日粮中赖氨酸和蛋氨酸比对断奶犊牛生长性能和消化代谢的影响

摘要

[目的]研究日粮中不同赖氨酸和蛋氨酸比例对断奶犊牛生长性能、消化代谢的影响.[方法]选取24头健康的荷斯坦断奶犊牛,按体重和出生时间随机分为4组,限量饲喂4种不同日粮,即对照组日粮(粗蛋白为14.67%),3种赖氨酸和蛋氨酸比例分别为2.5:1、3.0:1和3.5:1的日粮(粗蛋白为12.02%),试验期为8周.在试验开始和结束时对犊牛进行称重和采血,在试验第3周每组选取4头犊牛采用全收粪、尿法进行代谢试验.[结果]日粮中赖蛋比为3.0:1组的犊牛增重在数值上要高于其它3组(P>0.05).3个试验组犊牛血清尿素氮浓度要显著低于对照组(P<0.01),游离氨基酸浓度在数值上要低于对照组(蛋氨酸除外)(P>0.05).赖蛋比对血清尿素氮和游离氨基酸浓度无显著影响(精氨酸、缬氨酸除外).赖蛋氨酸比为3.0:1组和3.5:1组犊牛氮的总利用率和表观生物学价值在数值上要高于2.5:1组和对照组(P>0.05).[结论]在粗蛋白含量为12.02%的日粮中添加过瘤胃赖氨酸和过瘤胃蛋氨酸,犊牛的增重可超过粗蛋白为14.67%日粮的水平.赖氨酸和蛋氨酸比例为3.0:1有利于犊牛生长,并可提高氮的利用效率.%[Objective] This trial was designed to study the effects of dietary lysine to methionine ratio on growth performance,nutrient digestibility and nitrogen metabolism in weaned calves. [Method] Twenty four weaned calves were randomly allocated into four treatments either fed a control diet containing 14.76％DM CP or one of the three trial diets containing 12.02％ DM CP and the dietary lysine/methionine ratios were 2.5: 1, 3.0: 1 or 3.5: 1, respectively, for 8 weeks. The calves were weighed and blood samples were collected on the initial and final day of the experiment. Four calves were selected from each group and metabolism trials were conducted from the third week of the feeding experiment by total feces collection method. [Result] The results indicated that the gain of calves in group 3.0: 1 was higher than that of calves in other groups numerically (P＞0.05). Serum concentrations of urea nitrogen in calves fed test diets was lower than that in the control (P＜0.01). The concentrations of free amino acid in serum were lower (except methionine) in calves fed test diets than those in control group (P＞0.05). No difference was observed in serum concentration of urea nitrogen and free amino acids (except arginine and valine) among test groups. The utilization and apparent biological value of nitrogen in group 3.0: 1 and group 3.5: 1 were higher than group 2.5: 1 and control group numerically (P＞0.05). [Conclusion] The gain of calves fed diet addition of RPLys and RPMet with a crude protein level of 12.02％ was higher than that fed diet with a crude protein level of 14.67％. The ratio of lysine and methionine at 3.0: 1 in diets could enhance growth performance and utilization of nitrogen in weaned calves.