Submitted to: Aquaculture Research
Publication Type: Peer reviewed journal
Publication Acceptance Date: 2/25/2008
Publication Date: 6/1/2008
Citation: Aksoy, M., Lim, C.E., Li, M.H., Klesius, P.H. 2008. Interaction between dietary levels of victamin C and E on growth and immune responses in channel catfish, Ictalurus punctatus. Aquaculture Research. 39:1198-1209. Interpretive Summary: Vitamins C and E, which are very important antioxidants, are dietary essentials for most aquacultured species, including channel catfish. It has also been demonstrated that these vitamins are among the most important nutrients that influence the immune system. Vitamin C functions as a co-enzyme in many enzyme systems for the normal formation of collagen, cartilage and bones, and may be involved in several aspects of lipid metabolism in fish and has been shown to stimulate immune responses. Vitamin E is a constituent of all cellular membranes and is particularly abundant in immune cell membranes. Vitamin E depleted diets have been reported to reduce immune responses in several fish species. This study was conducted to evaluate the effect of dietary levels of vitamin C (0, 100, 2,000 mg/kg diet) and vitamin E (0, 50, 500 mg/kg diet), and their interaction on growth performance, liver contents of vitamins C and E, hematology and immune response of channel catfish. Each diet was fed to juvenile channel catfish in triplicate aquaria to apparent satiation (i.e., until fish no longer accept feed) twice daily for 12 weeks. Result showed that supplementation of 100 mg vitamin C/kg diet was required to prevent classical vitamin C-deficiency symptoms and promote good growth. However, vitamin E content in the basal diet (23.1 mg/kg) was sufficient to promote good growth of channel catfish. In the absence supplemental vitamin C, supplementation of vitamin E protected catfish against classical vitamin C-deficiency symptoms, but this had no effect on growth performance. Liver storage of vitamins C and E increased with increasing dietary levels of each vitamin. Dietary vitamin E levels had no effect on liver vitamin C content, but increasing dietary vitamin C increased liver vitamin E content. Supplementation of both vitamins was required for optimum hematological indices. Some measured immune parameters (serum protein and superoxide anion production) were enhanced by supplementation of vitamin C or E. In the absence of clear cut information and since these vitamins are dietary essential for catfish, supplementation of 100 mg vitamin C and 50 mg vitamin E/kg diet is recommended.
Technical Abstract: This study was conducted to evaluate the effect of dietary levels of vitamins C and E on growth performance, liver contents of vitamins C and E, hematology and immune response of channel catfish, Ictalurus punctatus. A basal practical diet containing 32% protein and 2,900 kcal DE kg-1 was supplemented with three levels of vitamin C (0, 100, 2,000 mg kg-1 diet) and three levels of vitamin E (0, 50, 500 mg kg-1 diet) at each level of vitamin C (3 x 3 factorial experiment). Each diet was fed to juvenile channel catfish in triplicate aquaria to apparent satiation twice daily for 12 weeks. Results indicate that the amount of vitamin E contained in the basal diet (23.1 mg kg-1) was sufficient to promote good growth, feed efficiency and survival of juvenile channel catfish. However, vitamin E supplementation (50-500 mg kg-1 diet) was needed to maintain high levels of white blood cells, hemoglobin, hematocrit and liver vitamin E. Supplementation of vitamin C (100 mg kg-1) to the basal diet containing 10.5 mg kg-1 was required for good growth, feed efficiency, survival and prevention of vertebral deformity. Liver storage of vitamins C and E increased with increasing dietary levels of each vitamin. A dietary vitamin C level of 2000 mg kg-1 was needed for maximum erythropoiesis (erythrocyte count and hemoglobin) and liver storage of both vitamins C and E. Dietary vitamin E levels had no effect on liver vitamin C content, but increasing dietary vitamin C increased liver vitamin E content. Supplementation of 100 mg kg-1of vitamin C was adequate to improve serum protein content and superoxide anion production by leukocytes. Increasing vitamin C level to 2,000 mg kg-1 adversely affected serum protein concentrations. Superoxide anion production was significantly stimulated by supplementation of vitamin E at 500 mg kg-1 diet, but their interaction had no effect on this parameter. Dietary levels of vitamins C or E or their interaction had no effect on macrophage chemotaxis ratio and phagocytosis. The interaction between dietary levels of vitamin C and E had no effect on weight gain, feed efficiency, survival, hemoglobin, hematocrit, liver levels of vitamins C and E and serum protein but significantly affected red blood cell and white blood cell counts.