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

Abstract: 【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 group