Dietary gallic acid influences serum enzymatic parameters and immunological responses in Cyprinus carpio exposed to crowding stress

Application of dietary feed additives is an excellent approach to improve fish health status under different stressful condition. The current study investigated the roles of different level of dietary gallic acid (GA) on growth performances, biochemical indices, digestive enzymes activity, antioxidant status and immunological responses in common carp (Cyprinus carpio) subjected to crowding stress. Fish were fed with the control diet (0 mg/kg GA) and four graded levels of GA (150, 300, 450 and 600 mg/kg) for 60 days each with three replicates. Moreover, fish were challenged with crowding stress for six hours. The results revealed significant improvement in growth performances, immune indices in common carp fed with dietary GA in comparison to the control diet. The study also demonstrated significant improvement feed utility through enhanced activities of digestive enzymes (amylase, lipase and protease) by dietary GA provision. Moreover, dietary GA noticeably enhanced the antioxidant status of common carp by improving superoxide dismutase, catalase, glutathione peroxidase, and lowering malondiadehyde specially after exposure to crowding stress. Considering these results, the current study reveals that dietary GA at the concentration of 450 mg/kg can successfully improve growth performances, biochemical indices, digestive enzymes activity, antioxidant status and immunological responses in common carp.