Dietary vitamin C and vitamin E interact to influence growth and tissue composition of juvenile hybrid striped bass (Morone chrysops (female) x M. saxatilis (male)) but have limited effects on immune responses.

Juvenile hybrid striped bass (initially 12.0 g) were fed diets containing deficient, adequate or excessive amounts of vitamin C and/or vitamin E in a factorial arrangement to investigate potential nutritional interaction and effects on immune responses. Nine semipurified diets were supplemented with 0, 25 or 2500 mg vitamin C/kg and 0, 30 or 300 mg vitamin E/kg and fed to fish in triplicate aquaria for 10 wk. Weight gain, feed efficiency, mortality and tissue vitamin levels were significantly (P < or = 0.05) affected by dietary vitamin levels. In addition, a significant interaction between vitamin C and vitamin E was observed. At inclusion levels of 25 and 2500 mg/kg, dietary vitamin C improved feed efficiency and protected fish fed vitamin E-deficient diets from growth depression and mortality. At inclusion levels of 30 and 300 mg/kg, vitamin E prevented mortality in fish fed vitamin C-deficient diets; however, 300 mg vitamin E/kg was necessary to prevent growth depression in vitamin C-deficient fish but was unable to improve feed efficiency. Lysozyme, bacterial killing ability, as well as plasma protein and total immunoglobulin levels of fish were not affected by dietary vitamin levels, whereas respiratory burst activity increased with vitamin E supplementation. Thus, interactions between vitamin C and vitamin E were observed in hybrid striped bass. These interactions may be due to the ability of vitamin C to regenerate vitamin E to its functional form but also suggest an ability of vitamin E to spare vitamin C.