STUDY OF VITAMIN-A SUPPLEMENTATION IN CAPTIVE NORTHERN FUR SEALS (CALLORHINUS-URSINUS) AND ITS EFFECT ON SERUM VITAMIN-E

Two experiments were conducted to determine the effect of vitamin A su pplementation on serum vitamin E in adult female northern fur seals (C allorbinus ursinus). In the first experiment five animals received, in addition to their routine dietary multivitamin supplement, a high-lev el vitamin A supplement (53 mu mol retinyl palmitate/d) for 30 d. Five seals consuming their routine dietary supplement served as controls. Serum vitamin E decreased significantly in animals receiving high-leve l vitamin A supplements. At the end of 30 d serum vitamin E averaged 1 8.6 mu g/mL in the control animals and 13.4 mu g/mL in the animals rec eiving the high-level vitamin A supplement. In experiment 2 ten animal s received the high level vitamin A supplement for 60 d. After 30 d, s erum vitamin E levels were reduced, but by 60 d had returned to baseli ne levels. However, the ratio of serum vitamin E to phospholipid, anot her index of vitamin E status, remained decreased. Although the exact mechanism of interaction is unknown, this study shows that when provid ing vitamin supplements for captive pinnipeds, vitamin interactions mu st be considered. The vitamin A supplementation currently used by some institutions seems unnecessary and may have detrimental effects on vi tamin E status.