Effect of dietary taurine supplementation on growth performance, digestive enzyme activities and antioxidant status of juvenile black carp (Mylopharyngodon piceus) fed with low fish meal diet

An 8-week feeding trial was conducted to determine the effects of dietary taurine supplementation on growth performance, activities of digestive enzymes, antioxidant status and the target of rapamycin (TOR) gene expression in black carp (initial body weight 5.94 +/- 0.02g) fed with low fish meal diet. Six isonitrogen and isolipidic diets were formulated. High fish meal-based diet (HFM) contained 20% fish meal and 24% soybean meal as a positive control. Fifty per cent of fish meal in HFM was replaced by soybean meal and were supplemented with 0, 0.05%, 0.1%, 0.2% and 0.4% dietary taurine respectively (designated as T-0.00 (a negative control), T-0.05, T-0.1, T-0.2 and T-0.4). The results showed that the partial replacement of fish meal by soybean meal without taurine supplementation resulted in a significant reduction in weight gain (WG), activities of amylase and lipase in intestine, superoxide dismutase (SOD) and glutathione peroxidase (GSH-px) in serum, with a significant increase in feed conversion rate (FCR), the content of malonaldehyde (MDA), triglyceride (TG) and total cholesterol (TC) in serum. WG in groups supplemented with equal or above to 0.1% dietary taurine was significantly higher compared with T-0 group. With increasing levels of dietary taurine, the activities of amylase, lipase, GSH-px and SOD and glutataione (GSH) content significantly increased (p<0.05). FCR, the content of MDA, TG and TC in serum and crude lipid content in whole body were significantly reduced after taurine treatment (p<0.05). In liver, TOR mRNA expression in groups with equal or above to 0.1% taurine was significantly higher than T-0 group (p<0.05).