补饲不同能量水平的精料对天祝白牦牛生长性能、瘤胃发酵参数和血清生化指标的影响

Effects of supplementing different energy levels of concentrate feed on growth performance,rumen fermentation parameters,and serum biochemical indicators of Tianzhu white yak

试验探究补饲不同能量水平精料对天祝白牦牛血清生化指标、生长性能以及瘤胃发酵参数的影响。试验共分两期,第一期为放牧的同时进行冬春季枯草期精料补饲,第二期为丰草期放牧,不进行补饲。试验选取6月龄、体重(46.62±4.37)kg、健康的天祝白牦牛公犊30只,根据随机区组设计分为3组,每组5个重复,每个重复两头牛。对照组正常放牧,不补饲精料;试验Ⅰ组和试验Ⅱ组在放牧后分别补饲代谢能为10.83、11.76 MJ/kg的精料,精料初始饲喂量为0.70 kg/头,每15 d增加0.05 kg,终期添加量为1.20 kg/头。试验期365 d,其中冬春季补饲期150 d,正常放牧期为215 d。结果显示,冷季补饲增加了牦牛在11、12和18月龄的体重和6~11月龄、12~18月龄的增重(P<0.05),且试验Ⅱ组各日龄的体重和增重高于试验Ⅰ组(P<0.05)。各组的Gompertz模型拟合度高于Bertalantty模型的拟合度,试验组拐点体重和拐点月龄高于对照组,试验Ⅱ组拐点体重和拐点月龄最大。试验Ⅰ组和试验Ⅱ组瘤胃液乙酸含量、乙酸/丙酸比值、pH值低于对照组(P<0.05),丙酸、异丁酸、丁酸、异戊酸、戊酸、氨态氮含量高于对照组(P<0.05),且试验Ⅱ组的氨态氮含量高于试验Ⅰ组(P<0.05)。试验Ⅰ组和试验Ⅱ组血清葡萄糖、总胆固醇、甘油三酯和总蛋白含量高于对照组(P<0.05)。研究表明,冷季补饲不同能量水平的精料促进了牦牛犊牛的生长发育,改变了瘤胃发酵模式和血清生化指标,补饲代谢能11.76 MJ/kg的精料效果较好。

The experiment explored the effects of supplementing different energy levels of concentrate feed on the serum biochemical indicators,growth performance,and ruminal fermentation parameters of Tianzhu white yak.The experiment was divided into two periods:The first period involved concentrate supplementation during the winter and spring grazing period,and the second period was the lush grass grazing period without supplementation.A total of 30 healthy male Tianzhu white yak calves,aged six months and weighing(46.62±4.37)kg,were selected and randomly divided into three groups with five replicates in each group and two yaks in each replicate according to a randomized block design.The control group was normally grazed without concentrate supplementation,while the experimental group Ⅰ and group Ⅱ were supplemented with concentrate feeds with metabolizable energy of 10.83 and 11.76 MJ/kg after grazing,respectively.The initial feeding amount of concentrate was 0.70 kg per head,with an increase of 0.05 kg every 15 days,and the final supplementation amount was 1.20 kg per head.The experimental period was 365 days,with a supplementation period of 150 days during the winter and spring,and a normal grazing period of 215 days.The results showed that cold-season supplementation increased the weight and weight gain of yaks at 11,12,and 18 months of age,and during the periods of 6~11 months and 12~18 months of age(P<0.05),with group Ⅱ having higher weight and weight gain at all ages compared to group Ⅰ(P<0.05).The Gompertz model fit better than the Bertalantty model for all groups,with the experimental groups having higher breakpoint weights and breakpoint months than the control group,and group Ⅱ having the highest breakpoint weight and month.The ruminal fluid acetic acid content,acetic acid/propionic acid ratio,and pH value in groups Ⅰ and Ⅱ were lower than in the control group(P<0.05),while the concentrations of propionic acid,isobutyric acid,butyric acid,isovaleric acid,valeric acid,and ammonia nitrogen were higher than in the control group(P<0.05),and the ammonia nitrogen concentration in the group Ⅱ was higher than that in the experimental group Ⅰ(P<0.05).The serum glucose,total cholesterol,triglycerides,and total protein concentration in groups Ⅰ and Ⅱ were higher than in the control group(P<0.05).The study indicates that cold-season supplementation with different energy levels of concentrate feed promoted the growth and development of yak calves,altered the ruminal fermentation patterns,and serum biochemical indicators,with the supplementation of concentrate feed with a metabolizable energy of 11.76 MJ/kg showing better results.