Effects of dietary vitamins C and E on alternative complement activity, hematology, tissue composition, vitamin concentrations and response to heat stress in juvenile golden shiner (Notemigonus crysoleucas)

The objective of this study was to characterize the response of golden shiner fed one of eight purified diets with wither 0 or 38 mg alpha-tocopherol (alpha-T) kg(-1) and one of four levels of ascorbic acid (AA) (23, 43, 98, or 222 mg kg(-1) diet) in a 2x4 factorial design. Growth, survival, signs of vitamin E deficiency, and immune and stress responses were monitored in groups of 30 golden shiners (mean average initial weight=0.79 g) fed the diets to apparent satiation twice daily in triplicate aquaria for 14-19 weeks. The average individual weight gain was not affected by dietary alpha-T concentrations at 14 weeks, but the survival of fish fed the alpha-T-unsupplemented diets was lower than that of fish fed the alpha-T-supplemented diets. After 10 weeks, fish fed the alpha-T-unsupplemented diets began to show vitamin-E-deficiency signs such as increased prevalence of fish with darkened skin. After 17 weeks the deficient fish had lower alpha-T concentrations in viscera, lower whole-body crude protein, total lipid, dry matter, hematocrit, hemoglobin, lymphocyte (%), alternative complement activity (ACH50), and survival after exposure to stressful water temperatures (36-37 degreesC) than those fed the alpha-T-supplemented diets. A sparing effect of vitamin E on vitamin C was evident. Elevated dietary vitamin C reduced the incidence and severity of vitamin E deficiency signs in a dose-dependent manner. The interactive effect of vitamins C and E on ACH50 activity and percentage of thrombocytes was also significant. Regardless of vitamin E levels, different vitamin C levels did not influence the alpha-T concentration in viscera and other interactions between vitamins C and E were not evident. (C) 2004 Elsevier B.V. All rights reserved.