Effects of Dietary Surfactin Supplementation on Growth, Digestive Enzyme Activity, and Antioxidant Potential in the Intestine of Growth Retarded Marbled Eel (Anguilla marmaorata) at Elver Stage

A 70 day trial was conducted to investigate the effects of surfactin on growth, digestive enzyme activity, and antioxidant potential in the intestine of growth retarded marbled eels (Anguilla marmorata) at the elver stage. Six hundred and forty marbled eels at elver stage were randomly divided into four treatment groups with four replicates per group, and 40 fish per replicate. The dietary surfactin level of the four experimental diets was 0, 25, 50, and 100 mg/kg, respectively. Final body weight, weight gain rate, survival rate, protease activity in the intestine, malondialdehyde level, total antioxidation capacity level, and activities of superoxide dismutase, and glutathione peroxidase in the intestine of fish, increased significantly with surfactin supplementation, and feed conversion rates improved significantly (P<0.05). No significant differences of growth performance, lipase activity (except in the 25 mg/kg surfactin supplementation group), amylase activity and CAT activities were found among surfactin supplemented groups (P>0.05). Results demonstrated that dietary surfactin supplementation could improve growth performance, some digestive enzyme activities, and antioxidant potential, in the intestine of growth retarded marbled eel at elver stage. Surfactin could be used as a dietary growth promoter for growth retarded eels.