EFFECT OF DIETARY VITAMIN-E AND SELENIUM ON GROWTH, SURVIVAL AND THE PREVALENCE OF RENIBACTERIUM-SALMONINARUM INFECTION IN CHINOOK SALMON (ONCORHYNCHUS-TSHAWYTSCHA)

Groups of juvenile spring chinook salmon naturally infected with Renib acterium salmoninarum, the causative agent of bacterial kidney disease , were fed diets containing different levels of vitamin E and selenium for 214 days in fresh water and 110 days in seawater. The fish were f ed vitamin E at concentrations of either 53 +/- 3 mg (designated e) or 299 +/- 9 mg (designated E) alpha-tocopheryl acetate equivalence/kg d ry diet in combination with sodium selenite to give selenium concentra tions of either 0.038 +/- 0.008 mg (designated s) or 2.49 +/- 0.15 mg (designated S)/kg dry diet. No mortality occurred in the group fed the S/E diet, whereas mortality was 3% in the groups fed the s/E and S/e diets, and 31% in the group fed the s/e diet. At the end of the experi ment, weight gain and hematocrit values were significantly greater in those fish fed the E diets compared with those fed the e diets, wherea s the hepato-somatic index was significantly higher in fish fed the e diets. Glutathione peroxidase activity in blood plasma was significant ly higher in fish fed the S diets compared with those fed the s diets. No definite effect of dietary vitamin E and selenium on the prevalenc e and severity of natural R. salmoninarum infections was demonstrated.