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Mémoire de Maîtrise
DOI
https://doi.org/10.11606/D.11.2019.tde-20191218-143800
Document
Auteur
Nom complet
Marco Antonio Alvares Balsalobre
Adresse Mail
Unité de l'USP
Domain de Connaissance
Date de Soutenance
Editeur
Piracicaba, 1996
Directeur
Titre en portugais
Desempenho de vacas em lactação sob pastejo rotacionado de Capim-Elefante (Pennisetum purpureum Schum.)
Mots-clés en portugais
CAPIM ELEFANTE
DESEMPENHO
PASTEJO ROTACIONADO
PRODUÇÃO LEITEIRA
VACA LACTANTE
Resumé en portugais
A gramínea tropical sofre efeito acentuado da maturidade fisiológica sobre sua qualidade, o que causa menor flexibilidade quanto ao manejo. Por outro lado, acredita-se que o potencial de produção de leite a pasto e a reprodução de animais melhorados é limitada. Os objetivos desse trabalho foram avaliar a qualidade do capim-elefante, determinar a resposta das vacas de diferentes potenciais de produção ao manejo da pastagem e avaliar o pastejo. No trabalho foram utilizadas 18 vacas recém-nascidas para avaliação de consumo de matéria seca, produção de leite e níveis de progesterona no sangue e três vacas fistuladas no rúmen para o trabalho de degradação da forragem in situ. Foram utilizadas 2,36 ha de pastagens de capim-elefante estabelecidos em solos férteis. O ciclo de pastejo foi de 47 dias (45 dias de descanso e 2 de ocupação). Após o pastejo eram avaliados o resíduo e as perdas. A forragem consumida pelos animais foi representada por pastejo simulado. Através de sacos de náilon suspensos no rúmen a extensão e taxa de degradação da MS, proteína e fibra foram avaliados. A cada sete dias foi coletado sangue, a cada 15 dias as vacas eram pesadas. O consumo foi avaliado em 3 períodos. A lotação foi de 7,19 UA/ha. Produção da forragem 8 ton MS/ha pastejo. Pressão de pastejo de 7,24%, aproveitamento de 32,20%. A produção não afetou a condição reprodutiva
Titre en anglais
Not avaliable
Resumé en anglais
Forage quality in tropical grasses is markedly affected by physiological maturity reducing their management flexibility. Conversely, milk yield potential and reproductive performance of improved animals is limited. The objectives of this research were to evaluate elephantgrass forage quality, to determine the response of cows with different production potentials to grazing management, and to evaluate the grazing process. Eighteen recently calved cows were used to evaluate dry matter intake, milk production and blood progesterone levels, and three fistulated cows for the evaluation of in situ forage degradation. The total elephantgrass pasture area was 2.36 ha, established on fertile soil. Grazing cycle length was 47 days (2 days of grazing plus 45 days of rest). Following grazing the residue and losses were evaluated. The forage consumed by the animals was represented by simulated grazing. The rate and extent of degradation of dry matter, protein components, and fiber were evaluated using nylon bags in the rumen and four incubation periods (3, 6, 24, and 48 hours). Blood was collected from each cow every seven days after calving to measure the level of progesterone by radioimmunoessay. Every 15 days the animals were weighed and assigned a body condition score (1 to 5). Intake was evaluated in three different periods. Between chromium oxide supply and fecal collection, 10 days were spent in each period. Forage samples representing the postgraze residue, leaf, stem, and the simulated grazing were analyzed for chemical composition. Data on milk production, dry matter intake, and progesterone levels were correlated using Proc Reg - SAS. Dry matter intake, milk production, plant minerals, forage production characteristics, chemical analyses, and in situ degradation data were analyzed by Proe GLM - SAS. The resulting stocking rate of 7.19 AU/ha does not reflect the production of dry matter available at each grazing (8 t/ha.grazing cycle). This was a result of low utilization of the forage on offer (33.20 %), obtained at an average grazing pressure of 7.29 %. Pasture management under high soil fertility conditions should be based on a proper correlation between grazing pressure and postgraze residue, so that the height of the residue is reduced and the efficiency of utilization is increased. Degradation· coefficients of NDF-N, ADF-N, and lignin were high, affecting the calculations of TDN when done by the WEISS (1993) equation. The level of milk production did not affect animal reproductive performance, and an average service period of 53 days was obtained. Peak milk production ranged from 12.50 to 23.60, and was observed 30 days after calving. The average diet TDN level and intake net energy for lactation were 61.84 % and 9.38 Mcal, respectively. The calculated maintenance requirement was 8.8 Mcal. Milk production by non-supplemented animals was 6.36 kg/cow.day and increased approximately 1.6 kg per kg of concentrate added to forage diet
 
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Date de Publication
2019-12-19
 
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