Effects of dietary vitamin E on growth performance, antioxidant capacity and lipid metabolism of juvenile golden pompano Trachinotus ovatus

In order to investigate the dietary requirement of Trachinotus ovatus for vitamin E (VE) and its effects on tissue polyunsaturated fatty acids (PUFA) reservation, a 56-day feeding trial was performed with five diets (D1-D5) supplemented with different levels of VE at 34.56, 47.35, 61.16, 91.06 and 144.88 mg VE/kg diet. A total of 375 fish (initial weight 13.40 +/- 0.08 g) were randomly distributed equally into 15 sea cages and each diet in triplicate cages. After 8 weeks of feeding, fish fed diet D3 exhibited significantly higher weight gain (WG), serum superoxide dismutase and glutathione peroxidase activities and also had higher docosahexaenoic acid (DHA) and n-3 PUFA contents in the raw muscle than those of fish fed diets D1 and D5 (p < .05). Moreover, n-6 PUFA and n-3 PUFA contents in cooked muscle of D3 and D4 groups were significantly higher than those of other groups (p < .05). Besides, the contents of hepatic arachidonic acids, eicosapentaenoic acid, DHA, n-6 PUFA and n-3 PUFA in fish of D3 and D4 groups were also significantly higher than those of D1 group (p < .05). Correspondingly, the transcript levels of genes related to PUFA beta-oxidation (cpt1 and ppar alpha) and synthesis (fas and elovl5) were lower in D3 and D4 groups. Based on regression analysis for WG, the optimum dietary VE level was 90.75 mg/kg, which was consistent with the above results that fish fed diets D3 and D4 displayed better growth performance, antioxidant capacity and muscle PUFA stability, where the last suggesting an effect of dietary VE against PUFA beta-oxidation.