Optimal dietary copper and zinc requirements for juvenile Chinese mitten crab, Eriocheir sinensis

Two independent 25-day feeding trials were conducted to determine the optimum dietary copper and zinc requirements of juvenile Chinese mitten crab, Eriocheir sinensis. In experiment I, megalopa (6.86±0.34 mg) were fed one of six experimental diets containing supplemental Cu sulfate at 0, 15, 30, 45, 60, or 75 mg/kg diet. In experiment II, megalopa (7.16±0.48 mg) were fed one of six experimental diets containing supplemental Zn sulfate at 0, 25, 50, 100, 200, or 400 mg/kg diet. Results indicate that the weight gain rate, survival rate, and cytochrome oxidase activity were significantly affected by the dietary copper level (p<0.05). Although no significant difference was observed in survival rate of juvenile crab fed diets with increasing zinc levels, there were significant differences in weight gain rate and carboxypeptidase A activity among dietary treatments (p<0.05). Broken-line regression analysis of the weight gain rate against the dietary copper and zinc levels indicates that the optimal dietary requirements for maximum growth of E. sinensis are 41 mg copper and 84 mg zinc per kg dry diet.