不同脂肪水平代乳粉对犊牦牛生长性能、血清免疫及抗氧化指标的影响

Effects of Milk Replacer with Different Fat Levels on Growth Performance,Serum Immunity and Antioxidant Indexes of Yak Calves

为探索青藏高原犊牦牛科学的早期断奶模式及犊牦牛代乳粉适宜的脂肪水平,本试验以西藏地区高山牦牛为试验动物,研究不同脂肪水平代乳粉对犊牦牛生长性能、血清免疫及抗氧化指标的影响。选取40头体重、日龄相近的新生犊牦牛,随机分为4组,每组10头。对照组(CON组)犊牦牛随母放牧哺乳,自然断奶;试验组犊牦牛自10日龄开始饲喂3种脂肪水平分别为22%(低脂肪组,LF组)、25%(中脂肪组,MF组)及28%(高脂肪组,HF组)的等蛋白质水平(24%)牦牛代乳粉,至90日龄。结果表明:1)与CON组相比,MF与HF组犊牦牛60、90日龄体重和1~90日龄平均日增重(ADG)均显著升高(P<0.05),各组犊牦牛90日龄体重以MF组最高。2)MF组犊牦牛血清非酯化脂肪酸(NEFA)含量显著低于CON组(P<0.05)。3)免疫与抗氧化指标方面,与CON组相比,MF与HF组犊牦牛血清免疫球蛋白A(IgA)含量显著升高(P<0.05),肿瘤坏死因子-α(TNF-α)含量显著降低(P<0.05),MF组犊牦牛血清免疫球蛋白G(IgG)含量显著高于CON组(P<0.05)。MF与HF组血清过氧化氢酶(CAT)活性与CON组相比显著升高(P<0.05),MF组犊牦牛血清超氧化物歧化酶(SOD)活性显著升高且丙二醛(MDA)含量显著降低(P<0.05)。4)MF与HF组血清胰岛素样生长因子-Ⅰ(IGF-Ⅰ)含量显著高于CON组(P<0.05),MF组血清生长激素(GH)含量较CON组显著升高(P<0.05)。综上所述,与传统放牧哺乳模式相比,早期断奶并饲喂代乳粉对犊牦牛生长性能有促进作用;适当提高代乳粉脂肪水平,能够进一步促进犊牦牛生长,增强机体免疫与抗氧化能力;综合各项指标,25%脂肪水平的代乳粉更适用于犊牦牛。

With the purpose of exploring the scientific early-weaning pattern of yak calves in Qinghai-Tibet plateau,and appropriate fat level in their milk replacer,Tibetan mountain yaks were chosen for this research to evaluate the effects of milk replacer with different fat levels on growth performance,serum immunity and antioxidant indexes of yak calves.A total of 40 newborn yak calves with similar age and body weight were divided into 4 groups randomly(n=10).Calves in control group(CON group)were breastfed by dam and weaned naturally.Experimental calves in the other 3 groups were fed milk replacers containing different levels of fat:22%(low fat,LF group),25%(middle fat,MF group),28%(high fat,HF group)and equal protein level(24%)from 10 to 90 days after birth,respectively.The results showed as follows:1)in comparison with CON group,calves in MF and HF groups had significantly higher body weight on 60 and 90 day of age,and average daily gain(ADG)during 1 to 90 days of age(P<0.05).The highest body weight of calves appeared in MF group.2)Serum non-esterified fatty acids(NEFA)content in MF group was significantly lower than that in CON group(P<0.05).3)As for immunity and antioxidant indexes,calves fed MF and HF milk replacers had significantly increased serum immunoglobulin A(IgA)content and reduced tumor necrosis factor-α(TNF-α)content(P<0.05).Serum immunoglobulin G(IgG)content in MF group was also significantly greater than that in CON group(P<0.05).Enzyme activity of catalase(CAT)in serum was significantly increased by MF and HF milk replacers(P<0.05).Calves in MF group had significantly higher serum super oxide dismutase(SOD)activity and lower serum content of malondialdehyde(MDA)than those in CON group(P<0.05).4)Serum insulin growth factor-Ⅰ(IGF-Ⅰ)content in MF and HF groups was significantly increased and growth hormone(GH)content was significantly higher in MF group when compared with CON group(P<0.05).In summary,there is a positive impact of early-weaning and milk replacer feeding on growth performance of yak calves in comparison with breastfeeding of dam.Growth,immunity and antioxidant functions of yak calves can be improved by increasing fat level in milk replacer properly.Taken together,milk replacer with 25%fat level is more applicable to yak calves.