Dietary vitamin E requirement of hybrid striped bass (Morone chrysopsfemale × M. saxatilismale)

Abstract

This study was conducted to determine the dietary vitamin E requirement of juvenile hybrid striped bass (Morone chrysops female x Morone saxatilis male). Semi-purified diets supplemented with 0.2 mg Se kg(-1) from Na(2)SeO(3) and either 0 (basal), 10, 20, 40, 60, or 80 mg vitamin E kg(-1) as DL-alpha-tocopheryl acetate were fed to hybrid striped bass initially averaging 1.8 +/- 0.1 g (mean +/- SD) for 12 weeks. Fish fed the basal diet, which contained 5.8 mg alpha-tocopherol kg(-1) dry weight, were darker in colour and had reduced weight gain, as well as generally reduced haematocrit values compared with fish fed diets supplemented with vitamin E. In addition, fish fed diets containing less than 20 mg supplemental vitamin E kg(-1) had significantly (P < 0.05) reduced weight gain and feed efficiency compared with those fed diets supplemented with vitamin E at 20-80 mg kg(-1). Dietary supplementation of vitamin E caused incremental increases in the concentration of alpha-tocopherol in both plasma and liver tissues. However, hybrid striped bass fed graded levels of vitamin E did not exhibit a dose response in terms of ascorbic acid-stimulated lipid peroxidation of hepatic microsomes. Regression analysis of weight gain data using broken-line model indicated a minimum vitamin E requirement (+/- SE) of 28 (+/- 3) mg kg(-1) dry diet. Based on these data, the dietary vitamin E requirement of hybrid striped bass appears to be similar to that determined for other fish species.