding of how variations in surface properties are captured by satellite sensors. In this context, the sensitivity of remote sensing data to the effects of grazing, or lack of grazing, has been little examined. This study examines time series of in situ vegetation measurements sampled under different grazing regimes at the Widou Thiengoly site in semi-arid Northern Senegal and compares these with several growing season parameters. These parameters are derived using the TIMESAT software from time series of MODIS Normalized Difference Vegetation Index (NDVI) product, with 16 day temporal and 250 meters spatial resolution. Areas excluded from grazing are found on average to produce more herbaceous biomass and experience a change in annual species composition, with a greater presence of higher fodder quality species. Furthermore the biomass production in these areas presents a higher correlation to annual rainfall than that observed in adjacent grazed areas. These noticeable differences are only subtly reflected in the growing season parameters derived from MODIS data; e.g. the higher herbaceous biomass and different species composition are not well captured by commonly used parameters such as amplitude or integral of the NDVI time series. In light of these results, conclusions should be made with caution if time series of NDVI metrics

  1. Explaining Research Utilization Among 4-H Faculty, Staff, and Volunteers: The Role of Self-Efficacy, Learning Goal Orientation, Training, and Previous Experience

    Directory of Open Access Journals (Sweden)

    Julianne Tillman

    2014-06-01

    Full Text Available An investigation of factors that facilitate the utilization of research evidence among faculty, staff, and volunteers in the 4-H Youth Development Program is presented in this paper. Participants (N= 368; 86 4-H faculty, 153 staff, and 129 volunteers represented 35 states; structural equation modeling was utilized in the analyses. Results of the path analysis explained 56% of variance in research utilization and 28% in research utilization self-efficacy. Among the factors impacting research utilization, self-efficacy played the most important role. In turn, self-efficacy for research utilization was positively influenced by participants’ learning goal orientation, frequency of 4-H training during the last 12 months, education in research-related areas, and investigative career interests. In addition, 4-H staff who were exposed to research at higher levels reported higher research utilization self-efficacy. The findings reinforce the importance of fostering research utilization self-efficacy among 4-H faculty, staff, and volunteers. Among the suggestions presented are regular 4-H training opportunities and on-going exposure to program evaluation and program improvement experiences.

  2. Influence of previous experience on the preference, food utilization and performance of Ascia monuste orseis wild larvae (Godart) (Lepidoptera: Pieridae) for three different hosts.

    Science.gov (United States)

    Santana, A F K; Zucoloto, F S

    2011-01-01

    The exhaustion of food resources which occurs during the ontogenetic growth of Ascia monuste orseis (Godart) results in the dispersion of older larvae to nearby plants in order to complete their development, which might expose these animals to the nutritional variation of the hosts found. This study aimed to verify whether the food ingested in the beginning of the development influences the larvae host preference and whether the shift to a new host can affect the digestion and performance of A. monuste orseis, using two natural hosts: kale (Brassica oleracea var. acephala) and rocket (Eruca sativa), or kale and cabbage (B. oleracea var. capitata). Larvae were reared throughout their larval development on a single host or on two different hosts. When a host change was tested, larvae were reared for four instars on a host, and offered the other host plant in the fifth instar. Development time, percentage of pupation and emergence, pupal weight, fecundity and digestive indices were evaluated. The change in feeding preference for kale and for rocket in the fourth instar, when those were the original hosts, respectively, shows that prior experience plays a major role in food preference of immature A. monuste orseis. The shift can be beneficial for larval development, depending on the order of the hosts; in general, larvae fed on kale at the end of the development showed better performance. Our results presented strong evidence of a considerable phenotypic plasticity in A. monuste orseis for host preferences.

  3. Effects of Yak grazing on plant community characteristics of meadow grasslands in the Qinghai-Tibetan Plateau, China

    Science.gov (United States)

    Chai, Linrong; Hou, Fujiang; Bowatte, Saman; Cheng, Yunxiang

    2017-04-01

    The Qinghai-Tibetan Plateau (QTP) is an important part of the global terrestrial ecosystem that provides many ecological roles such as biodiversity protection, upper watersheds for large rivers, circulation of materials, energy balance and provision of forage and habitat for livestock and wildlife. Approximately 40% of the QTP is alpine meadow grasslands and yak farming is one of the dominant land use activities. In recent years, the rapid increase in the number of yaks grazing on meadow grasslands has raised concerns about grassland degradation. In this study we examined the effects of yak grazing on the grassland community characteristics to evaluate the degradation potential of alpine meadow in the QTP. The experiment was carried out on three farms, in close proximity to each other, that were operating at different grazing intensities in Maqu county (N35°58', E101°53', altitude 3650m) of the QTP in the Gansu province in China. We tested 4 levels of yak grazing intensities; control (no grazing), light (2.6yak/ha), moderate (3.5yak/ha) and high (6.5yak/ha ). We hypothesized that greater intensity of grazing would significantly impact the plant community characteristics through trampling effects above and below ground. We found grazing significantly (Pgrazed area and lowest in the high grazing farm. In contrast, below ground biomass was significantly greater (pgrazing farm compared to the non grazed area. The plant community density and the proportion of edible grass biomass were not significantly affected by the grazing treatments. The species richness was significantly reduced (pintensity grazing farms compared to the non grazed area. The soil moisture at 0-10 cm depth was significantly lower at the high grazing intensity farm compared to the non grazed area and in contrast soil temperature was significantly higher. Our results indicate that increasing the yak grazing pressure affected the plant community characteristics in alpine meadow in the QTP, indicating

  4. Grazing effects on forage production and botanical composition in a Quercus ithaburensis subs. macrolepis silvopastoral system

    Science.gov (United States)

    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.

  5. Protozoan grazing reduces the current output of microbial fuel cells.

    Science.gov (United States)

    Holmes, Dawn E; Nevin, Kelly P; Snoeyenbos-West, Oona L; Woodard, Trevor L; Strickland, Justin N; Lovley, Derek R

    2015-10-01

    Several experiments were conducted to determine whether protozoan grazing can reduce current output from sediment microbial fuel cells. When marine sediments were amended with eukaryotic inhibitors, the power output from the fuel cells increased 2-5-fold. Quantitative PCR showed that Geobacteraceae sequences were 120 times more abundant on anodes from treated fuel cells compared to untreated fuel cells, and that Spirotrichea sequences in untreated fuel cells were 200 times more abundant on anode surfaces than in the surrounding sediments. Defined studies with current-producing biofilms of Geobacter sulfurreducens and pure cultures of protozoa demonstrated that protozoa that were effective in consuming G. sulfurreducens reduced current production up to 91% when added to G. sulfurreducens fuel cells. These results suggest that anode biofilms are an attractive food source for protozoa and that protozoan grazing can be an important factor limiting the current output of sediment microbial fuel cells. Copyright © 2015 The Authors. Published by Elsevier Ltd.. All rights reserved.

  6. Productivity of grasslands under continuous and rotational grazing

    NARCIS (Netherlands)

    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

  7. 36 CFR 222.11 - Grazing advisory boards.

    Science.gov (United States)

    2010-07-01

    ... 36 Parks, Forests, and Public Property 2 2010-07-01 2010-07-01 false Grazing advisory boards. 222... MANAGEMENT Grazing and Livestock Use on the National Forest System § 222.11 Grazing advisory boards. (a... statutory grazing advisory board in accordance with provisions of the Federal Land Policy and Management Act...

  8. Phytoplankton growth balanced by clam and zooplankton grazing and net transport into the low-salinity zone of the San Francisco Estuary

    Science.gov (United States)

    Kimmerer, Wim J.; Thompson, Janet K.

    2014-01-01

    We estimated the influence of planktonic and benthic grazing on phytoplankton in the strongly tidal, river-dominated northern San Francisco Estuary using data from an intensive study of the low salinity foodweb in 2006–2008 supplemented with long-term monitoring data. A drop in chlorophyll concentration in 1987 had previously been linked to grazing by the introduced clam Potamocorbula amurensis, but numerous changes in the estuary may be linked to the continued low chlorophyll. We asked whether phytoplankton continued to be suppressed by grazing and what proportion of the grazing was by benthic bivalves. A mass balance of phytoplankton biomass included estimates of primary production and grazing by microzooplankton, mesozooplankton, and clams. Grazing persistently exceeded net phytoplankton growth especially for larger cells, and grazing by microzooplankton often exceeded that by clams. A subsidy of phytoplankton from other regions roughly balanced the excess of grazing over growth. Thus, the influence of bivalve grazing on phytoplankton biomass can be understood only in the context of limits on phytoplankton growth, total grazing, and transport.

  9. Effects of chicory/perennial ryegrass swards compared with perennial ryegrass swards on the performance and carcass quality of grazing beef steers.

    Directory of Open Access Journals (Sweden)

    Christina L Marley

    Full Text Available An experiment investigated whether the inclusion of chicory (Cichorium intybus in swards grazed by beef steers altered their performance, carcass characteristics or parasitism when compared to steers grazing perennial ryegrass (Lolium perenne. Triplicate 2-ha plots were established with a chicory/ryegrass mix or ryegrass control. Forty-eight Belgian Blue-cross steers were used in the first grazing season and a core group (n = 36 were retained for finishing in the second grazing season. The experiment comprised of a standardisation and measurement period. During standardisation, steers grazed a ryegrass/white clover pasture as one group. Animals were allocated to treatment on the basis of liveweight, body condition and faecal egg counts (FEC determined 7 days prior to the measurement period. The measurement period ran from 25 May until 28 September 2010 and 12 April until 11 October 2011 in the first and second grazing year. Steers were weighed every 14 days at pasture or 28 days during housing. In the first grazing year, faecal samples were collected for FEC and parasite cultures. At the end of the first grazing year, individual blood samples were taken to determine O. ostertagi antibody and plasma pepsinogen levels. During winter, animals were housed as one group and fed silage. In the second grazing year, steers were slaughtered when deemed to reach fat class 3. Data on steer performance showed no differences in daily live-weight gain which averaged 1.04 kg/day. The conformation, fat grade and killing out proportion of beef steers grazing chicory/ryegrass or ryegrass were not found to differ. No differences in FEC, O. ostertagi antibody or plasma pepsinogen levels of beef steers grazing either chicory/ryegrass or ryegrass were observed. Overall, there were no detrimental effects of including chicory in swards grazed by beef cattle on their performance, carcass characteristics or helminth parasitism, when compared with steers grazing ryegrass.

  10. Study of Plant Species Richness in Habitats with Different Grazing Intensities at Golestan National Park and Surrounding Area

    Directory of Open Access Journals (Sweden)

    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.

  11. Effects of supplementing Leucaena leucocephala and conserved forages from natural pasture on the performance of grazing calves.

    Science.gov (United States)

    Ojo, Victoria Olubunmi A; Aina, Ayobami B J; Fasae, Oladapo A; Oni, Adebayo O; Aderinboye, Ronke Y; Dele, Peter A; Idowu, Oluwaseun J; Adelusi, Oludotun O; Shittu, Olalekan O; Okeniyi, Funmilayo A; Jolaosho, Alaba O

    2014-01-01

    Twelve white Fulani × N'dama cross-bred calves weighing 83.79 ± 1.16 kg were used in an 84-day experiment to investigate the utilization of forage resources from natural grazing land. The experimental diets were sole grazing, grazing + hay, grazing + silage and grazing + Leucaena leucocephala leaves. The calves were divided into four groups of three animals each and were randomly assigned to the four experimental diets. Crude protein (CP) contents of the forages ranged from 59 to 171 g/kg dry matter (DM). Neutral detergent fibre (NDF) and acid detergent fibre (ADF) contents of the forages ranged from 560 to 705 g/kg DM and 363 to 440 g/kg DM, respectively. Significantly (P forage resources. Variations (P forage resources from the natural pasture by the calves was attained on supplementation with conserved forages and L. leucocephala leaves without any deleterious effects on the haematological and serum parameters.

  12. Previous Experience a Model of Practice UNAE

    OpenAIRE

    Ruiz, Ormary Barberi; Pesántez Palacios, María Dolores

    2017-01-01

    The statements presented in this article represents a preliminary version of the proposed model of pre-professional practices (PPP) of the National University of Education (UNAE) of Ecuador, an urgent institutional necessity is revealed in the descriptive analyzes conducted from technical support - administrative (reports, interviews, testimonials), pedagogical foundations of UNAE (curricular directionality, transverse axes in practice, career plan, approach and diagnostic examination as subj...

  13. Previous experiences shape adaptive mate preferences

    NARCIS (Netherlands)

    Fawcett, Tim W.; Bleay, Colin

    2009-01-01

    Existing models of mate choice assume that individuals have perfect knowledge of their own ability to attract a mate and can adjust their preferences accordingly. However, real animals will typically be uncertain of their own attractiveness. A potentially useful source of information on this is the

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

    Directory of Open Access Journals (Sweden)

    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.

  15. Laparoscopy After Previous Laparotomy

    Directory of Open Access Journals (Sweden)

    Zulfo Godinjak

    2006-11-01

    Full Text Available Following the abdominal surgery, extensive adhesions often occur and they can cause difficulties during laparoscopic operations. However, previous laparotomy is not considered to be a contraindication for laparoscopy. The aim of this study is to present that an insertion of Veres needle in the region of umbilicus is a safe method for creating a pneumoperitoneum for laparoscopic operations after previous laparotomy. In the last three years, we have performed 144 laparoscopic operations in patients that previously underwent one or two laparotomies. Pathology of digestive system, genital organs, Cesarean Section or abdominal war injuries were the most common causes of previouslaparotomy. During those operations or during entering into abdominal cavity we have not experienced any complications, while in 7 patients we performed conversion to laparotomy following the diagnostic laparoscopy. In all patients an insertion of Veres needle and trocar insertion in the umbilical region was performed, namely a technique of closed laparoscopy. Not even in one patient adhesions in the region of umbilicus were found, and no abdominal organs were injured.

  16. Impact of grazing on carbon balance of a Belgian grassland

    Science.gov (United States)

    Jérôme, Elisabeth; Beckers, Yves; Bodson, Bernard; Moureaux, Christine; Dumortier, Pierre; Beekkerk van Ruth, Joran; Aubinet, Marc

    2013-04-01

    This work analyzes the impact of grazing on the carbon balance of a grassland grazed by the Belgian Blue breed of cattle. The research was run at the Dorinne terrestrial observatory (DTO). The experimental site is a permanent grassland of ca. 4.2 ha located in the Belgian Condroz (50° 18' 44" N; 4° 58' 07" E; 248 m asl.). Other studies are conducted at the DTO including measurements of methane (CH4) and nitrous oxide fluxes (Dumortier et al., Geophysical Research Abstracts, Vol. 15, EGU2013-2083-1, 2013; Beekkerk van Ruth et al., Geophysical Research Abstracts, Vol. 15, EGU2013-3211, 2013, respectively). Grassland carbon budget (Net Biome Productivity, NBP) was calculated from Net Ecosystem Exchange (NEE) measured by eddy covariance by taking imports and exports of organic C and losses of carbon as CH4 into account. After 2 years of measurements (May 2010 - May 2012), the grassland behaved on average as a CO2 source (NEE = 73 ±31 g C m-2 y-1). After inclusion of all the C inputs and outputs the site was closed to equilibrium (NBP = 23 ±34 g C m-2 y-1). To analyze the impact of grazing on CO2 fluxes, we studied the temporal evolution of gross maximal photosynthetic capacity GPPmax and dark respiration Rd (deduced from the response of daytime fluxes to radiation over 5-day windows). We calculated GPPmax and Rd variation between the end and the beginning of grazing or non-grazing periods (ΔGPPmax and ΔRd, respectively). We observed a significant decrease of GPPmax during grazing periods and measured a ΔGPPmax dependence on the average stocking rate. This allows us to quantify the assimilation reduction due to grass consumption by cattle. On the contrary, no Rd decrease was observed during grazing periods. Moreover, we found that cumulated monthly NEE increased significantly with the average stocking rate. In addition, a confinement experiment was carried out in order to analyze livestock contribution to Total Ecosystem Respiration. Each experiment extended over

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

    International Nuclear Information System (INIS)

    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

  18. Grazing and biodiversity: from selective foraging to wildlife habitats

    OpenAIRE

    Wallis de Vries, M.F.

    2016-01-01

    Livestock grazing in low-intensity farming systems is a key aspect in the conservation of Europe's biodiversity, which reaches high levels of species richness in semi-natural grasslands. With the demise of traditional grazing systems, the design of viable low-intensity grazing systems for the future requires a good understanding of grazing impacts on biodiversity. Here, I review various scale-dependent aspects of selective grazing and how they may affect biodiversity. Insects such as butterfl...

  19. Low intensity, mixed livestock grazing improves the breeding abundance of a common insectivorous passerine.

    Science.gov (United States)

    Evans, Darren M; Redpath, Stephen M; Evans, Sharon A; Elston, David A; Gardner, Charles J; Dennis, Peter; Pakeman, Robin J

    2006-12-22

    Livestock grazing is a major driver of ecosystem change and has been associated with significant declines in various bird species in Britain and worldwide. However, there is little experimental evidence to show how grazing affects bird populations. We manipulated livestock densities in a replicated field experiment and found that mixed sheep and cattle grazing, at low intensity, improved the breeding abundance of a common upland passerine, the meadow pipit Anthus pratensis, after two years. Plots stocked with sheep alone (at high or low density) or not stocked at all held fewer pipit territories. Despite a year-on-year decline in pairs of meadow pipits in intensively grazed plots, we found no effect of sheep number on breeding abundance. Our results support the hypothesis that mixed species of herbivores generate greater heterogeneity in vegetation structure, which modifies prey availability, resulting in a greater abundance of birds. The results of our study should inform the management of grassland areas and enhance the abundance of some bird species, particularly in areas that have seen significant shifts from mixed livestock grazing to grazing dominated by single species of animals.

  20. Dual-purpose wheat grain and animal production under different grazing periods

    Directory of Open Access Journals (Sweden)

    Christiano Santos Rocha Pitta

    2011-10-01

    Full Text Available The objective of this work was to evaluate the influence of different grazing periods on beef animal production and on wheat forage and grain yield. The experiment was carried out in Pato Branco, PR, Brazil. Six grazing periods were evaluated (0, 21, 42, 63, 84, and 105 days on dual-purpose wheat cultivar BRS Tarumã. Purunã steers, with average live weight of 162 kg and ten months of age, were kept under continuous grazing using a variable stocking rate, in order to maintain the established sward height of 25 cm. Greater increases in total animal gain (TAG occurred with longer grazing periods. However, there was little increase after 63 days (490 kg ha-1, and TAG decreased from 552 to 448 kg ha-1 between 84 and 105 days. Grain yield decreased from 2,830 to 610 kg ha-1 when the grazing period increased from 0 to 105 days, but there was little change after 63 days (750 kg ha-1. Cultivar BRS Tarumã shows excellent animal production potential, and the decision on how long wheat pastures should be grazed must be based on relative prices of grain and livestock.

  1. Lagrangian studies of phytoplankton growth and grazing relationships in a coastal upwelling ecosystem off Southern California

    Science.gov (United States)

    Landry, Michael R.; Ohman, Mark D.; Goericke, Ralf; Stukel, Michael R.; Tsyrklevich, Kate

    2009-12-01

    Experimental studies of phytoplankton growth and grazing processes were conducted in the coastal upwelling system off Point Conception, California to test the hypothesis that phytoplankton growth and grazing losses determine, to first order, the local dynamics of phytoplankton in the upwelling circulation. Eight experiments of 3-5 days each were conducted over the course of two cruises in May-June 2006 and April 2007 following the trajectories of satellite-tracked drifters. Rates of phytoplankton growth and microzooplankton grazing were determined by daily in situ dilution incubations at 8 depths spanning the euphotic zone. Mesozooplankton grazing was assessed by gut fluorescence analysis of animals collected from net tows through the euphotic zone. We compared directly the net rates of change observed for the ambient phytoplankton community to the net growth rates predicted from experimental determinations of each process rate. The resulting relationship accounted for 91% of the variability observed, providing strong support for the growth-grazing hypothesis. In addition, grazing by mesozooplankton was unexpectedly high and variable, driving a substantial positive to negative shift in phytoplankton net rate of change between years despite comparable environmental conditions and similar high growth rates and suggesting strong top-down control potential. The demonstrated agreement between net ambient and experimental community changes is an important point of validation for using field data to parameterize models. Data sets of this type may provide an important source of new information and rate constraints for developing better coupled biological-physical models of upwelling system dynamics.

  2. Microbial quality of soil from the Pampa biome in response to different grazing pressures

    Directory of Open Access Journals (Sweden)

    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.

  3. Grazing and pasture management for biodiversity benefit

    OpenAIRE

    Rook, Andrew; Tallowin, Jeremy

    2003-01-01

    International audience; The primary role of grazing animals in grassland biodiversity management is maintenance and enhancement of sward structural heterogeneity, and thus botanical and faunal diversity, by selective defoliation due to dietary choices, treading, nutrient cycling and propagule dispersal. Most research on dietary choices uses model systems that require considerable extrapolation to more complex communities. Grazing animals' diets are constrained by temporal and spatial changes ...

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

    Science.gov (United States)

    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

  5. Additives in ensiling palisade grass managed under grazing intensities

    Directory of Open Access Journals (Sweden)

    Felipe Barros Macedo

    2015-10-01

    Full Text Available Conservation of summer forage excess represents a management strategy to meet animals' needs for dry matter in the shortage period, but has been poorly studied. Silage can be used for this purpose. This study analyzed the production of palisade grass silage from pasture subjected to different grazing intensities with and without additive, determining losses by gases and effluents and chemical composition of silage. The experiment was a 4 x 3 factorial completely randomized design, with four replications. The factors were: 1st – herbage allowance of 5% (5 kg dry matter 100 kg-1 of animal weight day-1, 10, 15 and 20%. The pasture was managed under rotational stocking with 35-day grazing cycles (7 days of occupation and 28 days of rest and 2nd - additives: a control; b citrus pulp pellets; c biological inoculant for grass silage. The forage of palisade grass harvested from pastures subjected to low-intensity grazing showed quantitative and qualitative characteristics for ensiling. However, high humidity and low fermentable carbohydrate require the use of additive, favor the fermentation process and increase the nutritional quality of silage.

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

    Directory of Open Access Journals (Sweden)

    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

  7. Mineral supplementation for grazing ruminants

    International Nuclear Information System (INIS)

    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)

  8. 25 CFR 166.307 - Will the grazing capacity be increased if I graze adjacent trust or non-trust rangelands not...

    Science.gov (United States)

    2010-04-01

    ... 25 Indians 1 2010-04-01 2010-04-01 false Will the grazing capacity be increased if I graze... § 166.307 Will the grazing capacity be increased if I graze adjacent trust or non-trust rangelands not covered by the permit? No. You will not receive an increase in grazing capacity in the permit if you graze...

  9. Impacts of Grazing Intensity and Plant Community Composition on Soil Bacterial Community Diversity in a Steppe Grassland.

    Science.gov (United States)

    Qu, Tong-Bao; Du, Wei-Chao; Yuan, Xia; Yang, Zhi-Ming; Liu, Dong-Bo; Wang, De-Li; Yu, Li-Jun

    2016-01-01

    Soil bacteria play a key role in the ecological and evolutionary responses of agricultural ecosystems. Domestic herbivore grazing is known to influence soil bacterial community. However, the effects of grazing and its major driving factors on soil bacterial community remain unknown for different plant community compositions under increasing grazing intensity. Thus, to investigate soil bacterial community diversity under five plant community compositions (Grass; Leymus chinensis; Forb; L. chinensis & Forb; and Legume), we performed a four-year field experiment with different grazing intensity treatments (no grazing; light grazing, 4 sheep·ha-1; and heavy grazing, 6 sheep·ha-1) in a grassland in China. Total DNA was obtained from soil samples collected from the plots in August, and polymerase chain reaction (PCR) analysis and denaturing gradient gel electrophoresis (DGGE) fingerprinting were used to investigate soil bacterial community. The results showed that light grazing significantly increased indices of soil bacterial community diversity for the Forb and Legume groups but not the Grass and L. chinensis groups. Heavy grazing significantly reduced these soil bacterial diversity indices, except for the Pielou evenness index in the Legume group. Further analyses revealed that the soil N/P ratio, electrical conductivity (EC), total nitrogen (TN) and pH were the major environmental factors affecting the soil bacterial community. Our study suggests that the soil bacterial community diversity was influenced by grazing intensity and plant community composition in a meadow steppe. The present study provides a baseline assessment of the soil bacterial community diversity in a temperate meadow steppe.

  10. Annual and seasonal changes in production and composition of grazed clover-grass mixtures in organic farming

    Directory of Open Access Journals (Sweden)

    E. KUUSELA

    2008-12-01

    Full Text Available A grazed field experiment based on a randomised block design was conducted in Eastern Finland to evaluate the potential of alsike clover (Trifoliun hybridum L., red clover (Trifolium pratense L. and white clover (Trifolium repens L. to support herbage production from clover-grass mixtures under organic farming practices. The effect of seed mixture (alsike clover, red clover, white clover, white and alsike clover or grass mixture, year (1996, 1997 and 1998 and grazing period (5 per grazing season on pre- and post-grazing herbage mass (HM, botanical and chemical composition of pregrazing HM and post-grazing sward height was assessed. The nutritive value of herbage for milk production was also considered. Seed mixtures resulted in different pre-grazing HM and post-grazing sward heights, but similar pre- minus post-grazing HM. Compared with other mixtures, the proportion of clover was higher for white clover based mixtures. The white clover mixture had the highest crude protein content and lowest concentrations of cellulose and hemicellulose. In addition to seed mixture, the effect of year and grazing period on measured parameters was significant, highlighting the importance of grazing management. Moderate pasture herbage production of relative high nutritive value was achieved under organic practices, but the supply and nutritive value of herbage was variable and, in some cases, unable to meet the requirements of lactating dairy cows. The proportion of clover in all seed mixtures decreased year on year, and was subject to seasonal variations that altered the nutritional value of herbage. White clover was the most suitable perennial clover for pastures in Eastern Finland.;

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

    African Journals Online (AJOL)

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

    Directory of Open Access Journals (Sweden)

    Jeffrey M. Warren

    2008-12-01

    Full Text Available The Aspen Parkland of Canada is one of the most important breeding areas for temperate nesting ducks in North America. The region is dominated by agricultural land use, with approximately 9.3 million ha in pasture land for cattle grazing. However, the effects of using land for cattle grazing on upland-nesting duck production are poorly understood. The current study was undertaken during 2001 and 2002 to investigate how nest density and nesting success of upland-nesting ducks varied with respect to the intensity of cattle grazing in the Aspen Parkland. We predicted that the removal and trampling of vegetation through cattle grazing would reduce duck nest density. Both positive and negative responses of duck nesting success to grazing have been reported in previous studies, leading us to test competing hypotheses that nesting success would (1 decline linearly with grazing intensity or (2 peak at moderate levels of grazing. Nearly 3300 ha of upland cover were searched during the study. Despite extensive and severe drought, nest searches located 302 duck nests. As predicted, nest density was higher in fields with lower grazing intensity and higher pasture health scores. A lightly grazed field with a pasture score of 85 out of a possible 100 was predicted to have 16.1 nests/100 ha (95% CI = 11.7-22.1, more than five times the predicted nest density of a heavily grazed field with a pasture score of 58 (3.3 nests/100 ha, 95% CI = 2.2-4.5. Nesting success was positively related to nest-site vegetation density across most levels of grazing intensity studied, supporting our hypothesis that reductions in vegetation caused by grazing would negatively affect nesting success. However, nesting success increased with grazing intensity at the field scale. For example, nesting success for a well-concealed nest in a lightly grazed field was 11.6% (95% CI = 3.6-25.0%, whereas nesting success for a nest with the same level of nest-site vegetation in a heavily grazed

  13. Western land managers will need all available tools for adapting to climate change, including grazing: a critique of Beschta et al.

    Science.gov (United States)

    Svejcar, Tony; Boyd, Chad; Davies, Kirk; Madsen, Matthew; Bates, Jon; Sheley, Roger; Marlow, Clayton; Bohnert, David; Borman, Mike; Mata-Gonzàlez, Ricardo; Buckhouse, John; Stringham, Tamzen; Perryman, Barry; Swanson, Sherman; Tate, Kenneth; George, Mel; Ruyle, George; Roundy, Bruce; Call, Chris; Jensen, Kevin; Launchbaugh, Karen; Gearhart, Amanda; Vermeire, Lance; Tanaka, John; Derner, Justin; Frasier, Gary; Havstad, Kris

    2014-06-01

    In a previous article, Beschta et al. (Environ Manag 51(2):474-491, 2013) argue that grazing by large ungulates (both native and domestic) should be eliminated or greatly reduced on western public lands to reduce potential climate change impacts. The authors did not present a balanced synthesis of the scientific literature, and their publication is more of an opinion article. Their conclusions do not reflect the complexities associated with herbivore grazing. Because grazing is a complex ecological process, synthesis of the scientific literature can be a challenge. Legacy effects of uncontrolled grazing during the homestead era further complicate analysis of current grazing impacts. Interactions of climate change and grazing will depend on the specific situation. For example, increasing atmospheric CO₂ and temperatures may increase accumulation of fine fuels (primarily grasses) and thus increase wildfire risk. Prescribed grazing by livestock is one of the few management tools available for reducing fine fuel accumulation. While there are certainly points on the landscape where herbivore impacts can be identified, there are also vast grazed areas where impacts are minimal. Broad scale reduction of domestic and wild herbivores to help native plant communities cope with climate change will be unnecessary because over the past 20-50 years land managers have actively sought to bring populations of native and domestic herbivores in balance with the potential of vegetation and soils. To cope with a changing climate, land managers will need access to all available vegetation management tools, including grazing.

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

    Science.gov (United States)

    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

  15. Effect of grazing seedhead-suppressed tall fescue pasture on the vasoactivity of serotonin receptors

    Science.gov (United States)

    Previous research has demonstrated that exposure to ergot alkaloids reduces vasoactivity of serotonin (5HT) receptors. Chemical suppression of tall fescue seedhead production is a tool to reduce the level of exposure to ergot alkaloids by a grazing animal. Therefore, the objective was to evaluate co...

  16. Phenolic responses of mountain crowberry (Empetrum nigrum ssp. hermaphroditum) to global climate change are compound specific and depend on grazing by reindeer (Rangifer tarandus).

    Science.gov (United States)

    Väisänen, Maria; Martz, Françoise; Kaarlejärvi, Elina; Julkunen-Tiitto, Riitta; Stark, Sari

    2013-12-01

    Mountain crowberry (Empetrum nigrum ssp. hermaphroditum) is a keystone species in northern ecosystems and exerts important ecosystem-level effects through high concentrations of phenolic metabolites. It has not been investigated how crowberry phenolics will respond to global climate change. In the tundra, grazing by reindeer (Rangifer tarandus) affects vegetation and soil nutrient availability, but almost nothing is known about the interactions between grazing and global climate change on plant phenolics. We performed a factorial warming and fertilization experiment in a tundra ecosystem under light grazing and heavy grazing and analyzed individual foliar phenolics and crowberry abundance. Crowberry was more abundant under light grazing than heavy grazing. Although phenolic concentrations did not differ between grazing intensities, responses of crowberry abundance and phenolic concentrations to warming varied significantly depending on grazing intensity. Under light grazing, warming increased crowberry abundance and the concentration of stilbenes, but decreased e.g., the concentrations of flavonols, condensed tannins, and batatasin-III, resulting in no change in total phenolics. Under heavy grazing, warming did not affect crowberry abundance, and induced a weak but consistent decrease among the different phenolic compound groups, resulting in a net decrease in total phenolics. Our results show that the different phenolic compound groups may show varying or even opposing responses to warming in the tundra at different levels of grazing intensity. Even when plant phenolic concentrations do not directly respond to grazing, grazers may have a key control over plant responses to changes in the abiotic environment, reflecting multiple adaptive purposes of plant phenolics and complex interactions between the biotic and the abiotic factors.

  17. Response of Polygonum viviparum species and community level to long-term livestock grazing in alpine shrub meadow in Qinghai-Tibet Plateau.

    Science.gov (United States)

    Zhu, Zhi-Hong; Lundholm, Jeremy; Li, Yingnian; Wang, Xiaoan

    2008-06-01

    Grazing by domestic herbivores is generally recognized as a major ecological factor and an important evolutionary force in grasslands. Grazing has both extensive and profound effects on individual plants and communities. We investigated the response patterns of Polygonum viviparum species and the species diversity of an alpine shrub meadow in response to long-term livestock grazing by a field manipulative experiment controlling livestock numbers on the Qinghai-Tibet Plateau in China. Here, we hypothesize that within a range of grazing pressure, grazing can alter relative allocation to different plant parts without changing total biomass for some plant species if there is life history trade-offs between plant traits. The same type of communities exposed to different grazing pressures may only alter relative species' abundances or species composition and not vary species diversity because plant species differ in resistant capability to herbivory. The results show that plant height and biomass of different organs differed among grazing treatments but total biomass remained constant. Biomass allocation and absolute investments to both reproduction and growth decreased and to belowground storage increased with increased grazing pressure, indicating the increasing in storage function was attained at a cost of reducing reproduction of bulbils and represented an optimal allocation and an adaptive response of the species to long-term aboveground damage. Moreover, our results showed multiform response types for either species groups or single species along the gradient of grazing intensity. Heavy grazing caused a 13.2% increase in species richness. There was difference in species composition of about 18%-20% among grazing treatment. Shannon-Wiener (H') diversity index and species evenness (E) index did not differ among grazing treatments. These results support our hypothesis.

  18. Effects of Temperature, Salinity, pH, and Light on Filtering and Grazing Rates of a Calanoid Copepod (Schmackeria dubia

    Directory of Open Access Journals (Sweden)

    Changling Li

    2008-01-01

    Full Text Available Calanoid copepods are key components of the marine food web and the food sources of many larval fishes and planktivores, and grazers of phytoplankton. Understanding the ranges of major environmental variables suitable for their growth is essential to maintain the balance between trophic links and resources protection. In this study, the effects of temperature, salinity, pH, and light intensity on the filtering and grazing rates of a herbivorous copepod (Schmackeria dubia were conducted in several control experiments. Our results indicated that experimental animals grazed normally at water temperatures between 15 and 35°C. The filtering and grazing rates increased by onefold at water temperatures from 15 to 25°C, with a peak at around 30°C. S. dubia fed normally at salinity ranging from 20 to 30 ppt, with significantly low filtering and grazing rates at salinity below 15 ppt and above 35 ppt. The filtering and grazing rates increased as pH increased, peaked at approximately 8.5, and then decreased substantially. Light intensity also displayed an important impact on the filtering and grazing rates. Filtering and grazing rates were high when light intensity was greater than 20 and less than 200 µmol m-2 s-1. S. dubia nearly stopped feeding at low light intensity (less than 20 µmol m-2 s-1.

  19. Differential Responses of Soil Microbial Community to Four-Decade Long Grazing and Cultivation in a Semi-Arid Grassland

    Directory of Open Access Journals (Sweden)

    Yating He

    2017-01-01

    Full Text Available Grazing and cultivation are two important management practices worldwide that can cause significant soil organic carbon (SOC losses. However, it remains elusive how soil microbes have responded to soil carbon changes under these two practices. Based on a four-decade long field experiment, this study investigated the effects of grazing and cultivation on SOC stocks and microbial properties in the semi-arid grasslands of China. We hypothesize that grazing and cultivation would deplete SOC and depress microbial activities under both practices. However, our hypotheses were only partially supported. As compared with the adjacent indigenous grasslands, SOC and microbial biomass carbon (MBC were decreased by 20% or more under grazing and cultivation, which is consistent with the reduction of fungi abundance by 40% and 71%, respectively. The abundance of bacteria and actinomycetes was decreased under grazing but increased under cultivation, which likely enhanced microbial diversity in cultivation. Invertase activity decreased under the two treatments, while urease activity increased under grazing. These results suggest that nitrogen fertilizer input during cultivation may preferentially favor bacterial growth, in spite of SOC loss, due to rapid decomposition, while overgrazing may deteriorate the nitrogen supply to belowground microbes, thus stimulating the microbial production of nitrogen acquisition enzymes. This decade-long study demonstrated differential soil microbial responses under grazing and cultivation and has important applications for better management practices in the grassland ecosystem.

  20. Shifts in positive and negative plant interactions along a grazing intensity gradient.

    Science.gov (United States)

    Graff, Pamela; Aguiar, Martín R; Chaneton, Enrique J

    2007-01-01

    Isolating the single effects and net balance of negative and positive species effects in complex interaction networks is a necessary step for understanding community dynamics. Facilitation and competition have both been found to operate in harsh environments, but their relative strength may be predicted to change along gradients of herbivory. Moreover, facilitation effects through habitat amelioration and protection from herbivory may act together determining the outcome of neighborhood plant-plant interactions. We tested the hypothesis that grazing pressure alters the balance of positive and negative interactions between palatable and unpalatable species by increasing the strength of positive indirect effects mediated by associational resistance to herbivory. We conducted a two-year factorial experiment in which distance (i.e., spatial association) from the nearest unpalatable neighbor (Stipa speciosa) and root competition were manipulated for two palatable grasses (Poa ligularis and Bromus pictus), at three levels of sheep grazing (none, moderate, and high) in a Patagonian steppe community. We found that grazing shifted the effect of Stipa on both palatable grasses, from negative (competition) in the absence of grazing to positive (facilitation) under increasing herbivore pressure. In ungrazed sites, belowground competition was the dominant interaction, as shown by a significant reduction in performance of palatable grasses transplanted near to Stipa tussocks. In grazed sites, biomass of palatable plants was greater near than far from Stipa regardless of competition treatment. Proximity to Stipa reduced the amount of herbivory suffered by palatable grasses, an indirect effect that was stronger under moderate than under intense grazing. Our results demonstrate that facilitation, resulting mainly from protection against herbivory, is the overriding effect produced by unpalatable neighbors on palatable grasses in this rangeland community. This finding challenges the

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

    Directory of Open Access Journals (Sweden)

    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.

  2. Diversity and structure of a bacterial community in grassland soils disturbed by sheep grazing, in the Loess Plateau of northwestern China.

    Science.gov (United States)

    Gou, Y N; Nan, Z B; Hou, F J

    2015-12-15

    The relationship between disturbance, biodiversity, and ecosystem function has been a hot topic recently in international ecological research, and a universally applicable model remains elusive. In this study, we assessed the diversity and structure of a bacterial community in grassland soils along a disturbance gradient due to sheep grazing. Bacteria were identified based on 16S rDNA gene libraries prepared from a 12-year field experiment that included four grazing, intensity treatments: no grazing, light grazing, moderate grazing and heavy grazing in the Loess Plateau of northwestern China. We found that diversity indices of bacterial 16S rDNA increased with grazing intensity, suggesting that disturbance led to higher bacterial diversity. The bacterial community structure, measured as species composition, was also affected by grazing. In addition, the change in soil bacterial community composition was maximum under heavy grazing, based on the Sorensen similarity index. Overall, the relationship between disturbance and bacterial diversity is complex, therefore, more studies are required to determine the possibility of using microbial diversity as an indicator of ecosystem stability.

  3. Grazing impact of the invasive clam Corbula amurensis on the microplankton assemblage of the northern San Francisco Estuary

    Science.gov (United States)

    Greene, Valerie E.; Sullivan, Lindsay J.; Thompson, Janet K.; Kimmerer, Wim J.

    2011-01-01

    Grazing by the overbite clam Corbula amurensis (formerly known as Potamocorbula) may be the cause of substantial declines in phytoplankton biomass and zooplankton in the San Francisco Estuary (SFE) following its introduction in 1986. While grazing rates have been examined on bacteria, phytoplankton, and copepod nauplii, the consumption of protistan microzooplankton by C. amurensis has not previously been measured. In this study, laboratory feeding experiments revealed that C. amurensis cleared 0.5 l ind-1 h-1 of microzooplankton (ciliates) and 0.2 l ind-1 h-1 of chlorophyll (chl) a. Despite the higher clearance rate on microzooplankton, clams obtained more of their carbon from phytoplankton, which dominated the prey assemblage on most dates. When the measured clearance rates are extrapolated to field populations of clams, fractional loss rates (50 to 90% d-1) exceed the population growth capacity of microzooplankton. Although microzooplankton may not be a major component of the diet of these clams, C. amurensis may further alter food web dynamics through consumption of this important trophic intermediary, thus disrupting this link from bacteria and phytoplankton to higher trophic levels.

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

    Science.gov (United States)

    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

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

    Directory of Open Access Journals (Sweden)

    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.

  6. Effects of grazing intensity and environmental factors on species composition and diversity in typical steppe of Inner Mongolia, China.

    Science.gov (United States)

    Ren, Haiyan; Schönbach, Philipp; Wan, Hongwei; Gierus, Martin; Taube, Friedhelm

    2012-01-01

    In the present study, we aim to analyze the effect of grazing, precipitation and temperature on plant species dynamics in the typical steppe of Inner Mongolia, P.R. China. By uncoupling biotic and abiotic factors, we provide essential information on the main drivers determining species composition and species diversity. Effects of grazing by sheep were studied in a controlled experiment along a gradient of seven grazing intensities (from ungrazed to very heavily grazed) during six consecutive years (2005-2010). The results show that plant species composition and diversity varied among years but were little affected by grazing intensity, since the experimental years were much dryer than the long term average, the abiotic constraints may have overridden any grazing effect. Among-year differences were predominantly determined by the abiotic factors of precipitation and temperature. Most of the variation in species dynamics and coexistence between C3 and C4 species was explained by seasonal weather conditions, i.e. precipitation and temperature regime during the early-season (March-June) were most important in determining vegetation dynamics. The dominant C3 species Stipa grandis was highly competitive in March-June, when the temperature levels were low and rainfall level was high. In contrast, the most common C4 species Cleistogenes squarrosa benefited from high early-season temperature levels and low early-season rainfall. However, biomass of Stipa grandis was positively correlated with temperature in March, when effective mean temperature ranges from 0 to 5°C and thus promotes vernalization and vegetative sprouting. Our results suggest that, over a six-year term, it is temporal variability in precipitation and temperature rather than grazing that determines vegetation dynamics and species co-existence of grazed steppe ecosystems. Furthermore, our data support that the variability in the biomass of dominant species, rather than diversity, determine ecosystem

  7. Short-term spider community monitoring after cattle removal in grazed grassland

    Directory of Open Access Journals (Sweden)

    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.

  8. STRUCTURE AND NUTRITIVE VALUE OF DEFERRED PASTURE OF BRACHIARIA DECUMBENS CV. BASILISK DURING THE GRAZING PERIOD

    Directory of Open Access Journals (Sweden)

    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.

  9. An analysis of the fundamentals of grazing management systems ...

    African Journals Online (AJOL)

    An analysis of the fundamentals of grazing management systems. Booysen PD. Abstract. The resting and grazing components of grazing management cycles as practiced in South Africa are evaluated from the points of view of objective and effect. While the desirability of resting for seeding and an increase in vigour is ...

  10. Impact of Prosopis (mesquite) invasion and clearing on the grazing ...

    African Journals Online (AJOL)

    Our results indicate that Prosopis invasion (>13% mean canopy cover) can lower grazing capacity in Nama Karoo rangeland, whereas clearing Prosopis from such rangeland can, even under heavy grazing, substantially improve grazing capacity within 4–6 years. Keywords: exotic invasive plants, management, natural ...

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

    African Journals Online (AJOL)

    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. Grazing capacity estimates: why include biomass estimates from ...

    African Journals Online (AJOL)

    Forage for ruminants in the dry season were assessed and matched with feed requirements in three villages in Zimbabwe, namely; Chiweshe, Makande and Mudzimu. Stocking rates were compared with grazing capacity to determine grazing intensities. Grazing capacities were estimated with and without crop residues to ...

  13. Grazing and biodiversity: from selective foraging to wildlife habitats

    NARCIS (Netherlands)

    Wallis de Vries, M.F.

    2016-01-01

    Livestock grazing in low-intensity farming systems is a key aspect in the conservation of Europe's biodiversity, which reaches high levels of species richness in semi-natural grasslands. With the demise of traditional grazing systems, the design of viable low-intensity grazing systems for the future

  14. Livestock grazing behaviour along a degradation gradient in the ...

    African Journals Online (AJOL)

    Six each of male cattle, sheep, goats and camels, with average masses of 200, 35, 30 and 220 kg, respectively, were used and randomly assigned for unrestricted grazing. Species selectivity, grazing time, grazing intensity and number of bites were recorded. Forage mass intake per animal per day was estimated through a ...

  15. Recent trends in grazing management philosophy in South Africa ...

    African Journals Online (AJOL)

    In contrast, considerably more evidence has emerged to support the general philosophy which has built up over the years on such issues as optimum stocking rates, periods of absence, stocking densities and the required number of camps in grazing layouts. Keywords: change; grazing intensity; grazing management; herd ...

  16. Response of lambs to continuous and rotational grazing at four ...

    African Journals Online (AJOL)

    was grazed either continuously or rotationally at four grazing intensities by three successive sets of weaned lambs for the winter, spring and summer periods, respectively. The "put-and-take" system was applied. In the case of continuous grazing, amounts of available dry matter (DM) per hectare were varied, whereas with ...

  17. Impact of Livestock Grazing on Abundance and Community ...

    African Journals Online (AJOL)

    A survey of the impact of cattle grazing on macro invertebrate fauna of Ovia River was carried out between January and June 2004. Macro invertebrate and water samples were collected from three sampling locations; station I (new grazing area for cattle), station II (initial grazing area) and station III (control location). A total ...

  18. The economic cost of noxious weeds on Montana grazing lands

    Science.gov (United States)

    We distributed a 16-question survey concerning noxious weed abundances, impacts and management to livestock producers grazing on privately-owned or leased grazing lands in Montana. The noxious weeds most commonly reported as being present on respondents’ grazing units were Canada thistle (64% of gra...

  19. The evaluation of pastures and grazing management in terms of ...

    African Journals Online (AJOL)

    The evaluation of pastures and grazing management in terms of livestock production. ... African Journal of Range and Forage Science ... Abstract. Grazing research in South Africa has been largely pasture oriented and consequently there is still a need to fully evaluate many of our more important pasture types and grazing ...

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

    Science.gov (United States)

    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 ...

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

    African Journals Online (AJOL)

    The consequences of these affect lives, properties and the environment. The country now has approximately 210 persons and 180 grazing animals per kilometer square of land and 15,000 persons and 12,500 grazing animals per kilometer square of water. With the population of both man and grazing animals increasing at ...

  2. 25 CFR 166.305 - When is grazing capacity determined?

    Science.gov (United States)

    2010-04-01

    ... 25 Indians 1 2010-04-01 2010-04-01 false When is grazing capacity determined? 166.305 Section 166... and Operations Management § 166.305 When is grazing capacity determined? Before we grant, modify, or approve a permit, in consultation with the Indian landowners, we will establish the total grazing capacity...

  3. Grazing in juvenile stages of some estuarine calanoid copepods

    Energy Technology Data Exchange (ETDEWEB)

    Allan, J.D. (Univ. of Maryland, College Park); Richman, S.; Heinle, D.R.; Huff, R.

    1977-01-01

    The grazing of juvenile Eurytemora affinis, Acartia tonsa and A. clausi from the Chesapeak Bay (USA) was investigated using natural particle distributions and freshly caught copepods, live-sorted into stages. Data were analyzed in greater than or equal to 110 size channels using an electronic particle counter, and filtering rates (FR) were estimated based on total particle removal (mean FR), and that for each size channel (giving maximum FR). Mean and maximum filtering rates increased from NVI (Nauplius Stage VI) through CVI (Copepodid Stage VI). Both rates plotted against weight satisfied a log fit best for A. tonsa, and a linear fit best for E. affinis. Results for A. tonsa were quite variable, apparently due to differences in temperature between experiments. Particle selection was investigated from the shape of the filtering rate curve over particle size. We define selective feeding by a FR curve which is higher in some size categories, and non-selective feeding by a flat FR curve. The general pattern was one of selective feeding in all copepodid stages of the three calanoid copepods investigated. E. affinis tended to ''track'' biomass peaks while Acartia spp.'s feeding was more variable, including feeding in size ranges of greater particle concentration, on larger particles, and in other size categories as well. Experiments with nauplii tended to yield flat FR curves, and it may be that selective grazing appears with, or is greatly accentuated by, metamorphosis from NVI to CI (Copepodid Stage I).

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

    Directory of Open Access Journals (Sweden)

    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.

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

    African Journals Online (AJOL)

    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 ...

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

    DEFF Research Database (Denmark)

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

    2015-01-01

    experiment gave similar results for ingestion rates and daily rations. Krill biomass was highest in the central part of the fjord’s length, with T. raschii dominating. Community grazing rates from krill and copepods were comparable; however, their combined impact was low, estimated as

  7. Milk urea concentration as an indicator of ammonia emission from dairy cow barn under restricted grazing

    NARCIS (Netherlands)

    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

  8. Effects of perennial ryegrass cultivars on milk yield and nitrogen utilization in grazing dairy cows

    NARCIS (Netherlands)

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

    2006-01-01

    The effects of 4 diploid perennial ryegrass cultivars that differed in water-soluble carbohydrate (WSC) concentrations on milk yield and nitrogen (N) utilization in dairy cows were evaluated in a 2-yr grazing experiment. Twelve lactating dairy cows were assigned to 1 cultivar for a 2-wk period in a

  9. Response of a subalpine grassland to simulated grazing: Aboveground productivity along soil phosphorus gradients

    Science.gov (United States)

    C. Thiel-Egenter; A. C. Risch; M. F. Jurgensen; D. S. Page-Dumroese; B. O. Krusi; M. Schutz

    2007-01-01

    Interactions between grassland ecosystems and vertebrate herbivores are critical for a better understanding of ecosystem processes, but diverge widely in different ecosystems. In this study, we examined plant responses to simulated red deer (Cervus elaphus L.) grazing using clip-plot experiments in a subalpine grassland ecosystem of the Central...

  10. Intake Regulation and Grazing Behavior of Dairy Cows Under Continuous Stocking

    NARCIS (Netherlands)

    Taweel, H.Z.; Tas, B.M.; Dijkstra, J.; Tamminga, S.

    2004-01-01

    This experiment aimed at studying the behavioral strategies grazing dairy cows use to satisfy their nutritional needs as the day progresses and the possible role of rumen fill in controlling these behavioral strategies. The day was divided into 3 main periods (0600 to 1200 h, 1200 to 1800 h, and

  11. Yield and soil carbon sequestration in grazed pastures sown with two or five forage species

    Science.gov (United States)

    Increasing plant species richness is often associated with an increase in productivity and associated ecosystem services such as soil C sequestration. In this paper we report on a nine-year experiment to evaluate the relative forage production and C sequestration potential of grazed pastures sown to...

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

    NARCIS (Netherlands)

    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

  13. Chapter 2: Livestock and Grazed Lands Emissions

    Science.gov (United States)

    A total of 342 MMT CO2 eq. of greenhouse gasses (GHGs) were emitted from livestock, managed livestock waste, and grazed land in 2013. This represents about 66% of total emissions from the agricultural sector, which totaled 516 MMT CO2 eq. Compared to the base line year (1990), emissions from livesto...

  14. Dietary selection by steers grazing kikuyu

    African Journals Online (AJOL)

    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.

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

    African Journals Online (AJOL)

    Adopting a systems view and regenerative philosophy can indicate how to regenerate ecosystem function on commercial-scale agro-ecological landscapes. Adaptive multi-paddock grazing management is an example of an approach for grazinglands. Leading conservation farmers have achieved superior results in ...

  16. Estimating phosphorus intake by grazing sheep

    African Journals Online (AJOL)

    Estimating phosphorus intake in grazing sheep is ditficult since hand-picked ... Thus to establish the intake of phosphorus, a method other than forage .... between the mean (tSD) levels in the ribs of the sheep and the. S.-Afr. Tydskr. Veek. 19g3, l3(3) of phosphorus and feed they consumed. Determination. Specimen".

  17. 50 CFR 35.9 - Livestock grazing.

    Science.gov (United States)

    2010-10-01

    ... 50 Wildlife and Fisheries 6 2010-10-01 2010-10-01 false Livestock grazing. 35.9 Section 35.9 Wildlife and Fisheries UNITED STATES FISH AND WILDLIFE SERVICE, DEPARTMENT OF THE INTERIOR (CONTINUED) THE..., reconstruction or relocation of only those livestock management improvements and structures which existed within...

  18. Ecology of grazing lawns in Africa

    CSIR Research Space (South Africa)

    Hempson, GP

    2014-09-01

    Full Text Available rates of nitrogen cycling and of sodium levels to lawn maintenance. Grazer community composition and density has considerable significance to grazing lawn dynamics; not all grazers are adapted to foraging on short-grass swards, and differences in body...

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

    African Journals Online (AJOL)

    Rangeland management strategies must be based on robust ecological and economic concepts if they are to be effective and profitable. Thus, the aim of this paper was to examine concepts related to grazing and resting of grassland and associated effects on grassland productivity and energy flow to livestock. Our review ...

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

    African Journals Online (AJOL)

    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 ...

  1. The effects of zero grazing in Ethiopia

    NARCIS (Netherlands)

    Cao, De E.; Berg, van den M.M.; Tizale, C.Y.; Wondwosen, T.

    2013-01-01

    In the high lands of Ethiopia, almost every plot of farmland is allotted for crop husbandry, leaving no or only road sides and marginal lands for grazing. However, land is scarce in these areas and this limits the role of crop production in poverty alleviation and it also limits the availability of

  2. Using digital photography to examine grazing in montane meadows

    Science.gov (United States)

    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.

  3. Long-term reindeer grazing limits warming-induced increases in CO2 released by tundra heath soil: potential role of soil C quality

    International Nuclear Information System (INIS)

    Väisänen, Maria; Stark, Sari; Sjögersten, Sofie; Large, David; Drage, Trevor

    2015-01-01

    The current climate warming in the Arctic may increase the microbial degradation of vast pools of soil carbon (C); however, the temperature sensitivity of decomposition is often highly dependent on the quality of accumulated soil C. Grazing by reindeer (Rangifer tarandus L.) substantially affects the dominant vegetation and often increases graminoids in relation to dwarf shrubs in ecosystems, but the effect of this vegetation shift on the soil C quality has not been previously investigated. We analyzed the soil C quality and rate of microbially mediated CO 2 release at different temperatures in long-term laboratory incubations using soils from lightly grazed dwarf shrub-dominated and heavily grazed graminoid-dominated tundra ecosystem. The soil C quality was characterized by solid-state cross-polarization magic angle spinning (CPMAS 13 C NMR) spectroscopy, which showed a higher relative proportion of carbohydrate C under light grazing and higher relative proportion of aliphatic not-O-substituted C under heavy grazing. Initial measurements showed lower temperature sensitivity of the CO 2 release in soils under light grazing compared with soil under heavy grazing, but the overall CO 2 release rate and its temperature sensitivity increased under light grazing as the soil incubation progressed. At the end of incubation, significantly more carbohydrate C had been lost in soils under light grazing compared with heavy grazing. These findings indicate that there may be a link between the grazer-induced effects on soil C quality and the potential of soils to release CO 2 to atmosphere. We suggest that vegetation shifts induced by grazing could influence the proportion of accumulated soil C that is vulnerable to microbial degradation under warming climate. (letter)

  4. Woodlands Grazing Issues in Mediterranean Basin

    Science.gov (United States)

    Campos, P.

    2009-04-01

    In Mediterranean basin, woodlands grazing still continue to be important commercial owners' benefits. These owners manage woodlands vegetations as if they were not at risk of degradation and declining. Frequently, no temporally grazing set-aside is taken into account to avoid overgrazing of annual and perennial vegetations. Although less common, in the northern shore of Mediterranean basin undergrazing might increase the frequency and the number of catastrophic forest fires. This under/over grazing regime occurs in the Mediterranean basin woodlands with contrasted differences on land property rights, local economies and government livestock policy incentives. Spain and Tunisia are examples of these Mediterranean livestock contrasts. Most of Spanish Mediterranean woodlands and livestock herds are large private ownerships and owners could maintain their lands and livestock herds properties on the basis of moderate cash-income compensation against land revaluation and exclusive amenity self-consumption. The later is less tangible benefit and it could include family land legacy, nature enjoyment, country stile of life development, social status and so on. In public woodlands, social and environmental goals -as they are cultural heritage, biodiversity loss mitigation, soil conservation and employment- could maintain market unprofitable woodlands operations. Last three decades Spanish Mediterranean woodlands owners have increased the livestock herds incentivized by government subsidies. As result, grazing rent is pending on the level of European Union and Spanish government livestock subsidies. In this context, Spanish Mediterranean woodlands maintain a high extensive livestock stoking population, which economy could be called fragile and environmentally unsustainable because forest degradation and over/under grazing practices. Tunisian Mediterranean woodlands are state properties and livestock grazing is practice as a free private regimen. Livestock herds are small herd

  5. Testing for direct anthelmintic effects of bioactive forages against Trichostrongylus colubriformis in grazing sheep.

    Science.gov (United States)

    Athanasiadou, S; Tzamaloukas, O; Kyriazakis, I; Jackson, F; Coop, R L

    2005-02-28

    The aim of the present study was to investigate potential direct anthelmintic effects of forages that contain plant secondary metabolites (PSM) towards the intestinal nematode Trichostrongylus colubriformis. For this purpose, we introduced an experimental design, which enabled us to investigate the direct anthelmintic effects of PSM-rich forages, without significant interference of possible indirect immunological effects of PSM. Sixty parasite naive sheep were infected with 8000 T. colubriformis L(3) on day 1 of the experiment. On day 28, sheep entered one of the experimental plots, which consisted of four PSM-rich forages and one control: Lotus pedunculatus (lotus), Hedysarium coronarium (sulla), Onobrychis viciifolia (sainfoin), Cichorium intybus (chicory) and Lolium perenne/Trifolium repens (grass/clover). On day 35 of the experiment, all sheep were re-infected with 8000 T. colubriformis L(3) and were killed on day 42. By day 42, all parasites of the primary infection would have been recovered as adults, whereas those of the secondary challenge would have only developed to the fourth stage larvae within a week (i.e. days 35-42). The first batch of larvae would enable us to investigate possible direct anthelmintic effects of PSM-rich forages against adult T. colubriformis, whereas the second one whether grazing on the PSM-rich forages could affect the establishment of the incoming infective larvae. Sheep grazing on lotus tended to have a lower FEC compared to sheep grazing on grass/clover (P = 0.06), whereas daily faecal output was higher in sheep grazing lotus compared to those grazing on the other forages (P forages for a period of 2 weeks did not affect the immature and adult parasite populations. Although the present experimental design enabled us to test the experimental hypothesis, the lack of evidence on a direct anthelmintic effect of PSM-rich forages can not be considered conclusive, as the composition of PSM-rich forages is variable within and across

  6. Zooplankton Grazing Effects on Particle Size Spectra under Different Seasonal Conditions

    Science.gov (United States)

    Stamieszkin, K.; Poulton, N.; Pershing, A. J.

    2016-02-01

    Oceanic particle size spectra can be used to explain and predict variability in carbon export efficiency, since larger particles are more likely to sink to depth than small particles. The distribution of biogenic particle size in the surface ocean is the result of many variables and processes, including nutrient availability, primary productivity, aggregation, remineralization, and grazing. We conducted a series of grazing experiments to test the hypothesis that mesozooplankton shift particle size spectra toward larger particles, via grazing and egestion of relatively large fecal pellets. These experiments were carried out over several months, and used natural communities of mesozooplankton and their microbial prey, collected offshore of the Damariscotta River in the Gulf of Maine. We analyzed the samples using Fluid Imaging Technologies' FlowCam®, a particle imaging system. With this equipment, we processed live samples, decreasing the likelihood of losing or damaging fragile particles, and thereby lessening sources of error in commonly used preservation and enumeration protocols. Our results show how the plankton size spectrum changes as the Gulf of Maine progresses through a seasonal cycle. We explore the relationship of grazing community size structure to its effect on the overall biogenic particle size spectrum. At some times of year, mesozooplankton grazing does not alter the particle size spectrum, while at others it significantly does, affecting the potential for biogenic flux. We also examine prey selectivity, and find that chain diatoms are the only prey group preferentially consumed. Otherwise, we find that complete mesozooplankton communities are "evolved" to fit their prey such that most prey groups are grazed evenly. We discuss a metabolic numerical model which could be used to universalize the relationships between whole gazer and whole microbial communities, with respect to effects on particle size spectra.

  7. Design and development of grazing incidence x-ray mirrors

    Science.gov (United States)

    Zuo, Fuchang; Mei, Zhiwu; Ma, Tao; Deng, Loulou; Shi, Yongqiang; Li, Liansheng

    2016-01-01

    X-ray pulsar navigation has attracted extensive attentions from academy and engineering domains. The navigation accuracy is can be enhanced through design of X-ray mirrors to focus X-rays to a small detector. The Wolter-I optics, originally proposed based on a paraboloid mirror and a hyperboloid mirror for X-ray imaging, has long been widely developed and employed in X-ray observatory. Some differences, however, remain in the requirements on optics between astronomical X-ray observation and pulsar navigation. The simplified Wolter-I optics, providing single reflection by a paraboloid mirror, is more suitable for pulsar navigation. In this paper, therefore, the grazing incidence X-ray mirror was designed further based on our previous work, with focus on the reflectivity, effective area, angular resolution and baffles. To evaluate the performance of the manufactured mirror, the surface roughness and reflectivity were tested. The test results show that the grazing incidence mirror meets the design specifications. On the basis of this, the reflectivity of the mirror in the working bandwidth was extrapolated to evaluate the focusing ability of the mirror when it works together with the detector. The purpose of our current work to design and develop a prototype mirror was realized. It can lay a foundation and provide guidance for the development of multilayer nested X-ray mirror with larger effective area.

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

    Directory of Open Access Journals (Sweden)

    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.

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

    Science.gov (United States)

    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.

  10. Quantification of uncertainties in global grazing systems assessment

    Science.gov (United States)

    Fetzel, T.; Havlik, P.; Herrero, M.; Kaplan, J. O.; Kastner, T.; Kroisleitner, C.; Rolinski, S.; Searchinger, T.; Van Bodegom, P. M.; Wirsenius, S.; Erb, K.-H.

    2017-07-01

    Livestock systems play a key role in global sustainability challenges like food security and climate change, yet many unknowns and large uncertainties prevail. We present a systematic, spatially explicit assessment of uncertainties related to grazing intensity (GI), a key metric for assessing ecological impacts of grazing, by combining existing data sets on (a) grazing feed intake, (b) the spatial distribution of livestock, (c) the extent of grazing land, and (d) its net primary productivity (NPP). An analysis of the resulting 96 maps implies that on average 15% of the grazing land NPP is consumed by livestock. GI is low in most of the world's grazing lands, but hotspots of very high GI prevail in 1% of the total grazing area. The agreement between GI maps is good on one fifth of the world's grazing area, while on the remainder, it is low to very low. Largest uncertainties are found in global drylands and where grazing land bears trees (e.g., the Amazon basin or the Taiga belt). In some regions like India or Western Europe, massive uncertainties even result in GI > 100% estimates. Our sensitivity analysis indicates that the input data for NPP, animal distribution, and grazing area contribute about equally to the total variability in GI maps, while grazing feed intake is a less critical variable. We argue that a general improvement in quality of the available global level data sets is a precondition for improving the understanding of the role of livestock systems in the context of global environmental change or food security.

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

    Science.gov (United States)

    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.

  12. Efeito do pastejo rotacionado e alternado com bovinos adultos no controle da verminose em ovelhas Effect of rotational and alternate grazing with adult cattle on the control of nematode parasites in sheep

    Directory of Open Access Journals (Sweden)

    L.H. Fernandes

    2004-12-01

    Full Text Available Estudaram-se os efeitos do pastejo alternado de ovinos e bovinos e do pastejo rotacionado sobre o controle da verminose em ovelhas. Utilizou-se uma área experimental composta por três módulos de 1,67ha cada. Os módulos foram subdivididos em oito piquetes. Vinte ovelhas foram colocadas no módulo 1 e quatro bovinos adultos no módulo 2. Os animais permaneceram em cada piquete do módulo por cinco dias, totalizando 40 dias de permanência em cada módulo. Ao final desse período, as ovelhas foram transferidas para o módulo onde estavam os bovinos e estes para o módulo onde estavam os ovinos, mantendo esse esquema até o final do experimento. Um grupo-controle de 20 ovelhas foi mantido, também em sistema rotacionado, em um terceiro módulo, sem compartilhar a pastagem. As ovelhas submetidas ao manejo com bovinos apresentaram o menor grau de infecção por nematódeos gastrintestinais e os maiores valores de volume globular. O pastejo rotacionado de ovinos, sem a utilização de bovinos, não foi eficiente no controle da verminose das ovelhas. A utilização do pastejo rotacionado e alternado de ovinos e bovinos adultos exerceu efeito benéfico significativo no controle da verminose ovina.The effects of rotational and alternate grazing involving cattle and sheep on the control of nematode parasites in sheep were evaluated. Three areas with 1.67ha were subdivided into eight paddocks each. Twenty ewes and four cattle were allotted to areas 1 and 2, respectively. They grazed during five days in each of eight paddocks of each area. The sheep and cattle rotated in each area for 40 days. At the end of this period, ewes were transferred to the area where cattle were previously kept and these animals were transferred to the area where sheep had previously grazed. This arrangement was kept until the end of the experiment. A control group with 20 ewes rotated in the third area, also with eight paddocks. Ewes that alternately grazed with cattle showed

  13. Novel micro-reactor flow cell for investigation of model catalysts using in situ grazing-incidence X-ray scattering

    DEFF Research Database (Denmark)

    Kehres, Jan; Pedersen, Thomas; Masini, Federico

    2016-01-01

    -incidence small-angle X-ray scattering (GISAXS) in transmission through 10 µm-thick entrance and exit windows by using micro-focused beams. An additional thinning of the Pyrex glass reactor lid allows simultaneous acquisition of the grazing-incidence wide-angle X-ray scattering (GIWAXS). In situ experiments......The design, fabrication and performance of a novel and highly sensitive micro-reactor device for performing in situ grazing-incidence X-ray scattering experiments of model catalyst systems is presented. The design of the reaction chamber, etched in silicon on insulator (SIO), permits grazing...

  14. Degradation of abamectin and doramectin on sheep grazed pasture.

    Science.gov (United States)

    Erzen, Nevenka Kozuh; Kolar, Lucija; Flajs, Vesna Cerkvenik; Kuzner, Jernej; Marc, Irena; Pogacnik, Milan

    2005-08-01

    Avermectins are widely used veterinary medicines. They bind strongly to faeces in their non-metabolized form and their half-life in faeces depends on field conditions. There are conflicting data regarding the behaviour of avermectins in the environment. Therefore, we investigated the degradation of abamectin and doramectin on sheep grazed pasture under field conditions in soil, soil-faeces and faeces samples from day 6 to day 70 (abamectin) or to day 50 (doramectin) after sheep treatment. Field conditions were recorded periodically during the experiment. Degradation of abamectin in sheep faeces and in soil-faeces was observed until day 60, with small amounts present in faeces until 70 days post treatment. Because the concentration of abamectin residues in soil was very low on day 6 after treatment, further significant degradation could not be measured. The concentration of doramectin in all analysed matrices decreased rapidly until day 50. It can be concluded that high concentrations of both avermectins were present during the first 20 days after treatment and that field conditions have an important role in degradation of avermectins on grazed pasture of treated animals. Clear identification of the consequences of avermectin exposure and the period of the greatest environmental risk will require further investigations.

  15. Grazing season and forage type influence goat milk composition and rennet coagulation properties.

    Science.gov (United States)

    Inglingstad, R A; Steinshamn, H; Dagnachew, B S; Valenti, B; Criscione, A; Rukke, E O; Devold, T G; Skeie, S B; Vegarud, G E

    2014-01-01

    Two different types of pasture (cultivated and rangeland) and 2 different hay qualities (high and low quality) were examined for their effects on goat milk composition and rennet coagulation properties. Furthermore, the effect of dietary treatments in both the early and late grazing season was studied. As lactation stage is known to influence milk composition, the goats in the early and late grazing season were in the same lactation stage at the start of the experiment. The milk composition was influenced both by dietary treatment and season. Milk from goats on pasture was superior to those on hay by containing a higher content of protein and casein, and the goats on cultivated pasture had the highest milk yield. Casein composition was significantly influenced by forage treatment. Goats grazing on cultivated pasture had higher contents of αs1-casein and also of κ-casein compared with the other treatments, whereas goats grazing on rangeland had the highest content of β-casein. Factors such as milk yield, casein micelle size, αs2-casein, and calcium content were reduced in late compared with early season. More favorable rennet coagulation properties were achieved in milk from the early grazing season, with shorter firming time and higher curd firmness compared with milk from the late grazing season, but the firming time and curd firmness were not prominently influenced by forage treatment. The content of αs2-casein and calcium in the milk affected the firming time and the curd firmness positively. The influence of season and forage treatment on especially milk yield, casein content, and rennet coagulation properties is of economic importance for both the dairy industry and goat milk farmers. Copyright © 2014 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.

  16. The effect of gastrointestinal nematode infection level on grazing distance from dung.

    Directory of Open Access Journals (Sweden)

    Hizumi Lua Sarti Seó

    Full Text Available Avoiding grazing near feces is an efficient strategy to prevent parasitic infection and contamination; therefore, in the evolution of herbivorous species, this behavior may have developed as a mechanism to protect the host against infection by gastrointestinal nematodes. The aim of this study was to assess whether grazing distance from dung is related to the level of parasitic infection in cattle. Based on Fecal Egg Count (FEC means, 18 castrated male steers, aged 18 months, were divided into three groups: High (FEC ≥ 315; Medium (FEC = 130-160; and Low (FEC = 40-70. To analyze the response to a new natural infection by gastrointestinal nematodes and to standardize infection levels, all animals received anthelmintic treatment at twenty days prior to field observation. Three observers simultaneously collected data on grazing behavior for 2.5 hours/week for 12 weeks. Observers recorded the distance when grazing occurred at less than one meter from dung. Every two weeks, fecal samples were collected for FEC, as well as serum samples to measure immunoglobulin G (IgG levels against larvae and adult antigens of the parasitic species Haemonchus placei. All groups grazed farther from the dung on days of greater insolation (r = 0.62; P = 0.03. Animals with high levels of parasitism grazed farther from the dung (P < 0.05 but had lower levels (P < 0.0001 of IgG serum levels compared to those with medium and low levels of infection. FEC values varied over the experiment, remaining below 200 for the low and medium group and reaching 1000 (P < 0.01 for the animals with the highest rates of parasitism. Our results indicate that cattle showing high levels of parasitism are more likely to avoid contaminated areas than animals with lower infection levels, and the immune system seems to be involved in such behavior.

  17. The impact of sheep grazing on the carbon balance of a peatland.

    Science.gov (United States)

    Worrall, Fred; 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(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. Copyright © 2012 Elsevier B.V. All rights reserved.

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

    OpenAIRE

    Xinghu Qin; Xinghu Qin; Xinghu Qin; Jingchuan Ma; Jingchuan Ma; Xunbing Huang; Xunbing Huang; Robert L. Kallenbach; T. Ryan Lock; Md. Panna Ali; Zehua Zhang; Zehua Zhang

    2017-01-01

    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, ...

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

    Directory of Open Access Journals (Sweden)

    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.

  20. Influence of Restricted Grazing Time Systems on Productive Performance and Fatty Acid Composition of in Growing Lambs

    Directory of Open Access Journals (Sweden)

    Zhenzhen Wang

    2015-08-01

    Full Text Available Fifty 3-month-old male Tan lambs (similar in body weight were divided into 5 groups to investigate the effects of different restricted pasture grazing times and indoor supplementation on the productive performances and fatty acid composition of the intramuscular fat in growing lambs. The lambs grazed for different periods of time (12 h/d, 8 h/d, 4 h/d, 2 h/d, and 0 h and received various amounts of supplementary feedings during the 120-day trial. Pasture dry matter intake (DMI, total DMI, average daily gains and the live body weights of the lambs were measured during the experiment. The animals were slaughtered at the end of the study, their carcass traits were measured, and their longissimus dorsi muscles were sampled to analyze the intramuscular fat (IMF content and fatty acid profiles. The results indicated that the different durations of grazing and supplementary feedings affected the animal performances and the composition of fatty acids. Grazing for 8 h/d or 2 h/d with the corresponding supplementary concentrate resulted in lambs with higher body weights, carcass weights and IMF contents. Lambs with longer grazing times and less concentrate accumulated more healthy fatty acids such as conjugated linoleic acid and n-3 polyunsaturated fatty acid and had higher n-3/n-6 ratios. Overall, a grazing allowance of 8 h/d and the corresponding concentrate was recommended to maintain a high quantity and quality of lamb meat.

  1. Feed selection and radiocaesium intake by reindeer, sheep and goats grazing alpine summer habitats in southern Norway

    International Nuclear Information System (INIS)

    Staaland, H.; Garmo, T.H.; Hove, K.; Pedersen, O.

    1995-01-01

    Radiocaesium concentrations ( 137 Cs) were measured in extrusa from oesophageally fistulated sheep, goats and reindeer grazing alpine summer vegetation in Griningsdalen, Southern Norway in the period 1987-1989. The experiments with sheep and goats were conducted in different sub-alpine areas. The reindeer were, in addition, grazed in three areas in the low alpine zone. Grazing bouts lasted for 10-20 min and bite selections were recorded every 15 s through the grazing bout. Reindeer and goats had the most diverse food selection whereas sheep fed mainly on grasses, forbs and to some extent, on leaves of willow. The reindeer extrusa had the highest radiocaesium activity, apparently to a large extent caused by intake of lichens in areas where this type of plants were present. Depending on the type of vegetation in the grazed areas the transfer of radiocaesium from soil to grazed vegetation (Bq kg -1 dry extrusa/Bq m -2 soil) was estimated to 0.02-0.04 in sheep, 0.02-0.05 in goats and 0.02-0.43 in reindeer for 1987. (author)

  2. Model-based analysis of the environmental impacts of grazing management on Eastern Mediterranean ecosystems in Jordan.

    Science.gov (United States)

    Schaldach, Rüdiger; Wimmer, Florian; Koch, Jennifer; Volland, Jan; Geissler, Katja; Köchy, Martin

    2013-09-01

    Eastern Mediterranean ecosystems are prone to desertification when under grazing pressure. Therefore, management of grazing intensity plays a crucial role to avoid or to diminish land degradation and to sustain both livelihoods and ecosystem functioning. The dynamic land-use model LandSHIFT was applied to a case study on the country level for Jordan. The impacts of different stocking densities on the environment were assessed through a set of simulation experiments for various combinations of climate input and assumptions about the development of livestock numbers. Indicators used for the analysis include a set of landscape metrics to account for habitat fragmentation and the "Human Appropriation of Net Primary Production" (HANPP), i.e., the difference between the amount of net primary production (NPP) that would be available in a natural ecosystem and the amount of NPP that remains under human management. Additionally, the potential of the economic valuation of ecosystem services, including landscape and grazing services, as an analysis concept was explored. We found that lower management intensities had a positive effect on HANPP but at the same time resulted in a strong increase of grazing area. This effect was even more pronounced under climate change due to a predominantly negative effect on the biomass productivity of grazing land. Also Landscape metrics tend to indicate decreasing habitat fragmentation as a consequence of lower grazing pressure. The valuation of ecosystem services revealed that low grazing intensity can lead to a comparatively higher economic value on the country level average. The results from our study underline the importance of considering grazing management as an important factor to manage dry-land ecosystems in a sustainable manner. Copyright © 2012 Elsevier Ltd. All rights reserved.

  3. The current status of grazing incidence optics

    International Nuclear Information System (INIS)

    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)

  4. Neutron Reflectivity and Grazing Angle Diffraction

    OpenAIRE

    Ankner, J. F.; Majkrzak, C. F.; Satija, S. K.

    1993-01-01

    Over the last 10 years, neutron reflectivity has emerged as a powerful technique for the investigation of surface and interfacial phenomena in many different fields. In this paper, a short review of some of the work on neutron reflectivity and grazing-angle diffraction as well as a description of the current and planned neutron rcflectometers at NIST is presented. Specific examples of the characterization of magnetic, superconducting, and polymeric surfaces and interfaces are included.

  5. Neutron Reflectivity and Grazing Angle Diffraction.

    Science.gov (United States)

    Ankner, J F; Majkrzak, C F; Satija, S K

    1993-01-01

    Over the last 10 years, neutron reflectivity has emerged as a powerful technique for the investigation of surface and interfacial phenomena in many different fields. In this paper, a short review of some of the work on neutron reflectivity and grazing-angle diffraction as well as a description of the current and planned neutron rcflectometers at NIST is presented. Specific examples of the characterization of magnetic, superconducting, and polymeric surfaces and interfaces are included.

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

    Science.gov (United States)

    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

  7. Continuous feral horse grazing and grazing exclusion in mountain pampean grasslands in Argentina

    Science.gov (United States)

    de Villalobos, A. E.; Zalba, S. M.

    2010-09-01

    This paper evaluates changes in the composition and structure of plant communities and plant functional groups associated with the continuous presence of feral horses in mountain pampean grasslands in Argentina in order to explore the potential effects of horse removal on vegetation restoration. Specific and functional richness, diversity, evenness, spatial heterogeneity and above-ground biomass were compared between areas subjected to ten years of intensive grazing by horses and exclosures of the same age. Forbs, shrubs and rosettes were more abundant after ten years of grazing, while the spatial heterogeneity of perennial grasses was higher in long-term grazed areas. Nevertheless, grasslands showed good recovery after horse removal, with greater species diversity and evenness, higher abundance of perennial grasses, greater above-ground biomass and lower percentages of exotic species. An understanding of the effect of feral animals on plant communities will lead to the design of a strategy of adaptive management and monitoring tools for measuring the condition of grasslands.

  8. Effect of Restricted Grazing Time on the Foraging Behavior and Movement of Tan Sheep Grazed on Desert Steppe

    Directory of Open Access Journals (Sweden)

    Yong Chen

    2013-05-01

    Full Text Available To investigate the effect of restricted grazing time on behavior of Tan sheep on desert steppe, forty 4-months old male Tan sheep with an original body weight (BW of 15.62±0.33 kg were randomly allocated to 4 grazing groups which corresponded to 4 different restricted grazing time treatments of 2 h/d (G2, 4 h/d (G4, 8 h/d (G8 and 12 h/d (G12 access to pasture. The restricted grazing times had a significant impact on intake time, resting time, ruminating time, bite rate and movement. As the grazing time decreased, the proportion of time spent on intake, bite rate and grazing velocity significantly (p<0.05 increased, but resting and ruminating time clearly (p<0.05 decreased. The grazing months mainly depicted effect on intake time and grazing velocity. In conclusion, by varying their foraging behavior, Tan sheep could improve grazing efficiency to adapt well to the time-limited grazing circumstance.

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

    DEFF Research Database (Denmark)

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

    2011-01-01

    to a zero-grazing herd having automatic milking system. In traditional milking system, mortality was reduced to 75% in grazing compared to zero-grazing herds. Within the grazing herds, the risk of mortality decreased with increasing number of hours on pasture during the season. Free access between barn...... 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...

  10. OPTIMIZATION OF GRAZING CAPACITY IN TEMPORARY PASTURE CROPS, GRAZED WITH SHEEP, IN HILL AREAS

    Directory of Open Access Journals (Sweden)

    MARIA SAUER

    2009-05-01

    Full Text Available The researches performed in the Caransebeş hill area made evident the opportunities of the temporary pasture crops consisted of intensive red clover and perennial graminaceous associations. Each type of the associations studied produced the biggest DM yields under conditions of direct grazing with animals, at an animal load of 2 UVM/ha. The most balanced proportion between legume and graminaceous species (52 : 48% was obtained in the second year of production, in the variant grazed with 2 UVM/ha.

  11. Grazing of Raphanus sativus. L (Japanese radish). | N.F.G. | African ...

    African Journals Online (AJOL)

    The performance of young woolled sheep was markedly better when grazing Japanese radish early in winter, when more leaf was available. Continuous grazing resulted in better performance than rotational or zero grazing. Keywords: continuous grazing; grazing; japanese radish; leaves; nooitgedacht research station; ...

  12. Dynamics of grazing lawn formation: An experimental test of the role of scale-dependent processes

    NARCIS (Netherlands)

    Cromsigt, J.P.G.M.; Olff, H.

    2008-01-01

    Grazing lawns are characteristic for African savanna grasslands, standing out as intensely grazed patches of stoloniferous grazing-tolerant grass species. Grazing lawn development has been associated with grazing and increased nutrient input by large migratory herds. However, we argue that in

  13. Dynamics of grazing lawn formation : an experimental test of the role of scale-dependent processes

    NARCIS (Netherlands)

    Cromsigt, Joris P. G. M.; Olff, Han; Setälä, Heikki

    2008-01-01

    Grazing lawns are characteristic for African savanna grasslands, standing out as intensely grazed patches of stoloniferous grazing-tolerant grass species. Grazing lawn development has been associated with grazing and increased nutrient input by large migratory herds. However, we argue that in

  14. Reindeer grazing in subarctic boreal forest - influences on the soil carbon dynamics

    Science.gov (United States)

    Koster, Kajar; Berninger, Frank; Köster, Egle; Pumpanen, Jukka

    2015-04-01

    Reindeer (Rangifer tarandus L.) are the most important large mammalian herbivores in the northern ecosystems , which have many effects on plant diversity, soil nutrient cycling and soil organic matter decomposition. Changes caused by reindeer in vegetation have indirect effects on physical features of the soil e.g. soil microclimate, root biomass and also on soil C dynamics. Earlier, the role of reindeer grazing in ground vegetation dynamics and in soil carbon (C) dynamics has been mostly investigated in open tundra heaths. The objectives of this study were to examine if and how the reindeer grazing (and the possible temperature changes in soil caused by heavy grazing) is affecting the soil C dynamics (CO2 efflux from the soil, C storage in soil, microbial biomass in the soil). In a field experiment in Finnish Lapland, in Värriö Strict Nature Reserve (67° 46' N, 29° 35' E) we have assessed the changes occurring in above- and belowground biomasses, and soil C dynamics (CO2 efflux, soil C content, soil microbial biomass C) among areas grazed and ungrazed by reindeer. Our study areas are located in the northern boreal subarctic coniferous forest at the zone of the last intact forest landscapes in Fennoscandia, where large areas of relatively undisturbed subarctic Scots pine (Pinus sylvestris L.) forests can still be found. The sample plots located in the Värriö Strict Nature Reserve (10 sample plots in total established in year 2013) are situated along the borderline between Finland and Russia, where the ungrazed area was excluded from the reindeer grazing already in 1918, to prevent the Finnish reindeer from going to the Russian side and there are not many reindeer on Russian side of the area. To characterize the stands we have established circular sample plots on areas with a radius of 11.28 m, where different tree characteristics were measured (diameter at 1.3 m, height, height of a tree, crown height, crown diameter, stand age, etc.). On every sample plot

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

    OpenAIRE

    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 reasons, includingintake and milk production potential, substitution, grass allowance, quality, etc., which often means that grass utilisation and quality are compromised. Adaptation of grazing manage...

  16. Grazing intensity influences the strength of an associational refuge on temperate reefs.

    Science.gov (United States)

    Levenbach, Stuart

    2009-02-01

    Recent studies have emphasized the role of positive interactions in ecological communities, but few have addressed how positive interactions are mediated by abiotic stress and biotic interactions. Here, I investigate the effect of a facilitator species on the abundance of macroalgae over a gradient of herbivory. Grazing by sea urchins can be intense on temperate reefs along the California coast, with benthic macroalgae growing exclusively in physical refuges and interspersed within colonies of the strawberry anemone, Corynactis californica. Field experiments indicated that the net effect of C. californica on turf algae was strongly nonlinear over a gradient in density of sea urchins. At low intensities of urchin grazing, the anemone and macroalgae competed for space, with algae capable of overgrowing C. californica. At intermediate grazing intensities, C. californica provided a refuge for turf algae but not for juvenile kelp. Neither turf algae nor kelp benefited from the presence of C. californica at the highest levels of grazing intensity, as sea urchins consumed nearly all macroalgae. The hump-shaped effect observed for C. californica contrasts with the prevailing view in ecological theory that positive interactions are more common in harsh environmental conditions. The results reported here qualify this view and underscore the need to evaluate positive interactions over a range of abiotic stress and consumer pressure.

  17. Hydrologic variability affects invertebrate grazing on phototrophic biofilms in stream microcosms.

    Directory of Open Access Journals (Sweden)

    Serena Ceola

    Full Text Available The temporal variability of streamflow is known to be a key feature structuring and controlling fluvial ecological communities and ecosystem processes. Although alterations of streamflow regime due to habitat fragmentation or other anthropogenic factors are ubiquitous, a quantitative understanding of their implications on ecosystem structure and function is far from complete. Here, by experimenting with two contrasting flow regimes in stream microcosms, we provide a novel mechanistic explanation for how fluctuating flow regimes may affect grazing of phototrophic biofilms (i.e., periphyton by an invertebrate species (Ecdyonurus sp.. In both flow regimes light availability was manipulated as a control on autotroph biofilm productivity and grazer activity, thereby allowing the test of flow regime effects across various ratios of biofilm biomass to grazing activity. Average grazing rates were significantly enhanced under variable flow conditions and this effect was highest at intermediate light availability. Our results suggest that stochastic flow regimes, characterised by suitable fluctuations and temporal persistence, may offer increased windows of opportunity for grazing under favourable shear stress conditions. This bears important implications for the development of comprehensive schemes for water resources management and for the understanding of trophic carbon transfer in stream food webs.

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

    Science.gov (United States)

    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.

  19. Ecological Effects of Grazing in the Northern Tianshan Mountains

    Directory of Open Access Journals (Sweden)

    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.

  20. Nutritive value of elephantgrass and Mombaçagrass under irrigation influence and sequential grazing day

    Directory of Open Access Journals (Sweden)

    Enilson Geraldo Ribeiro

    2010-02-01

    Full Text Available The research aimed to evaluate the influence of irrigation and sequential grazing day on chemical composition and “in vitro” digestibility of Napiergrass and Mombaça-guinea grass. The irrigation supplied the previous ten-year mean daily evapotranpiration (ET0. It was adopted the rotational grazing, with grazing period of four days, resting period of 32 days and variable stocking, with grazing pressure of four kg of leaf dry matter per 100 kg live weight. The samples were collected during eight sequential days, corresponding to the four days of occupation of two plots, using four esophagus fistulated steers. During dry season, it was not observed irrigation influence on dry matter (DM, crude protein (CP, neutral detergent fiber (NDF, acid detergent fiber (ADF and lignin content, and on “in vitro” digestibility of extrusated DM (IVDMD for the two grass species, but it was observed higher organic matter (OM content in extrusa from irrigated forages. During season, forages did not differ regarding to OM, CP, ADF and lignin contents. However, Napier grass showed higher NDF content and IVDMD. During rainy season, irrigation had no influence on chemical composition or IVDMD and Napier grass showed lower contents of NDF, ADF and lignin than Mombaça grass and similar contents of DM, OM and CP and IVDMD. Regression analysis revealed linear decrease in the content of DM, CP and “in vitro” digestibility of extrusa DM (IVDMD as the occupation period of the plot advanced, which corresponded to 4.0% a day in protein content and to 2.0% a day in IVDMD. By the other hand, the contents of NDF, ADF and lignin increased by 2.0; 4.0 and 7.0 % each grazing day, respectively.

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

    Science.gov (United States)

    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.

  2. Iodine-129 in thyroids of grazing animals

    International Nuclear Information System (INIS)

    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)

  3. Influence of rainfall and grazing on the compositional change of the ...

    African Journals Online (AJOL)

    Keywords: Communal grazing; Grazing intensity; Mortality; Relative biomass; Sites; Sward structure changes; Treatments; Tuft size changes; Tuft sizes; cattle; digitaria eriantha; forbs; grazing; tuft size; herbaceous layer; composition; recruitment; herbaceous composition; sandveld; gazankulu; abundance; pogonarthria ...

  4. Modelling nitrous oxide emissions from grazed grassland systems

    International Nuclear Information System (INIS)

    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.

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

    Directory of Open Access Journals (Sweden)

    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.

  6. Grazing-incidence small-angle neutron scattering from structures below an interface.

    Science.gov (United States)

    Nouhi, Shirin; Hellsing, Maja S; Kapaklis, Vassilios; Rennie, Adrian R

    2017-08-01

    Changes of scattering are observed as the grazing angle of incidence of an incoming beam increases and probes different depths in samples. A model has been developed to describe the observed intensity in grazing-incidence small-angle neutron scattering (GISANS) experiments. This includes the significant effects of instrument resolution, the sample transmission, which depends on both absorption and scattering, and the sample structure. The calculations are tested with self-organized structures of two colloidal samples with different size particles that were measured on two different instruments. The model allows calculations for various instruments with defined resolution and can be used to design future improved experiments. The possibilities and limits of GISANS for different studies are discussed using the model calculations.

  7. Intensive rotational grazing assists control of gastrointestinal nematodosis of sheep in a cool temperate environment with summer-dominant rainfall.

    Science.gov (United States)

    Colvin, A F; Walkden-Brown, S W; Knox, M R; Scott, J M

    2008-05-06

    While rotational grazing methods have an accepted role in the management of gastrointestinal nematodosis (GIN) of small ruminants in humid tropical regions, their efficacy and application in cool temperate regions is more controversial. This study evaluated GIN over 2 years in three classes of fine wool Merino sheep (lambs, hoggets and ewes) under three different sheep management systems in a cool tableland environment near Armidale NSW Australia (950m altitude, 30 degrees 31'S, 151 degrees 39'E). The management systems were High input (HI) with high fertiliser inputs, a target of 100% sown pasture, high stocking rate (13.4 dry sheep equivalents/ha) and relatively long grazing periods; Typical (TYP) New England management system with moderate fertiliser inputs and stocking rate (9.3DSE/ha) and relatively long grazing periods; and Intensive rotational grazing (IRG) with moderate fertiliser inputs and stocking rate (8.8DSE/ha) but very short (mean 5 days) grazing periods and long (mean 103 days) rest periods. Twenty sheep of each class in each management treatment were sampled monthly for faecal worm egg counts (WEC, followed by larval differentiation), and body weights with a blood sample taken for haematology every second month. The proportion of sheep with WEC above zero did not differ between management systems but the magnitude of WEC did, with sheep under IRG displaying lower mean WEC than those on the other treatments (IRG: 326, HI: 594, TYP: 536, eggs/g PWEC and higher HCT, sheep under IRG also had significantly lower bodyweights and fleece weights overall, although this was only evident in sheep raised to adulthood prior to the experiment, not those raised during the 2-year experimental period. The results demonstrate that IRG systems with short grazing periods and long rest periods between grazing events can assist with control of GIN in cool temperate climates where H. contortus is the dominant parasite.

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

    Science.gov (United States)

    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.

  9. Field trial assessment of biological, chemical, and physical responses of soil to tillage intensity, fertilization, and grazing.

    Science.gov (United States)

    Vargas Gil, Silvina; Becker, Analia; Oddino, Claudio; Zuza, Mónica; Marinelli, Adriana; March, Guillermo

    2009-08-01

    Soil microbial populations can fluctuate in response to environmental changes and, therefore, are often used as biological indicators of soil quality. Soil chemical and physical parameters can also be used as indicators because they can vary in response to different management strategies. A long-term field trial was conducted to study the effects of different tillage systems (NT: no tillage, DH: disc harrow, and MP: moldboard plough), P fertilization (diammonium phosphate), and cattle grazing (in terms of crop residue consumption) in maize (Zea mays L.), sunflower (Heliantus annuus L.), and soybean (Glycine max L.) on soil biological, chemical, and physical parameters. The field trial was conducted for four crop years (2000/2001, 2001/2002, 2002/2003, and 2003/2004). Soil populations of Actinomycetes, Trichoderma spp., and Gliocladium spp. were 49% higher under conservation tillage systems, in soil amended with diammonium phosphate (DAP) and not previously grazed. Management practices also influenced soil chemical parameters, especially organic matter content and total N, which were 10% and 55% higher under NT than under MP. Aggregate stability was 61% higher in NT than in MP, 15% higher in P-fertilized soil, and also 9% higher in not grazed strips, bulk density being 12% lower in NT systems compared with MP. DAP application and the absence of grazing also reduced bulk density (3%). Using conservation tillage systems, fertilizing crops with DAP, and avoiding grazing contribute to soil health preservation and enhanced crop production.

  10. Aphanizomenon gracile increases in width in the presence of Daphnia. A defence mechanism against grazing?

    Directory of Open Access Journals (Sweden)

    Slawek Cerbin

    2013-10-01

    Full Text Available Filamentous cyanobacteria are frequently consumed by grazers like Daphnia, which can break filaments and make them more readily available to filter-feeders. However, various defence mechanisms against grazing have also been observed in cyanobacteria. Data concerning changes in the morphology of filamentous algae, especially their width in the presence of a grazer, are scarce. Field studies of filament morphology of cyanobacteria relate their changes to nutrient availability and temperature. Moreover, filament morphology displays significant differences in filament length and width among seasons. We hypothesised that the morphological changes in filament observed in the field – especially their width – could be a defence mechanism that is induced by the presence of a grazer, such as Daphnia. Thus, two experiments were conducted in order to test the influence of Daphnia (direct grazing and infochemicals together in the first experiment and the chemicals it released (grazing excluded, only chemicals present in the second experiment on Aphanizomenon gracile’s morphology, in controlled laboratory conditions. Aphanizomenon filaments became significantly shorter and thicker in both experiments. However, Daphnia’s grazing combined with excreted chemicals had stronger effect than chemicals alone. To our knowledge, this is the first report describing the shortening and thickening of filaments in the presence of Daphnia infochemicals. It seems that the Aphanizomenon filaments in the presence of Daphnia switch their growing mode and invest more heavily in width than length. Our results support the hypothesis that Daphnia is at least partly responsible for the changes in filament width observed in the field. This could be a strategy that helps Aphanizomenon to withstand grazer’s pressure during early stages of a bloom.

  11. On the Alignment and Focusing of the Marshall Grazing Incidence X-ray Spectrometer (MaGIXS)

    Science.gov (United States)

    Champey, Patrick; Winebarger, Amy; Kobayashi, Ken; Savage, Sabrina; Cirtain, Jonathan; Cheimets, Peter; Hertz, Edward; Golub, Leon; Ramsey, Brian; McCracken, Jeff

    2016-01-01

    The Marshall Grazing Incidence X-ray Spectrometer (MaGIXS) is a NASA sounding rocket instrument that is designed to observe soft X-ray emissions from 24 - 6.0 A (0.5 - 2.0 keV energies) in the solar atmosphere. For the rst time, high-temperature, low-emission plasma will be observed directly with 5 arcsecond spatial resolution and 22 mA spectral resolution. The unique optical design consists of a Wolter - I telescope and a 3-optic grazing- incidence spectrometer. The spectrometer utilizes a nite conjugate mirror pair and a blazed planar, varied line spaced grating, which is directly printed on a silicon substrate using e-beam lithography. The grating design is being nalized and the grating will be fabricated by the Massachusetts Institute of Technology (MIT) and Izentis LLC. Marshall Space Flight Center (MSFC) is producing the nickel replicated telescope and spectrometer mirrors using the same facilities and techniques as those developed for the ART-XC and FOXSI mirrors. The Smithsonian Astrophysical Observatory (SAO) will mount and align the optical sub-assemblies based on previous experience with similar instruments, such as the Hinode X-Ray Telescope (XRT). The telescope and spectrometer assembly will be aligned in visible light through the implementation of a theodolite and reference mirrors, in addition to the centroid detector assembly (CDA) { a device designed to align the AXAF-I nested mirrors. Focusing of the telescope and spectrometer will be achieved using the X-ray source in the Stray Light Facility (SLF) at MSFC. We present results from an alignment sensitivity analysis performed on the on the system and we also discuss the method for aligning and focusing MaGIXS.

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

    African Journals Online (AJOL)

    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 ...

  13. The selenium status of grazing herbivores in different regions of ...

    African Journals Online (AJOL)

    Unknown

    The selenium status of grazing herbivores in different regions of Southern Africa. J. B. J. van Ryssen. Dept of Animal and Wildlife Sciences, University of Pretoria, 0002 Pretoria, South Africa. E-mail:jvryssen@postino.up.ac.za. Although a substantial amount of information is available on the selenium status of grazing animals ...

  14. Influence of grazing management on the production of an irrigated ...

    African Journals Online (AJOL)

    The production of an irrigated grass/legume pasture was determined using Merino ewes on rotational and continuous grazing systems. The clover content of the pasture declined, while the grass content increased under both systems. The lucerne content of the rotationally-grazed pastures did not change, but lucerne failed ...

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

    African Journals Online (AJOL)

    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; ...

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

    International Nuclear Information System (INIS)

    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)

  17. Using dual-purpose crops in sheep-grazing systems.

    Science.gov (United States)

    Dove, Hugh; Kirkegaard, John

    2014-05-01

    The utilisation of dual-purpose crops, especially wheat and canola grown for forage and grain production in sheep-grazing systems, is reviewed. When sown early and grazed in winter before stem elongation, later-maturing wheat and canola crops can be grazed with little impact on grain yield. Recent research has sought to develop crop- and grazing-management strategies for dual-purpose crops. Aspects examined have been grazing effects on crop growth, recovery and yield development along with an understanding of the grazing value of the crop fodder, its implications for animal nutrition and grazing management to maximise live-weight gain. By alleviating the winter 'feed gap', the increase in winter stocking rate afforded by grazing crops allows crop and livestock production to be increased simultaneously on the same farm. Integration of dual-purpose wheat with canola on mixed farms provides further systems advantages related to widened operational windows, weed and disease control and risk management. Dual-purpose crops are an innovation that has potential to assist in addressing the global food-security challenge. © 2013 Society of Chemical Industry.

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

    African Journals Online (AJOL)

    ADOWIE PERE

    ABSTRACT: This study examines the effects of the emerging grazing policies on land degradation in Nigeria using soil, vegetation and sustainability as ... of the latter by the animals. In most areas strict rules exist to check this practice. .... grazing reserve also encourages the uniform deployment of the cattle. It is in view of ...

  19. Veld composition in relation to grazing capacity. | Barnes | African ...

    African Journals Online (AJOL)

    Present methods of evaluating veld composition in relation to grazing capacity can be criticised on grounds of subjectivity, especially with regard to the assignment of relative values to the constituent species. Data relating to botanical composition and estimated grazing capacity, derived from long-term animal production ...

  20. A theoretical analysis of foraging efficiency of grazing animals | RI ...

    African Journals Online (AJOL)

    A mathematical model of the change in quantity of forage during grazing is constructed, assuming (1) that forage requirement by grazing animals is constant, and (2) that intake is equal to requirement when forage is in free supply but (3) that below a certain supply level intake becomes restricted and is proportional to supply ...

  1. Day and night grazing by cattle in the Sahel

    NARCIS (Netherlands)

    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

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

    African Journals Online (AJOL)

    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 ...

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

    NARCIS (Netherlands)

    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

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

    African Journals Online (AJOL)

    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 ...

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

    African Journals Online (AJOL)

    The cellulase dry matter disappearance (CDMD) and herbage nitrogen (N) of Lolium perenne (perennial ryegrass) were evaluated for pastures grown under subtropical conditions for two years, under five combinations of grazing frequency and intensity, each applied in a rotational grazing system. These quality factors were ...

  6. Grazing Intensity Does Not Affect Plant Diversity in Shortgrass Steppe

    Science.gov (United States)

    Responses of livestock gain and forage production to grazing intensity in shortgrass steppe are well-established, but effects on basal cover and plant diversity are less so. A long-term grazing intensity study was initiated on shortgrass steppe at the Central Plains Experimental Range (USDA-Agricult...

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

    African Journals Online (AJOL)

    The feasibility of intensifying grazing studies in the tropics, particularly in Nigeria, to examine the behaviour of ruminants in highly heterogeneous pastures has the potential to provide integrated (sward, animal, management) strategies for sustainable livestock production in Nigeria. Key Words: Sward characteristics; Grazing ...

  8. Hydrologic properties of grazed perennial swards in semiarid ...

    African Journals Online (AJOL)

    Identification of plant resources that persist under grazing pressure, support desirable levels of production and at the same time protect the grazing environment is central to sustainable livestock production. This study assessed the infiltration capacity and soil loss associated with perennial swards subjected to different ...

  9. Identification of key grass species under grazing in the Highland ...

    African Journals Online (AJOL)

    Relative abundances of rangeland species have for many years been used to index trends in range condition following the impact of grazing. All species recorded in a botanical survey are usually classified according to their assumed reaction to grazing using the increaser and decreaser groups. We used a gradient ...

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

    African Journals Online (AJOL)

    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. Estimation of grazing by herbivores from analysis of dung | Mabinya ...

    African Journals Online (AJOL)

    The two acids can also be recovered from the dung of various herbivores and their presence can be used as evidence of grazing by animals such as cattle, hippopotamus and warthogs. The reduced presence of these compounds in the dung of goats supports the fact that goats both graze and browse. Analysis of the dung ...

  12. Grazing behaviour and diet selection of Barotse cattle on a ...

    African Journals Online (AJOL)

    Grazing behaviour and diet selection of cattle were studied on a communally grazed floodplain and its adjacent wooded uplands in western Zambia to identify the interaction between basic herd management practices, foraging behaviour and body condition of cattle. On average, the cattle spent nine hours and 29 minutes ...

  13. Review: Behavior and daily grazing patterns of cattle

    NARCIS (Netherlands)

    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

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

    African Journals Online (AJOL)

    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.

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

    African Journals Online (AJOL)

    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 ...

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

    African Journals Online (AJOL)

    Grasses on the shallow soils of the western grassland biome of South Africa were classified on their ecological status on the basis of their reaction to grazing. Vegetation data were gathered in such a way that those of different successional stages could be identified. An ordination technique was used to define the grazing ...

  17. Fish meal supplementation to early lactation Jersey cows grazing ...

    African Journals Online (AJOL)

    This trial was conducted to test the hypothesis that early lactation cows grazing ryegrass pasture and receiving maize and mineral supplementation could respond to additional supplementation with a protein source such as fish meal. Multiparous Jersey cows in early to mid lactation that grazed annual ryegrass pasture in ...

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

    African Journals Online (AJOL)

    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 ...

  19. Grazing depletes forb species diversity in the mesic grasslands of ...

    African Journals Online (AJOL)

    Forbs constitute over 80% of the species richness of mesic grassland but their response to grazing is largely unknown. The influence of grazing on the forb composition, richness and diversity of two species-rich grasslands in the coastal hinterland and midlands of KwaZulu-Natal, South Africa was examined in plots subject ...

  20. Impact of grazing intensity during drought in an Arizona grassland.

    Science.gov (United States)

    Loeser, Matthew R R; Sisk, Thomas D; Crews, Timothy E

    2007-02-01

    The ecological benefits of changing cattle grazing practices in the western United States remain controversial, due in part to a lack of experimentation. In 1997 we initiated an experimental study of two rangeland alternatives, cattle removal and high-impact grazing, and compared grassland community responses with those with more conventional, moderate grazing practices. The study was conducted in a high-elevation, semiarid grassland near Flagstaff, Arizona (U.S.A.). We conducted annual plant surveys of modified Whittaker plots for 8 years and examined plant composition shifts among treatments and years. High-impact grazing had strong directional effects that led to a decline in perennial forb cover and an increase in annual plants, particularly the exotic cheatgrass (Bromus tectorum L.). A twofold increase in plant cover by exotic species followed a severe drought in the sixth year of the study, and this increase was greatest in the high-impact grazing plots, where native cover declined by one-half. Cattle removal resulted in little increase in native plant cover and reduced plant species richness relative to the moderate grazing control. Our results suggest that some intermediate level of cattle grazing may maintain greater levels of native plant diversity than the alternatives of cattle removal or high-density, short-duration grazing practices. Furthermore, episodic drought interacts with cattle grazing, leading to infrequent, but biologically important shifts in plant communities. Our results demonstrate the importance of climatic variation in determining ecological effects of grazing practices, and we recommend improving conservation efforts in arid rangelands by developing management plans that anticipate this variation.

  1. Growth of nano-dots on the grazing incidence mirror surface under FEL irradiation: analytic approach to modeling

    Science.gov (United States)

    Kozhevnikov, I. V.; Buzmakov, A. V.; Siewert, F.; Tiedtke, K.; Störmer, M.; Samoylova, L.; Sinn, H.

    2017-05-01

    Simple analytic equation is deduced to explain new physical phenomenon detected experimentally: growth of nano-dots (40-55 nm diameter, 8-13 nm height, 9.4 dots/μm2 surface density) on the grazing incidence mirror surface under the three years irradiation by the free electron laser FLASH (5-45 nm wavelength, 3 degrees grazing incidence angle). The growth model is based on the assumption that the growth of nano-dots is caused by polymerization of incoming hydrocarbon molecules under the action of incident photons directly or photoelectrons knocked out from a mirror surface. The key feature of our approach consists in that we take into account the radiation intensity variation nearby a mirror surface in an explicit form, because the polymerization probability is proportional to it. We demonstrate that the simple analytic approach allows to explain all phenomena observed in experiment and to predict new effects. In particular, we show that the nano-dots growth depends crucially on the grazing angle of incoming beam and its intensity: growth of nano-dots is observed in the limited from above and below intervals of the grazing angle and the radiation intensity. Decrease in the grazing angle by 1 degree only (from 3 to 2 degree) may result in a strong suppression of nanodots growth and their total disappearing. Similarly, decrease in the radiation intensity by several times (replacement of free electron laser by synchrotron) results also in disappearing of nano-dots growth.

  2. Grazing intensity effects on the breeding avifauna of North Dakota native grasslands

    Science.gov (United States)

    Kantrud, H.A.

    1981-01-01

    A breeding bird census and plant survey was conducted on 180 samples of lightly, moderately, and heavily grazed and hayed native grasslands in North Dakota in 1974. The ten most important cover plants on each of eight major physiographic landforms in three of the four regions (the Agassiz Lake Plain excluded) overlapped so extensively that only 19 species were involved: 13 grasses or sedges, four forbs, one shrub, and one clubmoss. Bird densities were generally highest in (i) regions and landforms containing numerous natural basin wetlands, (ii) flatter, glaciated landforms containing more fertile soils, and (iii) landforms of greater relief and high habitat heterogeneity. Avian species richness tended to decrease with increased grazing intensity, but total bird density increased due to higher populations of a few species, and hayland that had been mowed and raked during the previous growing season was highly attractive to some species.

  3. A narrower gap of grazing intensity. Reply to Fetzel et al. 2017. Seasonality constrains to livestock grazing intensity

    Science.gov (United States)

    Fetzel et al. (2017) globally mapped the gap between observed and potential grazing intensity (GI): the ratio between consumption by livestock and ANPP. Fetzel et al. (2017) estimated grazing land, forage production and livestock demand at a half-degree resolution. They mapped GI below 15% for most ...

  4. Alterations in serotonin receptor-induced contractility of bovine lateral saphenous vein in cattle grazing endophyte-infected tall fescue.

    Science.gov (United States)

    Klotz, J L; Brown, K R; Xue, Y; Matthews, J C; Boling, J A; Burris, W R; Bush, L P; Strickland, J R

    2012-02-01

    As part of a 2-yr study documenting the physiologic impact of grazing endophyte-infected tall fescue on growing cattle, 2 experiments were conducted to characterize and evaluate effects of grazing 2 levels of toxic endophyte-infected tall fescue pastures on vascular contractility and serotonin receptors. Experiment 1 examined vasoconstrictive activities of 5-hydroxytryptamine (5HT), α-methylserotonin (ME5HT; a 5HT(2) receptor agonist), d-lysergic acid (LSA), and ergovaline (ERV) on lateral saphenous veins collected from steers immediately removed from a high-endophyte-infected tall fescue pasture (HE) or a low-endophyte-infected mixed-grass (LE) pasture. Using the same pastures, Exp. 2 evaluated effects of grazing 2 levels of toxic endophyte-infected tall fescue on vasoconstrictive activities of (±)-1-(2,5-dimethoxy-4-iodophenyl)-2-aminopropane hydrochloride (DOI), BW 723C86 (BW7), CGS-12066A (CGS), and 5-carboxamidotryptamine hemiethanolate maleate (5CT), agonists for 5HT(2A),( 2B), 5HT(1B), and 5HT(7) receptors, respectively. One-half of the steers in Exp. 2 were slaughtered immediately after removal from pasture, and the other one-half were fed finishing diets for >91 d before slaughter. For Exp. 1, maximal contractile intensities were greater (P grazing LE pastures than HE pastures for 5HT (73.3 vs. 48.9 ± 2.1%), ME5HT (52.7 vs. 24.9 ± 1.5%), and ERV (65.7 vs. 49.1 ± 2.6%). Onset of contractile response did not differ for 5HT (P = 0.26) and ERV (P = 0.93), but onset of ME5HT contraction was not initiated (P grazing steers. For Exp. 2, maximal contractile intensities achieved with DOI were 35% less (P grazing HE pastures. Contractile response to CGS did not differ between pasture groups, and there was an absence of contractile response to BW7 in both groups. There were no differences between endophyte content in contractile responses after animals were finished for >91 d. Experiment 1 demonstrated that grazing of HE pastures for 89 to 105 d induces

  5. Laboratory Grouping Based on Previous Courses.

    Science.gov (United States)

    Doemling, Donald B.; Bowman, Douglas C.

    1981-01-01

    In a five-year study, second-year human physiology students were grouped for laboratory according to previous physiology and laboratory experience. No significant differences in course or board examination performance were found, though correlations were found between predental grade-point averages and grouping. (MSE)

  6. Performance and Physiology of Yearling Steers Grazing Toxic Tall Fescue as Influenced by Feeding Soybean Hulls and Steroidal Implants

    Science.gov (United States)

    An endophyte (Neotyphodium coenophialum) that infests tall fescue (Lolium arundinaceum) produces ergot alkaloids that adversely affect performance and physiology of cattle to inflict a malady collectively termed ‘fescue toxicosis’. A two-yr grazing experiment was conducted with yearling steers graz...

  7. Multiple scattering in grazing-incidence X-ray diffraction : Impact on lattice-constant determination in thin films

    NARCIS (Netherlands)

    Resel, Roland; Bainschab, Markus; Pichler, Alexander; Dingemans, T.J.; Simbrunner, Clemens; Stangl, Julian; Salzmann, Ingo

    2016-01-01

    Dynamical scattering effects are observed in grazing-incidence X-ray diffraction experiments using an organic thin film of 2,2′:6′,2′′-ternaphthalene grown on oxidized silicon as substrate. Here, a splitting of all Bragg peaks in the out-of-plane direction (z-direction) has been observed, the

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

    Directory of Open Access Journals (Sweden)

    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

  9. Figure and finish of grazing incidence mirrors

    International Nuclear Information System (INIS)

    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

  10. Grazing angle X-ray fluorescence from periodic structures on silicon and silica surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Nowak, S.H., E-mail: nowak@ifg-adlershof.de [Physics Department, University of Fribourg, CH-1700 Fribourg (Switzerland); Banaś, D. [Institute of Physics, Jan Kochanowski University, 25-406 Kielce (Poland); Błchucki, W.; Cao, W.; Dousse, J.-Cl. [Physics Department, University of Fribourg, CH-1700 Fribourg (Switzerland); Hönicke, P. [Physikalisch-Technische Bundesanstalt (PTB), D-10587 Berlin (Germany); Hoszowska, J. [Physics Department, University of Fribourg, CH-1700 Fribourg (Switzerland); Jabłoński, Ł. [Institute of Physics, Jan Kochanowski University, 25-406 Kielce (Poland); Kayser, Y. [Physics Department, University of Fribourg, CH-1700 Fribourg (Switzerland); Kubala-Kukuś, A.; Pajek, M. [Institute of Physics, Jan Kochanowski University, 25-406 Kielce (Poland); Reinhardt, F. [Physikalisch-Technische Bundesanstalt (PTB), D-10587 Berlin (Germany); Savu, A.V. [Microsystems Laboratory (LMIS1), Ecole Polytechnique Fédérale de Lausanne, CH-1015 Lausanne (Switzerland); Szlachetko, J. [Institute of Physics, Jan Kochanowski University, 25-406 Kielce (Poland); Paul Scherrer Institut, CH-5232 Villigen PSI (Switzerland)

    2014-08-01

    Various 3-dimensional nano-scaled periodic structures with different configurations and periods deposited on the surface of silicon and silica substrates were investigated by means of the grazing incidence and grazing emission X-ray fluorescence techniques. Apart from the characteristics which are typical for particle- and layer-like samples, the measured angular intensity profiles show additional periodicity-related features. The latter could be explained by a novel theoretical approach based on simple geometrical optics (GO) considerations. The new GO-based calculations were found to yield results in good agreement with experiment, also in cases where other theoretical approaches are not valid, e.g., periodic particle distributions with an increased surface coverage.

  11. Grazing angle X-ray fluorescence from periodic structures on silicon and silica surfaces

    International Nuclear Information System (INIS)

    Nowak, S.H.; Banaś, D.; Błchucki, W.; Cao, W.; Dousse, J.-Cl.; Hönicke, P.; Hoszowska, J.; Jabłoński, Ł.; Kayser, Y.; Kubala-Kukuś, A.; Pajek, M.; Reinhardt, F.; Savu, A.V.; Szlachetko, J.

    2014-01-01

    Various 3-dimensional nano-scaled periodic structures with different configurations and periods deposited on the surface of silicon and silica substrates were investigated by means of the grazing incidence and grazing emission X-ray fluorescence techniques. Apart from the characteristics which are typical for particle- and layer-like samples, the measured angular intensity profiles show additional periodicity-related features. The latter could be explained by a novel theoretical approach based on simple geometrical optics (GO) considerations. The new GO-based calculations were found to yield results in good agreement with experiment, also in cases where other theoretical approaches are not valid, e.g., periodic particle distributions with an increased surface coverage

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

    DEFF Research Database (Denmark)

    Søegaard, Karen

    2009-01-01

    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...... 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...... management in the rest of the experiment. N-response was greatly affected by management. Under cutting it was higher in Year 1 [16 kg dry matter (DM) kg-1 N] than in Year 2 (9 and 13 kg DM kg-1 N with and without residual effects of fertilization in Year 1). Under grazing with one or two rest periods...

  13. Golimumab in patients with active rheumatoid arthritis who have previous experience with tumour necrosis factor inhibitors: results of a long-term extension of the randomised, double-blind, placebo-controlled GO-AFTER study through week 160

    NARCIS (Netherlands)

    Smolen, Josef S.; Kay, Jonathan; Landewé, Robert B. M.; Matteson, Eric L.; Gaylis, Norman; Wollenhaupt, Jurgen; Murphy, Frederick T.; Zhou, Yiying; Hsia, Elizabeth C.; Doyle, Mittie K.

    2012-01-01

    The aim of this study was to assess long-term golimumab therapy in patients with rheumatoid arthritis (RA) who discontinued previous tumour necrosis factor alpha (TNFα) inhibitor(s) for any reason. Results through week 24 of this multicentre, randomised, double-blind, placebo-controlled study of

  14. Riparian Meadow Response to Modern Conservation Grazing Management

    Science.gov (United States)

    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.

  15. Riparian Meadow Response to Modern Conservation Grazing Management.

    Science.gov (United States)

    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. Examining ecological consequences of feral horse grazing using exclosures

    Science.gov (United States)

    Beever, E.A.; Brussard, P.F.

    2000-01-01

    Although feral horses have inhabited western North America since the end of the 16th century, relatively little synecological research has been conducted to quantitatively characterize how they interact with ecosystem components. Because feral horses exhibit watering behavior markedly different from that of domestic cattle, it is particularly important to evaluate response of ecosystem elements near water sources to horse use. To assess this response, we performed live-trapping of small mammals and 2-tiered vegetative sampling in 2 mountain ranges in central Nevada in the interior Great Basin, USA. At low elevations, plots around horse-excluded springs exhibited notably greater plant species richness, percent cover, and abundance of grasses and shrubs, as well as more small mammal burrow entrances than plots at horse-grazed springs. At high elevations, meadows protected from grazing exhibited maximum vegetation heights 2.8 times greater than vegetation grazed by horses only and 4.5 times greater than vegetation grazed by horses and cattle. Species richness in quadrats was most different between the horse-and-cattle-grazed meadow and its ungrazed counterpart, suggesting the possibility of synergistic effects of horse and cattle grazing in the same location. This study, the first in the Great Basin to investigate quantitatively ecosystem consequences of feral horse use with exclosures, represents a preliminary step in identifying factors that determine the magnitude of horse grazing impacts. 

  17. Managing variations in dairy cow nutrient supply under grazing.

    Science.gov (United States)

    Peyraud, J L; Delagarde, R

    2013-03-01

    Grazed pasture, which is the cheapest source of nutrients for dairy cows, should form the basis of profitable and low-input animal production systems. Management of high-producing dairy cows at pasture is thus a major challenge in most countries. The objective of the present paper is to review the factors that can affect nutrient supply for grazing dairy cows in order to point out areas with scope for improvement on managing variations in nutrient supply to achieve high animal performance while maintaining efficient pasture utilisation per hectare (ha). Reviewing the range in animal requirements, intake capacity and pasture nutritive values shows that high-producing cows cannot satisfy their energy requirements from grazing alone and favourable to unfavourable situations for grazing dairy cows may be classified according to pasture quality and availability. Predictive models also enable calculation of supplementation levels required to meet energy requirements in all situations. Solutions to maintain acceptable level of production per cow and high output per ha are discussed. Strategies of concentrate supplementation and increasing use of legumes in mixed swards are the most promising. It is concluded that although high-producing cow cannot express their potential milk production at grazing, there is scope to improve animal performance at grazing given recent developments in our understanding of factors influencing forage intake and digestion of grazed forages.

  18. Grazing as an alternative for utilization of saline-sodic soils in the San Joaquin Valley: Selenium accretion and performance of beef heifers

    International Nuclear Information System (INIS)

    Juchem, Sérgio O.; Benes, Sharon E.; Robinson, P.H.; Grattan, Stephen R.; Vasquez, Pablo; Chilibroste, Pablo; Brito, Martin

    2012-01-01

    Two experiments were conducted to evaluate Se accumulation and health of non-pregnant, non-breeding beef cattle grazing on forages with a high Se content due to irrigation with saline drainage water. Heifers grazed experimental pastures of “Jose” tall wheatgrass (TWG; Thinopyrum ponticum var. “Jose”) and creeping wildrye (CWR; Leymus triticoides var. “Rio”) for190 days in Experiment 1 (2007) and for 165 days in Experiment 2 (2008). In experiment 1, mean Se concentrations were similar in TWG and CWR herbage (4.0 versus 3.7 ± 0.26 mg/kg dry weight; p = 0.34) as was crude protein (113 versus 114 ± 7.9 g/kg dry weight; p = 0.94). Concentrations of Se in blood increased by 300% during the grazing period, and were similar for heifers grazing the TWG or CWR pastures (0.94 versus 0.87 ± 0.03 mg/kg; p = 0.89). Heifers grazing on TWG gained more body weight than did heifers grazing on CWR (0.59 versus 0.27 ± 0.07 kg/days; p < 0.01). In experiment 2, concentration of Se (4.0 versus 2.8 mg/kg ± 0.19 mg/kg dry weight; p < 0.01) and crude protein (79 versus 90 ± 5.6 g/kg dry weight; p < 0.01) differed, for TWG and CWR, respectively. Within 20 days, Se concentrations in blood had increased by 300% and by nearly 200% in heifers grazing on TWG or CWR. All data cited are least square means ± standard error of the mean. Data from our two grazing seasons are consistent in demonstrating the safety of grazing beef cattle for a period of up to 6 months on TWG and CWR forages having high levels of Se due to irrigation with saline drainage water. This suggests that forage production using saline drainage water is a viable alternative for saline soils with limited potential for producing high value, salt-sensitive, crops. - Highlights: ► Forages irrigated with saline drainage water may contain high levels of selenium. ► High concentration of selenium in forages can be toxic to grazing cattle. ► Cattle accumulated high levels of selenium in blood, liver and muscle

  19. Grazing as an alternative for utilization of saline-sodic soils in the San Joaquin Valley: Selenium accretion and performance of beef heifers

    Energy Technology Data Exchange (ETDEWEB)

    Juchem, Sergio O., E-mail: sdjuchem@gmail.com [Department of Animal Science, University of California, Davis, CA 95616 (United States); Department of Plant Science, California State University, Fresno, CA 93740-8033 (United States); Benes, Sharon E. [Department of Plant Science, California State University, Fresno, CA 93740-8033 (United States); Robinson, P.H. [Department of Animal Science, University of California, Davis, CA 95616 (United States); Grattan, Stephen R. [Department of Land and Water Resources, University of California, Davis, CA 95616 (United States); Vasquez, Pablo [Department of Plant Science, California State University, Fresno, CA 93740-8033 (United States); Chilibroste, Pablo [Instituto Nacional de Investigacion Agropecuaria, Paysandu (Uruguay); Brito, Martin [Department of Plant Science, California State University, Fresno, CA 93740-8033 (United States)

    2012-03-01

    Two experiments were conducted to evaluate Se accumulation and health of non-pregnant, non-breeding beef cattle grazing on forages with a high Se content due to irrigation with saline drainage water. Heifers grazed experimental pastures of 'Jose' tall wheatgrass (TWG; Thinopyrum ponticum var. 'Jose') and creeping wildrye (CWR; Leymus triticoides var. 'Rio') for190 days in Experiment 1 (2007) and for 165 days in Experiment 2 (2008). In experiment 1, mean Se concentrations were similar in TWG and CWR herbage (4.0 versus 3.7 {+-} 0.26 mg/kg dry weight; p = 0.34) as was crude protein (113 versus 114 {+-} 7.9 g/kg dry weight; p = 0.94). Concentrations of Se in blood increased by 300% during the grazing period, and were similar for heifers grazing the TWG or CWR pastures (0.94 versus 0.87 {+-} 0.03 mg/kg; p = 0.89). Heifers grazing on TWG gained more body weight than did heifers grazing on CWR (0.59 versus 0.27 {+-} 0.07 kg/days; p < 0.01). In experiment 2, concentration of Se (4.0 versus 2.8 mg/kg {+-} 0.19 mg/kg dry weight; p < 0.01) and crude protein (79 versus 90 {+-} 5.6 g/kg dry weight; p < 0.01) differed, for TWG and CWR, respectively. Within 20 days, Se concentrations in blood had increased by 300% and by nearly 200% in heifers grazing on TWG or CWR. All data cited are least square means {+-} standard error of the mean. Data from our two grazing seasons are consistent in demonstrating the safety of grazing beef cattle for a period of up to 6 months on TWG and CWR forages having high levels of Se due to irrigation with saline drainage water. This suggests that forage production using saline drainage water is a viable alternative for saline soils with limited potential for producing high value, salt-sensitive, crops. - Highlights: Black-Right-Pointing-Pointer Forages irrigated with saline drainage water may contain high levels of selenium. Black-Right-Pointing-Pointer High concentration of selenium in forages can be toxic to grazing

  20. S-shaped bifurcation curves for logistic growth and weak Allee effect growth models with grazing on an interior patch

    Directory of Open Access Journals (Sweden)

    Dagny Butler

    2013-10-01

    Full Text Available We study the positive solutions to the steady state reaction diffusion equations with Dirichlet boundary conditions of the form $$displaylines{ -u''= cases{ lambda[u - frac{1}{K}u^2 - c frac{u^2}{1+u^2}], & $x in (L,1-L$,cr lambda[u - frac{1}{K}u^2], & $x in (0,Lcup(1-L,1$, } cr u(0=0, quad u(1=0 }$$ and displaylines{ -u''= cases{ lambda[u(u+1(b-u - c frac{u^2}{1+u^2}], & $x in (L,1-L$, cr lambda[u(u+1(b-u], & $x in (0,Lcup(1-L,1$, } cr u(0=0,quad u(1=0. }$$ Here, $lambda, b, c, K, L$ are positive constants with 0grazing, and the second model describes weak Allee effect with grazing. In both cases, u is the population density, $1/lambda$ is the diffusion coefficient, and c is the maximum grazing rate. These models correspond to the case of symmetric grazing on an interior region. Our goal is to study the existence of positive solutions. Previous studies when the grazing was throughout the domain resulted in S-shaped bifurcation curves for certain parameter ranges. Here, we show that such S-shaped bifurcations occur even if the grazing is confined to the interior. We discuss the results via a modified quadrature method and Mathematica computations.

  1. Quantifying the impact of livestock grazing on soil physical properties

    Science.gov (United States)

    Fučík, Petr; Zajíček, Antonín; Holubík, Ondřej

    2014-05-01

    Livestock grazing is considered to have a noticeable influence on soil properties, when pedocompaction / soil pore reduction induced either by cattle or sheeps may curtail water residence time and accelerate the beginning and volume of overland flow. However, direct measurements of soil physical parameters and their changes under different pastoral management are seldom reported in central European conditions. Knowledge about these alterations are indispensable for setting the proper, soil and water conservative grazing management in the view of increasing areas of pastures, not only in the Czech Republic. Impact of cattle grazing on changes of soil properties was studied in three experimental upland catchments in the Czech Republic, differing in soil characteristics and grazing management. Values of soil saturated hydraulic conductivity (Ks), assessed three times a year in-situ during 2012 - 2013 with pressure infiltrometers, were compared for grazed and ungrazed cambisols, pseudogleys and gleysols, for grazing intensity ranging from 0.5 to 2 Livestock units / ha. Soil bulk density (BD) and macroporosity (MP) were determined before and after grazing season every year with ring 100 cm3 steel cyllinders. These parameters were measured also on heavily treaded plots by cattle - hotspots - in each catchment. Ks values on grazed plots were significantly lower (on average by 39 - 66 %) than on ungrazed sites, BD values were reduced on average by 15 % and MP values were lower roughly about 22 % on grazed plots. Ks values on hotspots were lower by 50 - 90 %, BD values by 5 - 18 % and MP values by 8 - 28 % comparing to the rest of grazed areas. Decrease of soil infiltration capacity was influenced by grazing intensity and soil characteristics. The greatest reductions concerning infiltration capacity were manifested in soils being periodically waterlogged (either by surface or by groundwater). A profound influence on the infiltration process was revealed in pasture soils

  2. Economic modelling of grazing management against gastrointestinal nematodes in dairy cattle

    NARCIS (Netherlands)

    Voort, van der M.; Meensel, Van J.; Lauwers, L.; Haan, de M.H.A.; Evers, A.G.; Huylenbroeck, Van G.; Charlier, J.

    2017-01-01

    Grazing management (GM) interventions, such as reducing the grazing time or mowing pasture before grazing, have been proposed to limit the exposure to gastrointestinal (GI) nematode infections in grazed livestock. However, the farm-level economic effects of these interventions have not yet been

  3. The effect of continuous and rotational grazing of sourveld on the ...

    African Journals Online (AJOL)

    It was thus concluded that cattle continued to graze selectively regardless of the grazing method or the stocking intensity. Keywords: cattle grazing; crude protein; digestibility; dry matter digestibility; grasses; grazing; herbage; kokstad agricultural research station; leaf fraction; leaves; oesophageal fistulas; protein; rotational ...

  4. Impact of grazing management on hibernating caterpillars of the butterfly Melitaea cinxia in calcareous grasslands

    NARCIS (Netherlands)

    Noordwijk, C.G.E.; Flierman, D.E.; Remke, E.; Wallis de Vries, M.F.; Berg, M.P.

    2012-01-01

    Semi-natural grasslands are increasingly grazed by large herbivores for nature conservation purposes. For many insects such grazing is essential for the conservation of their habitat, but at the same time, populations decrease at high grazing intensity. We hypothesised that grazing management may

  5. Impact of grazing on hibernating caterpillars of the calcareous grassland butterfly Melitaea cinxia.

    NARCIS (Netherlands)

    van Noordwijk, C.G.E.; Flierman, D.E.; Remke, E.; Wallis de Vries, M.F.; Berg, M.P.

    2012-01-01

    Semi-natural grasslands are increasingly grazed by large herbivores for nature conservation purposes. For many insects such grazing is essential for the conservation of their habitat, but at the same time, populations decrease at high grazing intensity. We hypothesised that grazing management may

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

    Science.gov (United States)

    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...

  7. Compensatory growth of Festuca rubra after grazing : can migratory herbivores increase their own harvest during staging?

    NARCIS (Netherlands)

    Van der Graaf, AJ; Stahl, J; Bakker, JP

    2005-01-01

    1. The grazing optimization hypothesis predicts increased production and quality of plants grazed at intermediate grazing pressures. Following this hypothesis, herbivores will be able to increase their own harvest by repeated grazing. We tested the predictions of this hypothesis for Barnacle Geese,

  8. Movement analysis of free-grazing domestic ducks in Poyang Lake, China: A disease connection

    Science.gov (United States)

    Prosser, Diann J.; Palm, Eric C.; Takekawa, John Y.; Zhao, Delong; Xiao, Xiangming; Li, Peng; Liu, Ying; Newman, Scott H.

    2015-01-01

    Previous work suggests domestic poultry are important contributors to the emergence and transmission of highly pathogenic avian influenza throughout Asia. In Poyang Lake, China, domestic duck production cycles are synchronized with arrival and departure of thousands of migratory wild birds in the area. During these periods, high densities of juvenile domestic ducks are in close proximity to migratory wild ducks, increasing the potential for the virus to be transmitted and subsequently disseminated via migration. In this paper, we use GPS dataloggers and dynamic Brownian bridge models to describe movements and habitat use of free-grazing domestic ducks in the Poyang Lake basin and identify specific areas that may have the highest risk of H5N1 transmission between domestic and wild birds. Specifically, we determine relative use by free-grazing domestic ducks of natural wetlands, which are the most heavily used areas by migratory wild ducks, and of rice paddies, which provide habitat for resident wild ducks and lower densities of migratory wild ducks. To our knowledge, this is the first movement study on domestic ducks, and our data show potential for free-grazing domestic ducks from farms located near natural wetlands to come in contact with wild waterfowl, thereby increasing the risk for disease transmission. This study provides an example of the importance of movement ecology studies in understanding dynamics such as disease transmission on a complicated landscape.

  9. Estimating half-saturation constants of microzooplankton grazing in the sea

    Science.gov (United States)

    Chen, B.; Laws, E. A.

    2016-02-01

    To obtain the grazing half-saturation constant (K) of natural microzooplankton assemblages, we used three nonlinear grazing models (rectilinear, Holling type II, and Holling type III) to fit the detailed data (phytoplankton net specific growth rate vs. dilution factor) of individual dilution experiments that show significant concave curves. In the dataset consisting of 528 experiments, 96 experiments show significant concave curves, and the associated chlorophyll a (Chl a) concentrations are significantly higher than those of experiments showing linear or convex curves. Experiments showing concave curves likely reflect that these microzooplankton assemblages were under top-down control. The three models perform equally well in fitting the data. The K values estimated from these 96 experiments vary over three orders of magnitude and are log-log linearly related with ambient Chl a concentrations, but not correlated with temperatures. Estimates of K of natural microzooplankton assemblages tend to be smaller than estimates from laboratory cultures. For the experiments not showing concave curves, it is hard to obtain a robust estimate of K.

  10. Structural characteristics and forage mass of Tifton 85 pastures managed under three post-grazing residual leaf areas

    Directory of Open Access Journals (Sweden)

    Wilton Ladeira da Silva

    2013-04-01

    Full Text Available The experiment was carried out on Cynodon spp cv. Tifton 85 pastures grazed by sheep under rotational stocking, with the objective of evaluating the structural characteristics as well as the forage mass of the pastures subjected to three grazing intensities in successive cycles. Treatments were composed of three residual leaf area indices (rLAI; 2.4; 1.6 and 0.8, allocated in completely randomized blocks with seven replications, totaling 21 experimental units. Tiller population density, pasture height, leaf area index, forage morphological composition and pasture forage mass were evaluated. The rLAI modified the tiller population density, which increased linearly with decrease in the rLAI of the pastures. Dry masses of leaf blade, stem and dead material were inferior when the rLAI imposed were lower, which resulted in differentiated forage production among the treatments. Tifton 85 pastures grazed by sheep in rotational stocking under tropical conditions with different rLAI show a modified sward structure over successive grazing cycles, mainly by alteration in the height and LAI of the plants at pre-grazing and by light interception post-grazing, which change the tiller population density. The residual leaf area index of 1.6 is the most suitable for pasture management for being equivalent to the heights of entrance and exit of animals on and from paddocks of 33 and 19 cm, respectively, which avoid great accumulation of dead material and excessive stem elongation, in addition to ensuring tillering in the sward.

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

    African Journals Online (AJOL)

    grazing Dorper ewes, with (+ P) and without (- P) phosphorus (P) supplementation, was investigated over 4,5 years at Armoedsvlakte (notorious for its P-deficient soils) to establish whether sheep are as susceptible to a P deficiency as cattle.

  12. Which grazing management practices are most appropriate for ...

    African Journals Online (AJOL)

    continuous, conventional, or high-intensity grazing by sheep, cattle, or sheep plus cattle) on grassland biodiversity integrity. Selected indicators covered landscape composition, structure and functioning. High-intensity systems and continuous ...

  13. Fertility of Zero-Grazed Dairy Cattle following Hormone Treatment ...

    African Journals Online (AJOL)

    Time Artificial Insemination. ... delayed onset of puberty are some of the limiting factors to attainment of optimum reproductive efficiency in zero-grazed herds. ... Treated animals had timed artificial insemination (AI) 8-24 hours after the last injection.

  14. Seasonal variation in invertebrate grazing on Chara connivens and C. tomentosa in Kõiguste Bay, NE Baltic Sea

    Science.gov (United States)

    Kotta, Jonne; Torn, Kaire; Martin, Georg; Orav-Kotta, Helen; Paalme, Tiina

    2004-04-01

    Charophytes are a highly endangered group of algae. In the Baltic Sea, the number of species, distribution area and biomass of charophytes have significantly decreased in recent decades. Although eutrophication triggers their initial decline, the mechanism of the final extinction of charophyte populations is not fully understood. An in situ experiment was performed to study the role of the mesoherbivores Idotea baltica, Gammarus oceanicus and Palaemon adspersus in the decline of charophytes in the north-eastern Baltic Sea. Invertebrate grazing showed a clear seasonality: grazing pressure was low in April, moderate in July, and high in October. Grazing on charophytes by P. adspersus was negligible, whereas I. baltica and G. oceanicus significantly reduced the biomass of charophytes in the field. Low photosynthetic activity (high decomposition rate) of the charophytes favoured grazing. The invertebrates studied preferred Chara tomentosa to C. connivens. Low consumption of C. connivens may reflect its non-native origin. The experiment suggests that, under moderately eutrophic conditions, grazers are not likely to control charophyte populations. However, grazers have the potential to eliminate charophytes in severely eutrophic systems under the stress of filamentous algae.

  15. Grazing Exclusion to Recover Degraded Alpine Pastures Needs Scientific Assessments across the Northern Tibetan Plateau

    Directory of Open Access Journals (Sweden)

    Chengqun Yu

    2016-11-01

    Full Text Available The northern Tibetan Plateau is the most traditional and important semi-nomadic region in Tibet. The alpine vegetation is sensitive and vulnerable to climate change and human activities, and is also important as an ecological security in protecting the headwaters of major rivers in Asia. Therefore, the Tibetan alpine grasslands have fundamental significance to both Mainland China and South Asia. The pasture degradation, however, likely threatens the livelihood of residents and the habitats of wildlife on this plateau. Since 2004, the government has launched a series of ecological restoration projects and economic compensatory payment polices. Many fences were additionally built on degraded pastures to prevent new degradation, to promote functionality recovery, and to balance the stocking rate with forage productivity. The grazed vs. fenced paired pastures across different zonal grassland communities along evident environmental gradients provide us with a natural comparative experiment platform to test the relative contributions of natural and anthropogenic factors. This study critically reviews the background, significance of and debates on short-term grazing exclusion with fences in this region. We also aim to figure out scientific and standardized workflows for assessing the effectiveness of grazing exclusion and compensatory payments in the future.

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

    International Nuclear Information System (INIS)

    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

  17. Advanced grazing-incidence techniques for modern soft-matter materials analysis

    Directory of Open Access Journals (Sweden)

    Alexander Hexemer

    2015-01-01

    Full Text Available The complex nano-morphology of modern soft-matter materials is successfully probed with advanced grazing-incidence techniques. Based on grazing-incidence small- and wide-angle X-ray and neutron scattering (GISAXS, GIWAXS, GISANS and GIWANS, new possibilities arise which are discussed with selected examples. Due to instrumental progress, highly interesting possibilities for local structure analysis in this material class arise from the use of micro- and nanometer-sized X-ray beams in micro- or nanofocused GISAXS and GIWAXS experiments. The feasibility of very short data acquisition times down to milliseconds creates exciting possibilities for in situ and in operando GISAXS and GIWAXS studies. Tuning the energy of GISAXS and GIWAXS in the soft X-ray regime and in time-of flight GISANS allows the tailoring of contrast conditions and thereby the probing of more complex morphologies. In addition, recent progress in software packages, useful for data analysis for advanced grazing-incidence techniques, is discussed.

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

    Directory of Open Access Journals (Sweden)

    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.

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

    Directory of Open Access Journals (Sweden)

    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.

  20. Increasing importance of precipitation variability on global livestock grazing lands

    Science.gov (United States)

    Sloat, Lindsey L.; Gerber, James S.; Samberg, Leah H.; Smith, William K.; Herrero, Mario; Ferreira, Laerte G.; Godde, Cécile M.; West, Paul C.

    2018-02-01

    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.

  1. Meso- and microzooplankton responses to an in situ iron fertilization experiment (SEEDS II) in the northwest subarctic Pacific

    Science.gov (United States)

    Tsuda, Atsushi; Saito, Hiroaki; Machida, Ryuji J.; Shimode, Shinji

    2009-12-01

    A mesoscale iron fertilization experiment was carried out in the western subarctic Pacific during summer 2004. The iron-patch was traced for 26 days after the enrichment, and the abundance and behavior of meso- and microzooplankton was compared with those outside of the patch. The surface chlorophyll- a concentration in the patch was high between days 10 and 13 (2.5 mg m -3) and decreased to the initial level after day 20. Microzooplankton grazing rates, estimated by a dilution method, was mostly balanced with phytoplankton growth rates throughout the observed period. Dominant mesozooplankton species in the upper 200 m were copepods: dominated by Eucalanus bungii, Neocalanus plumchrus and Metridia pacifica. Species composition did not change in the patch over the observation period. The copepod biomass was 3-5 times higher than in Subarctic Pacific Iron Experiment for Ecosystem Dynamics Study (SEEDS), the previous iron-enrichment experiment in the same area, before the bloom, and exponentially increased both inside and outside the patch, which was mainly brought by the development of N. plumchrus. The development rates of N. plumchrus were not significantly different between inside and outside the patch. Estimated grazing rate suggest that the copepod grazing was main cause of the low accumulation of phytoplankton biomass, and dominance of grazing-resistant organisms such as large ciliates, large diatoms and diatoms with extremely long setae. "Arrested migration" for M. pacifica and upward shift of vertical distribution by E. bungii were observed during the bloom period, even if the accumulation of phytoplankton biomass was very low compared to other iron-enrichment experiments. These results indicate that the copepod grazing shaped the food-web structure of the lower trophic levels (biomass and species composition) in SEEDS II.

  2. Population fluctuations, losses to grazing, and reproductive success of Dactylorhiza sambucina on Bornholm, Denmark

    DEFF Research Database (Denmark)

    Sonne, Mette Nordvig; Hauser, Thure Pavlo

    2014-01-01

    Populations of the orchid Dactylorhiza sambucina are declining in number and size on the island of Bornholm, Denmark. To study the reasons for this trend, we compiled previously unpublished estimates of population sizes from 1987–2010 and found complicated fluctuations, as population sizes...... 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...

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

    NARCIS (Netherlands)

    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. Grazing management in an integrated crop-livestock system: soybean development and grain yield

    Directory of Open Access Journals (Sweden)

    Taise Robinson Kunrath

    Full Text Available ABSTRACTGrazing livestock in integrated crop-livestock systems can cause impacts in the subsequent crop cycle. Aiming to investigate how grazing could affect soybean, the 9th crop cycle of a pasture/soybean rotation was assessed. Treatments were grazing intensities (10, 20, 30 and 40 cm of sward height applied since 2001 in a mixed of oat and annual ryegrass; and an additional no grazing area as control. Treatments were arranged in a completely randomized block design with three replicates. Grazing affected soybean population and the mass of individual nodules (P0.05. Soybean yield showed differences among treatments, but no difference was found between grazed and non-grazed areas. Grazing intensities impact the coverage and frequency of weeds (P>0.05. In conclusion, grazing intensity impacts different parameters of soybean yield and development, but only the grazing intensity of 10 cm can jeopardize the succeeding soybean crop.

  5. Alfalfa weevil (Coleoptera:Curculionidae) management in alfalfa by spring grazing with cattle.

    Science.gov (United States)

    Buntin, G D; Bouton, J H

    1996-12-01

    The effect of continuous, intensive grazing by cattle in the 1st alfalfa growth cycle on larval densities of the alfalfa weevil, Hyera postica (Gyllenhal), was evaluated in "Alfagraze' and "Apollo' alfalfa, which are tolerant and not tolerant to grazing, respectively. In small-cage exclusion trials, grazing reduced larval numbers in 1991 by 65% in Alfagraze and by 32% in Apollo. Larval numbers in 1992 were low (alfalfa weevil larvae caused moderate leaf injury in 1993 and severe injury in 1994 before grazing reduced larval numbers. Use of permethrin at 0.11 kg (AI)/ha or carbofuran or chlorpyrifos at 0.28 kg (AI)/ha effectively reduced larval numbers and prevented leaf injury before grazing began. Therefore, a combination of an early application of an insecticide treatment with a short grazing restriction followed by continuous grazing will control alfalfa weevil larvae while allowing cattle to graze and directly use forage of grazing-tolerant alfalfa.

  6. Grazing-induced BVOC fluxes from a managed grassland

    Science.gov (United States)

    Mozaffar, Ahsan; Schoon, Niels; Bachy, Aurelie; Digrado, Anthony; Heinesch, Bernard; Aubinet, Marc; Fauconnier, Marie-laure; Delaplace, Pierre; Dujardin, Patrick; Amelynck, Crist

    2017-04-01

    Grassland ecosystems cover one fourth of the Earth's land surface and are both sources and sinks of Biogenic Volatile Organic Compounds (BVOCs) which play an important role in atmospheric chemistry and air pollution. The use of grassland for cattle breeding is a common practice in many parts of the world. As it has been widely demonstrated that plants emit large bursts of BVOCs when they are mechanically damaged, grass tearing and trampling during grazing are expected to induce large BVOC emissions as well. Nevertheless, to the best of our knowledge, no study has been performed on BVOC fluxes from grazed grassland yet. Therefore investigations were performed using automated dynamic chambers in a managed grassland in Belgium over the 2015 and 2016 growing season. BVOC fluxes, together with carbon dioxide (CO2) and water vapor (H2O) fluxes from grazed and undisturbed grassland were followed simultaneously using PTR-MS (Proton Transfer Reaction-Mass Spectrometry) and a LI-840 non-dispersive IR gas analyzer. In addition, air in the chamber was sampled occasionally for GC-MS (Gas Chromatography-Mass Spectrometry) analysis to assist compound identification. Significant differences between grazed and undisturbed grassland patches were observed in terms of BVOC, CO2 and H2O vapor fluxes. Grazing by cows was found to result in enhanced emissions of several BVOCs such as methanol, acetaldehyde, acetone, acetic acid and Green Leaf Volatiles (GLVs), and induced BVOC emissions generally lasted for around 5 days following a grazing event. Quantitative data on the impact of grazing on BVOC, CO2 and H2O exchange between grassland and the atmosphere will be presented, and correlations between BVOC fluxes and environmental conditions will be discussed.

  7. Functional diversity increases ecological stability in a grazed grassland.

    Science.gov (United States)

    Hallett, Lauren M; Stein, Claudia; Suding, Katharine N

    2017-03-01

    Understanding the factors governing ecological stability in variable environments is a central focus of ecology. Functional diversity can stabilize ecosystem function over time if one group of species compensates for an environmentally driven decline in another. Although intuitively appealing, evidence for this pattern is mixed. We hypothesized that diverse functional responses to rainfall will increase the stability of vegetation cover and biomass across rainfall conditions, but that this effect depends on land-use legacies that maintain functional diversity. We experimentally manipulated grazing in a California grassland to create land-use legacies of low and moderate grazing, across which we implemented rainout shelters and irrigation to create dry and wet conditions over 3 years. We found that the stability of the vegetation cover was greatly elevated and the stability of the biomass was slightly elevated across rainfall conditions in areas with histories of moderate grazing. Initial functional diversity-both in the seed bank and aboveground-was also greater in areas that had been moderately grazed. Rainfall conditions in conjunction with this grazing legacy led to different functional diversity patterns over time. Wet conditions led to rapid declines in functional diversity and a convergence on resource-acquisitive traits. In contrast, consecutively dry conditions maintained but did not increase functional diversity over time. As a result, grazing practices and environmental conditions that decrease functional diversity may be associated with lasting effects on the response of ecosystem functions to drought. Our results demonstrate that theorized relationships between diversity and stability are applicable and important in the context of working grazed landscapes.

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

    Directory of Open Access Journals (Sweden)

    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.

  9. Influence of pasture and concentrates in the diet of grazing dairy cows on the fatty acid composition of milk.

    Science.gov (United States)

    Stockdale, C Richard; Walker, Glen P; Wales, William J; Dalley, Dawn E; Birkett, Anne; Shen, Zhiping; Doyle, Peter T

    2003-08-01

    In five short-term experiments conducted in Victoria in 1997 and 1998, grazing dairy cows were given either pasture alone or pasture supplemented with high-energy concentrates, and the fatty acid profiles of milk fat were measured. We established the effects of these feeds on some aspects of milk fat of importance for human nutrition, but we specifically focused on the hypothesis that conjugated linoleic acid (CLA) concentrations in milk fat increase as pasture intake increases, and decrease as more concentrates are fed. In agreement with previous research, feeding fresh pasture alone resulted in high concentrations (1.0-1.8 g/100 g milk fat) of CLA. When the effect of level of pasture consumption on CLA content was examined, a significant positive relationship (r2 = 0.35; P milk fat generally declined (P milk fat concentration. The use of cereal grain concentrates also generally resulted in significant (P milk fat, from 4.5 to 3.9 g/100 g milk fat, on average.

  10. Soil and ecosystem respiration responses to grazing, watering and experimental warming chamber treatments across topographical gradients in northern Mongolia.

    Science.gov (United States)

    Sharkhuu, Anarmaa; Plante, Alain F; Enkhmandal, Orsoo; Gonneau, Cédric; Casper, Brenda B; Boldgiv, Bazartseren; Petraitis, Peter S

    2016-05-01

    Globally, soil respiration is one of the largest fluxes of carbon to the atmosphere and is known to be sensitive to climate change, representing a potential positive feedback. We conducted a number of field experiments to study independent and combined impacts of topography, watering, grazing and climate manipulations on bare soil and vegetated soil (i.e., ecosystem) respiration in northern Mongolia, an area known to be highly vulnerable to climate change and overgrazing. Our results indicated that soil moisture is the most important driving factor for carbon fluxes in this semi-arid ecosystem, based on smaller carbon fluxes under drier conditions. Warmer conditions did not result in increased respiration. Although the system has local topographical gradients in terms of nutrient, moisture availability and plant species, soil respiration responses to OTC treatments were similar on the upper and lower slopes, implying that local heterogeneity may not be important for scaling up the results. In contrast, ecosystem respiration responses to OTCs differed between the upper and the lower slopes, implying that the response of vegetation to climate change may override microbial responses. Our results also showed that light grazing may actually enhance soil respiration while decreasing ecosystem respiration, and grazing impact may not depend on climate change. Overall, our results indicate that soil and ecosystem respiration in this semi-arid steppe are more sensitive to precipitation fluctuation and grazing pressure than to temperature change.

  11. Evaluation of soil intake by growing Creole young bulls in common grazing systems in humid tropical conditions.

    Science.gov (United States)

    Jurjanz, S; Collas, C; Lastel, M L; Godard, X; Archimède, H; Rychen, G; Mahieu, M; Feidt, C

    2017-08-01

    Soil is the main matrix which contributes to the transfer of environmental pollutants to animals and consequently into the food chain. In the French West Indies, chlordecone, a very persistent organochlorine pesticide, has been widely used on banana growing areas and this process has resulted in a long-term pollution of the corresponding soils. Domestic outside-reared herbivores are exposed to involuntary soil intake, and tethered grazing commonly used in West Indian systems can potentially favour their exposure to chlordecone. Thus, it appears necessary to quantify to what extent grazing conditions will influence soil intake. This experiment consisted of a cross-over design with two daily herbage allowance (DHA) grazed alternatively. Six young Creole bulls were distributed into two groups (G1 and G2) according to their BW. The animals were individually tethered and grazed on a restrictive (RES) or non-restrictive (NRES) levels of DHA during two successive 10-days periods. Each bull progressed on a new circular area every day. The two contrasting levels of DHA (P0.05) due to the lower DMI of RES compared with NRES treatment.

  12. Unexpected Decrease in Milk Production after Fenbendazole Treatment of Dairy Cows during Early Grazing Season

    Science.gov (United States)

    Ravinet, Nadine; Chartier, Christophe; Bareille, Nathalie; Lehebel, Anne; Ponnau, Adeline; Brisseau, Nadine; Chauvin, Alain

    2016-01-01

    Gastrointestinal nematodes (GIN) infection can impair milk production (MP) in dairy cows. To investigate whether MP would be optimized by spring targeted-selective anthelmintic treatment in grazing cows, we assessed (1) the effect on MP of an anthelmintic treatment applied 1.5 to 2 months after turn-out, and (2) herd and individual indicators associated with the post-treatment MP response. A randomized controlled clinical trial was conducted in 13 dairy farms (578 cows) in western France in spring 2012. In each herd, lactating cows of the treatment group received fenbendazole orally, control cows remained untreated. Daily cow MP was recorded from 2 weeks before until 15 weeks after treatment. Individual serum pepsinogen and anti-Ostertagia antibody levels (expressed as ODR), faecal egg count and bulk tank milk (BTM) Ostertagia ODR were measured at treatment time. Anthelmintic treatment applied during the previous housing period was recorded for each cow. In each herd, information regarding heifers’ grazing and anthelmintic treatment history was collected to assess the Time of Effective Contact (TEC, in months) with GIN infective larvae before the first calving. The effect of treatment on weekly MP averages and its relationships with herd and individual indicators were studied using linear mixed models with two nested random effects (cow within herd). Unexpectedly, spring treatment had a significant detrimental effect on MP (-0.92 kg/cow/day on average). This negative MP response was particularly marked in high producing cows, in cows not treated during the previous housing period or with high pepsinogen levels, and in cows from herds with a high TEC or a high BTM ODR. This post-treatment decrease in MP may be associated with immuno-inflammatory mechanisms. Until further studies can assess whether this unexpected result can be generalized, non-persistent treatment of immunized adult dairy cows against GIN should not be recommended in early grazing season. PMID

  13. Daily intake of lactating crossbred cows grazing elephant grass rotationally

    Directory of Open Access Journals (Sweden)

    Aroeira Luiz Januário Magalhães

    2001-01-01

    Full Text Available The goal of this trial was to estimate the total dry matter (TDMI and daily pasture dry matter intakes (PDMI by lactating crossbred Holstein - Zebu cows grazing elephant grass (Pennisetum purpureum Schum. paddocks submitted to different rest periods. Three groups of 24 cows were used during two years. The paddocks were grazed during three days at the stocking rate of 4.5 cows/ha. Treatments consisted of resting periods of 30 days without concentrate and resting periods of 30, 37.5 and 45 days with 2 kg/cow/day of 20.6% crude protein concentrate. From July to October, pasture was supplemented with chopped sugarcane plus 1% urea. Total daily dry matter intake was estimated using the extrusa in vitro dry matter digestibility and the fecal output with chromium oxide. Regardless of the treatment the estimated average TDMI was 2.7, 2.9 and 2.9±0.03% and the mean PDMI was 1.9, 2.1 and 2.1±0.03% of body weight in the first, second and third grazing day, respectively (P<0.05. Only during the summer pasture quality was the same whichever the grazing day. Sugarcane effectively replaced grazing pasture, mainly in the first day when pasture dry matter intake was lowest.

  14. Sediment losses and gains across a gradient of livestock grazing and plant invasion in a cool, semi-arid grassland, Colorado Plateau, USA

    Science.gov (United States)

    Belnap, J.; Reynolds, R.L.; Reheis, M.C.; Phillips, S.L.; Urban, F.E.; Goldstein, H.L.

    2009-01-01

    Large sediment fluxes can have significant impacts on ecosystems. We measured incoming and outgoing sediment across a gradient of soil disturbance (livestock grazing, plowing) and annual plant invasion for 9 years. Our sites included two currently ungrazed sites: one never grazed by livestock and dominated by perennial grasses/well-developed biocrusts and one not grazed since 1974 and dominated by annual weeds with little biocrusts. We used two currently grazed sites: one dominated by annual weeds and the other dominated by perennial plants, both with little biocrusts. Precipitation was highly variable, with years of average, above-average, and extremely low precipitation. During years with average and above-average precipitation, the disturbed sites consistently produced 2.8 times more sediment than the currently undisturbed sites. The never grazed site always produced the least sediment of all the sites. During the drought years, we observed a 5600-fold increase in sediment production from the most disturbed site (dominated by annual grasses, plowed about 50 years previously and currently grazed by livestock) relative to the never grazed site dominated by perennial grasses and well-developed biocrusts, indicating a non-linear, synergistic response to increasing disturbance types and levels. Comparing sediment losses among the sites, biocrusts were most important in predicting site stability, followed by perennial plant cover. Incoming sediment was similar among the sites, and while inputs were up to 9-fold higher at the most heavily disturbed site during drought years compared to average years, the change during the drought conditions was small relative to the large change seen in the sediment outputs. ?? 2009 Elsevier B.V. All rights reserved.

  15. Atypical myopathy in grazing horses: a first exploratory data analysis.

    Science.gov (United States)

    Votion, Dominique-M; Linden, Annick; Delguste, Catherine; Amory, Hélène; Thiry, Etienne; Engels, Patrick; van Galen, Gaby; Navet, Rachel; Sluse, Francis; Serteyn, Didier; Saegerman, Claude

    2009-04-01

    Over the last decade, atypical myopathy (AM) in grazing horses has emerged in several European countries. An exploratory analysis was conducted to determine horse- and pasture-level indicators or factors associated with AM in Belgium. Belgian cases of AM confirmed by histology (n=57) were compared to their healthy co-grazing horses (n=77) and to pastured horses not involved with AM as controls (n=386). The pastures where confirmed cases were grazing (42 pastures; 38 sites; 44 incidences of AM) were compared with those of the controls (216 pastures; 96 sites; no incidence of AM). Statistically significant (Phorses (young age, inactivity, body condition poor to normal), management practices (permanent pasturing, spreading of manure) and pasture characteristics (humid, sloping pastures, accumulated dead leaves, presence of waterway) may increase the risk of AM. Specific interventions based on these factors might help to reduce the incidence of AM.

  16. 1000 years of sustainable grazing in Nordic conditions?

    DEFF Research Database (Denmark)

    Brandt, Jesper

    , in practice linking detailed contextualized accumulated knowledge on nature processes at landscape level with constant social conflict regulations at a local and regional level. Often it worked, but in some situations (e.g. with marked changes in social or economic conditions, or by changing climatic...... 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...... conditions) it did not. Based on many years of studying the landscape and ecological and social conditions of the Faroese grazing system since the first Faeroese law  the Sheep Letter from 1298  I have tried to derive some lessons concerning possibilities and limitations in the use of historical knowledge...

  17. Changes in vegetation and grazing capacity following honey mesquite control

    Science.gov (United States)

    McDaniel, Kirk C.; Brock, John H.; Haas, Robert H.

    1982-01-01

    Honey mesquite kill and suppression, vegetation response, and changes in grazing use and capacity were evaluated following brush control in north-central Texas. Tree grubbing was most effective for eliminating honey mesquite, but because of soil and plant damage the treatment did not increase grazing capacity or improve range condition compared to nontreated rangeland. Aerial application of 2,4,5-T + picloram was more effective in klllmg and defoliating honey mesquite than 2,4,5-T alone, but both treatments significantly increased forage production. The 2,4,5-T + picloram and 2,4,5-T sprays provided a 7 to 16% increase in grazing capacity over a 4-year period on light and heavy honey mesquite infested pastures, respectively.

  18. Soil organic carbon stocks and composition under grazed and ungrazed Kobresia pygmaea pasture of the Tibetan Plateau

    Science.gov (United States)

    Breidenbach, Andreas; Schleuß, Per; Kuzyakov, Yakov; Guggenberger, Georg

    2015-04-01

    Kobresia pastures represent the world's largest alpine ecosystem and an important sink but also a potential source of CO2. Specific features of Kobresia root mats provide unique mechanisms protecting against degradation even by moderate overgrazing and leading to large carbon storage in soil. Thus it is necessary to analyse how management- and/or climate-induced changes in above and belowground litter production affect the OC stock and composition in these grassland soils. We analyzed soils from a grazing exclosure experiment to study alterations using elemental analysis and analysis of solvent extractable as well as hydrolysable aliphatic lipids (e.g. n-alkanes, n-alkanols, n-alkanoic acids, as well as cutin- and suberin-derived hydroxy-fatty acids). We investigated bulk soils and density fractions taken from three different depth increments (0-5 cm, 5-15 cm and 15-35 cm) from two grazed and two ungrazed plots. Grazing exclosure resulted in an OC gain up to 1.0 kg m-2 at the site where plant community changes after grazing cessation were most pronounced. These OC gains were caused by increased stocks of OC in the particulate fraction of the two deeper soil increments whereas the OC of the mineral associated fraction and the depth increment 0-5 cm showed no changes. Moreover, the concentration of solvent extractable C16 and C18 acids decreased in the particulate fraction whereas the concentration of C24 and C26 acids increased. Our results show that seven years of grazing cessation increased the OC-pool with short turnover rates and changed its chemical composition, but had no major impact on the more stable OC pools of the mineral soil.

  19. Nearly-grazing optimal trajectories for aeroassisted orbital transfer

    Science.gov (United States)

    Miele, A.; Mease, K. D.; Basapur, V. K.

    1986-01-01

    In the present treatment of optimal control problems arising in the study of coplanar aeroassisted orbital transfer, the hybrid combination of propulsive parameters in space and aerodynamic maneuvers employing lift modulation in the sensible atmosphere indicates that the optimal energy-viewpoint solution is the grazing trajectory; this trajectory is characterized by favorable values of the peak heating rate and the peak dynamic pressure. Numerical solutions are obtained by means of the sequential gradient restoration algorithm for optimal control problems. It is found that nearly-grazing trajectories yielding the least-square value of the path inclination have desirable characteristics from the standpoints of energy, heating rate, and dynamic pressure.

  20. Preliminary results from a shallow water benthic grazing study

    Science.gov (United States)

    Jones, N.L.; Monismith, Stephen G.; Thompson, Janet K.

    2005-01-01

    The nutrient-rich, shallow waters of San Francisco Bay support high rates of primary production, limited not by nutrients but by light availability and benthic grazing (Alpine and others 1992; Cloern 1982). Phytoplankton blooms are an important food source for upper trophic levels. Consequently animal populations, such as fish, may suffer under conditions of high benthic bivalve grazing. It has been hypothesized that several species of fish are suffering as a result of severe decreases in available phytoplankton since the introduction of Potamocorbula amurensis into San Francisco Bay (Feyrer 2003).

  1. X-ray grazing incidence diffraction from multilayers

    Energy Technology Data Exchange (ETDEWEB)

    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.

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

    NARCIS (Netherlands)

    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 Mediterranean land mass. It is a

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

    Science.gov (United States)

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

    2013-03-01

    Two experiments were conducted to evaluate effects of corn dry distiller grains plus condensed solubles (DDGS) supplementation level on performance digestion characteristics of steers grazing native range during the forage growing season. In the performance study, 72 (206 ± 23.6 kg; 2008) and 60 (230 ± 11.3 kg; 2009) English crossbred steer calves were used in a randomized complete block design replicated over 2 yr. The grazing periods lasted 56 and 58 d and started on August 11 and 18 for 2008 and 2009, respectively. Each year, steers were blocked by BW (light, medium, and heavy), stratified by BW within blocks, and randomly assigned to 1 of 4 grazing groups. Each grazing group (6 steers in 2008 and 5 in 2009) was assigned to a DDGS supplementation levels (0, 0.2, 0.4, and 0.6% BW). Grazing group served as the experimental unit with 12 groups per year receiving 1 of 4 treatments for 2 yr (n = 6). In the metabolism study, 16 English crossbred steers (360 ± 28.9 kg) fitted with ruminal cannulas grazing native range during the summer growing season were used in a completely randomized design to evaluate treatment effects on forage intake and digestion. The experiment was conducted during the first and second weeks of October 2008. Steers were randomly assigned to supplement level (0, 0.2, 0.4, and 0.6% BW; n = 4) and grazed a single native range pasture with supplements offered individually once daily at 0700 h. In the performance study, ADG (0.64, 0.75, 0.80, and 0.86 ± 0.03 kg/d for 0, 0.2, 0.4, and 0.6% BW, respectively) increased linearly (P = 0.01) with increasing DDGS supplementation level. In the metabolism study, forage OM, NDF, CP, and ether extract (EE) intake decreased (P ≤ 0.05) linearly with increasing DDGS supplementation level. Total CP and EE intake increased (P ≤ 0.002) with increasing DDGS supplementation level. Digestibility of OM, NDF, and EE increased (linear; P ≤ 0.008) whereas the soluble CP fraction of forage masticate sample

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

    OpenAIRE

    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.

  5. Optimization of Grazing Incidence Optics for Wide-Field X-Ray Survey Imaging

    Science.gov (United States)

    Roming, P. W. A.; Burrows, D. N.; Garmire, G. P.; Roush, W. B.

    1999-12-01

    Optimization of wide-field X-ray optics could greatly enhance X-ray surveys. Discussions of optimizing wide-field X-ray optics, with field-of-views less-than 1.1 degree-squared, have been made previously in the literature. However, very little has been published about the optimizing of wide-field X-ray optics with larger fields-of-view. We have been working on the design of a wide-field (3.1 degree-squared field-of-view), short focal length (190.5 cm), grazing incidence mirror shell set, with a desired rms image spot size of 15 arcsec. The baseline design incorporates Wolter I type mirror shells with polynomial perturbations applied to the grazing incidence surface. By optimizing the polynomial, the rms image spot size can be minimized for a large range of grazing angles. The overall minimization technique is to efficiently optimize the polynomial coefficients that directly influence the angular resolution, without stepping through the entire multidimensional coefficient space. The multidimensional minimization techniques that have been investigated include: the downhill simplex method; the coupling of genetic algorithms with full and fractional, including Plackett-Burman, factorial designs; and the coupling of genetic algorithms with Box-Behnken and central composite response surface designs. We have also examined the use of neural networks, coupled with genetic algorithms, as a method of multidimensional minimization. Investigations of backpropagation, probabilistic (PNN), general regression (GRNN), and group method of data handling (GMDH) neural networks have been made. We report our findings to date. This research is funded by NASA grant #NAG5-5093.

  6. Life strategy and grazing intensity responses of Brachionus calyciflorus fed on different concentrations of microcystin-producing and microcystin-free Microcystis aeruginosa.

    Science.gov (United States)

    Liang, Ye; Ouyang, Kai; Chen, Xinglan; Su, Yuqi; Yang, Jiaxin

    2017-02-23

    The occurrence of Microcystis blooms is a worldwide concern due to the numerous adverse effects on zooplankton. We therefore hypothesized that the cyanobacterium Microcystis aeruginosa is harmful to rotifer growth. Population and individual experiments were conducted with the same proportional volumes of Chlorella and Microcystis for given food densities. Life-table parameters, life-history traits, and the grazing intensity of Brachionus calyciflorus were evaluated after they had fed on microcystin-producing and microcystin-free Microcystis, both alone and combined with an edible alga (Chlorella pyrenoidosa), at concentrations of 1 × 10 5 , 1 × 10 6 , and 1 × 10 7 cells mL -1 . The results showed that the interactive effects of food density and type appeared to be synergistic on generation time (T), net reproduction rate (R 0 ), body length, swimming speed, and reproduction time. In contrast, these effects appeared to be antagonistic on intrinsic growth rate (r), finite rate of increase (λ), time to first brood, post-reproductive time and total offspring per female. The grazing rate of rotifers decreased with grazing time. Although the toxins released after grazing on M. aeruginosa had negative effects on rotifer growth and reproduction, B. calyciflorus changed its life strategy and grazing intensity in response to eutrophic conditions.

  7. [Effects of mowing and grazing on soil nutrients and soil microbes in rhizosphere and bulk soil of Stipa grandis in a typical steppe].

    Science.gov (United States)

    Hu, Jing; Hou, Xiang-yang; Wang, Zhen; Ding, Yong; Li, Xi-liang; Li, Ping; Ji, Lei

    2015-11-01

    This study conducted experiments using Stipa grandis, the dominant species of the typical steppe in Inner Mongolia. The research explored the different effects of mowing and grazing on organic carbon, total nitrogen, available nitrogen, total phosphorus and available phosphorus in rhizosphere and bulk soil. The results showed that: Both mowing and grazing inhibited assemble and storage capacity of rhizosphere, and decreased the organic carbon, total nitrogen, and available nitrogen contents in rhizosphere soil. The rhizosphere effect on total phosphorus in soil was found to be insignificant because of its high immobility. Available phosphorus in soil was distributed heterogeneously. Available soil phosphorus under mowing and grazing changed but the difference was not significant between rhizosphere and bulk soil. Grazing drastically reduced the number of soil microbes. The availability of soil nutrients was significantly correlated with soil microbial numbers. The status of soil nutrients could be more closely aligned with the change in bacteria and fungi. Grazing brought about greater soil nutrient loss and soil microbe loss than did mowing.

  8. Effect of stocking density on performance, diet selection, total-tract digestion, and nitrogen balance among heifers grazing cool-season annual forages.

    Science.gov (United States)

    Brunsvig, B R; Smart, A J; Bailey, E A; Wright, C L; Grings, E E; Brake, D W

    2017-08-01

    Grazing annual cool-season forages after oat grain harvest in South Dakota may allow an opportunity to increase efficient use of tillable land. However, data are limited regarding effects of stocking density on diet selection, nutrient digestion, performance, and N retention by cattle grazing annual cool-season forage. Heifers were blocked by initial BW (261 ± 11.7 kg) and randomly assigned to 1 of 12 paddocks (1.1 ha) to graze a mixture of grass and brassica for 48 d. Each paddock contained 3, 4, or 5 heifers to achieve 4 replicates of each stocking density treatment. Ruminally cannulated heifers were used to measure diet and nutrient intake. Effects of stocking density on diet and nutrient selection were measured after 2, 24, and 46 d of grazing, and BW was measured at the beginning, middle, and end of the experiment as the average of d 1 and 2, d 22 and 23, and d 47 and 48 BW, respectively. Measures of DMI and DM, OM, NDF, and ADF digestion were collected from d 18 to 23. Increased stocking density increased intake of brassica relative to grass on d 24 (quadratic, = 0.02), but increased stocking density decreased (linear, ≤ 0.01) intake of brassica compared with grass on d 48 (stocking density × time, forage resources. Increased stocking density may facilitate a more rapid adaptation to and intake of brassica among cattle grazing brassica-grass-based pastures.

  9. Effect of grazing cycle on milk production of cows on kikuyu pasture ...

    African Journals Online (AJOL)

    The effect of different rotational grazing cycle lengths on milk production, body weight, herbage intake, digestibility and grazing time was investigated. Pastures were stocked at two Friesian cows per ha and grazed for l, 2 or 4-day periods of 15, 30 or 60 days rotation cycles, respectively. Data were recorded during the ...

  10. Ruminant Grazing of Cover Crops: Effects on Soil Properties and Agricultural Production

    Science.gov (United States)

    Poffenbarger, Hanna

    2010-01-01

    Integrating livestock into a cropping system by allowing ruminant animals to graze cover crops may yield economic and environmental benefits. The effects of grazing on soil physical properties, soil organic matter, nitrogen cycling and agricultural production are presented in this literature review. The review found that grazing cover crops…

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

    African Journals Online (AJOL)

    LWG/ha by optimum dravermoe relatief klein. Keywords: Herbage availability, stocking rate, weight gain, con- tinuous grazing, rotational grazing, Coastcross II. Introduction. Stocking rate is known to be one of the most important fac- tors affecting live weight gain (LWG) of animals grazing pastures (Jones & Sandland, 1974).

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

    Science.gov (United States)

    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...

  13. [Microbial community structure of the alpine meadow under different grazing styles in Naqu prefecture of Tibet].

    Science.gov (United States)

    Niu, Lei; Liu, Ying-hui; Li, Yue; Ouyang, Sheng-nan

    2015-08-01

    To clarify the effects of grazing styles on the soil microbial community in the alpine meadow, we explored the changes of soil microbial community structure in the alpine meadow located in Naqu district of Tibet Autonomous Region by analyzing the soil chemical properties and phospholipid fatty acids (PLFAs). The results showed that the contents of soil total organic carbon, total phosphate and nitrate nitrogen under the different grazing styles followed the trend of 7-year rest grazing > free grazing > grazing prohibition. Except for the ratio of fungal PLFAs/bacterial PLFAs, total PLFAs, the bacterial PLFAs, the fungal PLFAs, the gram negative bacterial and the gram positive bacterial PLFAs over the different grazing types were in the order of 7-year rest grazing > 5-year grazing prohibition > 7-year and 9-year grazing prohibition. The principal component analysis (PCA) presented that the first principal component (PC1 = 74.6%) was mainly composed of monounsaturated fatty acids, polyunsaturated fatty acids and branched fatty acids, and the second principal component (PC2 = 13.2%) was mainly composed of saturated fatty acids and some monounsaturated fatty acids. Total PLFAs content was significantly positively correlated with microbial biomass carbon content. Compared with grazing prohibition, fallow grazing was best for the alpine meadow in Naqu district, and free grazing with light intensity was good for the alpine meadow.

  14. Seasonal changes in the quality of diet selected by cattle grazing the ...

    African Journals Online (AJOL)

    It is recommended that protein supplementation of animals grazing veld be initiated in February in the area. Keywords: cattle; cattle grazing; consumption; crude protein; diet; digestibility; dundee research station; grazing; in vitro digestibility; leaves; natal sour sandveld; plant parts; protein; quality; seasonal changes; south ...

  15. 36 CFR 251.103 - Mediation of term grazing permit disputes.

    Science.gov (United States)

    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...

  16. 25 CFR 166.306 - Can the BIA adjust the grazing capacity?

    Science.gov (United States)

    2010-04-01

    ... 25 Indians 1 2010-04-01 2010-04-01 false Can the BIA adjust the grazing capacity? 166.306 Section 166.306 Indians BUREAU OF INDIAN AFFAIRS, DEPARTMENT OF THE INTERIOR LAND AND WATER GRAZING PERMITS Land and Operations Management § 166.306 Can the BIA adjust the grazing capacity? Yes. In consultation...

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

    Science.gov (United States)

    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. Books average previous decade of economic misery.

    Science.gov (United States)

    Bentley, R Alexander; Acerbi, Alberto; Ormerod, Paul; Lampos, Vasileios

    2014-01-01

    For the 20(th) century since the Depression, we find a strong correlation between a 'literary misery index' derived from English language books and a moving average of the previous decade of the annual U.S. economic misery index, which is the sum of inflation and unemployment rates. We find a peak in the goodness of fit at 11 years for the moving average. The fit between the two misery indices holds when using different techniques to measure the literary misery index, and this fit is significantly better than other possible correlations with different emotion indices. To check the robustness of the results, we also analysed books written in German language and obtained very similar correlations with the German economic misery index. The results suggest that millions of books published every year average the authors' shared economic experiences over the past decade.

  19. The ability of winter grazing to reduce wildfire size, intensity, and fire-induced plant mortality was not demonstrated: A comment on Davies et al. (2015)

    Science.gov (United States)

    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 peren...

  20. Effects of a blended garlic and cinnamon essential oil extract with and without monensin sodium on the performance of grazing steers

    Science.gov (United States)

    A series of stocker grazing experiments were conducted with the objective to determine the efficacy of supplementing growing calf diets with essential oils from garlic and cinnamon extracts (GCOE) in promoting growth on cool-season annuals in Arkansas (SWREC) and Oklahoma (SPRRS), or native rangelan...

  1. Forage nutritive value and steer responses to grazing intensity and seed-head suppression of endophyte-free tall fescue in mixed pastures

    Science.gov (United States)

    A 2-yr grazing experiment was conducted with 8- to 10-mo old steers on pastures of endophyte-free tall fescue (Lolium arundinaceum) in mixture with other grasses to assess the effect of seed head suppression (SHS) of fescue on steer performance and forage nutritive values. With and without SHS were...

  2. Phytoplankton reduction in near-bottom water caused by filter-feeding Nereis diversicolor - Implications for worm growth and population grazing impact

    DEFF Research Database (Denmark)

    Larsen, Poul Scheel; Riisgård, H. U.; Poulsen, L.

    1996-01-01

    diversicolor in realizing its grazing capacity (estimated at 13.8 m3 m-2 d-1 in the shallow bay of Kertinge Nor, Denmark, in July 1994). Field-growth experiments were performed with worms transferred to U-shaped glass tubes placed at different heights (0, 4, 10 and 20 cm) above the seafloor. A considerably...

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

    African Journals Online (AJOL)

    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 ...

  4. Radiobiological problems concerning grazing animals following the Chernobyl accident

    International Nuclear Information System (INIS)

    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

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

    Directory of Open Access Journals (Sweden)

    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.

  6. Phosphorus and the grazing ruminant. 4. Blood and faecal grab ...

    African Journals Online (AJOL)

    Blood plasma and faecal grab samples were evaluated as indicators of P status of cattle grazing at two experimental sites (Glen and Armoedsvlakte). Plasma Pj levels clearly identified the - P cattle at Armoedsvlakte as being P deficient whilst at Glen the - P group tended towards lower levels than the supplemented cattle ...

  7. Grazing Incidence X-ray Scattering and Diffraction

    Indian Academy of Sciences (India)

    IAS Admin

    tion. In thia article, various aspects of surface X- ray diffraction and scattering are discussed with illustrations of some typical applications of these techniques. 1. ..... ray reflectivity. Here, X-rays are incident on the sample at very small grazing angles to the surface and below the critical angle, αc. As explained earlier, this ...

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

    African Journals Online (AJOL)

    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 ...

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

    African Journals Online (AJOL)

    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 ...

  10. Contrasting effects of large herbivore grazing on smaller herbivores

    NARCIS (Netherlands)

    Bakker, E. S.; Olff, H.; Gleichman, J. M.

    2009-01-01

    Assemblages of large herbivores may compete For food or facilitate one another. However, small vertebrate herbivore species co-occurring with large herbivores may be affected by large herbivore grazing through changes in plant species composition, nutrient content and vegetation structure. These

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

    African Journals Online (AJOL)

    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 ...

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

    African Journals Online (AJOL)

    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. Sound management may sequester methane in grazed rangeland ecosystems

    Science.gov (United States)

    Considering their contribution to global warming, the sources and sinks of methane (CH4) should be accounted when undertaking a greenhouse gas inventory for grazed rangeland ecosystems. The aim of this study was to evaluate the mitigation potential of current ecological management programs implement...

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

    African Journals Online (AJOL)

    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 ...

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

    Directory of Open Access Journals (Sweden)

    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.

  16. Enhancing soil and landscape quality in smallholder grazing systems

    Science.gov (United States)

    Grasslands constitute the largest global land use and are an important part of agricultural and ecological systems on every continent, across a wide range of potential productivity. Ruminant livestock grazing on these lands constitutes an important form of agricultural production. It is estimated th...

  17. Methane emissions measured directly from grazing livestock in New Zealand

    Science.gov (United States)

    Lassey, Keith R.; Ulyatt, Marcus J.; Martin, Ross J.; Walker, Carolyn F.; David Shelton, I.

    We report measurements of methane emissions from individual ruminant livestock-both sheep and dairy cows-grazing pasture typical of New Zealand lowlands in the temperate southwest Pacific. These are the first measurements reported from grazing sheep, and among the first from grazing cattle. The measurement technique, developed at Washington State University, enables emission rates to be determined from analyses of "breath" samples collected while grazing. More than 250 measurements of daily methane emission from 50 sheep (8 months old) were made, with flock-mean emission 18.9 ± 0.8 g hd -1 d -1. Although emissions were weakly correlated with feed intake, they represented a 4.6 ± 0.1 % average loss of gross dietary energy. The corresponding mean emission based on 40 measurements of daily emissions from 10 lactating dairy cows was 263 ± 10 g hd -1 d -1, approximately 6.2% of estimated gross energy intake. A notable feature was the large inter-sheep variability in daily methane emission (factor of 1.4 range) that could not be attributed to variable intake. This would appear to suggest an appreciable diversity of methanogenetic response to digestion, and may be significant in the search for strategies to control emissions of this greenhouse gas.

  18. Effect of continuous grazing in the Dohne Sourveld on species ...

    African Journals Online (AJOL)

    As the intensity of defoliation increases, decrease in grass cover is associated with an increase of forbs, such as Senecio retrorsus. Keywords: andropogon appendiculatus; basal cover; botanical composition; continuous grazing; defoliation; disturbance history; dohne sourveld; elionurus muticus; grass cover; grasses; ...

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

    NARCIS (Netherlands)

    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

  20. Mixed livestock grazing in diverse temperate and semi-arid ...

    African Journals Online (AJOL)

    ... and continuity and for animal welfare will increasingly drive production processes. In this paper, the potential of mixed grazing for higher output of quality animal products, within these constraints, is assessed under both temperate and semi-arid conditions. Complementary behavioural patterns between domestic livestock ...

  1. Grazing on Regeneration Sites Encourages Pine Seedling Growth

    Science.gov (United States)

    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...

  2. (Orthoptera: Acridoidea) in communally grazed and protected savanna

    African Journals Online (AJOL)

    1995-01-18

    Jan 18, 1995 ... pared with a lightly grazed area and a mowed airstrip, in adjacent protected land, in the Mpumalanga lowveld,. South Africa. Plant species ... and frost was rare. The areas were underlain by Basement. Complex strata of the Bandelierkop Complex, typified by potassic granites and grandiorite. Sampling was ...

  3. Butterfly responses to prairie restoration through fire and grazing

    Science.gov (United States)

    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.

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

    African Journals Online (AJOL)

    ADOWIE PERE

    build in agroforestry system of agriculture to suit each ecological zone. This is with a view to solving socio-economic problems of ... Free grazing has a number of ecological effects which may be either positive or negative. .... because it reduces water and air movement into and through the soil, and therefore reduces water.

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

    African Journals Online (AJOL)

    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 ...

  6. Performance assessment and grazing pattern of semi-intensively ...

    African Journals Online (AJOL)

    Performance assessment and grazing pattern of semi-intensively managed Maradi goats supplemented with Palm Kernel Cake and Poultry Dropping ... Animals that were supplemented with T1 had highest significant (P<0.05) water consumption compared with animals supplemented with T2, T3 and T4 which had similar ...

  7. Long-term livestock grazing increases the recruitment success of ...

    African Journals Online (AJOL)

    These effects are proportional to density. ... However, these changes did not alter landscape-scale mound basal area or volume. ... We suggest that livestock grazing provides additional forage resources for termites through litter breakup and dung production, leading to greater mound recruitment and thus densities, whilst ...

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

    African Journals Online (AJOL)

    This study aimed at investigating the animal health management practices in zero grazing dairy units. A questionnaire was used to assess the veterinary practices including the administration of antibiotics and other veterinary inputs to promote growth, prevent and treat diseases. Sixty-five (65) respondents were involved in ...

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

    African Journals Online (AJOL)

    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 ...

  10. Magnetic alignment in grazing and resting cattle and deer

    Czech Academy of Sciences Publication Activity Database

    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

  11. Prevalence of cryptosporidium oocyst in calves grazing along river ...

    African Journals Online (AJOL)

    The present study was conducted to investigate the point prevalence of Cryptosporidium oocysts infection in calves grazing along the bank of Rima River Sokoto in October 2011. The river bank is a converging zone for domestic animals reared in different quarters of the town and the surrounding settlements. A total number ...

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

    African Journals Online (AJOL)

    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.

  13. Creation and preservation of vegetation patterns by grazing

    NARCIS (Netherlands)

    Mouissie, A. Maarten; Apol, M. Emile F.; Heil, Gerrit W.; van Diggelen, Rudy

    2008-01-01

    Structural patterns of tall stands ("tussock") and short stands ("lawn") are observed in grazed vegetation throughout the world. Such structural vegetation diversity influences plant and animal diversity. A possible mechanism for the creation and preservation of such patterns is a positive feedback

  14. Grazing trials with sheep on kikuyu ( Pennisetum clandestinum ...

    African Journals Online (AJOL)

    Grazing capacity was proportional to the yield of foggage. Although the percentage leaf in the foggage in the different treatments varied from 72 to 89, only some 50% of the total herbage was utilized. The estimates of quality indicated that a higher level of utilization would have resulted in poorer sheep performance.

  15. Soil and vegetation changes across a Succulent Karoo grazing ...

    African Journals Online (AJOL)

    Over-grazed areas close to the watering point had shallow soils with a greater potential for crusting and therefore poorer water capacity. Mainly short-lived succulents (Mesembryanthemaceae) were recorded here, while under-utilised veld far from the watering point was identified by plant groupings dominated by Antimima ...

  16. Occurrence of Clinical Dermatophilosis in Zero-grazed Dairy Cattle ...

    African Journals Online (AJOL)

    Dermatophilosis was clinically diagnosed and confirmed by isolation of Dermatophilus congolensis in three cows in a herd of seven zero-grazed dairy cattle. The lesions observed were matting together of hair into small tufts (greasy crusts) and discrete circumscribed lesions covered with creamy greasy crusts. The matting ...

  17. 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

    Science.gov (United States)

    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

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

    International Nuclear Information System (INIS)

    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

  19. Effect of concentrate feed level on methane emissions from grazing dairy cows.

    Science.gov (United States)

    Jiao, H P; Dale, A J; Carson, A F; Murray, S; Gordon, A W; Ferris, C P

    2014-11-01

    Although the effect of nutrition on enteric methane (CH4) emissions from confined dairy cattle has been extensively examined, less information is available on factors influencing CH4 emissions from grazing dairy cattle. In the present experiment, 40 Holstein-Friesian dairy cows (12 primiparous and 28 multiparous) were used to examine the effect of concentrate feed level (2.0, 4.0, 6.0, and 8.0 kg/cow per day; fresh basis) on enteric CH4 emissions from cows grazing perennial ryegrass-based swards (10 cows per treatment). Methane emissions were measured on 4 occasions during the grazing period (one 4-d measurement period and three 5-d measurement periods) using the sulfur hexafluoride technique. Milk yield, liveweight, and milk composition for each cow was recorded daily during each CH4 measurement period, whereas daily herbage dry matter intake (DMI) was estimated for each cow from performance data, using the back-calculation approach. Total DMI, milk yield, and energy-corrected milk (ECM) yield increased with increasing concentrate feed level. Within each of the 4 measurement periods, daily CH4 production (g/d) was unaffected by concentrate level, whereas CH4/DMI decreased with increasing concentrate feed level in period 4, and CH4/ECM yield decreased with increasing concentrate feed level in periods 2 and 4. When emissions data were combined across all 4 measurement periods, concentrate feed level (2.0, 4.0, 6.0, and 8.0 kg/d; fresh basis) had no effect on daily CH4 emissions (287, 273, 272, and 277 g/d, respectively), whereas CH4/DMI (20.0, 19.3, 17.7, and 18.1g/kg, respectively) and CH4-E/gross energy intake (0.059, 0.057, 0.053, and 0.054, respectively) decreased with increasing concentrate feed levels. A range of prediction equations for CH4 emissions were developed using liveweight, DMI, ECM yield, and energy intake, with the strongest relationship found between ECM yield and CH4/ECM yield (coefficient of determination = 0.50). These results demonstrate that

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

    Science.gov (United States)

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

    2017-01-01

    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.

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

    Science.gov (United States)

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

    2009-01-20

    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. 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. 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.

  2. Is grazing exclusion effective in restoring vegetation in degraded alpine grasslands in Tibet, China?

    Directory of Open Access Journals (Sweden)

    Yan Yan

    2015-06-01

    Full Text Available Overgrazing is considered one of the key disturbance factors that results in alpine grassland degradation in Tibet. Grazing exclusion by fencing has been widely used as an approach to restore degraded grasslands in Tibet since 2004. Is the grazing exclusion management strategy effective for the vegetation restoration of degraded alpine grasslands? Three alpine grassland types were selected in Tibet to investigate the effect of grazing exclusion on plant community structure and biomass. Our results showed that species biodiversity indicators, including the Pielou evenness index, the Shannon–Wiener diversity index, and the Simpson dominance index, did not significantly change under grazing exclusion conditions. In contrast, the total vegetation cover, the mean vegetation height of the community, and the aboveground biomass were significantly higher in the grazing exclusion grasslands than in the free grazed grasslands. These results indicated that grazing exclusion is an effective measure for maintaining community stability and improving aboveground vegetation growth in alpine grasslands. However, the statistical analysis showed that the growing season precipitation (GSP plays a more important role than grazing exclusion in which influence on vegetation in alpine grasslands. In addition, because the results of the present study come from short term (6–8 years grazing exclusion, it is still uncertain whether these improvements will be continuable if grazing exclusion is continuously implemented. Therefore, the assessments of the ecological effects of the grazing exclusion management strategy on degraded alpine grasslands in Tibet still need long term continued research.

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

    Science.gov (United States)

    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.

  4. Grazing effects on plant community succession of early- and mid-seral seeded grassland compared to shortgrass steppe

    Science.gov (United States)

    Milchunas, Daniel G.; Vandever, Mark W.

    2013-01-01

    Questions: Grazing may speed or slow secondary succession, and the direction may depend on seral stage and relative tolerance of native perennial grasses compared with annual invasive species. How does grazing affect succession where undisturbed communities have a long evolutionary history of grazing by native herbivores and are tolerant to livestock grazing?

  5. Large-Grazing-Angle, Multi-Image Kirkpatrick-Baez Microscope as the Front End to a High-Resolution Streak Camera for OMEGA

    International Nuclear Information System (INIS)

    Gotchev, O.V.; Hayes, L.J.; Jaanimagi, P.A.; Knauer, J.P.; Marshall, F.J.; Meyerhofer, D. D.

    2003-01-01

    (B204)A new, high-resolution x-ray microscope with a large grazing angle has been developed, characterized, and fielded at the Laboratory for Laser Energetics. It increases the sensitivity and spatial resolution in planar direct-drive hydrodynamic stability experiments, relevant to inertial confinement fusion (ICF) research. It has been designed to work as the optical front end of the PJX-a high-current, high-dynamic-range x-ray streak camera. Optical design optimization, results from numerical ray tracing, mirror-coating choice, and characterization have been described previously [O. V. Gotchev, et al./Rev. Sci. Instrum. 74, 2178 (2003)]. This work highlights the optics' unique mechanical design and flexibility and considers certain applications that benefit from it. Characterization of the microscope's resolution in terms of its modulation transfer function (MTF) over the field of view is shown. Recent results from hydrodynamic stability experiments, diagnosed with the optic and the PJX, are provided to confirm the microscope's advantages as a high-resolution, high-throughput x-ray optical front end for streaked imaging

  6. Large-grazing-angle, multi-image Kirkpatrick-Baez microscope as the front end to a high-resolution streak camera for OMEGA

    International Nuclear Information System (INIS)

    Gotchev, O.V.; Hayes, L.J.; Jaanimagi, P.A.; Knauer, J.P.; Marshall, F.J.; Meyerhofer, D.D.

    2003-01-01

    A high-resolution x-ray microscope with a large grazing angle has been developed, characterized, and fielded at the Laboratory for Laser Energetics. It increases the sensitivity and spatial resolution in planar direct-drive hydrodynamic stability experiments, relevant to inertial confinement fusion research. It has been designed to work as the optical front end of the PJX - a high-current, high-dynamic-range x-ray streak camera. Optical design optimization, results from numerical ray tracing, mirror-coating choice, and characterization have been described previously [O. V. Gotchev, et al., Rev. Sci. Instrum. 74, 2178 (2003)]. This work highlights the optics' unique mechanical design and flexibility and considers certain applications that benefit from it. Characterization of the microscope's resolution in terms of its modulation transfer function over the field of view is shown. Recent results from hydrodynamic stability experiments, diagnosed with the optic and the PJX, are provided to confirm the microscope's advantages as a high-resolution, high-throughput x-ray optical front end for streaked imaging

  7. Testing the limits of resistance: a 19-year study of Mediterranean grassland response to grazing regimes.

    Science.gov (United States)

    Sternberg, Marcelo; Golodets, Carly; Gutman, Mario; Perevolotsky, Avi; Ungar, Eugene D; Kigel, Jaime; Henkin, Zalmen

    2015-05-01

    A synthesis of a long-term (19 years) study assessing the effects of cattle grazing on the structure and composition of a Mediterranean grassland in north-eastern Israel is presented, with new insights into the response of the vegetation to grazing management and rainfall. We hypothesized that the plant community studied would be resistant to high grazing intensities and rainfall variability considering the combined long history of land-use and unpredictable climatic conditions where this community evolved. Treatments included manipulations of stocking densities (moderate, heavy, and very heavy) and of grazing regimes (continuous vs. seasonal), in a factorial design. The effect of interannual rainfall variation on the expression of grazing impacts on the plant community was minor. The main effects of grazing on relative cover of plant functional groups were related to early vs. late seasonal grazing. Species diversity and equitability were remarkably stable across all grazing treatments. A reduction in tall grass cover at higher stocking densities was correlated with increased cover of less palatable groups such as annual and perennial thistles, as well as shorter and prostrate groups such as short annual grasses. This long-term study shows that interannual fluctuations in plant functional group composition could be partly accounted for by grazing pressure and timing, but not by the measured rainfall variables. Grazing affected the dominance of tall annual grasses. However, the persistence of tall grasses and more palatable species over time, despite large differences in grazing pressure and timing, supports the idea that Mediterranean grasslands are highly resistant to prolonged grazing. Indeed, even under the most extreme grazing conditions applied, there were no signs of deterioration or collapse of the ecosystem. This high resistance to grazing intensity and interannual fluctuation in climatic conditions should favor the persistence of the plant community under

  8. Effects of different grazing intensities on grassland production in China: a meta-analysis.

    Science.gov (United States)

    Yan, Liang; Zhou, Guangsheng; Zhang, Feng

    2013-01-01

    Grazing is one of the main grassland disturbances in China, and it is essential to quantitatively evaluate the effects of different grazing intensities on grassland production for grassland carbon budget and sustainable use. A meta-analysis was conducted to reveal general response patterns of grassland production to grazing in China. We used weighted log response ratio to assess the effect size, and 95% confidence intervals to give a sense of the precision of the estimate. Grazing effects were estimated as a percentage change relative to control (%). A total of 48 studies, including 251 data sets, were included in the meta-analysis. Grazing significantly decreased total biomass by 58.34% (95% CI: -72.04%∼-37.94%, CI: Confidence Interval), increased root/shoot ratio by 30.58% and decreased litter by 51.41% (95% CI: -63.31%∼-35.64%). Aboveground biomass and belowground biomass decreased significantly by 42.77% (95% CI: -48.88%∼-35.93%) and 23.13% (95% CI: -39.61%∼-2.17%), respectively. However, biomass responses were dependent on grazing intensity and environmental conditions. Percentage changes in aboveground biomass to grazing showed a quadratic relationship with precipitation in light grazing intensity treatment and a linear relationship in moderate and heavy grazing intensity treatment, but did not change with temperature. Grazing effects on belowground biomass did not change with precipitation or temperature. Compared to the global average value, grazing had greater negative effects on grassland production in China. Grazing has negative effects on grassland biomass and the grazing effects change with environmental conditions and grazing intensity, therefore flexible rangeland management tactics that suit local circumstances are necessary to take into consideration for balancing the demand of grassland utilization and conservation.

  9. Effects of different grazing intensities on grassland production in China: a meta-analysis.

    Directory of Open Access Journals (Sweden)

    Liang Yan

    Full Text Available Grazing is one of the main grassland disturbances in China, and it is essential to quantitatively evaluate the effects of different grazing intensities on grassland production for grassland carbon budget and sustainable use.A meta-analysis was conducted to reveal general response patterns of grassland production to grazing in China. We used weighted log response ratio to assess the effect size, and 95% confidence intervals to give a sense of the precision of the estimate. Grazing effects were estimated as a percentage change relative to control (%.A total of 48 studies, including 251 data sets, were included in the meta-analysis. Grazing significantly decreased total biomass by 58.34% (95% CI: -72.04%∼-37.94%, CI: Confidence Interval, increased root/shoot ratio by 30.58% and decreased litter by 51.41% (95% CI: -63.31%∼-35.64%. Aboveground biomass and belowground biomass decreased significantly by 42.77% (95% CI: -48.88%∼-35.93% and 23.13% (95% CI: -39.61%∼-2.17%, respectively. However, biomass responses were dependent on grazing intensity and environmental conditions. Percentage changes in aboveground biomass to grazing showed a quadratic relationship with precipitation in light grazing intensity treatment and a linear relationship in moderate and heavy grazing intensity treatment, but did not change with temperature. Grazing effects on belowground biomass did not change with precipitation or temperature. Compared to the global average value, grazing had greater negative effects on grassland production in China.Grazing has negative effects on grassland biomass and the grazing effects change with environmental conditions and grazing intensity, therefore flexible rangeland management tactics that suit local circumstances are necessary to take into consideration for balancing the demand of grassland utilization and conservation.

  10. [Effects of compensation capacity and palatability on the dominance of plant species in grazing community].

    Science.gov (United States)

    Pan, Sheng-wang; Wang, Hai-yang; Du, Guo-zhen; Lei, Shu-qing; Wei, Shi-qiang

    2008-08-01

    With simulated mowing experiment and field survey, the compensation capacity and dominance shift of nine alpine plant species in grazing community were studied. The results showed that for most test species, there existed definite correlations between their compensation capacity and palatability. The species with better palatability, i.e., Astragalus polycladus, Medicago rythenica, Kobresia humilis, and Polygonum viviparvum, had higher compensation capacity, with their compensation index being 1.013, 0.907, 0.849, and 0.802, respectively, followed by Elymus nutans, with its compensation index being 0.668, while the species with poorer palatability, i.e., Taraxacum tibetanum, Swertis bimaculata, and Ajania tenuifolia had lower compensation capacity, with their compensation index being 0.649, 0.587, and 0.553, respectively. Festuca sinensis was more palatable but had the lowest compensation index (0.473). The nine species had three types of dominance shift, i.e., decreasing, increasing, and neutral. F. sinensis was of decreasing type, E. nutans, A. polycladus and P. viviparvum were of neutral, and the other five species were of increasing type. The compensation capacity and palatability of plant species in grazing community could explain their dominance shift to a certain extent.

  11. Filter-feeding ascidians ( Ciona intestinalis) in a shallow cove: Implications of hydrodynamics for grazing impact

    Science.gov (United States)

    Riisgård, Hans Ulrik; Jürgensen, Carsten; Clausen, Torben

    1996-06-01

    The grazing impact by a dense population of filter-feeding ascidians Ciona intestinalis on horizontally flowing water (driven by density circulation) in a shallow cove (Kertinge Nor, Denmark) has been described and quantified by means of a simple one-dimensional numerical model. The agreement between observations and modelled predictions was satisfactory. The applied numerical model has the following analytical solution in the idealized case: Cx = C0e -( fx/ Y2) , where Cx = algal concentration at a downstream distance x, C0 = initial concentration, f = F/ vc; F = area specific population filtration rate; vc = current velocity; Y 2 = depth of mixed layer below halocline. The numerical model quantifies the actual grazing impact while the analytical model illustrates the governing physics in well-known terms. To describe situations with no current ( i.e. stagnant water), we performed simulation studies in the laboratory and measured vertical profiles of algal cells over filter-feeding C. intestinalis. The results showed that phytoplankton became reduced in a near-bottom water layer of 20-30 cm thickness. Such water layers may develop in stagnant water (calm days and no advective currents), thus uncoupling the pelagic food and the filter feeders which within a short time will experience extremely meagre food conditions.

  12. Livestock Grazing Shapes the Vegetation Structure and Subsequent Habitat Use by the Endangered Skipper Pyrgus ruralis lagunae (Lepidoptera: Hesperiidae).

    Science.gov (United States)

    Marschalek, Daniel A; Faulkner, David K; Deutschman, Douglas H

    2017-06-01

    Many species adapted to alpine and montane meadow ecosystems are at risk of extinction. The skipper Pyrgus ruralis lagunae Scott is a mountaintop butterfly restricted to San Diego County, CA, a federally listed endangered species, and is in imminent risk of extinction. Historically, P. r. lagunae was found in the Laguna and Palomar mountains. We did not detect the skipper in the Laguna Mountains, and the species has likely been extirpated from this area, which represents half of its historical range and is the type locality. We studied three populations on Palomar Mountain. Skippers primarily occupied areas close to creeks or in adjacent ravines at two nongrazed sites. The third site is grazed by cattle, and skippers were found close to the forest edge. At nongrazed locations, creek areas had higher cover of intermediate-height vegetation, more bare ground, and more flowers compared with unoccupied areas of the same meadow. The vegetation at occupied and unoccupied areas within the grazed meadow were similar. Even so, skippers occupied areas with more bare ground as well as greater species richness of flowering plants. A grazing exclosure was previously installed in an attempt to protect and enhance skipper habitat, but skippers did not use the dense grasslands that developed inside the exclosures. Contrary to the prevailing theory, protection from grazing did not improve skipper habitat. This illustrates how management based on inadequate biological information can hinder well-intentioned conservation efforts. © The Authors 2017. Published by Oxford University Press on behalf of Entomological Society of America. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

  13. EFFECT OF FEED PROCESSING ON VOLATILE FATTY ACID PRODUCTION RATES MEASURED WITH 13C-ACETATE IN GRAZING LACTATING DAIRY COWS

    Directory of Open Access Journals (Sweden)

    R. Tothi

    2007-06-01

    Full Text Available The effect of processed cereal grain supplementation on volatile fatty acid (VFA production rates of grazing, lactating Holstein-Friesian cows were measured in a 5x5 Latin square experiment. The experimental treatments were as follows: control (only grazing, no supplement addition, NS, pelleted barley (PB, pelleted maize (PM, toasted and subsequently pelleted barley (TPB, and toasted and subsequently pelleted maize (TPM as supplements. An isotope dilution technique using stable isotope of carbon (13C as an internal marker was employed for the estimation of VFA production. At the beginning of a 3-hour long allowed grazing time, 100 mg of 99% enriched 13C2 Na-acetate were introduced in the rumen and repeated after grazing with 50 mg isotope, after which the cows were starved for 6 hours until evening milking. During grazing disappearance rate (kdis and production rate (kprod of acetate, propionate and butyrate were significantly higher (P≤0.05 in supplemented than in NS cows. Moreover the effect of barley grain and pelleting treatment was higher than the effect of maize grain and toasting. During starvation significantly higher (P≤0.05 kdis and kprod of VFAs were observed in PM and TPM treatments. Total VFA production for the experimental period (grazing + starvation were 49.5, 78.7, 69.9, 88.5, 80.8 mol/day for NS, PB, TPB, PM and TPM, respectively. The higher VFA productions measured in supplemented animals emphasis the extensive digestion that occurs in the rumen after feeding processed grains. In methodological terms, 13C2 Na-acetate labelling appears to be a useful means for examining the VFA acetate production in ruminants.

  14. Sward canopy structure and performance of beef heifers under supplementation in Brachiaria brizantha cv. Marandu pastures maintained with three grazing intensities in a continuous stocking system

    Directory of Open Access Journals (Sweden)

    Daniel Rume Casagrande

    2011-10-01

    Full Text Available The objective of this study was to assess the sward canopy structure of Brachiaria brizantha cv. Marandu pastures maintained in three grazing intensities under continuous stocking system during the rainy season, along with the behavior and performance of grazing beef heifers supplemented with mineral salt or an energy/protein supplement. Three levels of forage allowance were assessed: 2.0, 2.5 and 3.0 kg of forage/kg of live weight, combined with two supplements (ad libitum mineral salt, and an energy/protein supplement at 0.3% of live weight/day, supplied daily. The experiment was designed as a randomized block study with two replications. The supplements did not influence the variables related to the canopy structure. Canopy height was greater at higher forage allowances during the late summer and early fall. Similarly, the stem mass was greater in pastures with higher forage allowances. Animals fed protein supplement spent less time grazing than animals supplemented with mineral salt. Stocking rate was higher in pastures with lower forage allowance levels, which increased the live weight gain per grazing area. Daily weight gain did not vary according to the forage allowance levels. The use of an energy/protein supplement did not affect the stocking rate; however, it increased individual live weight gain and live weight gain per grazing area compared with mineral salt supplementation. The use of energy/protein supplements is an efficient alternative to enhance animal performance and production under grazing systems during the rainy season

  15. An improved grazed class method to estimate species selection and dry matter intake by cows at pasture

    OpenAIRE

    Bruno Martin; Giampiero Lombardi; Philippe Pradel; Anne Farruggia; Mauro Coppa

    2011-01-01

    Research has recently focused on pasture species intake by ruminants due to their influence on animal product quality. A field-applicable method which investigates species intake and selection, was tested on two dairy cow grazing systems: continuous grazing on a highly-biodiverse pasture (C) and rotational grazing on a moderately-diverse sward (R). In addition to the grazed class method, which evaluates the percentage of grazed dry matter (DM) per species according to the residual height of t...

  16. Adjustable Grazing-Incidence X-Ray Optics

    Science.gov (United States)

    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.

  17. Active Full-Shell Grazing-Incidence Optics

    Science.gov (United States)

    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.

  18. An X-ray grazing incidence phase multilayer grating

    CERN Document Server

    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.

  19. Relationship between reproductive allocation and relative abundance among 32 species of a Tibetan alpine meadow: effects of fertilization and grazing.

    Directory of Open Access Journals (Sweden)

    Kechang Niu

    Full Text Available Understanding the relationship between species traits and species abundance is an important goal in ecology and biodiversity science. Although theoretical studies predict that traits related to performance (e.g. reproductive allocation are most directly linked to species abundance within a community, empirical investigations have rarely been done. It also remains unclear how environmental factors such as grazing or fertilizer application affect the predicted relationship.We conducted a 3-year field experiment in a Tibetan alpine meadow to assess the relationship between plant reproductive allocation (RA and species relative abundance (SRA on control, grazed and fertilized plots. Overall, the studied plant community contained 32 common species.At the treatment level, (i RA was negatively correlated with SRA on control plots and during the first year on fertilized plots. (ii No negative RA-SRA correlations were observed on grazed plots and during the second and third year on fertilized plots. (iii Seed size was positively correlated with SRA on control plots. At the plot level, the correlation between SRA and RA were not affected by treatment, year or species composition.Our study shows that the performance-related trait RA can negatively affect SRA within communities, which is possibly due to the tradeoffs between clonal growth (for space occupancy and sexual reproduction. We propose that if different species occupy different positions along these tradeoffs it will contribute to biodiversity maintenance in local communities or even at lager scale.

  20. Understanding the effects of a new grazing policy: the impact of seasonal grazing on shrub demography in the Inner Mongolian steppe

    NARCIS (Netherlands)

    Li, Shou-Li; Yu, F.H.; Werger, M.J.A.; Dong, M.; Ramula, S.; Zuidema, P.A.

    2013-01-01

    1.Grazing by livestock is a common land use in arid and semi-arid areas. Developing sustainable grazing regimes that conserve vegetation and maintain productivity is therefore important in these ecosystems. To solve environmental problems induced by overgrazing in Chinese semi-arid regions, the

  1. Milk yield and somatic cell score of northeastern United States organic dairy farms during the grazing and non-grazing seasons

    Science.gov (United States)

    The objective of this study was to evaluate milk yield and composition of organically-certified dairy herds during grazing season (GS) and non-grazing season (NGS) in the Northeast region of the United States. Dairy Herd Improvement records of Holstein, Jersey, and Holstein-Jersey crossbred cows fro...

  2. Impacts of Current and Previous Land Use on Greenhouse Gas Fluxes for Biofuel Cropping Systems

    Science.gov (United States)

    Del Grosso, S.; Parton, W.; Adler, P.; Ogle, S.; West, T.

    2008-12-01

    Biofuel cropping systems are both a source and sink of greenhouse gases (GHG). Fertilizer and pesticide manufacture and transport, farm machinery operation, and processing of biomass into fuel all lead to carbon dioxide (CO2) emissions, but the largest GHG sources for biofuel systems are often soil nitrous oxide (N2O) emissions and loss of organic carbon as a result of land use change. However, improved land management can increase soil carbon levels and decrease N2O emissions, thus complementing the CO2 sink from displaced fossil fuel combustion. Previously cropped land, grazed land, and Conservation Reserve Program (CRP) land is being converted to biofuel cropping. We report results for the central US because most of the land used for biofuel cropping is in the central region of the country (corn/soy belt). The primary tool for this analysis is the DAYCENT ecosystem model. The ability of the model to simulate soil GHG fluxes and crop yields is demonstrated and results from simulations of different land management scenarios are presented. Our analyses suggest that conversion of CRP or grazed land to corn ethanol cropping under conventional management leads to a net source of GHG, but that converting these lands to perennial cellulosic biofuel cropping results in a GHG sink. Previously cropped land converted to corn ethanol under conventional management is a small GHG sink, but improved management and conversion to cellulosic based crops can greatly increase this sink strength.

  3. Influence of elk grazing on soil properties in Rocky Mountain National Park

    Science.gov (United States)

    Binkley, Dan; Singer, F.; Kaye, M.; Rochelle, R.

    2003-01-01

    We used three 35-year exclosures to examine the effects of high elk populations on a variety of soil properties in three vegetation types: upland sagebrush, aspen, and meadow. Grazing and hoof action by elk significantly increased bulk density (from 0.87 kg/l ungrazed to 0.94 kg/l grazed), with greater effects on soils with fewer rocks. Grazing substantially reduced extractable calcium, magnesium, potassium and phosphorus in the sagebrush type, but not in the aspen or meadow types. The only grazing effect on pH came in aspen types, where grazing prevented aspen establishment, and kept soil pH about 0.7 units higher than under aspen inside the exclosures. Grazing had no overall effect on total soil C and N across all exclosures and vegetation types. The availability of soil nitrogen, indexed by in-field resin bags and net mineralization in soil cores, showed little overall effect of grazing. Limited data on soil leaching indicated a possibility of strong increases in nitrate leaching with grazing for an aspen vegetation type at one exclosure. Although we found little effect of grazing on soil N supply, we note that N fertilization doubled the production of grasses and shrubs; if grazing eventually led to changes in soil N supply, species composition and growth would likely change. ?? 2003 Elsevier B.V. All rights reserved.

  4. Effect of grazing on methane uptake from Eurasian steppe of China.

    Science.gov (United States)

    Tang, Shiming; Zhang, Yujuan; Zhai, Xiajie; Wilkes, Andreas; Wang, Chengjie; Wang, Kun

    2018-03-20

    The effects of grazing on soil methane (CH 4 ) uptake in steppe ecosystems are important for understanding carbon sequestration and cycling because the role of grassland soil for CH 4 uptake can have major impacts at the global level. Here, a meta-analysis of 27 individual studies was carried out to assess the response patterns of soil CH 4 uptake to grazing in steppe ecosystems of China. The weighted log response ratio was used to assess the effect size. We found that heavy grazing significantly depressed soil CH 4 uptake by 36.47%, but light and moderate grazing had no significant effects in grassland ecosystem. The response of grassland soil CH 4 uptake to grazing also was found to depend upon grazing intensity, grazing duration and climatic types. The increase in soil temperature and reduced aboveground biomass and soil moisture induced by heavy grazing may be the major regulators of the soil CH 4 uptake. These findings imply that grazing effects on soil CH 4 uptake are highly context-specific and that grazing in different grasslands might be managed differently to help mitigate greenhouse gas emissions.

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

    Directory of Open Access Journals (Sweden)

    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.

  6. Transcriptome responses in alfalfa associated with tolerance to intensive animal grazing

    Science.gov (United States)

    Wang, Junjie; Zhao, Yan; Ray, Ian; Song, Mingzhou

    2016-01-01

    Tolerance of alfalfa (Medicago sativa L.) to animal grazing varies widely within the species. However, the molecular mechanisms influencing the grazing tolerant phenotype remain uncharacterized. The objective of this study was to identify genes and pathways that control grazing response in alfalfa. We analyzed whole-plant de novo transcriptomes from grazing tolerant and intolerant populations of M. sativa ssp. falcata subjected to grazing by sheep. Among the Gene Ontology terms which were identified as grazing responsive in the tolerant plants and differentially enriched between the tolerant and intolerant populations (both grazed), most were associated with the ribosome and translation-related activities, cell wall processes, and response to oxygen levels. Twenty-one grazing responsive pathways were identified that also exhibited differential expression between the tolerant and intolerant populations. These pathways were associated with secondary metabolite production, primary carbohydrate metabolic pathways, shikimate derivative dependent pathways, ribosomal subunit composition, hormone signaling, wound response, cell wall formation, and anti-oxidant defense. Sequence polymorphisms were detected among several differentially expressed homologous transcripts between the tolerant and intolerant populations. These differentially responsive genes and pathways constitute potential response mechanisms for grazing tolerance in alfalfa. They also provide potential targets for molecular breeding efforts to develop grazing-tolerant cultivars of alfalfa. PMID:26763747

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

    DEFF Research Database (Denmark)

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

    2012-01-01

    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...... concentrations of 23, 19 and 13 mg/L for an estimated proportion area occupied by urine patches of 0.33, 0.26 and 0.16, respectively. Thus, N concentrations in G and CG exceeded the EU limit of 11.3 mg N/L. Under the prevailing conditions, the time of urination did not appear important. The estimated background...

  8. Carbon sputtering yield measurements at grazing incidence

    International Nuclear Information System (INIS)

    Kolasinski, Robert D.; Polk, James E.; Goebel, Dan; Johnson, Lee K.

    2008-01-01

    In this investigation, carbon sputtering yields were measured experimentally at varying angles of incidence under Xe + bombardment. The measurements were obtained by etching a coated quartz crystal microbalance (QCM) with a low energy ion beam. The material properties of the carbon targets were characterized with a scanning electron microscope (SEM) and Raman spectroscopy. C sputtering yields measured under Ar + and Xe + bombardment at normal incidence displayed satisfactory agreement with previously published data over an energy range of 200 eV-1 keV. For Xe + ions, the dependence of the yields on angle of incidence θ was determined for 0 o ≤ θ ≤ 80 deg. Over this range, an increase in C sputtering yield by a factor of 4.8 was observed, with the peak in yield occurring at 70 o . This is a much higher variation compared to Xe + → Mo yields under similar conditions, a difference that may be attributed to higher scattering of the incident particles transverse to the beam direction than in the case of Xe + → C. In addition, the variation of the yields with θ was not strongly energy dependent. Trapping of Xe in the surface was observed, in contrast to observations using the QCM technique with metallic target materials. Finally, target surface roughness was characterized using atomic force microscope measurements to distinguish between the effects of local and overall angle of incidence of the target

  9. Levels of Supplementation for Grazing Beef Heifers

    Science.gov (United States)

    Cabral, Carla Heloisa Avelino; Paulino, Mario Fonseca; Detmann, Edenio; de Campos Valadares Filho, Sebastião; de Barros, Lívia Vieira; Valente, Ériton Egidio Lisboa; de Oliveira Bauer, Maristela; Cabral, Carlos Eduardo Avelino

    2014-01-01

    The objective of this experiment was to evaluate the effect of providing different levels of a supplement on the nutritional characteristics and productive performance of heifers on pasture during the rainy-dry transition and dry season in Brazil or tropical area. Thirty crossbred heifers with predominance of Zebu breed were used in a completely randomized experimental design. Treatments consisted of a mineral supplement and 0.5, 1.0, 1.5, or 2.0 kg/animal/d of a protein supplement containing 300 g crude protein (CP)/kg of dry matter (DM). In the rainy-dry transition season there was quadratic effect of the protein supplementation (pdaily weight gain (DWG). A linear relationship (p0.10); the microbial efficiency (g CPmic/kg TDN) and the relationship of microbial nitrogen flow with nitrogen intake (g/g nitrogen intake) were negative linear profiles. In the dry season, the descriptive pattern least squares means showed a trend of stabilization of DWG from the supply of 0.98 kg of protein supplement; the intakes of DM, OM, CP, EE, NFC, and TDN showed increasing linear relationship (pheifers and that 1.0 kg/d of supplement per animal gives the maximum increment of weight gain. PMID:25050018

  10. Competition drives the response of soil microbial diversity to increased grazing by vertebrate herbivores.

    Science.gov (United States)

    Eldridge, David J; Delgado-Baquerizo, Manuel; Travers, Samantha K; Val, James; Oliver, Ian; Hamonts, Kelly; Singh, Brajesh K

    2017-07-01

    Scientists have largely neglected the effects of grazing on soil microbial communities despite their importance as drivers of ecosystem functions and services. We hypothesized that changes in soil properties resulting from grazing regulate the diversity of soil microbes by releasing/suppressing subordinate microbial taxa via competition. To test this, we examined how intensity of vertebrate herbivores influences the diversity and composition of soil bacteria and fungi at 216 soil samples from 54 sites across four microsites. Increasing grazing intensity reduced soil carbon, suppressing the dominant bacterial phylum Actinobacteria (indirectly promoting bacterial diversity) and increasing the dominant fungal phylum Ascomycetes (indirectly reducing fungal diversity). Our data provide novel evidence that grazing modulates the diversity and composition of soil microbes via increases or reductions in competition by dominant taxa. Our results suggest that grazing can potentially alter soil function by altering microbial community composition, providing a clear link between grazing management, carbon availability and ecosystem functions. © 2017 by the Ecological Society of America.

  11. Grazing in juvenile stages of some estuarine calanoid copepods. [Acartia tonsa, A. clausi, Eurytemora affinis

    Energy Technology Data Exchange (ETDEWEB)

    Allan, J.D.; Heinle, D.R.

    1976-01-01

    The grazing of subadult stages of Acartia tonsa and A. clausi and Eurytemora affinis on natural particle distributions was investigated using animals from wild populations sorted into stages. Filtering rates and particle selection are compared for various stages from late nauplius through adult, using copepods and particles from the middle of Chesapeake Bay. Filtering rates increased continuously during development in Eurytemora but results were more variable with Acartia. Experiments on particle selection yielded results which in some cases conformed to the null hypothesis of no particle selection and in some cases indicated higher filtering rates and particle selection at or near the control biomass peak. Tables and graphs are presented to show results. (HLW)

  12. Placental complications after a previous cesarean section

    OpenAIRE

    Milošević Jelena; Lilić Vekoslav; Tasić Marija; Radović-Janošević Dragana; Stefanović Milan; Antić Vladimir

    2009-01-01

    Introduction The incidence of cesarean section has been rising in the past 50 years. With the increased number of cesarean sections, the number of pregnancies with the previous cesarean section rises as well. The aim of this study was to establish the influence of the previous cesarean section on the development of placental complications: placenta previa, placental abruption and placenta accreta, as well as to determine the influence of the number of previous cesarean sections on the complic...

  13. Reindeer grazing and soil nutrient cycling in boreal and tundra ecosystems

    OpenAIRE

    Stark, S. (Sari)

    2002-01-01

    Abstract In northernmost Fennoscandia, grazing by reindeer (Rangifer tarandus L.) has a substantial impact on the vegetation of boreal forests and arctic-alpine tundra heaths, which are reflected in below-ground processes, such as nutrient mineralization and soil organic matter decomposition. In the present thesis, the effects of reindeer grazing on soil nutrient cycling were studied by comparing grazed situation with an ungrazed control area in ten boreal forests a...

  14. Effects of precipitation on grassland ecosystem restoration under grazing exclusion in Inner Mongolia, China

    Science.gov (United States)

    Lu Hao; Ge Sun; Yongqiang Liu; Zhiqiu Gao; Junjie He; Tingting Shi; Bingjuan Wu

    2014-01-01

    China launched the ‘‘Returning Grazing Lands to Grasslands’’ project about a decade ago to restore severely degraded grasslands. Grassland grazing exclusion was one of the experimental approaches for achieving the grand goal. Here, we evaluate the long-term regional ecological effects of grassland grazing exclusion in the Xilingol region of Inner Mongolia, China. The...

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

    Directory of Open Access Journals (Sweden)

    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

  16. Grazing Soybean to Increase Voluntary Cow Traffic in a Pasture-based Automatic Milking System

    Directory of Open Access Journals (Sweden)

    C. E. F. Clark

    2014-03-01

    Full Text Available Pasture-based automatic milking systems (AMS require cow traffic to enable cows to be milked. The interval between milkings can be manipulated by strategically allocating pasture. The current experiment investigated the effect of replacing an allocation of grazed pasture with grazed soybean (Glycine max with the hypothesis that incorporating soybean would increase voluntary cow traffic and milk production. One hundred and eighty mixed age, primiparous and multiparous Holstein-Friesian/Illawarra cows were randomly assigned to two treatment groups (n = 90/group with a 2×2 Latin square design. Each group was either offered treatments of kikuyu grass (Pennisetum clandestinum Hoach ex Chiov. pasture (pasture or soybean from 0900 h to 1500 h during the experimental period which consisted of 2 periods of 3 days following 5 days of training and adaptation in each period with groups crossing over treatments after the first period. The number of cows trafficking to each treatment was similar together with milk yield (mean ≈18 L/cow/d in this experiment. For the cows that arrived at soybean or pasture there were significant differences in their behaviour and consequently the number of cows exiting each treatment paddock. There was greater cow traffic (more cows and sooner exiting pasture allocations. Cows that arrived at soybean stayed on the allocation for 25% more time and ate more forage (8.5 kg/cow/d/allocation relative to pasture (4.7 kg/cow/d/allocation. Pasture cows predominantly replaced eating time with rumination. These findings suggest that replacing pasture with alternative grazeable forages provides no additional incentive to increase voluntary cow traffic to an allocation of feed in AMS. This work highlights the opportunity to increase forage intakes in AMS through the incorporation of alternative forages.

  17. Testing for the induction of anti-herbivory defences in four Portuguese macroalgae by direct and water-borne cues of grazing amphipods

    Science.gov (United States)

    Yun, Hee Young; Cruz, Joana; Treitschke, Michaela; Wahl, Martin; Molis, Markus

    2007-09-01

    Herbivory is a key factor in regulating plant biomass, thereby driving ecosystem performance. Algae have developed multiple adaptations to cope with grazers, including morphological and chemical defences. In a series of experiments we investigated whether several species of macroalgae possess anti-herbivore defences and whether these could be regulated to demand, i.e. grazing events. The potential of direct grazing on defence induction was assessed for two brown ( Dictyopteris membranacea, Fucus vesiculosus) and two red seaweeds ( Gelidium sesquipedale, Sphaerococcus coronopifolius) from São Rafael and Ria Formosa, Portugal. Bioassays conducted with live algal pieces and agar-based food containing lipophilic algal extracts were used to detect changes in palatability after exposure to amphipod attacks (=treatment phase). Fucus vesiculosus was the only species significantly reducing palatability in response to direct amphipod-attacks. This pattern was observed in live F. vesiculosus pieces and agar-based food containing a lipophilic extract, suggesting that lipophilic compounds produced during the treatment phase were responsible for the repulsion of grazers. Water-borne cues of grazed F. vesiculosus as well as non-grazing amphipods also reduced palatability of neighbouring conspecifics. However, this effect was only observed in live tissues of F. vesiculosus. This study is the first to show that amphipods, like isopods, are capable to induce anti-herbivory defences in F. vesiculosus and that a seasonally variable effectiveness of chemical defences might serve as a dynamic control in alga-herbivore interactions.

  18. Moderation is best: effects of grazing intensity on plant--flower visitor networks in Mediterranean communities.

    Science.gov (United States)

    Lazaro, Amparo; Tscheulin, Thomas; Devalez, Jelle; Nakas, Georgios; Stefanaki, Anastasia; Hanlidou, Effie; Petanidou, Theodora

    2016-04-01

    The structure of pollination networks is an important indicator of ecosystem stability and functioning. Livestock grazing is a frequent land use practice that directly affects the abundance and diversity of flowers and pollinators and, therefore, may indirectly affect the structure of pollination networks. We studied how grazing intensity affected the structure of plant-flower visitor networks along a wide range of grazing intensities by sheep and goats, using data from 11 Mediterranean plant-flower visitor communities from Lesvos Island, Greece. We hypothesized that intermediate grazing might result in higher diversity as predicted by the Intermediate Disturbance Hypothesis, which could in turn confer more stability to the networks. Indeed, we found that networks at intermediate grazing intensities were larger, more generalized, more modular, and contained more diverse and even interactions. Despite general responses at the network level, the number of interactions and selectiveness of particular flower visitor and plant taxa in the networks responded differently to grazing intensity, presumably as a consequence of variation in the abundance of different taxa with grazing. Our results highlight the benefit of maintaining moderate levels of livestock grazing by sheep and goats to preserve the complexity and biodiversity of the rich Mediterranean communities, which have a long history of grazing by these domestic animals.

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

    Directory of Open Access Journals (Sweden)

    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.

  20. Produção de forragem e de grãos de aveia branca sob pastejo Forage and grain yield of white oat under grazing

    Directory of Open Access Journals (Sweden)

    Patrícia Cambrussi Bortolini

    2005-12-01

    Full Text Available Os objetivos neste estudo foram quantificar os efeitos da desfolhação resultante de diferentes períodos de pastejo em aveia branca (Avena sativa L., avaliar os potenciais forrageiro e granífero do cultivar FAPA 2 e determinar o período máximo de permanência dos animais em pastejo para possibilitar colheita de forragem sem afetar a produção de grãos. Os tratamentos (sem pastejo, 1, 2, 3, 4, 5, 6, 7 e 8 semanas de pastejo foram distribuídos em delineamento experimental de blocos ao acaso, com três repetições, em subparcelas, nas quais foram avaliados os períodos de pastejo. O cultivar de aveia branca avaliado demonstrou adequada recuperação à desfolhação para produção de altas quantidades de matéria seca, desde que a duração de pastejo não ultrapasse quatro semanas. Em pastejos prolongados (cinco, seis, sete e oito semanas, ocorre queda na produção de matéria seca e lenta recuperação de área foliar. O aumento no rendimento de grãos de aveia branca ocorre em períodos de 1 a 4 semanas de pastejo, em decorrência da redução do acamamento e da menor altura do meristema apical. Em desfolhações de 5 a 8 semanas de pastejo, a redução no rendimento de grãos acompanha o declínio do número de espigas por área, de espiguetas por espiga e de grãos por espiga. O pastejo controlado até quatro semanas estimula a produção de matéria seca e permite a produção de grãos, além de promover oportunidade para produção animal, demonstrando a alta aptidão desse cultivar ao sistema de duplo propósito.To quantify defoliation effects resulting from several grazing periods with cattle on white oat (Avena sativa L. an experiment was run at Experimental Station of Fundação Agrária de Pesquisa Agropecuária in Guarapuava, Paraná State, Brazil, from April to November of 1999. The specific objectives were to evaluate potential forage and grain yield of white oat cv. FAPA 2 after different grazing periods as well as to

  1. Stable carbon isotope composition of perirenal adipose tissue fatty acids from Engadine sheep grazing either mountain or lowland pasture.

    Science.gov (United States)

    Richter, E K; Spangenberg, J E; Willems, H; Kreuzer, M; Leiber, F

    2012-03-01

    To provide further insights into ruminant lipid digestion and metabolism, and into cis-9,trans-11 18:2 synthesis, 12 growing Engadine lambs grazing either mountain pasture (2,250 m above sea level; n = 6) or lowland pasture (400 m above sea level; n = 6) were studied. Both pastures consisted exclusively of C(3) plants. Before the experiment, all animals grazed a common pasture for 6 wk. Grasses and perirenal adipose tissues of the sheep were analyzed for fatty acids by gas chromatography. Stable C-isotope ratios (δ(13)C values in ‰ vs. the Vienna Pee Dee Belemnite standard) were determined in the composite samples by elemental analysis-isotope ratio mass spectrometry. The δ(13)C of the individual fatty acids were measured by gas chromatography-combustion-isotope ratio mass spectrometry. The δ(13)C value of the entire mountain pasture grass was -27.5‰ (SD 0.31), whereas that of the lowland pasture grass was -30.0‰ (SD 0.07). This difference was reflected in the perirenal adipose tissues of the corresponding sheep (P perirenal fat differed between mountain and lowland lambs (P perirenal cis-9,trans-11 18:2 were of endogenous origin and discrimination against (13)C occurred during Δ(9)-desaturation. The same discrimination was indicated by the isotopic shift between 16:0 and cis-9 16:1 in the mountain grazing group. Furthermore, the δ(13)C values of cis-9,trans-11 18:2 were smaller relative to the precursor fatty acids in the mountain lambs compared with the lowland group. This result suggests a reduced extent of biohydrogenation in lambs grazing on mountain grass in comparison with those grazing on lowland grass. This was supported by the smaller cis-9,trans-11 18:2 concentrations in total fatty acids found in the adipose tissues of the lowland lambs (P < 0.001). The results of this study demonstrate that natural differences between δ(13)C values of swards from different pastures and the adipose tissue fatty acids could be used as tracers in studies of

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

    Science.gov (United States)

    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.

  3. Preoperative screening: value of previous tests.

    Science.gov (United States)

    Macpherson, D S; Snow, R; Lofgren, R P

    1990-12-15

    To determine the frequency of tests done in the year before elective surgery that might substitute for preoperative screening tests and to determine the frequency of test results that change from a normal value to a value likely to alter perioperative management. Retrospective cohort analysis of computerized laboratory data (complete blood count, sodium, potassium, and creatinine levels, prothrombin time, and partial thromboplastin time). Urban tertiary care Veterans Affairs Hospital. Consecutive sample of 1109 patients who had elective surgery in 1988. At admission, 7549 preoperative tests were done, 47% of which duplicated tests performed in the previous year. Of 3096 previous results that were normal as defined by hospital reference range and done closest to the time of but before admission (median interval, 2 months), 13 (0.4%; 95% CI, 0.2% to 0.7%), repeat values were outside a range considered acceptable for surgery. Most of the abnormalities were predictable from the patient's history, and most were not noted in the medical record. Of 461 previous tests that were abnormal, 78 (17%; CI, 13% to 20%) repeat values at admission were outside a range considered acceptable for surgery (P less than 0.001, frequency of clinically important abnormalities of patients with normal previous results with those with abnormal previous results). Physicians evaluating patients preoperatively could safely substitute the previous test results analyzed in this study for preoperative screening tests if the previous tests are normal and no obvious indication for retesting is present.

  4. Adolescents previously involved in Satanism experiencing mental health problems

    Directory of Open Access Journals (Sweden)

    H Heathcote

    1999-09-01

    Full Text Available No research has previously been done regarding the phenomenon of adolescents who have previously been involved in Satanism and who experience obstacles in their strive for mental health. Adolescents previously involved in Satanism present behavioral problems like aggressive outbursts, depression, “ psychosis” or suicide attempts, that could lead to suicide. In the phenomenonanalysis semi-structured, phenomenological interviews were performed with the respondents and their parents. The respondents were requested to write a naïve sketch about their life. After completion of the data-control, guidelines for nursing staff were set.

  5. Effects of grazing intensity and the use of veterinary medical products on dung beetle biodiversity in the sub-mountainous landscape of Central Italy

    Directory of Open Access Journals (Sweden)

    Mattia Tonelli

    2017-01-01

    Full Text Available Grazing extensification and intensification are among the main problems affecting European grasslands. We analyze the impact of grazing intensity (low and moderate and the use of veterinary medical products (VMPs on the dung beetle community in the province of Pesaro-Urbino (Italy. Grazing intensity is a key factor in explaining the diversity of dung beetles. In the case of the alpha diversity component, sites with a low level of grazing activity—related in a previous step to the subsequent abandonment of traditional farming—is characterized by a loss of species richness (q = 0 and a reduction in alpha diversity at the levels q = 1 and q = 2. In the case of beta diversity, sites with a different grazing intensity show remarkable differences in terms of the composition of their species assemblages. The use of VMPs is another important factor in explaining changes in dung beetle diversity. In sites with a traditional use of VMPs, a significant loss of species richness and biomass is observed, as is a notable effect on beta diversity. In addition, the absence of indicator species in sites with a historical use of VMPs corroborates the hypothesis that these substances have a ubiquitous effect on dung beetles. However, the interaction between grazing activity and VMPs when it comes to explaining changes in dung beetle diversity is less significant (or is not significant than the main effects (each factor separately for alpha diversity, biomass and species composition. This may be explained if we consider that both factors affect the various species differently. In other words, the reduction in dung availability affects several larger species more than it does very small species, although this does not imply that the former are more susceptible to injury caused by the ingestion of dung contaminated with VMPs. Finally, in order to prevent negative consequences for dung beetle diversity, we propose the maintenance of a moderate grazing intensity and

  6. Effects of grazing intensity and the use of veterinary medical products on dung beetle biodiversity in the sub-mountainous landscape of Central Italy.

    Science.gov (United States)

    Tonelli, Mattia; Verdú, José R; Zunino, Mario E

    2017-01-01

    Grazing extensification and intensification are among the main problems affecting European grasslands. We analyze the impact of grazing intensity (low and moderate) and the use of veterinary medical products (VMPs) on the dung beetle community in the province of Pesaro-Urbino (Italy). Grazing intensity is a key factor in explaining the diversity of dung beetles. In the case of the alpha diversity component, sites with a low level of grazing activity-related in a previous step to the subsequent abandonment of traditional farming-is characterized by a loss of species richness ( q = 0) and a reduction in alpha diversity at the levels q = 1 and q = 2. In the case of beta diversity, sites with a different grazing intensity show remarkable differences in terms of the composition of their species assemblages. The use of VMPs is another important factor in explaining changes in dung beetle diversity. In sites with a traditional use of VMPs, a significant loss of species richness and biomass is observed, as is a notable effect on beta diversity. In addition, the absence of indicator species in sites with a historical use of VMPs corroborates the hypothesis that these substances have a ubiquitous effect on dung beetles. However, the interaction between grazing activity and VMPs when it comes to explaining changes in dung beetle diversity is less significant (or is not significant) than the main effects (each factor separately) for alpha diversity, biomass and species composition. This may be explained if we consider that both factors affect the various species differently. In other words, the reduction in dung availability affects several larger species more than it does very small species, although this does not imply that the former are more susceptible to injury caused by the ingestion of dung contaminated with VMPs. Finally, in order to prevent negative consequences for dung beetle diversity, we propose the maintenance of a moderate grazing intensity and the rational use

  7. Assessing the potential to restore historic grazing ecosystems with tortoise ecological replacements.

    Science.gov (United States)

    Griffiths, Christine J; Zuël, Nicolas; Jones, Carl G; Ahamud, Zairabee; Harris, Stephen

    2013-08-01

    The extinction of large herbivores, often keystone species, can dramatically modify plant communities and impose key biotic thresholds that may prevent an ecosystem returning to its previous state and threaten native biodiversity. A potentially innovative, yet controversial, landscape-based long-term restoration approach is to replace missing plant-herbivore interactions with non-native herbivores. Aldabran giant (Aldabrachelys gigantea) and Madagascan radiated (Astrochelys radiata) tortoises, taxonomically and functionally similar to the extinct Mauritian giant tortoises (Cylindraspis spp.), were introduced to Round Island, Mauritius, in 2007 to control the non-native plants that were threatening persistence of native species. We monitored the response of the plant community to tortoise grazing for 11 months in enclosures before the tortoises were released and, compared the cost of using tortoises as weeders with the cost of using manual labor. At the end of this period, plant biomass; vegetation height and cover; and adult, seedling, flower, and seed abundance were 3-136 times greater in adjacent control plots than in the tortoise enclosures. After their release, the free-roaming tortoises grazed on most non-native plants and significantly reduced vegetation cover, height, and seed production, reflecting findings from the enclosure study. The tortoises generally did not eat native species, although they consumed those native species that increased in abundance following the eradication of mammalian herbivores. Our results suggest that introduced non-native tortoises are a more cost-effective approach to control non-native vegetation than manual weeding. Numerous long-term outcomes (e.g., change in species composition and soil seed bank) are possible following tortoise releases. Monitoring and adaptive management are needed to ensure that the replacement herbivores promote the recovery of native plants. © 2013 Society for Conservation Biology.

  8. Subclinical ketosis in dairy cows: prevalence and risk factors in grazing production system.

    Science.gov (United States)

    Garro, C J; Mian, L; Cobos Roldán, M

    2014-10-01

    The purpose of this study was to estimate the prevalence of Subclinical ketosis (SCK) between 4 and 19 days in milk (DIM) in a grazing production system and investigate the importance of potential risk factors for SCK. This cross-sectional study was conducted in dairy cows (n = 107), which had more of two parities. The concentration of β-hydroxybutyric (BHB) in blood was quantified through a hand-held meter. Potential risk factors evaluated were calving interval (CI), milk yield in previous lactation, metritis, dystocia, calf sex (male), parity (≤3 vs. ≥4) and pre-partum body condition score (BCS ≤ 3.5 vs. ≥3.75). Prevalence of SCK was 10.3% (95% CI 4.7-15) between 4 and 19 DIM. Risk factors identified were the occurrence of both metritis and pre-partum BCS ≥ 3.75. Cows with metritis had 4.9 (95% CI 1.17-20.98) times more risk of developing SCK than cows without metritis. And the cows with pre-partum BCS ≥ 3.75 had 5.25 (95% CI 1.32-21.11) times more risk of developing SCK than cows with pre-partum BCS ≤ 3.5. Metritis could induce a lower feed intake and promote the development of SCK. High pre-partum BCS could induce a greater mobilization of body reserves altering liver function and aggravating post-partum NEB. The results are indicative of the expected prevalence of SCK in grazing production system. Factors associated could help to identify cattle at risk of SCK and improve the management of strategies to limit the effects. Journal of Animal Physiology and Animal Nutrition © 2013 Blackwell Verlag GmbH.

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

    CERN Document Server

    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.

  10. Grazing studies on selected plutonium-contaminated areas in Nevada

    International Nuclear Information System (INIS)

    Smith, D.D.

    1975-01-01

    A grazing study in Area 13 of the Nevada Test Site (NTS) was initiated in May of 1973 and is proceeding on schedule. The accomplishments to date in this study include the quarterly collection of ingesta samples from fistulated steers, the quarterly sacrifice and sampling of a goat, the semiannual sacrifice and sampling of selected adult and young cattle, and the quarterly determination of digestibility of range plants. Dietary habits were tabulated with favored plant species being: two grasses, Indian ricegrass and galleta; two shrubs, winter fat and four-winged saltbush; and one forb, Russian thistle. Other analytical data are not yet available. (auth)

  11. Grazing incidence XAFS under non-specular conditions

    International Nuclear Information System (INIS)

    Keil, Patrick; Luetzenkirchen-Hecht, Dirk; Frahm, Ronald

    2005-01-01

    The extended X-ray absorption fine structure technique (EXAFS) in the reflection mode under specular and non-specular conditions was used for the ex situ investigation of a sputter-deposited thin copper film on a float glass substrate. We prove the existence of a fine structure similar to EXAFS, which can be observed in the region of diffusely scattered intensities. It is shown that this new technique is surface sensitive for grazing angles above the critical angle of total reflection and an even higher surface sensitivity with respect to conventional reflection mode EXAFS can be achieved

  12. Review of grazing studies on plutonium-contaminated rangelands

    International Nuclear Information System (INIS)

    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

  13. Milk production responses to different strategies for feeding supplements to grazing dairy cows.

    Science.gov (United States)

    Auldist, M J; Marett, L C; Greenwood, J S; Wright, M M; Hannah, M; Jacobs, J L; Wales, W J

    2016-01-01

    Milk production responses of grazing cows offered supplements in different ways were measured. Holstein-Friesian cows, averaging 45 d in milk, were allocated into 8 groups of 24, with 2 groups randomly assigned to each of 4 feeding strategies. These were control: cows grazed a restricted allowance of perennial ryegrass pasture supplemented with milled wheat grain fed in the milking parlor and alfalfa hay offered in the paddock; FGM: same pasture and allowance as the control supplemented with a formulated grain mix containing wheat grain, corn grain, and canola meal fed in the parlor and alfalfa hay fed in the paddock; PMRL: same pasture and allowance as the control, supplemented with a PMR consisting of the same FGM but mixed with alfalfa hay and presented on a feed pad after each milking; and PMRH: same PMR fed in the same way as PMRL but with a higher pasture allowance. For all strategies, supplements provided the same metabolizable energy and grain:forage ratio [75:25, dry matter (DM) basis]. Each group of 24 cows was further allocated into 4 groups of 6, which were randomly assigned to receive 8, 12, 14, or 16 kg of DM supplement/cow per d. Thus, 2 replicated groups per supplement amount per dietary strategy were used. The experiment had a 14-d adaptation period and a 14-d measurement period. Pasture allowance, measured to ground level, was approximately 14 kg of DM/d for control, FGM, and PMRL cows, and 28 kg of DM/d for the PMRH cows, and was offered in addition to the supplement. Positive linear responses to increasing amounts of supplement were observed for yield of milk, energy-corrected milk, fat, and protein for cows on all 4 supplement feeding strategies. Production of energy-corrected milk was greatest for PMRH cows, intermediate for FGM and PMRL cows, and lowest for control cows. Some of these differences in milk production related to differences in intake of pasture and supplement. Milk fat concentration decreased with increasing amount of supplement

  14. Grazing intensity differentially regulates ANPP response to precipitation in North American semiarid grasslands.

    Science.gov (United States)

    Irisarri, J Gonzalo N; Derner, Justin D; Porensky, Lauren M; Augustine, David J; Reeves, Justin L; Mueller, Kevin E

    2016-07-01

    Grazing intensity elicits changes in the composition of plant functional groups in both shortgrass steppe (SGS) and northern mixed-grass prairie (NMP) in North America. How these grazing intensity-induced changes control aboveground net primary production (ANPP) responses to precipitation remains a central open question, especially in light of predicted climate changes. Here, we evaluated effects of four levels (none, light, moderate, and heavy) of long-term (>30 yr) grazing intensity in SGS and NMP on: (1) ANPP; (2) precipitation-use efficiency (PUE, ANPP : precipitation); and (3) precipitation marginal response (PMR; slope of a linear regression model between ANPP and precipitation). We advance prior work by examining: (1) the consequences of a range of grazing intensities (more grazed vs. ungrazed); and (2) how grazing-induced changes in ANPP and PUE are related both to shifts in functional group composition and physiological responses within each functional group. Spring (April-June) precipitation, the primary determinant of ANPP, was only 12% higher in NMP than in SGS, yet ANPP and PUE were 25% higher. Doubling grazing intensity in SGS and nearly doubling it in NMP reduced ANPP and PUE by only 24% and 33%, respectively. Increased grazing intensity reduced C 3 graminoid biomass and increased C 4 grass biomass in both grasslands. Functional group shifts affected PUE through biomass reductions, as PUE was positively associated with the relative abundance of C 3 species and negatively with C 4 species across both grasslands. At the community level, PMR was similar between grasslands and unaffected by grazing intensity. However, PMR of C 3 graminoids in SGS was eightfold higher in the ungrazed treatment than under any grazed level. In NMP, PMR of C 3 graminoids was only reduced under heavy grazing intensity. Knowing the ecological consequences of grazing intensity provides valuable information for mitigation and adaptation strategies in response to predicted

  15. Automatic electromagnetic valve for previous vacuum

    International Nuclear Information System (INIS)

    Granados, C. E.; Martin, F.

    1959-01-01

    A valve which permits the maintenance of an installation vacuum when electric current fails is described. It also lets the air in the previous vacuum bomb to prevent the oil ascending in the vacuum tubes. (Author)

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

    Directory of Open Access Journals (Sweden)

    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

  17. FORAGES AND PASTURES SYMPOSIUM: Improving soil health and productivity on grasslands using managed grazing of livestock.

    Science.gov (United States)

    Russell, J R; Bisinger, J J

    2015-06-01

    Beyond grazing, managed grasslands provide ecological services that may offer economic incentives for multifunctional use. Increasing biodiversity of plant communities may maximize net primary production by optimizing utilization of available light, water, and nutrient resources; enhance production stability in response to climatic stress; reduce invasion of exotic species; increase soil OM; reduce nutrient leaching or loading in surface runoff; and provide wildlife habitat. Strategically managed grazing may increase biodiversity of cool-season pastures by creating disturbance in plant communities through herbivory, treading, nutrient cycling, and plant seed dispersal. Soil OM will increase carbon and nutrient sequestration and water-holding capacity of soils and is greater in grazed pastures than nongrazed grasslands or land used for row crop or hay production. However, results of studies evaluating the effects of different grazing management systems on soil OM are limited and inconsistent. Although roots and organic residues of pasture forages create soil macropores that reduce soil compaction, grazing has increased soil bulk density or penetration resistance regardless of stocking rates or systems. But the effects of the duration of grazing and rest periods on soil compaction need further evaluation. Because vegetative cover dissipates the energy of falling raindrops and plant stems and tillers reduce the rate of surface water flow, managing grazing to maintain adequate vegetative cover will minimize the effects of treading on water infiltration in both upland and riparian locations. Through increased diversity of the plant community with alterations of habitat structure, grazing systems can be developed that enhance habitat for wildlife and insect pollinators. Although grazing management may enhance the ecological services provided by grasslands, environmental responses are controlled by variations in climate, soil, landscape position, and plant community

  18. Combined effects of climatic gradient and domestic livestock grazing on reptile community structure in a heterogeneous agroecosystem.

    Science.gov (United States)

    Rotem, Guy; Gavish, Yoni; Shacham, Boaz; Giladi, Itamar; Bouskila, Amos; Ziv, Yaron

    2016-01-01

    Grazing plays an important role in shaping ecological communities in human-related ecosystems. Although myriad studies have explored the joint effect of grazing and climate on plant communities, this interactive effect has rarely been studied in animals. We hypothesized that the effect of grazing on the reptile community varies along a climatic gradient in relation to the effect of grazing on habitat characteristics, and that grazing differentially affects reptiles of different biogeographic regions. We tested our hypotheses by collecting data on environmental characteristics and by trapping reptiles in four heterogeneous landscapes experiencing differing grazing intensities and distributed along a sharp climatic gradient. We found that while reptile diversity increased with grazing intensity at the mesic end of the gradient, it decreased with grazing intensity at the arid end. Moreover, the proportion of reptile species of differing biogeographic origins varied with the interactive effect of climate and grazing. The representation of species originating in arid biogeographic zones was highest at the arid end of the climatic gradient, and representation increased with grazing intensity within this area. Regardless of the climatic context, increased grazing pressure results in a reduction in vegetation cover and thus in changes in habitat characteristics. By reducing vegetation cover, grazing increased habitat heterogeneity in the dense mesic sites and decreased habitat heterogeneity in the arid sites. Thus, our results suggest that the same direction of habitat alteration caused by grazing may have opposite effects on biodiversity and community composition in different climatic contexts.

  19. Leaf Tissue C:N and Soil N are Modified by Growing Season and Goose Grazing Phenology in a Sub-Arctic Coastal Wetland of Western Alaska

    Science.gov (United States)

    Choi, R. T.; Beard, K. H.; Leffler, A. J.; Schmutz, J. A.; Welker, J. M.

    2014-12-01

    Climate change in Arctic wetlands is resulting in a widening phenological mismatch between the onset of the growing season and the arrival and hatch date of migratory geese, the primary consumers in the system. During the past three decades, the growing season has advanced but geese have not advanced arrival or hatch date at the same rate. Geese now arrive into a system that has been growing longer than in the past with potential changes in forage quality because sedges have their highest nutrient density shortly following emergence. One potential concomitant result of this phenological gap is altered carbon to nitrogen ratio (C:N) of leaf tissue being returned to the ecosystem as feces that is more N-poor. Altering the C:N of these inputs can further influence C and N cycling in the system. We examine the influence of advanced growing season and different arrival times by black brant on leaf and soil C:N ratio and soil N-form. Our experiment consists of six blocks with nine study plots each. Half the plots are warmed to advance the growing season. Two plots each receive early, typical, late, and no grazing; one plot is a control that is not warmed and grazing is natural. Leaf tissue was collected to determine C and N concentration using an elemental analyzer. Anion and cation exchange membranes were used to monitor inorganic N forms in soil; samples were analyzed via fluorescence following extraction. Soil water collected from lysimeters was analyzed for organic N. Warming advanced plant growth between one and two weeks and resulted in higher C:N of leaf tissue Geese maintained 'grazing lawns', areas of exceptionally short vegetation, where plants had high N compared to non-grazed areas. Grazing early in the season promoted higher N content of leaves and soil while grazing late had little influence on N. The timing of the growing season and grazing both have important implications for C and N in this system.

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

    Directory of Open Access Journals (Sweden)

    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