Abstract:

【Objective】 The current study was performed to investigate the effects of different energy levels on nutrition’s digestion metabolism and serum biochemical parameters of early weaned calves. 【Method】 Twelve neonatal Holstein calves were selected and assigned randomly to receive 1 of 3 treatments that contained 18.51, 19.66 and 20.80 MJ?kg-1 gross energy, respectively (n=4 per treatment). Digestion and metabolism trials were carried out at 5 phases (12-20, 22-30, 32-40, 42-50, 52-60 d). At the same time, blood metabolites were determined at 21, 31, 41, 51 and 61 days of age prior to morning feeding. 【Result】The results indicated that either DM, OM, and GE apparent digestibility or N and P retention tended to increase as age advanced. The average value of DM、OM apparent digestibility and Ca retention in high-energy treatment were significantly lower than that of other groups (P＜0.05). There were no significant differences in the concentration of serum glucose, triglyceride and urea N among treatments, whereas a significant effect of age was found on the level of triglyceride (P＜0.05). 【Conclusion】 To sum up, the medium-energy milk replacer seems to be more benefical for GE digestibility and N utilization, whereas low-energy milk replacer appears to be more rewarding for Ca and P utilization.

Key words: calf, milk replacer, energy, apparent digestibility, metabolic rate