低蛋白质日粮补充合成氨基酸对荷斯坦肉牛生长性能、氮代谢及胴体性状的影响

Effects of low protein diet supplemented with synthetic amino acids on growth performance,nitrogen metabolism and carcass traits of Holstein beef cattle

文章旨在评估低蛋白质日粮补充合成氨基酸对肉牛生长性能、氮代谢及胴体性状的影响。试验将体重接近的120头肉牛随机分为2组,每组6个重复,每个重复10头。在20周的饲养试验期,对照组饲喂粗蛋白质水平为17.5%的全混合日粮,处理组饲喂粗蛋白质水平为15.0%的全混合日粮,同时补充赖氨酸、蛋氨酸和苏氨酸。结果:处理组肉牛0~10 w平均日增重较对照组显著提高6.84%(P<0.05),但0~10 w和0~20 w料重比较对照组分别显著降低6.63%和3.67%(P<0.05)。与对照组相比,处理组肉牛试验第10周氮摄入量、20 w氮摄入量、尿氮排泄量和氮沉积量分别显著提高3.76%、17.86%、14.02%和63.95%(P<0.05)。对照组与处理组对大部分胴体性状指标的影响无显著差异(P>0.05)。与对照组相比,处理组肉牛肌肉背膘厚度、眼肌面积和蛋白质含量分别显著提高14.44%、11.07%和14.19%(P<0.05)。结论:低蛋白质日粮补充合成氨基酸可以改善肉牛生长前期的日增重和饲料报酬,提高氮沉积、背膘厚度、眼肌面积和肌肉粗蛋白质含量。

This experiment was conducted to evaluate the effects of synthetic amino acids supplementation in low protein diet on growth performance,nitrogen metabolism and carcass traits of beef cattle.A total of 120 beef cattle with similar body weight were randomly divided into 2 groups with 6 replicates per group and 10 cattle per replicate.During the 20-week feeding experiment,the control group was fed a 17.5%total mixed diet,and the treatment group was fed a 15.0%total mixed diet addition of lysine,methione and threonine.Results:Compared with the control group,the average daily gain of beef cattle in the treatment group was significantly increased by 6.84%(P<0.05)at 0~10 W,but the feed/gain of beef cattle in the treatment group was significantly decreased by 6.63%and 3.67%(P<0.05)at 0~10 W and 0~20 W,respectively.Compared with control group,nitrogen intake at 10 W,nitrogen intake at 20 W,urinary nitrogen excrement and nitrogen deposition in treatment group were significantly increased by 3.76%,17.86%,14.02%and 63.95%(P<0.05),respectively.There were no significant differences in most carcass traits between control group and treatment group(P>0.05).Compared with control group,muscle backfat thickness,eye muscle area and protein content of beef cattle in treatment group were significantly increased by 14.44%,11.07%and 14.19%(P<0.05),respectively.Conclusion:Supplementation of synthetic amino acids in low protein diet can improve daily gain and feed return,and increase nitrogen deposition,backfat thickness,eye muscle area and muscle crude protein content of beef cattle in early growth period.