不同蛋白水平对犊牛消化代谢及血清生化指标的影响

Effect of Different Protein Levels on Nutrient Digestion Metabolism and Serum Biochemical Indexes in Calves

【目的】研究蛋白水平对犊牛生长发育、营养物质消化吸收及血清生化代谢的影响。【方法】选取9头新生荷斯坦公犊牛,分为A、B、C3组,分别饲喂等能值粗蛋白含量为18%、22%及26%的3种代乳品。分别在犊牛12～20日龄、22～30日龄、32～40日龄、42～50日龄和52～60日龄期间进行五期消化代谢试验。【结果】3组犊牛11～61日龄内各生长指标变化曲线相似,22%组犊牛增重速度比18%、26%组分别高9.75%、24.19%。随日龄增长犊牛对DM的消化率逐渐下降,对EE的消化率略有上升,对日粮氮的消化率有上升趋势;3组犊牛对日粮氮的平均消化率分别为69.39%、75.36%及74.55%。日粮钙磷的消化率和存留率全期内趋于稳定,26%组犊牛对日粮磷的平均消化率为63.83%,显著低于18%组的70.40%及22%组的69.73%。22%组血清TP、ALB、GLOB含量均显著高于其它两组;血清GLU含量以22%组为最高,试验结束时22%组为5.38mmol·L-1,显著高于18%组的3.71mmol·L-1及26%组的4.09mmol·L-1。【结论】蛋白质水平和不同生理阶段影响犊牛生长性能、消化代谢及血清生化指标,22%蛋白含量组犊牛的相关性能优于其它两组。

[Objective] The current study was performed to examine the effects of different protein levels on growth, nutriment digestion and absorption as well as blood serum biochemical parameters in calves. [Method] Nine healthy new born calves were selected, randomly divided into 3 groups （labeled as groups A, B and C） and fed with three kinds of milk replacers that contain 18%, 22% or 26% of protein, respectively. Five period-digestion-metabolism trials were taken between 12-20 days, 22-30 days,.32-40 days, 42-50 days and 52-60 days after birth. [Result] All three groups showed similar growth curve during 11 to 61 days of experiment, however, the growth rate of group B was 8.89% higher than that of group A and 19,48% higher than that of group C, respectively. As age increased, the apparent digestibility of DM declined gradually and the apparent digestibility of EE rose slightly, whereas the apparent digestibility and retention of N showed a trend of increase, Compared with groups B and C, calves in group A had a poor performance in the apparent digestibility of DM, EE and N. The average apparent digestibilities of N in the tested groups were 69,39%, 75.36% and 74.55%, respectively, Both the apparent digestibility and retention of Ca, P went steadily throughout the whole trials, but the average apparent digestibility of P in group C was only 63.83% which was markedly lower than that of group A （70.40%） and group B （69.73%）. In addition, the blood serum levels of TP, ALB and GLOB of group B were greater than those in groups A and C. The serum urea content in group A, on the other hand, was significantly lower than that in the other two groups. The highest Gin concentration was found in group B （5.38mmol·L^-1） as compared to groups A （3.71mmol·L^-1） and C （4.09mmol·L^1） at the end of the trials. [ Conclusion ] The protein levels in the milk replacer affected the digestion metabolism of nutrition and the serum biochemical parameters of calves at different physiological phases, Calves fed with 22% CP milk replacer had a better growth performance than the other groups.