Vitamin E amelioration of oxidative stress and low immunity induced by high-lipid diets in hybrid grouper (♀ Epinephelus fuscoguttatus × ♂ E. lanceolatu)

The experiment was conducted to investigate the effects of vitamin E (VE) on growth, oxidative stress and immunity for hybrid grouper (♀ Epinephelus fuscoguttatus × ♂ E. lanceolatu) fed high-lipid diet. Six groups of iso-protein (50.23%) and iso-lipidic high-lipid (15.36%) experimental diets were prepared by adding 0 (basic diet control), 0.01%, 0.02%, 0.03%, 0.04%, 0.05% α-tocopherol respectively in basic diet. Each treatment consisted of 3 replicates and 30 fish (10.20 ± 0.02 g) in each replicate for 8 weeks. The results showed that: 1) compared with the control group, the growth performance of grouper was not affected by the addition of VE in high-lipid diet, but the specific growth rate (SGR) in high VE dose (0.6%) group were significantly decreased compared with 0.02% and 0.03% groups. 2) Adding VE to high-lipid diet can alleviate the hepatic oxidative damage caused by high-lipid diet, and significantly improve the serum and liver antioxidant enzyme activity. 3) Compared with the control group, appropriate VE significantly increased the expression of liver anti-inflammatory factors TGF-β and IL10, and significantly decreased the expression of proinflammatory factors IL8 and IL6. In conclusion, adding appropriate amount of VE into high-lipid diet can improve antioxidant capacity and immunity of grouper, we speculated that VE may alleviate lipid peroxidation by improving antioxidant capacity to reduce the inflammatory response. In combination with the results of the current study, we recommend an additional dose of 0.02%-0.03% of α-tocopherol in this experiment under high-lipid conditions.