Desempenho produtivo de vacas da raça Gir linhagem leiteira alimentadas com níveis crescentes de concentrados e proteínas em confinamento ou pastejo

• Ano de defesa: 2008
• Autor(a) principal: Teixeira, Rafael Monteiro Araújo
• Orientador(a): Lana, Rogério de Paula
• Banca de defesa: Fernandes, Leonardo de Oliveira , Oliveira, André Soares de
• Tipo de documento: Tese
• Tipo de acesso: Acesso aberto
• Idioma: por
• Instituição de defesa: Universidade Federal de Viçosa
• Programa de Pós-Graduação: Doutorado em Zootecnia
• Departamento: Genética e Melhoramento de Animais Domésticos; Nutrição e Alimentação Animal; Pastagens e Forragicul
• País: BR
• Palavras-chave em Português: Bovino de leite; Desempenho; Equações
• Palavras-chave em Inglês: Dairy cattle; Perfomance; Equations
• Área do conhecimento CNPq: CNPQ::CIENCIAS AGRARIAS::ZOOTECNIA::NUTRICAO E ALIMENTACAO ANIMAL
• Link de acesso: http://locus.ufv.br/handle/123456789/1718

Two experiments were performed with milking Gyr cows with the objective of evaluating the efficiency of utilization of supplements in milk production. The first experiment was carried out with 20 cows confined in feedlot in the dry season of the year, being distributed in casualized blocks design, with four treatments and five replicates. The experimental treatments were constituted of four diets containing four levels of concentrate (LC) and four levels of crude protein (CP, dietary dry matter basis): 11.7% LC and 11% CP; 23.2% LC and 12% CP; 35.2% LC and 14% CP; and 46.8% LC and 16% CP. Sorghum silage was used as forage. In the second experiment, 21 cows were evaluated with increasing levels of concentrate, being the animals maintained in pastures of elephant grass (Pennisetum purpureum) in the rainy season. The treatments consisted of three levels of concentrate ration (2, 4, and 6 kg/cow/day) and two levels of crude protein in the total dietary dry matter (14 and 16%), plus an control treatment in which the cows only received mineral mixture, in an 3 x 2 + 1 factorial arrangement of treatments. In the experiment with cows confined in feedlot the increases in LC and CP caused a greater increase in the total dry matter intake (P<0,05), as well as for crude protein, ether extract, organic matter, total carbohydrates, non fiber carbohydrates and total digestible nutrients. By comparing mean fecal excretion obtained by the internal markers iDM, iADF and iNDF, it was not observed differences (P>0.05), as well as for estimation of fecal excretion in kg of dry matter per day (P>0.05) using the two types of bags (Ankon and TNT). The coefficient of digestibility of crude protein (CDCP) was influenced by greater LC and CP in the diet (P<0.05), in which the diet with 46.8% of LC and 16% CP resulted the greatest CDCP. The milk production in kg/day was greater (P<0.05) in the treatments with greater LC and CP in the diet, when compared with the treatment with lower LC and CP (11.7:11). However there was no difference among the treatments 23.3, 35.2 and 46.8% LC and 12, 14, and 16% CP, respectively. The experiment with cows on pasture, the pasture dry matter intake was not affected by treatments, but the total dietary dry matter increased (P<0.05), in an addictive way, in 45% mean value, with inclusion of concentrate in the diet. However, milk production only increased (P<0.05) 17% (1.76 kg more milk per day) with use of concentrate. In the data of animal response to supplementation it was applied the statistical technique called Lineweaver-Burk, by applying linear regression of the reciprocal of milk production as a function of reciprocal of nutrients supply. The theoretical maximum milk production was 12.94 and 12.77 kg of milk/cow/day and the amount of supplement to reach half of theoretical maximum milk production (Ks) was 0.34 and 0.17 kg/cow/day, respectively, for the animals maintained in feedlot and pasture. The increase of feed concentrate to the Gir breed cows milk is similar to enzymatic and microbial models, where production efficiency due to the increase of feed concentrate is decreasing.