Finishing of Nellore steers, castrated and no-castrated, in feedlot diet with high-grain

SUMMARY This study aimed to evaluate the finishing Nellore steers castrated and no-castrated in feedlot receiving high-grain diet through the nutrients intake, productive performance and economic viability of the diet. 180 Nellore animals were divided into two treatments (castrated and no-castrated), with 90 animals per treatments, with an average initial weight of 415.64kg, receiving high-grain diet with 85% corn grain and 15% supplement mineral-protein-energy. The experimental period was 63 days with 15 days for adaptation diets and 48 days of feedlot. Was no significant effect on intake of nutrients (P<0.05), presenting a mean intake of dry matter (DM) of 7.60 and 7.96kg for castrated and no-castrated. Effects were observed for productive performance as a function of sex condition (castrated and no-castrated). The not castrated animals had higher (P<0.05) slaughter weight, total weight gain, hot carcass weight, carcass yield and better feed conversion when compared to castrated animals finished in feedlot receiving high-grain diet. Castrated animals have a higher fat thickness that animals no-castrated, 4.80 and 3.40mm, respectively. The no-castrated animals showed profit margin lucre/animal of R$ 256.00 and R$ 202.80 for castrated. Receiving the termination of Nellore steers in a feedlot is recommended high-grain diet. The no-castrated animals showed greater weight gain and profit in the feedlot finishing system receiving high-grain diet.

摘要：本研究旨在通过养分摄入量、生产性能及日粮经济可行性，评估饲喂高谷物日粮（high-grain diet）的舍饲育肥内洛尔牛（Nellore）去势与未去势阉牛的育肥效果。本试验选取180头内洛尔牛，按处理分为去势组与未去势组两组，每组90头，初始平均体重为415.64kg，饲喂含85%玉米谷物及15%矿质-蛋白质-能量补充料的高谷物日粮。试验周期共63天，其中15天为日粮适应期，48天为育肥饲养期。试验结果显示，两组的养分摄入量未呈现显著差异（P<0.05），去势组与未去势组的干物质（DM）平均摄入量分别为7.60kg与7.96kg。不同去势状态对生产性能存在显著影响。与饲喂高谷物日粮的舍饲育肥去势牛相比，未去势牛的屠宰体重、总增重、热胴体重、胴体出肉率及饲料转化率均更优（P<0.05）。去势牛的背膘厚高于未去势牛，分别为4.80mm与3.40mm。未去势牛的单头净利润为256.00雷亚尔，去势牛为202.80雷亚尔。针对舍饲育肥的内洛尔阉牛，推荐采用高谷物日粮开展育肥收尾饲养。在饲喂高谷物日粮的舍饲育肥体系中，未去势牛表现出更优的增重效果与经济效益。