Livestock best management practices (BMPs) such as streamside exclusion fencing are installed to reduce cattle impacts on stream water quality such as increases in bacteria through direct deposition and sediment through trampling. The main objective of this study is to assess the effects of different cattle management strategies on water quality. The project site was located near Keezletown, VA encompassing Cub Run and Mountain Valley Road Tributary streams. During two, one-week studies, eight automatic water samplers took two-hour composites for three periods: baseline, cattle access, and recovery. During the cattle access period, livestock were able to enter the riparian zone normally fenced off. Water samples were analyzed for E.coli, sediment, and nutrients to understand the short-term, high-density, or flash grazing, impact on water quality. Additional weekly grab and storm samples were collected. Results show that cattle do not have significant influence on pollutant concentrations except in stream locations where cattle gathered for an extensive period of time. Approximately three cattle in the stream created an increase in turbidity above baseline concentrations. E.coli and TSS concentrations of the impacted sites returned to baseline within approximately 6 to 20 hours of peak concentrations. Weekly samples show that flash grazing does not have a significant influence on pollutant concentrations over a two-year time frame. Sediment loads from storms and a flash grazing event showed similar patterns. Pollutant concentrations through the permanent exclusion fencing reach tended to decrease for weekly and flash grazing samples. / Master of Science

M.S.

No / Microwear patterns and formation processes are examined in modern browsing and grazing Gotland sheep from Denmark. Clear differences in microwear patterning are identified between Gotland sheep, which included a high proportion of leaves, bark and twigs of deciduous trees and shrubs in their diet, and those which primarily had access to graze species, with the browsing group exhibiting enamel surfaces dominated by pitted microwear features, the grazers a predominance of striations. Analysis of abrasives in dung suggests that these trends can be attributed to higher levels of soil ingestion in the grazing population and are a consequence both of grassland management practices and height of feeding within the vegetation canopy. These findings question previous interpretations of microwear patterning in browsing and grazing ungulates, which have equated striated enamel features with the ingestion of high levels of opal phytoliths, and thus have significant implications for palaeodietary reconstruction in such species, both within archaeological and palaeontological contexts. To address further the implications of these results, comparison is made between the Gotland sheep and modern grazing and fodder-fed sheep and goats from elsewhere in Europe. It is concluded that dental microwear analysis has the potential to address questions relating to grassland management practices and the use of certain fodders, such as leafy-hay, but that it may ultimately prove more difficult to distinguish `fresh¿ browsing sheep from some grazing populations, specifically those in which levels of soil ingestion are reduced.

Alfalfa (<i>Medicago sativa</i>, L. cv. Arc) productivity, regrowth, and quality as affected by summer grazing management and K fertilization (560 kg K/ha) was investigated with sheep. Sheep grazed alfalfa for 2-, 4-, or 6-weeks following a 2 July hay cut when regrowth was 450 kg/ha dry matter; beginning in early bud for 10 days (delayed); at early bloom for 7 days (conventional); and non-grazed (hay removed at 1/10 bloom). Forage yields, leaf area index (LAI), tiller numbers, crude protein (CP), and in vitro dry matter digestibility ( IVDMD) generally declined during grazing. Neutral detergent fiber (NDF), lignin, and cellulose content generally increased on all grazing systems. Forage at the end of grazing was nigher in percent leaf, CP, Mg, P, Kand IVDMD and lower in cellulose, lignin and NDF on 2-, 4-, and 6-week systems than forage remaining on the other systems. A late summer hay cut at 1/10 bloom was made on 2-week, delayed and non-grazed systems. Grazing by the 2-week system decreased yield, LAI, and plant height but forage quality as measured by percent leaf, NDF, lignin, and cellulose was increased, compared to the non-grazed system. Grazing by the delayed system resulted in similar results as the 2-week system but differences were not as great. There were no differences in IVDMD. On 1 Oct., 4-week and conventional grazing systems had reduced yields, plant height, tiller number, and root total nonstructural, but had no significant effect on forage quality. Conventional grazing resulted in the least damage to yield and productivity measurements. Percent weed increased in 2-, 4-, and 5-week systems in fall but no differences were measured in percent weed, yield, or tiller number in regrowth the following spring. / M.S.

This study investigated the role of grazing as a possible cause for the upper limit of distribution of algae on a typical South African south coast.

How so many species coexist while utilizing the same resources is both of ecological interest and important for the management of wildlife communities and parks. This thesis endeavours to understand how grazing herbivores co-exist, with special emphasis on understanding the mechanisms of competition and facilitation over temporal and spatial scales. I compared the dry season use of grasslands, grass species, grass height and grass greenness by white rhino and three other ungulate species, zebra, wildebeest, and impala. I was specifically interested in the extent to which white rhinos, with their capacity to graze both short and tall grass, either competed with or facilitated other grazers. In Chapter Two, I clarify the mechanisms of facilitation and competition in terms of temporal and spatial scales, and discuss why there is little evidence in the literature to support these mechanisms. I conclude that evidence for facilitation through stimulation of grass re-growth during the growing season appears stronger than that for increased resource access through removal of obstructing grass structures during the dormant season. Facilitation may benefit the nutritional gains obtained by certain species in the short term, but these benefits do not appear to be translated into the expected population consequences. In collaboration with co-author Norman Owen-Smith, we suggested this could be due to seasonal tradeoffs between facilitation and competition, as well as to restrictions on the spatial extent of trophic overlap. In Chapter 3 Norman Owen-Smith and I compared the grass height use in relation to body size. We expected that the grass height favoured would increase with the body size of the herbivore species, as suggested from past studies of resource partitioning among large mammalian herbivores. Instead we found that the largest of these species, white rhino, concentrated on the shortest grass, while the smallest species, impala, favoured grass heights intermediate between those grazed by wildebeest and zebra. Results suggest that the scaling of mouth width relative to body size, and hence metabolic demands, is the primary factor governing grass height selection, rather than body size alone. Hence grazing successions governed by body size differences may not be a typical feature of their ecology, contrary to past suggestions. Furthermore, there was considerable overlap in grass height grazed among these four species, indicating that niche separation by grass height is inadequate alone to explain their coexistence. More attention needs to be paid to other aspects such as the grass species selected and habitat structure favoured. Chapter Four compared the overlap in grassland use and grass species use, as well as grass height and grass greenness of swards utilized by the herbivores as the dry season advances. I show that all species prefer grazing lawns during times of abundance, and that zebra leave grazing lawns before other species, and wildebeest leave grazing lawns before white rhino and impala. This suggests zebra and wildebeest may be competitively excluded from grazing lawns through a reduction in grass height, by white rhino and impala, during the dry season. However, white rhino are also potentially the ‘supreme’ facilitator increasing the availability of nutritious grazing lawns, as well as increasing the quality of those lawns through grazing in the wet season. A better understanding of the trade-off between “habitat facilitation” and competitive exclusion by white rhino, allows us to better understand how grazing herbivores co-exist.

O pastejo é considerado um fator determinante para a manutenção e conservação da vegetação campestre (campos) no sul do Brasil, sendo considerado o responsável por construir a heterogeneidade estrutural, a composição de espécies e a diversidade dos campos. Porém o manejo do pastejo é fundamental para sucesso da atividade pecuária, uma vez que longos períodos de pastejo excessivo e intenso ao invés de manter áreas campestres pode degradá-las, diminuindo a diversidade e produtividade, tornando os campos suscetíveis a invasão por espécies exóticas. Para o sucesso da relação construída entre o manejador, os animais e a vegetação, as estratégias de manejo que possibilitem uma pecuária rentável, mas que busque conservar a vegetação campestre, são fundamentais. O objetivo desta tese foi verificar os efeitos do pastejo sobre a vegetação campestre, tendo como ferramenta principal para isso, diferentes manejos. Os efeitos do pastejo foram avaliados através de índices de diversidade taxonômica e funcional, e da variação de atributos funcionais de gramíneas, analisando especificamente: (1) como estratégias de manejo contínuo e rotativo influenciam a dinâmica da vegetação campestre (biomassa, diversidade, riqueza e equitabilidade); (2) a influência do manejo do pastejo na composição e diversidade funcional de comunidades campestres descritas por gramíneas, e os efeitos sobre a variação intra- e interespecífica de atributos foliares (SLA e LDMC) das espécies de gramíneas; (3) o efeito de diferentes intensidades de pastejo (ofertas de forragem) nas diversidades alfa e beta das comunidades de plantas. Foram verificadas mudanças na diversidade, equitabilidade, riqueza de espécies, biomassa condicionadas pelo pastejo rotativo, que se mostrou benéfico para vegetação campestre. O pastejo rotativo proporcionou também um incremento na diversidade funcional, condicionado pela variação intra- e interespecífica nos atributos das gramíneas. Diferentes intensidades de pastejo promoveram diferenças de alfa e beta diversidade sob diferentes intensidades de pastejo. O pastejo demonstrou exercer papel determinante em toda a dinâmica campestre, tendo efeitos consideráveis em todos os níveis de avaliação, desde a riqueza de espécies até na diversidade funcional, ficando evidente que a decisão do manejo é fundamental tanto para a produtividade quanto para a manutenção da vegetação campestre. / Grazing is considered a determining factor for the maintenance and conservation of grasslands in southern Brazil and is considered one of the main driver of the structural heterogeneity, species composition and diversity of the grasslands. But the management of grazing is key to the success of livestock farming, since long periods of excessive and intense grazing instead of maintaining grassland, can degrade them, reducing the diversity and productivity, leading the grassland susceptible to invasion of exotic species. For the success of the relationship built between managers, animals and vegetation, a strategic management that allows an efficient farming together with the conservation of grassland vegetation is essential. The objective of this thesis was to investigate the effects of grazing on the grassland, based on different managements of grazing. The effects of grazing were evaluated by taxonomic and functional diversity indices, and the variation of functional traits of grasses, analyzing specifically: (1) how continuous and rotational grazing management influence the dynamics of grassland vegetation (biomass, diversity, richness and evenness); (2) the influence of grazing management on the functional composition and functional diversity in grassland communities described by grasses, and its effects on the intra- and interspecific variation of leaf traits (SLA and LDMC) of grass species; (3) the effect of different grazing intensities (forage dry matter offer) in the alpha and beta diversity of plant communities. Changes in diversity, evenness, species richness, and biomass were verified, which were conditioned by the rotational grazing that proved beneficial to grassland. The rotational grazing provided also an increase in functional diversity, due to intra and interspecific variation of the grasses traits. Different grazing intensities promoted differences in alpha and beta diversity under different grazing intensities. Grazing demonstrated to have a decisive role in the whole dynamics of grassland communities, with considerable effects on all levels here assessed, from the species richness to the functional diversity, becoming apparent that the management decision is very important for both the productivity and the maintenance of grassland structure and diversity.

O entendimento das relações entre as características do pasto e as respostas do comportamento ingestivo animal é fundamental para o aprimoramento de inovações no manejo de pastagens, tornando os sistemas pastoris mais eficientes e competitivos. Neste estudo comparamos dois métodos de pastoreio (Rotativo x Contínuo) e duas intensidades de pastejo (Moderada e Baixa) a fim de compreendermos como as características de pastos de azevém anual (Lolium multiflorum Lam.) influenciam o comportamento ingestivo e o ganho médio diário de ovinos. Observamos que o método de pastoreio afeta a quantidade de folhas e inflorescências, influenciando a composição química da forragem, além da taxa de bocados e o tempo de pastejo dos ovinos. Por outro lado, as intensidades de pastejo influenciaram os bocados por estação alimentar e o número de refeições. Além disso, variáveis como: estação alimentar por minuto, duração das refeições e tempo de pastejo foram positivamente correlacionadas com o ganho médio diário dos animais, assim, podem ser utilizadas como preditoras do ganho médio diário de ovinos. Encontramos evidências de que em pastoreio rotativo, ambas as intensidades de pastejo estudadas promoveram um rebaixamento em torno de 45% da altura pré-pastejo. A estrutura do pasto e a composição química da forragem foram adequadas para o pastejo de ovinos até o início do estádio reprodutivo do azevém anual. No entanto, ao final do estádio reprodutivo da pastagem, ambas as intensidades de pastejo restringiram os padrões de comportamento ingestivo dos ovinos nas maiores escalas espaço-temporais. Essa restrição é acentuada durante o rebaixamento do pasto, em decorrência da redução no percentual de lâminas foliares, alterando o comportamento ingestivo de ovinos. Logo, a resposta comportamental de ovinos depende de: (i) taxa de lotação, (ii) nível de desfolha do dossel, (iii) período do estádio reprodutivo do azevém anual e composição estrutural da forragem durante o rebaixamento. / The understanding of the relationships between sward characteristics and the animals' ingestive behavior responses is fundamental for the improvement of sward management innovations, making pastoral systems more efficient and competitive. In this study, we compared two stocking methods (Continuous and Rotational) and two grazing intensities (Moderate and Low) to understand how the sward characteristics of annual ryegrass (Lolium multiflorum Lam.) influence the ingestive behavior and the average daily gain of sheep. We observed that the stocking method affect the quantity of leaf blades and inflorescences influenced forage chemical composition, as well as the bite rate and grazing time of sheep. On the other hand, grazing intensities had influence the bites by feeding station and meals number. Moreover, variables as feeding station per minute, meals duration and grazing time were positively correlated with the average daily gain, thus, they can be used as predictors for the average daily gain of sheep. We found evidence that both grazing intensities studied promote a grazing down around 45% of pre-grazing sward height in rotational stocking. Sward structure and forage chemical composition, were adequate for sheep grazing until the beginning of the sward reproductive stage. However, from the stage 2 of grazing down at the end of the sward reproductive stage, both grazing intensities apparently restricted the sheep‟s ingestive behavior patterns in the larger spatial and temporal scales of grazing. Therefore sheep‟s behavioral response depends on: (i) stocking rate, (ii) canopy defoliation level, (iii) period of sward reproductive stage and forage structural composition during grazing down.

O manejo do pastejo e a plasticidade fenotípica das plantas forrageiras determinam a estrutura do dossel que, associados a fatores edafoclimáticos, definem o padrão de acúmulo de forragem da pastagem. Estudos observaram que o critério de 95% de interceptação luminosa (IL) durante a rebrotação para interrupção do crescimento do dossel forrageiro e entrada dos animais no pasto propicia o maior acúmulo líquido de folhas e reduzido acúmulo de colmo e de material morto. Segundo o mecanismo de compensação tamanho/densidade populacional de perfilhos, o dossel forrageiro pode atingir o índice de área foliar crítico (IAF crítico) e interceptar 95% da luz incidente sob diferentes alturas de manejo e tamanho de perfilho, o que poderia gerar flexibilidade para as metas de entrada nos pastos. O objetivo deste estudo foi avaliar as características estruturais, a compensação tamanho/densidade de perfilhos e o acúmulo de forragem em pastos de Urochloa brizantha cv. Marandu manejados com alturas pré-pastejo inferiores ou igual a 25 cm, esta última associada aos 95% de IL em trabalhos anteriores, para verificar a possibilidade de flexibilização do manejo dessa planta forrageira. O experimento foi conduzido no Departamento de Zootecnia da USP/ESALQ entre maio de 2017 e abril de 2018. Esse período foi dividido em fase de adaptação, verão e outono. Os tratamentos foram determinados por alturas pré-pastejo de 25, 22, 19 e 16 cm com severidade de pastejo moderada, caracterizada por uma altura pós-pastejo equivalente a 50% daquela de entrada (12,5; 11,0; 9,5 e 8,0 cm; respectivamente). O delineamento experimental foi de blocos completos casualizados, com quatro repetições, totalizando 16 unidades experimentais (piquetes de 1.200 m2). Foram avaliadas as variáveis-reposta intervalo de pastejo; massa de forragem pré e pós-pastejo; composição morfológica pré e pós-pastejo; índice de área foliar pré e pós-pastejo; densidade populacional de perfilhos; peso seco por perfilho; área foliar por perfilho; volume por perfilho; peso específico por perfilho; relação área foliar:volume do perfilho; interceptação luminosa em pré e pós-pastejo; ângulo médio da folhagem em pré e pós-pastejo; taxa de acúmulo de forragem; taxa de acúmulo de folhas, de colmos e de material morto. O capim-marandu demonstrou alta plasticidade fenotípica associada à compensação tamanho/densidade populacional de perfilhos plena entre as alturas pré/pós-pastejo de 19/9,5 cm e 25/12,5 cm. Não houve variações em IAF e em taxa de acúmulo de forragem, de folhas, de colmo e de material morto entre os tratamentos. Os perfilhos apresentaram padrão de crescimento isométrico, não havendo variações na relação área foliar:volume do perfilho e densidade aparente. Dessa forma, é possível flexibilizar as metas pré-pastejo do capim-marandu em sistemas rotativos com alturas de entrada variando de 19 a 25 cm desde que a severidade de desfolhação seja moderada (redução de 50% da altura pré-pastejo). / Grazing management and phenotypic plasticity of perennial forage grasses determine sward structure, which defines the pattern of herbage accumulation depending on edaphoclimatic conditions. Different studies have indicated that the 95% canopy light interception (LI) criteria for interrupting regrowth allows for maximum leaf dry matter accumulation and reduces stem and dead material accumulation. According to the tiller size/density compensation mechanism it is possible that the sward reaches the critical leaf area index (critical LAI) and intercepts 95% of the incident light at different grazing heights and tiller sizes, a condition that could generate flexibility for the pre- grazing targets of rotational grazing. The objective of this study was to evaluate structural characteristics, tiller size/density compensation and herbage accumulation in Urochloa brizantha cv. Marandu (Palisade grass) managed with pre-grazing heights lower than or equal to 25 cm, the last associated with the 95% LI in previous experiments, to verify the possibility of generating flexibility in grazing management. The experiment was carried out at \"Luiz de Queiroz\" College of Agriculture, Piracicaba - SP, from May/2017 to April/2018. The period was divided into adaptation phase, summer and autumn. Treatments corresponded to four pre-grazing heights (25, 22, 19 and 16 cm) associated to moderate defoliation characterized by a post-grazing height equivalent to 50% of the pre-grazing height (12,5; 11,0; 9,5 e 8,0 cm; respectively). The experimental design was a complete randomized block with four replications (1.200 m2 paddocks). The response variables evaluated were: grazing interval; pre and post-grazing herbage mass; morphological composition; pre and post-grazing leaf area index; tiller population density; tiller dry mass; tiller leaf area; tiller volume; tiller density; tiller leaf area:volume ratio; pre and post-grazing light interception; pre and post-grazing mean foliage angle; rates of total dry matter, leaf, stem and dead material accumulation. Palisade grass showed high phenotypic plasticity associated with full tiller size/density compensation within the 19/9,5 cm and 25/12,5 cm treatments. There was no difference in LAI and rate of total dry matter, leaf, stem and dead material accumulation. Tillers showed an isometric pattern of growth with no differences in tiller leaf area:volume ratio and aparent density. Thus, it is possible to flexibilize the pre-grazing height targets of palisade grass with pre- grazing heights varying from 19 to 25 cm, provided that the defoliation severity is moderate (post-grazing height equivalent to 50% of the pre-grazing height).

Multispecies grazing research was conducted using meat-type goats (Capra hircus L.) and Jersey heifers (Bos taurus L.) to determine the relationships between multiple grazing treatments and pasture utilization. The study was conducted for 60 days on the Western Kentucky University Farm in Bowling Green, KY. Cattle and goats have shown to differ in grazing preferences and to be economically important to the area. Grazing treatments included goats and cattle grazing simultaneously, sequentially, and goats grazing alone. A typical established Kentucky pasture was utilized with no weed management practices employed. Predominant forage species included tall fescue (Festuca arundinacea Schreb.), orchardgrass (Dactylis glomerata L.), Kentucky bluegrass (Poa pratensis L.), and white clover (Trifolium repens L.). Exclosures were utilized as controls. Data included forage quality, composition, availability, height, visual weed cover and live ground cover, and thistle consumption, collected every 15 days. Results indicated a significant difference in sample dry weights between grazing treatments and ungrazed controls in every treatment except when goats followed cattle. At day 60, grazed areas had significantly lower forage heights than the control when goats grazed with and before cattle. Instances where goats followed cattle resulted in significantly higher NDF compared to the control. All treatments containing goats had significantly lower leaf numbers per thistle plant (Carduus nutans L.) than cattle only treatment. Based on this study, sequential and simultaneous grazing of cattle and goats may be an effective nodding thistle control strategy, but future experimentation is needed for determination of forage utilization and quality relationships.