Effect of dietary protein level on hepatic function and antioxidant capacity of juvenile common carp (Cyprinus carpio)

Common carps (Cyprinus carpio) with average body weight of (10±1.2) g were randomly divided into five treatments with three replicates (35 fish in each treatment), to investigate the effect of dietary protein level on hepatic function and antioxidant capacity by feeding diets at five protein levels (30%, 30.5%, 31%, 31.5% and 32%).Every four weeks, the related physiological and biochemical indices were determined.At the 4^th and 8^th week, the results show:1) Activities of alanine transaminase (ALT) and aspartate transaminase (AST) in serum and hepatopancreas in 31% protein group were significantly higher (P < 0.05).2) Compared with the fish fed with the other treatment groups, those fed with 31% protein group had significantly higher activities of superoxide dismutase (SOD), catalase (CAT) and lysozyme (LZM) (P < 0.05).3) Contents of malonaldehyde (MDA) of fish which were fed with 31% protein group decreased significantly (P < 0.05).Considering the cost of feed preparation for common carps, dietary protein of 31% meets the requirement for hepatic function and antioxidant capacity for the juveniles.