Effect of dietary copper on the growth performance, non-specific immunity and resistance to Aeromonas hydrophila of juvenile Chinese mitten crab, Eriocheir sinensis

An 8-week feeding trial was conducted to determine the dietary copper (Cu) on growth performance and immune responses of juvenile Chinese mitten crab Eriocheir sinensis. Six semi-purified diets with six copper levels (1.88, 11.85, 20.78, 40.34, 79.56 and 381.2 mg kg−1 diet) of CuSO4·5H2O were fed to E. sinensis (0.45 ± 0.01 g). Each diet was fed to the crab in five replicates. The crab fed diets with 20.78 and 40.34 mg Cu kg−1 diet had significantly greater weight gain and hemolymph oxyhemocyanin content than those fed diets with 1.88 and 381.2 mg Cu kg−1 diet. Survival rates of crab were not significantly different between all treatment groups. The activities of copper–zinc superoxide dismutase (Cu–Zn SOD), phenoloxidase (PO), and total hemocyte count (THC) significantly increased when the supplementation of dietary copper reached 20.78–40.34 mg Cu kg−1 diets. In the bacteria challenge experiment with Aeromonas hydrophila, survival rates significantly increased and reached a plateau when the dietary copper increased from 1.88 to 40.34 mg kg−1, whereas significantly decreased when the dietary copper increased from 40.34 to 381.2 mg kg−1. This study indicates that the level of dietary copper is important in regulating growth and immune response in crab.

► The level of dietary copper is important in regulating growth and immunity in crab.
► Dietary optimal copper could enhance the resistance to pathogen infection in crab.
► The optimal range of dietary copper to improve crab immunity is 20.78–40.34 mg kg−1.