浓缩料粗蛋白质水平对荷斯坦肉牛生长性能、氮代谢及胴体性状的影响

Effects of crude protein level in concentrate feed on growth performance, nitrogen metabolism and carcass traits of Holstein beef cattle

文章旨在研究浓缩料不同粗蛋白质水平对肉牛生长性能、氮代谢及胴体性状的影响。试验选择体重接近的24头荷斯坦肉牛,随机分为2组,每组6个重复,每个重复2头牛。低蛋白和高蛋白组肉牛在整个试验期间分别饲喂粗蛋白质水平为15.5%和17.5%的浓缩基础日粮,每天自由采食小麦秸秆,试验共进行140 d。结果:低蛋白和高蛋白组肉牛各阶段体重、平均日增重、饲料报酬及71~140 d和1~140 d平均日采食量均无显著差异(P>0.05)。低蛋白组肉牛1~70 d的平均日采食量较高蛋白组显著提高0.60%(P<0.05)。低蛋白和高蛋白组肉牛140 d粪氮量及70 d粪氮、尿氮和氮沉积量无显著差异(P>0.05)。高蛋白组肉牛70 d氮摄入量较低蛋白组显著提高4.97%(P<0.05)。与低蛋白组相比,高蛋白组肉牛氮摄入量、尿氮和氮沉积量分别显著提高19.88%、17.24%和54.28%(P<0.05)。浓缩料蛋白质水平对肉牛胴体大部分性状无显著影响(P>0.05),但高蛋白组肉牛肌肉背膘厚度、眼肌面积和粗蛋白质含量较低蛋白组分别显著提高6.16%、13.07%和9.98%(P<0.05)。结论:浓缩料高蛋白质水平降低了肉牛育肥前期的采食量,对饲料报酬和日增重无负面影响,但高蛋白质日粮可以提高氮沉积、背膘厚度、眼肌面积和肌肉粗蛋白含量。

The experiment was conducted to study the effects of different crude protein levels of concentrate on growth performance,nitrogen metabolism and carcass traits of beef cattle.Twenty-four Holstein cattle with similar body weight were randomly divided into 2 groups with 6 replicates per group and 2 cows per replicate.Beef cattle in low and high protein groups were fed 15.5%and 17.5%concentrated basal diet with crude protein,respectively,and fed Wheat straw freely every day during the whole experiment for 140 days.Results:There were no significant differences in body weight,average daily gain,feed return and average daily feed intake at 71~140 d and 1~140 d between low protein and high protein groups(P>0.05).The average daily feed intake of beef cattle from 1 to 70 days in low protein group was significantly increased by 0.60%compared with high protein group(P<0.05).There were no significant differences in fecal nitrogen at 140 d,fecal nitrogen,urinary nitrogen and nitrogen deposition at 70 d between low protein and high protein groups(P>0.05).Nitrogen intake at 70 d in high protein group was significantly increased by 4.97%compared with that in low protein group(P<0.05).Compared with low protein group,nitrogen intake,urinary nitrogen and nitrogen deposition of beef cattle in high protein group were significantly increased by 19.88%,17.24%and 54.28%,respectively(P<0.05).Concentrate protein level had no significant effect on most carcass traits of beef cattle(P>0.05),but the backfat thickness,eye muscle area and crude protein content of beef cattle in high protein group were significantly increased by 6.16%,13.07%and 9.98%(P<0.05)compared with those in low protein group,respectively.Conclusions:High protein level of concentrated feed can reduce feed intake in early fattening period,and has no negative effects on feed return and daily gain,but high protein diet can increase nitrogen deposition,backfat thickness,eye muscle area and muscle crude protein content of beef cattle.