Uréia de liberação lenta em dietas para vacas leiteiras mestiças em pasto ou confinadas

• Ano de defesa: 2010
• Autor(a) principal: Abreu, Daniel Carneiro de
• Orientador(a): Lana, Rogério de Paula
• Banca de defesa: Fonseca, Dilermando Miranda da , Mâncio, Antonio Bento , Gomes, Marília Fernandes Maciel
• Tipo de documento: Dissertação
• Tipo de acesso: Acesso aberto
• Idioma: por
• Instituição de defesa: Universidade Federal de Viçosa
• Programa de Pós-Graduação: Mestrado em Zootecnia
• Departamento: Genética e Melhoramento de Animais Domésticos; Nutrição e Alimentação Animal; Pastagens e Forragicul
• País: BR
• Palavras-chave em Português: Consumo; Leite; Uréia protegida, Ração
• Palavras-chave em Inglês: Intake; Milk; Urea protected; Ration
• Área do conhecimento CNPq: CNPQ::CIENCIAS AGRARIAS::ZOOTECNIA::NUTRICAO E ALIMENTACAO ANIMAL
• Link de acesso: http://locus.ufv.br/handle/123456789/5664

Two studies using crossbred Holstein-Zebu dairy cows were conducted at the experimental station of Cachoeirinha, DZO/UFV, to evaluate the potential of slow release urea in the diet of dairy cows. In Experiment 1, eight adult cows in third and fifth lactations were used. The animal s mean weight was 448 ± 74 kg at the beginning of the trial. The objective of the first experiment was to evaluate the effect of four levels of slow release urea (40, 80, 160 and 320 g/animal/day) on the performance of crossbred dairy cows fed diets based on sugar cane. The animals were divided into two 4 x 4 Latin squares with four periods of 14 days (seven days of adaptation and seven days of collection). There was no effect for any of the urea levels on intake of dry matter, neutral detergent fiber and ether extract. However, the crude protein intake increased linearly with the supply of slow release urea. Milk production increased 0.396 kg for each 0.1 kg of non-protein nitrogenous (3.96 g milk/1.0 g of slow release urea). The milk production corrected for 3.5% fat and fat content, milk protein, milk lactose and total solids and nonfatty milk were not affected by the slow release urea. It is recommended to provide 320 g of slow release urea/cow/day in diets based on sugarcane and corn for dairy cows, only if the price of slow release urea is non more than 3.96 times the price of milk. In the Experiment 2, 21 crossbred Holstein-Zebu cows (499 ± 61 kg body weight, 167 days is milk) were assigned to grazing Elephant grass (crude protein = 11.5% and neutral detergent fiber corrected for ashes and protein = 60%) with the objective of evaluating the effect of the use of conventional urea or slow release urea in concentrated supplements at levels of 2, 4 or 6% (dry matter) to replace soybean meal in addition to the control treatment, only with soybean meal as protein source from grain. The cows were divided into three incomplete latin squares, in three periods, each with 21 days (14 days of adaptation and seven days of samples collection in each period). Isonitrogenous concentrates (crude protein = 24%, dry matter) were provided in the amount of 3.2 kg/cow/day (fresh matter). There was no effect of crude protein source (soybean vs. non-protein nitrogenous), non-protein nitrogenous source, level of non-protein nitrogenous, and interaction between source and non-protein nitrogenous on the level of milk production (10.0 kg/day), milk production corrected for 3.5% fat (10.7 kg/day), milk fat (4.01%), milk protein (3.66%), milk lactose (4.16%), milk total solids (12.86%) and non-solids fat (8.60%) in milk. The replacement of urea by slow release urea does not promote improvement in the productive performance of crossbred dairy cows grazing Elephant grass. Urea (fast or slow release) can be included up to 6% of dry matter concentrates supplements to replace soybean meal without affecting the productive performance of dairy cows grazing elephant grass in the rainy season.