500~550 kg西门塔尔杂交牛蛋白质代谢规律及需要量研究

Study on Protein Metabolism Rule and Requirement of 500 to 550 kg Simmental Hybrid Beef Cattle

本试验旨在探索500~550 kg西门塔尔杂交牛蛋白质代谢规律及需要量。试验选用30头健康、体重[(497.73±43.84)kg]相近的西门塔尔杂交公牛,随机分成5个组,每组6个重复,每个重复1头牛。预试期10 d,正试期45 d。试验期各组饲粮的综合净能均为6.12 MJ/kg,粗蛋白质(CP)水平分别为9.53%、10.53%、11.53%、12.53%和13.53%,通过饲养试验和消化代谢试验等方法,探讨饲粮不同CP水平对西门塔尔杂交公牛生长性能和蛋白质消化代谢情况的影响,并建立500~550 kg西门塔尔杂交牛CP需要量预测模型。结果表明:1)随着饲粮CP水平的提高,各组肉牛的平均日增重(ADG)呈先上升后下降的趋势,其中12.53%组的ADG最高,显著高于9.53%组和13.53%组(P<0.05),12.53%组的料重比(F/G)最低,显著低于13.53%组(P<0.05)。2)不同饲粮CP水平对500~550 kg西门塔尔杂交牛的CP消化率无显著影响(P>0.05),10.53%组肉牛的粪氮排泄量最高,显著高于9.53%组和12.53%组(P<0.05);12.53%组肉牛的CP沉积率最高,显著高于其余各组(P<0.05)。3)500~550 kg西门塔尔杂交牛的CP需要量方程为CP=7.89W^(0.75)+68.60ADG,其维持粗蛋白需要量(CPm)为7.89 g/(kg W^(0.75)·d),每千克增重的粗蛋白质(CPg)需要量为68.60 g;可消化粗蛋白质(DCP)需要量方程为DCP=6.68W^(0.75)+61.19ADG,其维持可消化粗蛋白质(DCPm)需要量为6.68 g/(kg W^(0.75)·d),每千克增重的可消化粗蛋白质(DCPg)需要量为61.19 g。在本试验条件下,500~550 kg西门塔尔杂交公牛的最适饲粮CP水平为12.53%,本研究结果可为500~550 kg西门塔尔杂交公牛蛋白质需要提供数据参考。

This experiment was conducted to investigate the protein metabolism rule and requirement of 500 to 550 kg Simmental hybrid beef cattle.Thirty healthy Simmental hybrid bulls with similar weight of(497.73±43.84)kg were randomly divided into 5 groups with 6 replicates per group and 1 cow per replicate.The pre-feeding period was 10 days,and the formal experiment period was 45 days.The comprehensive net energy of all diets was 6.12 MJ/kg.The crude protein(CP)levels of the diets were 9.53%,10.53%,11.53%,12.53%and 13.53%,respectively.The effects of different dietary CP levels on growth performance and protein metabolism of Simmental hybrid cattle were studied through feeding experiment and digestion and metabolism experiment.A prediction model of protein requirement of 500 to 550 kg Simmental hybrid cattle was established.The results showed as follows:1)with the increase of dietary CP level,the average daily gain(ADG)of beef cattle in all groups was firstly increased and then decreased,and the ADG in 12.53%group was the highest,which was significantly higher than that in 9.53%and 13.53%groups(P<0.05),and the feed/gain(F/G)in 12.53%group was the lowest,which was significantly lower than that in 13.53%group(P<0.05).2)Different dietary CP levels had no significant effects on CP digestibility of 500 to 550 kg Simmental hybrid cattle(P>0.05).Fecal nitrogen excretion of beef cattle in 10.53%group were the highest,which was significantly higher than that in 9.53%and 12.53%groups(P<0.05),and CP deposition rate of beef cattle in 12.53%group was the highest,which was significantly higher than that in other groups(P<0.05).3)The CP requirement equation of 500 to 550 kg Simmental cross cattle was CP=7.89W^(0.75)+68.60ADG,the maintenance CP(CPm)requirement was 7.89 g/(kg W^(0.75)·d),and the CP per kilogram of weight gain(CPg)requirement was 68.60 g.The digestible CP(DCP)requirement equation is DCP=6.68W^(0.75)+61.19ADG,the maintain digestible CP(DCPm)requirement is 6.68 g/(kgW^(0.75)·d),and the digestible CP per kilogram of weight gain(DCPg)requirement is 61.19 g.Under the conditions of this experiment,the optimal dietary CP level for 500 to 550 kg Simmental hybrid bulls is 12.53%,and the results of this study can provide data reference for protein requirements of 500 to 550 kg Simmental hybrid bulls.