Partial replacement of soybean meal for urea and forage cactus in lactating cows diets: I. Performance

[摘要] The work was carried out to evaluate the partial replacement of soybean meal by urea and forage cactus on the performance of lactating dairy Holstein. Eight cows with 90 days in milk and 600 kg of initial average LW, were assigned in a two 4 X4 latin square design. The urea represented 0.0, 0.8, 1.54 and 2.40% of dry matter (DM) of the diets, correspondent to 2.32, 4.65, 6.66 and 8.02% of crude protein (CP) levels in the form of non protein nitrogen compounds (NPN), that represented the experimental treatments. There was a quadratics effect of levels of NPN on the intake of CP, with maximum intake of 3.3 kg/day with 4.71 % of NPN. The calcium (Ca) intake increased, and dray matter (DM); organic matter (OM), ether extract (EE), total carbohydrates (TCH), non fibercarbohydrates (NFC), acid detergent fiber (ADF) and total digestible nutrients (TDN) intakes decreased linearly. The intakes of neutral detergent fiber (NDF) and Phosphorus (P) was not affected by NPN levels. The milk production and fat corrected milk (3,5%) decresed linearly as levels of urea and forage cactus increased. The yield of fat, protein, milk composition and feed:eficiency ration was not affected by NPN levels.

[学科分类] 兽医学