Dietary vitamin E requirement of fingerling channel catfish.

Two experiments were conducted to reevaluate the dietary vitamin E requirement of fingerling channel catfish. Purified diets containing 1% cod liver oil, 4% stripped lard and adequate selenium supplemented with graded levels of DL-alpha-tocopheryl acetate were used in both experiments. The results indicate that the previously reported requirement value, which was based on growth and pathological changes, was underestimated. The minimum dietary vitamin E requirement in the form of DL-alpha-tocopheryl acetate was determined to be 50 mg/kg of diet based on 16-week liver microsomal ascorbic acid-stimulated lipid peroxidation data. No differences were observed in growth rates or feed efficiencies in either experiment. No gross pathologies or hematological changes were evident in fish fed different levels of vitamin E for 20 weeks, except red blood cell hemolysis, which was elevated at the lower levels. Histological lesions were only observed in fish receiving the 0 mg/kg diet. A marked multifocal splenic hemosiderosis was observed in these fish. A mild multi-focal hemosiderosis was observed in the pancreatic tissue surrounding the hepatic vasculature. The pancreatic tissue appeared reduced from that observed in fish fed higher levels of vitamin E. No significant lesions were observed in the other tissues examined.