Teores de proteína bruta no concentrado e níveis de suplementação para vacas em lactação

• Ano de defesa: 2008
• Autor(a) principal: Pimentel, Joabe Jobson de Oliveira
• Orientador(a): Lana, Rogério de Paula
• Banca de defesa: Graça, Décio de Souza , Matos, Leovegildo Lopes 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; Alimentação e rações; Nutrição animal
• Palavras-chave em Inglês: Dairy cattle; Feeds and feeding; Animal nutrition
• Área do conhecimento CNPq: CNPQ::CIENCIAS AGRARIAS::ZOOTECNIA::NUTRICAO E ALIMENTACAO ANIMAL
• Link de acesso: http://locus.ufv.br/handle/123456789/1725

Four experiments were carried out in Viçosa-MG, Carlos Chagas-MG and Januária-MG. In the first experiment was evaluated the response of 40 crossbred Holstein/Zebu cows, in pasture of Brachiaria brizantha, to four concentrate supplements, represented by: control treatment (T1) - 200 grams of mineral supplement with 10% of P; treatment 2 (T2) - 2.0 kg of supplement containing 50% crude protein (CP); treatment 03 (T3) - 3.5 kg of supplement containing 28.6% CP; and treatment 4 (T4) - 5.0 kg of supplement containing 20% CP, in a randomized blocks design with 10 replicates per treatment. The supplements were given in two daily portions, after milking, in individual pens. Between milking and supplementation, all the cows were conducted to a same pasture. At every 21 days after calving, up to 84 days, it was measured milk and animals weight as well as the evaluation of body condition score. The treatment 3 allowed higher milk production in all evaluated periods, showing that this formulation adjusted better for the conditions of the experiment. The evaluation of the response in milk production showed values of 1,040; 1,200; and 0.630 kg f milk per kg of concentrate, respectively, for the treatments T02, T03, and T04 in relation to the control treatment (T01). The animals of treatment T1 showed higher loss of live weight and body condition score, with no difference among the other treatments. In the second experiment the objective was to evaluate the nutrient consumption, the production and composition of milk and body weight change of dairy cows fed diets based on sorghum silage, supplemented or not with concentrates. Nine crossbred cows Holstein/Gyr, 500 kg live wight and in mid lactation were distributed in three balanced Latin squares 3x3. The cows received sorghum silage as forage and supplements with 2.6 kg or 5.0 kg per day, with 38.5 and 20.0% of PB respectively. The consumption of dry matter differed from treatments being 11.9; 15.5 and 17.5 kg/cow/day for treatments 1, 2 and 3, respectively. The milk production (8.8; 12.9 and 12.8 kg/cow/day) was bigger for the treatments with concentrate that did not differ between tem. The milk response in kg of milk per kg of concentrate was of 1.67 and 0.83 for the minor and higher supplementation level, respectively. Milking cows receiving sorghum silage, producing up to 13 kg of milk per day have higher milk response when supplement with high protein and mineral level was used. By using 2.6 kg per day of concentrate with 38.5% of CP and high mineral content it is possible to keep milk production up to 13 kg per day with cows receiving sorghum silage. The third experiment aimed to evaluate the effects of supplement amount on milk production and composition. Eight crossbred Holstein-Zebu cows (517±40 kg) were allotted in two 4 x 4 Latin squares, in four periods of 14 days. The experiment was conducted on pasture of elephant grass (Pennisetum purpureum, Schum) in the rainy season, and the treatments included a control (mineral mixture) and supplement with 24% CP in dry matter at levels of 1.25, 2.5, and 5.0 kg/animal/day, based on corn, soybean meal, urea and mineral mixture. The experiment was analyzed as Latin square design including effects of treatment, Latin square, animal within Latin square and period. There was no treatment effect (P>0.05) due to high coefficient of variation. The mean milk production as a function of supplementation was curvilinear, following a Michaelis-Menten relationship of enzymatic systems and was explained by the following equation of Lineweaver-Burk: 1/Milk = 0.0125*(1/Suppl) + 0.0826; r2 = 1.00. The theoretical maximum milk production (1/a) was 12.1 kg/animal/day, and the amount of concentrate to cause half maximum milk production (b/a) was verified with 5.2% of that necessary to reach 95% maximum response. Therefore, the marginal increase in milk production reduces with increasing supplementation, different of the 2001 dairy NRC that consider linear responses for both energy and protein supplies. In the last study it was evaluated the effects of supplement levels on milk production and composition of cows in feedlot. Eight crossbred Holstein-Zebu cows (515 kg) were distributed in two 4x4 Latin square, in four periods of 15 days, and received as a forage around 40 kg/day of chopped sugarcane added 0.25% of mixture of urea/ammonia sulfate (nine parts of urea and one part of ammonia sulfate). The treatments consisted of a control treatment which only mineral mixture was supplemented and supplementation with three concentrate levels: 1.25; 2.5; and 5.0 kg/animal/day of supplements containing corn meal, soybean meal, mixture of urea/ammonia sulfate 9:1 and mineral salt in the proportion of 00.0:76.0:11.5:12.5; 42.2:46.2:5.9:5.7; and 75.4:18.8:2.9:2.9 (treatments 2, 3 and 4, respectively). The experiment was analyzed as Latin square (LS) including effects of treatment, LS, animal/LS and period. In spite of lack of treatment effects on the evaluated variables, the response in milk was curvilinear, following the Michaelis-Menten relationship, and was explained by the following equation of Lineweaver-Burk: 1/milk = 0.0199* (1/suppl) + 0.1032; r2 = 0.96. The theoretical maximum milk production (1/a) was of 9.7 kg/animal/day, and the amount of concentrate to cause half of the maximum milk production (b/a) was verified with 5.2% of that needed to reach 95% maximum response.