Substituição do alimento volumoso por casca de soja na terminação de cordeiros das raças Texel e Ideal em confinamento

Abstract

This study was conducted to evaluate the effect of increasing levels of substitution of sorghum silage by soybean hulls on nutrient intake, weight gain and carcass characteristics of lambs and Texel breeds Ideal ending in system containment and evaluate the effect of increasing levels of soybean hulls, replacing sorghum silage on apparent digestibility of nutrients and on nitrogen balance in sheep and to evaluate the feeding behavior of lambs from Texel and Ideal, feedlot, fed different levels of soybean hulls in place of sorghum silage diet. The treatments consisted of two breeds (Texel and Ideal) and four levels of food roughage (sorghum silage) for soybean hulls (% of DM), with: No replacement (0% soybean hulls) Partial Replacement (33.5% soybean hulls) Partial replacement (66.5% soybean hulls) Replacement Total (100% soybean hulls). The roughage used was sorghum silage (Sorghum bicolor (L.) Moench), and the concentrate was made up of disintegrated corn, soybean meal and mineral mixture. Diets were formulated to be isoproteic, according to NRC (National Research Council, 1985). In experiment I (consumption and performance) no interaction was observed between race and levels of soybean hulls tested. The nutrient intake increased linearly, in various forms in which it was expressed with increasing inclusion of soybean hulls in the diets. In experiment II (apparent digestibility and nitrogen balance) the apparent digestibility of Dry Matter (DM), organic matter and Neutral Detergent Fiber (NDF) exhibit quadratic behavior with increasing level of soybean hulls in the diet. With respect to fecal nitrogen excretion and total, it is observed that there was a linear growth with the increase of soybean hulls in the diet. As for the nitrogen retained in the animal body, was also observed linear growth due to the increase in the proportion of soybean hulls in the diet. In experiment III (feeding behavior) were significantly reduced (P <0.01) percentage of time and rumination, and as a consequence, reduction in time and percentage of total chewing (eating + ruminating) with increasing level of soybean hulls in the diet. The maximum weight gain of lambs in confinement when completed is obtained by replacing sorghum silage by soybean hulls at a rate of 56.7%. Texel lambs had a better daily weight gain and increased hot carcass, cold carcass yield and improved the cooling rate of breakdown of the ideal breed animals that, when finished in feedlot. The maximum Dry Matter (DM) digestibility is obtained for a degree of substitution of sorghum silage by soybean hulls, 55.9%, corresponding to an apparent digestibility of Dry Matter (DM) of 79.31%.