RRR-alpha-tocopheryl succinate is a less bioavailable source of vitamin E than all-rac-alpha-tocopheryl acetate for red drum, Sciaenops ocellatus
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abstract
Bioavailability of the succinate ester of -tocopherol has never been investigated with aquatic animals to date. Therefore, a 12-week feeding trial was conducted to compare bioavailability of -tocopheryl acetate and -tocopheryl succinate by slope ratio analysis. The semi-purified diets were supplemented with either 0 (basal), 10, 20 and 40IU vitamin E/kg as all-rac--tocopheryl acetate or 10, 20, or 40IU vitamin E/kg as RRR--tocopheryl succinate. Red drum juveniles were conditioned by feeding the basal diet for 8weeks prior to the experimental period to reduce whole-body tocopherols. Fish initially averaging 12.2 0.4g/fish (mean SD) were fed experimental diets at a rate approaching apparent satiation for 12weeks. Weight gain and feed efficiency responses of fish fed diets were not significantly altered by the type or level of vitamin E supplemented. However, -tocopherol levels in liver and plasma were significantly (P < 0.01) influenced by dietary vitamin E level and ester form. The liver retention of -tocopheryl acetate was 14 times higher than -tocopheryl succinate, while thiobarbituric acid reactive substances (TBARS) in liver of fish fed -tocopheryl acetate tended to be (P < 0.1) lower than that of fish fed -tocopheryl succinate. In addition, plasma ascorbic acid in fish fed graded levels of -tocopheryl acetate was significantly higher than fish fed graded levels of -tocopheryl succinate. Fish fed the basal diet and 10IU -tocopheryl succinate/kg showed edema in the heart, while fish fed all other diets did not exhibit this pathology. Within the dose range of 0-40IU/kg diet, hematocrit, neutrophil oxidative radical production and intracellular superoxide anion production of head kidney macrophages were not significantly influenced by -tocopherol ester or dietary supplementation level. In conclusion, -tocopheryl succinate is not readily available to juvenile red drum compared to the widely used -tocopheryl acetate. 2008 Elsevier B.V. All rights reserved.
