Abstract: [Objective] To investigate the effects of dietary supplementation of γ-polyglutamic acid on serum biochemical parameters of weaned calves. [Method] A total of 16 weaned Holstein calves with similar weights were divided into control group and experimental group with 8 calves in each group according to the principle of homogeneity. Calves in the two groups were fed with 3 kg pellet feed per head per day, and corn stover was fed ad libitum. In the experimental group, γ-polyglutamic acid （pasted liquid, containing 20% γ-polyglutamic acid） was added to the pellet feed at the rate of 5 ‰. The experiment lasted for 70 days, including a 10-day-long pre-experimental period and a 60-day-long formal experimental period. Blood samples were collected on the last day of the trial to determine the serum biochemical parameters. [Result] The serum levels of IgG, IgA and IgM as well as the activities of serum SOD and GSH-Px of the control group were significantly （P<0.05） higher than those of the experimental group. There was no significant （P>0.05） difference in activities of AST and ALT between the control group and the experimental group. No significant （P>0.05） differences in serum contents of TP, ALB, BUN, NEFA, GLU, Ca, P, Fe and Zn between the control group and the experimental group were observed, while the serum contents of Cu, VA and VC of the experimental group were significantly （P<0.05） lower than those of the control group. [Conclusion] For weaned Holstein calves, dietary supplementation of γ-polyglutamic acid reduces their serum contents of immunoglobulin (IgG, IgM, IgA), has the potential to improve their antioxidant capacity, promotes their absorption and utilization of Cu, VA and VC, and exhibits no negative effects on their liver function, energy metabolism, energy balance and protein utilization.

Key words: γ-polyglutamic acid, weaned calves, serum biochemical parameters