Different levels of dietary DL-α-tocopheryl acetate affect the vitamin E status of juvenile Korean rockfish, Sebastes schlegeli

This experiment was conducted to study the effects of different levels of DL-alpha-tocopheryl acetate on vitamin E status of juvenile Korean rockfish and estimate the dietary vitamin E requirement. After 6 weeks of conditioning with a basal diet, fish were divided into six groups and fed semipurified diets for 20 weeks. The experimental diets were supplemented with 0, 20, 40, 60, 120 or 500 mg DL-alpha-tocopheryl acetate/kg diet (E-0, E-20, E-40, E-60, E-120 and E-500). These diets contained approximately 16 mg of endogenous alpha-tocopherol/kg, Fish averaging 12.3 g were fed twice a day during the first 8 weeks, and then once a day during the second 16 weeks. Fish were fed to satiation throughout the experimental periods. Fish fed diet E-0 began to show lower appetite and reduced growth rate after 16 weeks. Fish fed diet E-0 had lower (P < 0.05) weight gain, feed conversion ratio, and hematocrit compared to fish fed diets E-20-E-120. Vitamin E deficiency signs such as muscular dystrophy, shortened operculae and exophthalmia were observed only in fish fed diet E-0. Fish fed diets E-0 and E-20 had lower (P < 0.05) liver alpha-tocopherol concentration than did fish feed diet E-120. The highest level of DL-alpha-tocopheryl acetate supplementation (diet E-500) did not result in greater growth performance or liver alpha-tocopherol concentration than the other diets. Fatty acid composition of muscle and liver were only affected by the diet E-0 (P < 0.05). Based on broken line analysis of weight gain, the optimum level of dietary vitamin E was determined to be about 45 mg/kg diet for good growth and maximum tissue accretion in juvenile Korean rockfish. (C) 1998 Elsevier Science B.V.