Effects of dietary vitamin e supplementation on growth performance, lipid peroxidation and tissue fatty acid composition of black sea bream (Acanthopagrus schlegeli) fed oxidized fish oil

A 9-week feeding experiment was conducted to evaluate the effects of dietary vitamin E supplementation on growth, lipid peroxidation and fatty acid composition of black sea bream fed oxidized oil. The FL and OL diets contained fresh fish oil and oxidized oil, respectively, without additional vitamin E supplementation. Another four α-tocopherol levels (150, 250, 450 and 800 mg kg^-1 diet) were used within the OL diet, giving a total of six experimental diets. Fish were hand-fed to apparent satiation twice daily. At end of the trial, the weight gain and survival rate of fish were significantly reduced by diets with oxidized oil, whereas hepatosomatic index was remarkably high in fish fed oxidized oil diet. However, vitamin E supplementation to diet significantly improved growth performance and increased vitamin E content in the liver. Although, liver thiobarbituric acid reactive substances and docosahexaenoic acid were significantly increased by dietary oxidized oil, their levels were reduced by dietary vitamin E supplementation. Our results indicate that the fish were performing the best at intermediate concentrations of α-tocopherol and a dose of >150 mg α-tocopherol kg^-1 diet could reduce lipid peroxidation and improve fish growth performance when oxidized oils exist in diet.