本试验旨在研究精料补充料能量水平对早期断奶犊牦牛生产性能、血清生化指标和营养物质表观消化率的影响。选取体况良好、平均体重为(56.27±4.70) kg的3月龄犊牦牛18头,随机分为3组,每组3个重复,每个重复2头牛。饲喂粗蛋白质水平为17.00%,增重净能分别为5.60、6.50、7.40 MJ/kg的3种精料补充料。试验共39 d,其中预试期7 d,饲养试验28 d,消化试验4 d。结果表明:1)6.50、7.40 MJ/kg组犊牦牛平均日增重显著高于5.60 MJ/kg组(P〈0.05);5.60 MJ/kg组精料补充料/增重显著高于其他2组(P〈0.05)。2)6.50 MJ/kg组犊牦牛血清葡萄糖、甘油三酯含量显著高于5.60 MJ/kg组(P〈0.05),与7.40 MJ/kg组差异不显著(P〉0.05)。3)6.50 MJ/kg组犊牦牛干物质、有机物、总能表观消化率显著高于5.60 MJ/kg组(P〈0.05)。随能量水平升高,钙(P=0.06)、磷(P=0.10)表观消化率有降低的趋势。综上所述,牦牛可在3月龄断奶舍饲饲养,精料补充料增重净能为6.50 MJ/kg时,更有利于舍饲的3月龄断奶犊牦牛的营养物质消化,促进生长。
This experiment was conducted to investigate the effects of energy level of concentrate supplement on performance, serum biochemical parameters and nutrient apparent digestibility of early-weaner yak calves. Eighteen healthy 3-month-old yak calves with an average body weight of (56.27?4.70) kg were randomlves allocated to 3 groups with 3 replicates per group and 2 calves per replicate. Calves were fed concentrate supplements with the same crude protein content (17.00%) and different net energy for gain (NEg) levels (5.60, 6.50 and 7.40 MJ/kg, respectively) for 39 days (7-day pretrial period, 28-day feeding trial and 4-day digestion trial). The results showed as follows: 1) the average daily gain of yak calves in 6.50 and 7.40 MJ/kg groups was significantly higher than that in 5.60 MJ/kg group (P〈0.05); the concentrate supplement/gain of yak calves in 5.60 MJ/kg group was significantly higher than that in 6.50 and 7.40 MJ/kg groups (P〈0.05). 2) The contents of serum glucose and triglyceride in 6.50 MJ/kg group were significantly higher than those in 5.60 MJ/kg group (P〈0.05), but were not significantly different from those in 7.40 MJ/kg group (P〉0.05). 3) Dry matter, organic matter and gross energy apparent digestibility in 6.50 MJ/kg group were significantly higher than those in 5.60 MJ/kg group (P〈0.05); calcium (P=0.06) and phosphorus apparent digestibility (P=0.10) tended to be decreased with the increase of energy level. Overall, yak calves can be weaned at 3 months of age when the NEg of concentrate supplement is 6.50 MJ/kg, which is beneficial for nutrient digestion and body growth.