Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 4/27/2007
Publication Date: 5/16/2007
Citation: Lim, C.E., Aksoy, M., Li, M., Welker, T.L., Klesius, P.H. 2007. Growth, Immune Response and Resistance to Streptococcus iniae of Nile Tilapia Fed Diets Containing Various Levels of Vitamin C and E. 31st Fish Feed and Nutrition Workshop. Auburn University, Auburn, AL.
Technical Abstract: The effect of dietary levels of vitamins C and E on growth performance, immune response and resistance of Nile tilapia to Streptococcus iniae challenge were evaluated. A basal practical diet containing 32% protein and 2900 kcal DE/kg was supplemented with three levels of vitamin C (0, 100, 2000 mg/kg diet) and three levels of vitamin E (0, 50, 500 mg/kg diet) at each level of vitamin C (3 x 3 factorial experiment). Each diet was fed to juvenile Nile Tilapia (6.73 ± 0.18 g) in triplicate aquaria to apparent satiation twice daily for 12 weeks. Supplementation of vitamin C at 100 mg/kg to the basal diet containing 10.5 mg/kg was sufficient for good growth, feed intake and feed efficiency. Survival was not affected by dietary vitamin C levels. The amount of vitamin E contained in the basal diet (23.1 mg/kg) was sufficient to promote good growth, and feed intake and efficiency, but supplementation of 50 mg vitamin E was necessary for good survival. Vitamin C and E interaction had no effect on these parameters. Body moisture was higher and protein was lower in fish fed the vitamin C-unsupplemented diets. Fish fed the vitamin E-unsupplemented diet had increased body moisture and ash but reduced body protein and fat. These variables were not affected by the interaction between vitamin C and E. Liver vitamin C and E content increased with increasing dietary vitamin C levels, but the values were significantly higher only at a dietary vitamin C level of 2000 mg/kg. Dietary levels of vitamin E had no effect on liver vitamin C content, but liver vitamin E significantly increased at 500 mg vitamin E/kg. Neither vitamin had any effect on hepatosomatic index (HI). The interaction between vitamin C and E had no effect on liver vitamin C and HI, but liver vitamin E significantly increased when supplemental vitamin C and E levels were higher that 100 and 50 mg, respectively. Fish fed the vitamin C-unsupplemented diet had significantly lower red blood cell count and hemoglobin, but dietary levels of vitamin C had no effect on white blood cell count or hematocrit. None of these variables was affected by dietary levels of vitamin E or the interaction between vitamins E and C. Serum protein and alternative complement were not affected by dietary vitamin C levels, but total immunoglobulin and lysozyme activity significantly increased and decreased, respectively in fish fed the 2000 mg/kg vitamin C diet. Supplementation of vitamin E had no effect on serum protein, total immunoglobulin and lysozyme activity, but vitamin E supplementation at 500 mg/kg significantly decreased serum alternative complement. Serum protein, immunoglobulin and lysozyme were not affected by the interaction between vitamin C and E. Serum alternative complement, however, significantly increased with increasing dietary vitamin C but decreased with increasing dietary vitamin E. Dietary levels of vitamin C had no effect on mortality following S. iniae challenge, but mortality significantly decreased in fish fed vitamin E-supplemented diets The interaction of these vitamins has no effect on mortality. Neither vitamin C or E nor their interaction affected antibody titer of fish 15 days post-challenge with S. iniae.