ALPHA-TOCOPHEROL LEVELS IN DIFFERENT ORGANS OF ATLANTIC SALMON (SALMO-SALAR L) - EFFECT OF SMOLTIFICATION, DIETARY LEVELS OF N-3 POLYUNSATURATED FATTY-ACIDS AND VITAMIN-E

Atlantic salmon (Salmo salar) juveniles were fed a basal diet coated with 16% sardine or capelin oil (68 or 42 g n-3 PUFA per kg dry diet, respectively), each supplemented or not with 300 mg DL-alpha-tocopheryl acetate per kg. The unsupplemented diets contained 28 +/- 4 and 31 +/- 9 mg/kg alpha-tocopherol, respectively, There was a 5-7-fold increase in whole body alpha-tocopherol concentration in response to vitamin E supplementation, but the relative distribution of alpha-tocopherol between organs was similar in all groups, There was only a weak effect of dietary n-3 PUFA on the tissue levels of alpha-tocopherol, The ratio of alpha-tocopherol to PUFA in the fish tissues is probably critical in protection against lipid oxidation, and may modulate the vitamin E requirement. During smoltification, the whole body alpha-tocopherol concentration was unchanged or slightly increasing. All groups showed a 40-50% reduction of alpha-tocopherol concentration in the kidney and adipose tissue, possibly linked to changes in osmoregulation and mobilization of vitamin E. The body level of alpha-tocopherol seems to be higher in fish than in mammals, A species-specific tissue ''distribution key'' for alpha-tocopherol appears to be present in several fish and mammal species.