Substitution of soybean meal for urea in diets based on deferred buffelgrass hay for feedlot sheep

ABSTRACT The objective of this study was to evaluate the effect of substituting soybean meal for urea in diets based on deferred buffelgrass on the performance of feedlot sheep. Thirty mixed-breed sheep with an average initial body weight of 17±1.5 kg were distributed in a completely randomized design in which the experimental treatments consisted of five diets with six replicates. Diets were composed of deferred buffelgrass plus concentrates and calculated to be isoproteic. Treatments were represented by the substitution of soybean meal for the urea levels (0, 25, 50, 75, and 100%). Nutrient intake did not differ among animals fed diets with urea levels. Hot and cold carcass weights, hot and cold carcass dressing percentages, initial and final pH, and weight of commercial cuts did not differ among animal fed diets with urea levels. There was no difference for non-carcass components among animals, except for the empty carcass, gall bladder, and perirenal fat weights, which were influenced by dietary urea levels. Substituting the crude protein from soybean meal for the protein from urea provides a similar performance in sheep consuming deferred buffelgrass.

摘要：本研究旨在评估以延迟刈割非洲狼尾草（buffelgrass）为基础日粮时，用豆粕替代尿素对舍饲育肥绵羊生产性能的影响。选取30只初始平均体重为17±1.5 kg的杂种绵羊，采用完全随机试验设计，设置5种日粮处理组，每组6个重复。试验日粮均由延迟刈割非洲狼尾草与精补料构成，并配制为等氮日粮，各处理组分别以豆粕替代0%、25%、50%、75%和100%的尿素。
试验结果表明，不同尿素替代比例日粮组的绵羊营养物质采食量无显著差异；各组绵羊的热胴体重、冷胴体重、热屠宰率、冷屠宰率、初始及终末pH值，以及商品分割肉重量均无显著差异。绵羊的非胴体组分重量除空胴体、胆囊及肾周脂肪重量受日粮尿素替代比例影响外，其余组分均无显著差异。
综上，在饲喂延迟刈割非洲狼尾草的绵羊日粮中，用豆粕来源粗蛋白替代尿素来源蛋白，可使绵羊获得相近的生产性能。