脂肪水平对早期断奶犊牛生长性能及血清生化指标的影响

早期断奶犊牛饲喂不同脂肪含量代乳品，研究脂肪水平对犊牛生长性能、血清生化指标及饲料进食量的影响，为犊牛生长规律和脂肪需要提供科学依据，为实际生产中犊牛早期断奶和培育提供技术指导。试验选取12头新生荷斯坦公犊牛，分为EE9、EE13、EE17 3组，每组４头，分别饲喂蛋白质水平相同、脂肪含量为9%、13%及17%的3种代乳品。每日记录犊牛开食料的采食情况，并于犊牛10、20、30、40、50、60日龄清晨空腹测定犊牛体重及体尺指标，同时采集犊牛的血液样本进行分析。研究结果表明,3组犊牛哺乳期的饲料日进食量分别为706.9、666.9、569.3 g；10~60日龄的平均日增重分别为498、544、488 g，EE13组犊牛日增重高于EE9、EE17组的犊牛；犊牛60日龄时，EE13组犊牛的体高、体斜长及管围均高于其它2组。血清尿素氮、血糖、甘油三酯的水平不受代乳品脂肪含量的影响，但日龄对哺乳期犊牛甘油三酯含量的影响差异显著(P<0.05)。随日龄的增加，犊牛的生长速度和饲料的进食量逐渐增加，低脂肪的代乳品(EE9)不能满足犊牛的能量需要，高脂肪的代乳品（EE17）抑制了犊牛对开食料的采食量，饲喂脂肪含量13％的代乳品（EE13）对犊牛生长发育优于其它2组。脂肪含量对犊牛血清生化指标的影响不显著。

Effects of Increasing Fat Content of Milk Replacer on Growth Performance and Blood Metabolites of Calves

Feeding trials have been performed to investigate the effects of increasing fat levels of milk replacer on growth performance，changes in selected blood metabolites and starter consumption，which provides scientific basis to research on the development of calf growth and fat requirement. It is also instructive for the practical operation of calf early-weaning and breeding. Twelve newborn Holstein calves were used and assigned randomly to receive 1 of 3 experimental treatments consisted of 8%， 13% and 17% fat， respectively (n=4 per treatment). A pellet starter was offered ad libitum and refusal were weighed daily. Changes in body weight、growth parameters and concentration of blood metabolites were determined at 10， 20， 30， 40， 50 and 60 days of age prior to morning feeding. The starter consumption of calves fed with EE8， EE13 and EE17 was 706.9,666.9,569.3 g，respectively. And the average daily gain (from day10~60) was498，544g and 488 g/day， respectively.Body weight gains of EE13 treated group was greater than the other groups. On the 60 days of age， wither height、body length and cannon bone circumference were significantly higher with EE13 treatment(P<0.05).There were no significant differences in the concentration of serum glucose、triglyceride and urea N among treatments， whereas a significant age effect was found on the level of triglyceride(P<0.05). The growth rate and starter consumption improved as age increased. Low-fat content (EE9) milk replacer could not satify the energy requirement of calves，on the other hand，high level of fat content (EE17) impressed starter consumption that would delay the development of rumen in the animal. Thus， medium-fat milk replacer (EE13) seemed to be the most optimal level for the calves.In addition，no significant differences in the concentration of blood metabolites was observed among groups.