Effects of dietary methionine supplementation on feeding, growth and antioxidant ability of juvenile Chinese mitten crab, Eriocheir sinensis

This study was conducted to evaluate the effects of dietary methionine supplementation in cottonseed meal- based diets on the growth performance, digestibility and antioxidant ability of juvenile Chinese mitten crab, Eriocheir sinensis. Five diets were formulated using a basic diet, in which cottonseed meal accounted for 40%, supplemented with 0.00%, 0.14%, 0.28%, 0.42%, and 0.56% methionine, respectively. another diet was full fish meal-based (fish meal accounted for 64.4%) and served as the control. Each diet was fed to juvenile E. sinensis (0.390.02) g of five replicates for 6 weeks. The results showed that weight gain, specific growth rate and feed conversion ratio in crabs fed 0.42%Met diet did not differ from those of the control group (P0.05). Crabs fed with 0.28%Met and 0.42% Metdiets exhibited higher food intake and protein deposition rate than those fed diets with 0.00%Met, 0.14%Met, 0.56%Met (P0.05). There were no significant differences in whole body moisture, lipid, and ash (P0.05) among all treatments. However, compared with the 0.00% Met diets group, crude protein contents in crab fed with methionine supplemented diets were significantly higher (P0.05). Dry matter, protein, lipid digestibility, and trypsinase activity of crabs fed with 0.42% Metdiets did not differ from those of the control (P0.05). No differences were found in malondiaedehyde content, serum superoxide dismutase and glutathione peroxidase activity in crabs fed with the control diet and those fed with 0.28% Met, 0.42%Met and 0.56% Metdiets (P0.05). The results suggest that 0.42%Met added to the diet (cottonseed meal accounted for 40%) could significantly accelerate the growth performance, digestibility and antioxidant ability of juvenile E. sinensis.