Stimulatory effect of dietary taurine on growth performance, digestive enzymes activity, antioxidant capacity, and tolerance of common carp, Cyprinus carpio L., fry to salinity stress.

The present study was carried out to evaluate the effect of dietary taurine (Tau) on performance, digestive enzymes, antioxidant activity, and resistance of common carp, Cyprinus carpio L., fry to salinity stress. Fish (0.97 ± 0.033 g) were fed on different taurine levels of 0.0 (control), 5, 10, 15, or 20 g/kg diet up to satiation twice daily for 8 weeks. At the end of the feeding trial, fish were stressed by exposure to 10 ppt salinity for 3 days during which fish mortality was observed. Fish performance was significantly (P < 0.05) improved by dietary taurine up to 15 g Tau/kg diet after which fish growth and feed intake were almost the same. Also, taurine supplementation significantly (P < 0.05) elevated activities of intestinal amylase, lipase, and protease resulting in an improving in feed intake giving better performance. Furthermore, Tau-stimulated antioxidant activity of common carp was observed in a dose-related manner, where activities of superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GPx) were significantly (P < 0.05) higher, but malondialdehyde (MDA) value was significantly (P < 0.05) lower in Tau-fed fish groups than those fed the control diet. In salinity stress experiment, highest survival rate was observed at fish fed Tau-supplemented diets without significant (P > 0.05) differences over fish fed the control diet. It appears that taurine could be used as a feed supplement to confer better growth and health of common carp fry with optimal level of 15 g/kg diet.