Made available in DSpace on 2014-06-11T19:32:58Z (GMT). No. of bitstreams: 0 Previous issue date: 2010-07-01Bitstream added on 2014-06-13T19:03:45Z : No. of bitstreams: 1 ribeiro_tmd_dr_botfmvz.pdf: 1175902 bytes, checksum: e83fea39c577b1ede76fa2c826ee8e78 (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / Universidade Estadual Paulista (UNESP) / O trabalho objetivou avaliar as características da pastagem de Azevém sobressemeada em Tifton-85 e a produtividade de cordeiros desmamados submetidos a três níveis de suplementação. Os cordeiros pastejaram azevém sobressemeado em Tifton-85 e foram avaliados de acordo com a suplementação recebida: sem suplementação, suplementação em 0,9% do peso corporal (PC), suplementação em 1,8% PC e suplementação ad libitum. Os cordeiros foram pesados a cada 14 dias com jejum prévio de 16 horas. O método de utilização da pastagem foi o de pastejo com lotação contínua e taxa de lotação variável, procurando manter a altura da pastagem em 15 cm, sendo mensurada a cada 7 dias. A taxa de crescimento da pastagem foi mensurada pela técnica do triplo emparelhamento. Foi calculada a disponibilidade de forragem, o número de cordeiros/ha e a carga animal. O ganho de peso médio diário aumentou linearmente com a elevação do nível de suplementação concentrada oferecida aos cordeiros. Os níveis de suplementação concentrada tiveram relação linear negativa com a taxa de acúmulo, a matéria seca acumulada e a disponibilidade de matéria seca da forragem; e relação quadrática com a altura da pastagem, a taxa de lotação de cordeiros/ha e a carga animal (kgPC/ha). Concluise que a suplementação dos cordeiros em pastagem proporcionou melhor ganho de peso diário dos animais. Os níveis de suplementação interferem na altura e na disponibilidade de forragem. O efeito de substituição da pastagem pelo concentrado promoveu diminuição do crescimento da pastagem e da produção acumulada de forragem. Níveis de suplementação ad libitum possibilitaram aumentar o número de animais/ha e a carga animal / This study objected to evaluate ryegrass pasture characteristics oversowned on Tifton-85 and the performance of grazing weaned lambs supplemented in three levels of concentrate. The lambs grazed in ryegrass oversowned on Tifton-85 and were evaluate according to the supplementation that they had fed: no supplementation (control), 0,9% of body weight (BW), 1,8% of BW and ad libitum. The animals were weighted to each 14 days with 16 hour of water fasting. Grazing management was continuous variable stocking to keep pasture in 15 cm, being taken every 7 days. The herbage accumulation rate was measuredby triple cage technique. Availability of forage, number of lambs per hectare and animal stocking were calculated. The average daily weight gain increase linearly with increasing levels of concentrate supplementation offered to lambs. The level of concentrate supplementation had a negative linear relation with herbage growth rate, accumulated dry mater and available forage dry matter; and a quadratic relation with pasture height, number of lambs per hectare and animal stocking rate (kgBW/ha). It could be concluded that supplementation for grazing lambs provided better daily weight gain animals. The levels of supplementation interfered in height and availability of forage. The effect of substitution of grazing for concentrate promoted decreased of pasture daily growth and availability of forage dry matter. Levels of supplementation ad libitum increase number of animal/ha and animal stocking

Forage intake by animals is an important factor in determining production of livestock products from rangelands. However, relatively little is known of effects of such forage variables as availability and distribution in space upon intake. Even less is known about how the grazing animal modifies its feeding tactics when confronted with diminishing or limited supplies of available forage and how such altered behavior may affect the animal's energetic cost for existence. Forage intake, body weight gain, grazing time and biting rate of Angus heifers was related to forage availability and plant height on semiarid crested wheatgrass rangeland during the late summer. Forage availability was estimated within 10 percent of the 2 mean (P2plots. Forage intake was estimated from data on fecal production and in vitro digestibility of forage. Fecal production was determined by total collection, using fecal collection bags, and by a single-dose marker technique, used to estimate fecal production indirectly. Digestibility was determined by an in vitro procedure. Additionally crude protein and cell contents of forage were determined. Grazing time was measured by mechanical grazing clocks (Vibracorders) mounted on animals' necks. Biting rate was determined visually using a stop watch to time specific grazing intervals during which all bites were counted. There were a total of four 4-day trials during 1977 and five 4-day trials during 1978. Crude protein content within years was significantly higher during the third period in 1977 and during the fifth period in 1978 when regrowth occurred. Within years, in vitro digestibility was significantly higher only for the fifth trial during 1978. Cell contents decreased as grazing progressed only during 1978. Crude protein content, cell contents and in vitro digestibility were higher during 1977 than 1978. Forage intake of heifers did not vary significantly among successive grazing trials as forage availability declined from 919 to 143 kg DM/ha. Heifers apparently compensated for the diminishing forage availability by increasing grazing time from 380 to 656 min/day and biting rate from 37 to 50 bites/min. Grazing time was inversely related to forage availability and was expressed by the relationship y = 676.8 - 0.3x; r2 = 0.93. Biting rate was less correlated with forage availability and was described as y = 50.4 - 0.02x; r2 = 0.86. However, biting rate was more closely correlated with plant height as described by the relationship y = 53.0 - 0.48x; r2 = 0.95. Heifers maintained or gained 0.1 to 0.7 kg/head/day weight during all trials except the last trial in 1978 when they lost approximately 1.1 kg/head/day. The weight loss for this trial was apparently not a result of restricted forage intake or limited forage quality but partly due to extra maintenance energy expenditures attributable to increased grazing time and biting rate. Correlation between estimates of fecal output by the single dose marker technique with total fecal collection were not significant (P

Feral horse management has become a subject of significant controversy in the United States. This is because of differing opinions and minimal recent empirical data on feral horses. In recent years, numbers of feral horses have increased due to governmental horse removal restrictions (specifically the Wild Horse and Burro act of 1971). With increasing numbers of feral horses on rangelands, land managers are challenged with identifying the appropriate course of action for satisfying groups with differing opinions. The purpose of this study is to characterize diet consumption through the use of stable isotope dietary analysis (δ15N and δ13C). We did this in order to measure the impact of feral horse forage consumption on rangelands and to propose strategies for improving habitat management and conservation. We obtained tail hair isotopic values from tail hair removed while horses that were held in squeeze chutes following a roundup. Resulting isotopic values were compared to plant isotopic values using plant samples obtained from the geographical areas as the horses in order to characterize diet. Contribution of the various plant species to the tail hair mixture values was determined using the EPA program IsoSource©. Initial analysis of tail hair isotopes demonstrated seasonal variation. During summer months, shrubs (mostly Artemesia spp, and Purshia Tridentate), Elymus elymoides, Juncus balticus, and Festuca idahoensis were the predominantly consumed vegetative species. During fall months, Leymus cinereus and Juncus balticus played a more significant role in feral horse diet. In the winter, shrubs were more heavily consumed along with Poa secunda. Springtime showed a shift towards forb consumption. Changes in seasonal consumption of forages are most likely linked to forage availability as well as equine preference. We analyzed plant metrics (specifically biomass, abundance, and cover) to compare a site with horses present to a site where horses had been removed the previous year and found relatively few differences between the two sites. With nearly all differences we found higher plant production (forage availability) on the site where horses were still present. In riparian areas however, there was more vegetation (specifically Carex rossii, Juncus balticus, and Poa secunda) on the site where horses had been removed. Within riparian areas, only Bromus tectorum (a plant not typically found in riparian areas but characteristic of degraded areas) showed significantly greater amounts of biomass on the site with horses present. Knowledge of plant species consumption will allow land managers greater ability to make scientifically based decisions regarding feral horse population control which is important in determining appropriate management levels of populations.

Resumo: O trabalho objetivou avaliar as características da pastagem de Azevém sobressemeada em Tifton-85 e a produtividade de cordeiros desmamados submetidos a três níveis de suplementação. Os cordeiros pastejaram azevém sobressemeado em Tifton-85 e foram avaliados de acordo com a suplementação recebida: sem suplementação, suplementação em 0,9% do peso corporal (PC), suplementação em 1,8% PC e suplementação ad libitum. Os cordeiros foram pesados a cada 14 dias com jejum prévio de 16 horas. O método de utilização da pastagem foi o de pastejo com lotação contínua e taxa de lotação variável, procurando manter a altura da pastagem em 15 cm, sendo mensurada a cada 7 dias. A taxa de crescimento da pastagem foi mensurada pela técnica do triplo emparelhamento. Foi calculada a disponibilidade de forragem, o número de cordeiros/ha e a carga animal. O ganho de peso médio diário aumentou linearmente com a elevação do nível de suplementação concentrada oferecida aos cordeiros. Os níveis de suplementação concentrada tiveram relação linear negativa com a taxa de acúmulo, a matéria seca acumulada e a disponibilidade de matéria seca da forragem; e relação quadrática com a altura da pastagem, a taxa de lotação de cordeiros/ha e a carga animal (kgPC/ha). Concluise que a suplementação dos cordeiros em pastagem proporcionou melhor ganho de peso diário dos animais. Os níveis de suplementação interferem na altura e na disponibilidade de forragem. O efeito de substituição da pastagem pelo concentrado promoveu diminuição do crescimento da pastagem e da produção acumulada de forragem. Níveis de suplementação ad libitum possibilitaram aumentar o número de animais/ha e a carga animal / Abstract: This study objected to evaluate ryegrass pasture characteristics oversowned on Tifton-85 and the performance of grazing weaned lambs supplemented in three levels of concentrate. The lambs grazed in ryegrass oversowned on Tifton-85 and were evaluate according to the supplementation that they had fed: no supplementation (control), 0,9% of body weight (BW), 1,8% of BW and ad libitum. The animals were weighted to each 14 days with 16 hour of water fasting. Grazing management was continuous variable stocking to keep pasture in 15 cm, being taken every 7 days. The herbage accumulation rate was measuredby triple cage technique. Availability of forage, number of lambs per hectare and animal stocking were calculated. The average daily weight gain increase linearly with increasing levels of concentrate supplementation offered to lambs. The level of concentrate supplementation had a negative linear relation with herbage growth rate, accumulated dry mater and available forage dry matter; and a quadratic relation with pasture height, number of lambs per hectare and animal stocking rate (kgBW/ha). It could be concluded that supplementation for grazing lambs provided better daily weight gain animals. The levels of supplementation interfered in height and availability of forage. The effect of substitution of grazing for concentrate promoted decreased of pasture daily growth and availability of forage dry matter. Levels of supplementation ad libitum increase number of animal/ha and animal stocking / Orientador: Ciniro Costa / Coorientador: Alda Lucia Gomes Monteiro / Banca: Cledson Garcia / Banca: Wagner dos Reis / Banca: Paulo Meirelles / Banca: Mario Arrigoni / Doutor