低蛋白质日粮补充亮氨酸和色氨酸对断奶期犊牛生长性能和血液参数的影响

Effects of low-protein diet supplemented with leucine and tryptophan on growth performance and blood parameters of weaned calves

试验旨研究在低蛋白日粮补充亮氨酸和色氨酸对断奶犊牛生长性能、血清生化指标、免疫性能及抗氧化能力的影响。选取健康状况良好、初生重为(42±2)kg的中国荷斯坦犊牛,随机分为5组,分别为HK组(22%粗蛋白(CP)水平的开食料)、LK组(19%CP水平的开食料)、L组(19%CP水平、含有1.15%亮氨酸(Leu)的开食料)、T组(19%CP水平、含有0.26%色氨酸(Trp)的开食料)、LT组(19%CP水平、含有1.15%Leu+0.26%Trp的开食料)。每组12个重复,每个重复1头犊牛。试验期72 d。结果显示,LT组断奶犊牛末重、平均日采食量和平均日增重高于HK组(P<0.05)。断奶前3 d,与HK组相比,LT组断奶犊牛血清尿素氮(BUN)、白细胞介素-1(IL-1)含量显著降低(P<0.05),总蛋白(TP)、免疫球蛋白M(IgM)、干扰素-γ(IFN-γ)含量及超氧化物歧化酶(SOD)、过氧化氢酶(CAT)活性显著升高(P<0.05)。断奶当天,与HK组相比,LT组断奶犊牛血清TP、免疫球蛋白A (IgA)、白细胞介素-2 (IL-2)含量及总抗氧化能力(T-AOC)显著升高(P<0.05)。断奶后3 d,与HK组相比,LT组断奶犊牛血清肿瘤坏死因子-α(TNF-α)含量显著升高(P<0.05)。研究表明,低蛋白质日粮中补充1.15%Leu和0.26%Trp可提高断奶期犊牛的平均日增重和平均日采食量,改善犊牛生长性能,增强了断奶犊牛免疫力及抗氧化能力。

The purpose of this study was to study the effects of leucine and tryptophan supplementation in low-protein diet on growth performance and blood parameters of weaned calves.Chinese Holstein calves with good health and similar birth weight(45±2 kg)were randomly divided into 5 groups with 12 calves in each group.They were HK group(22%CP level of open food),LK group(19%CP level of open food),L group(19%CP level containing 1.15%Leu of open food),T group(19%CP level of 0.26%Trp of open food),LT group(19%CP level of 1.15%Leu+0.26%Trp of open food).The experimental period was 72 days.The results showed that:1)the final weight,average daily feed intake(ADMI)and average daily gain(ADG)were increased in LT group(P<0.05).2)three days before weaning,the contents of urea nitrogen(BUN)and interleukin-1(IL-1)were significantly decreased(P<0.05),while the contents of total protein(TP),immunoglobulin M(IgM),interferon-gamma(IFN-γ),superoxide dismutase(SOD)and catalase(CAT)activities were significantly increased in LT group(P<0.05).3)on the day of weaning,the activities of TP,IgA,T-AOC,IgM,IL-2,LYS,SOD and CAT increased significantly(P<0.05),while the contents of BUN,Cort,Hpt and IL-1 decreased significantly in LT group(P<0.05).4)on the 3rd day after weaning,the contents of TP,IL-2,IgM and the activities of LYS,SOD and CAT were significantly decreased(P<0.05),while the contents of Hpt,tumor necrosis factor-α(TNF-α),and Cort were significantly increased in LT group(P<0.05).The results showed that low protein diet(19%CP)decreased ADG and ADFI of weaned calves,and had negative effects on antioxidation and inflammatory factor immunoglobulin,which aggravated weaning stress.However,supplementation of Leu(1.15%)and Trp(0.26%)in low protein diet increased ADG and ADFI of weaned calves,enhanced immunity and oxidation ability of weaned calves,and alleviated weaning stress.