Dietary copper affects antioxidant status of shrimp (Penaeus monodon) reared in low salinity water

Graded levels of supplemental copper (Cu) (0, 10, 25, 40, 55 and 110 mg/kg) were fed to juvenile tiger shrimp (Penaeus monodon) reared in 5 parts per thousand salinity water for 8 weeks. According to the results, shrimps fed a diet supplemented with 40 mg/kg Cu had the highest weight gain (WG). Shrimps fed a diet with 110 mg/kg supplemental Cu had the lowest total haemocyte count (THC) and the highest reactive oxygen species (ROS) production and apoptotic ratio in haemocytes, suggesting that excessive levels of dietary Cu caused oxidative stress and induced haemocyte apoptosis. In plasma, the activities of copper, zinc-superoxide dismutase (Cu, Zn-SOD) and total superoxide dismutase (T-SOD) were higher in shrimps fed diets with 40 and 55 mg/kg supplemental Cu than those fed diets with <= 25 and 110 mg/kg supplemental Cu. Hepatic Cu, Zn-SOD activity increased in shrimps fed diets with 25-55 mg/kg supplemental Cu, while hepatic T-SOD activity increased in shrimps fed diets with 40 and 55 mg/kg supplemental Cu. In addition, diets with 25-55 mg/kg supplemental Cu increased the plasma total antioxidant capacity (T-AOC), while diets with 10-55 mg/kg supplemental Cu increased the hepatic T-AOC. Hepatic malondialdehyde (MDA) content was lowest in shrimps fed diets with 25 and 40 mg/kg supplemental Cu and highest in shrimps fed a diet with 110 mg/kg. Based on the growth and antioxidant activities, the optimum requirement of Cu for the antioxidant status of P. monodon was 30.7-61.9 mg/kg.