中文摘要：

为探讨夏南牛蛋白质需要量及修订饲养标准,选择30头体况良好、体质量相近（275.57±8.99） kg的11～12月龄夏南牛公牛,按完全随机试验设计,将试验牛分为5个处理,每个处理6头牛,采用饲养试验和氮平衡试验,测定了夏南牛日增重、粗蛋白采食量、粪氮排泄量与尿氮排泄量.结果表明：在本试验条件下,夏南牛单位代谢体质量维持粗蛋白（CPm）需要量为5.40 g/（kg·d）,每千克增重的粗蛋白（CPg）需要量为359.35 g/kg;可消化粗蛋白维持需要量为2.79g/（kg·d）,每千克增重的可消化蛋白需要量（DCPg）为260.69 g/kg.夏南牛以代谢体质量（W0.75）与平均日增重（ADG）为预测因子的粗蛋白、可消化蛋白需要量预测模型分别为：CP =5.40×W0.75＋359.35 ×ADG,（R2=0.997）DCP =2.79×W0.75＋260.69 ×ADG,（R2 =0.998）

英文摘要：

The purpose of this study is to make feeding standard and to estimate the protein requirement of Xianan cattle.11 to 12-month-old Xianan cattles with similar body weight （275.57 ± 8.99） kg were assigned randomly into 5 groups each with 6 replicates.Feeding trial and nitrogen balance experiment were conducted to measure the amount of daily gain,crude protein intake,fecal and urinary N excretion in Xianan cattle.The results showed that：the crude protein and digestible crude protein requirements for maintenance of Xianan cattle were 5.40 g/kg and 2.79 g/kg.The crude protein and digestible crude protein requirements needed for gain were 359.35 g/kg and 260.69 g/kg respectively for per kilogram of weight increase.The models of predicting crude protein or digestible crude protein requirements of Xianan cattle with W0.75 and ADG were as follows：CP =5.40 × W0.75 ＋ 359.35 × ADG,（R2 =0.997）DCP =2.79 × W0.75 ＋ 260.69 × ADG,（R2 =0.998）