Composição e processamento do leite de vacas F1 (Holândes x Zebu) alimentadas com níveis crescentes de ureia

Abstract

The objective of this work was to evaluate the composition and processing of milk from F1 cows (Holstein x Zebu) fed increasing levels of urea (0, 33 %, 66 % and 100 %, corresponding to 0, 0.92, 1.84% CP and 2.77% of CP as NNP), replacing soybean meal. The experiment was conducted at the Department of Agricultural Sciences UNIMONTES Campus Janaúba-MG. Four experimental diets were used, which were formulated according to NRC (2001) to be isoprotein and for a potential production of 10 kg of milk corrected to 3.5 % fat day-1 . The experimental design was two 4 x 4 Latin squares consisting of four animals, four treatments and four periods each. The experiment lasted 72 days, divided into four periods of 18 days. We used eight primiparous F1 Holstein x Zebu with lactation period of approximately 150 days in the beginning of the experiment. The complete ration was supplied twice daily, at 8 h and 16 h, and adjusted every day, so that the remains represent 10 % of the total offered. Milk samples from each cow, from milking in the morning and in the afternoon, were collected, mixed and analyzed for physical-chemical composition and fatty acid profile. On the third day of collection, the milk produced from each treatment was cold for the production of Minas fresh cheese that after processing were weighed to determine the yield and analyzed for texture and the physicochemical characteristics. After that, subjected to microbiological analyses and the test of general acceptance by consumer and fatty acid profile. Contents of fat, protein, fixed mineral, lactose, total and nonfat dry extract, acidity, density, casein, cryoscopic index, somatic cell count and the profile of milk fatty acids were not influenced by inclusion levels of urea in the diet, as well as the characteristics of texture, yield, physical and chemical composition, sensory analysis and the Minas fresh cheese fatty acid profile also did not show significant differences between diets evaluated. Total replacement of soybean meal for urea does not influence the composition and milk fatty acid, as well as it does not influence the texture, yield, physical and chemical composition, acceptance and fatty acid profile of Minas fresh cheese from milk of cows primiparous F1 Holstein x Zebu, producing up to 10 kg/day L-1.