Influence of dietary vitamin E (DL-alpha-tocopheryl acetate) and diludine (diethyl 1,4-dihydro-2,6-dimethyl-3,5-pyridinedicarboxylate) levels on growth and lipid peroxidation in rainbow trout, Oncorhynchus mykiss

We aimed to investigate the influence of dietary vitamin E and diludine on growth and lipid peroxidation (malondialdehyde; MDA) in rainbow trout. Fish (1.5 g) were fed different dietary levels of vitamin E (0, 50 and 100 mg/kg) and diludine (0, 0.5 and 1 g/kg) for 10 weeks. Growth performance and feed conversion ratio (FCR) were significantly affected by dietary vitamin E (p < .05) but not diludine. Fish fed 50 mg/kg dietary vitamin E with no diludine had significantly better growth and lower FCR than those fed vitamin E free diets. Liver vitamin E content was significantly influenced by dietary vitamin E and diludine (p < .05). The highest hepatic vitamin E was in fish fed the highest dietary vitamin E and diludine levels. Hepatic MDA level was significantly affected by dietary vitamin E and diludine (p < .05), decreasing with the increase in both dietary vitamin E and diludine. According to our results, diludine had no significant effect on growth; however, decreased hepatic lipid peroxidation independent of vitamin E. Our results reveal that 50 mg/kg vitamin E content is suitable for optimal growth and FCR in rainbow trout juveniles. However, dose dependent effects of dietary diludine remain uncertain and need further researches.