Effect of dietary astaxanthin on the growth performance and nonspecific immunity of red swamp crayfish Procambarus clarkii

This trial was conducted to investigate the effect of dietary astaxanthin on the growth performance and nonspecific immunity of red swamp crayfish Procambarus clarkia. Crayfishes with body weight of 7.15 +/- 0.21 g were randomly divided into five groups. One group was fed with basic diet, whereas the other four groups were fed with diets containing 100, 200, 400 and 800 mg/kg astaxanthin. After eight weeks of feeding, 200, 400 and 800 mg/kg astaxanthin increased the body weight, gain rate, survival rate, serum lysozyme (LYZ) activity, protein level, alkaline phosphatase activity, hepatopancreatic superoxide dismutase activity and glutathione peroxidase activity and decreased the feed conversion rate, serum alanine aminotransferase activity and glutamic oxaloacetic transaminase activity compared with those of the control group. All levels of astaxanthin improved the resistance to Aeromonas hydrophilia compared with the control group. However, an increased level (400 mg/kg) of astaxanthin caused no further improvement in the efficiency of astaxanthin. Hence, this compound might be used as dietary supplement for crayfish.