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

Abstract

Two experiments were conducted to determine the effect of vitamin A supplementation on serum vitamin E in adult female northern fur seals (Callorhinus ursinus). In the first experiment five animals received, in addition to their routine dietary multivitamin supplement, a high-level vitamin A supplement (53 pmol 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-level vitamin A supplements. At the end of 30 d serum vitamin E averaged 18.6 pg I mL in the control animals and 13.4 pg/mL in the animals receiving the high-eve1 vitamin A supplement. In experiment 2 ten animals received the high level vitamin A supplement for 60 d. After 30 d, serum vitamin E levels were reduced, but by 60 d had returned to baseline levels. However, the ratio of serum vitamin E to phospholipid, another index of vitamin E status, remained decreased. Although the exact mechanism of interaction is unknown, this study shows that when providing vitamin supplements for captive pinnipeds, vitamin interactions must be considered. The vitamin A supplementation currently used by some institutions seems unnecessary and may have detrimental effects on vitamin E status.

Serum Retinol, alpha‐tocopherol, and lipids in four species of adult captive pinnipeds

“…When we recalculated, not correcting for body weight, there was no difference in total daily vitamin A intake levels between the two families (Table 2). Likewise, in a previous study with northern fur seals, serum retinol did not appear to be influenced by the amount of vitamin A consumed [Mazzaro et al, 1995a].…”

“…In a previous study with northern fur seals, serum vitamin E varied with dietary intake and supplement consumed by the animals [Mazzaro et al, 1995a]. In the current study, the animals received similar diets.…”

“…However, excess vitamin A can effect the metabolism of other fat-soluble vitamins. Depressed vitamin E utilization with high dietary vitamin A has been noted in many species, including northern fur seals, in which moderately high levels of vitamin A supplementation had a negative influence on circulating vitamin E [Mazzaro et al, 1995a].…”

“…Mazzaro et al [1995a] reported on the effect of vitamin A supplementation on serum vitamin E levels in northern fur seals (Callorhinus ursinus). The results of this study confirmed a reduction in serum a-tocopherol in animals fed high levels of vitamin A.…”

Changes in haematological parameters in relation to prey switching in a wild population of harbour seals

“…However, all marine fish are relatively rich in these nutrients (Braekkan 1962;Holland, Brown & Buss 1993) and dietary deficiencies seem unlikely. Alternatively, nutrients or antimetabolites present in certain prey may interact with, and affect the absorption of these or other essential nutrients (Geraci 1981;Mazzaro et al 1995). Anaemia has previously been reported in farmed mink and foxes fed gadoids, and experiments suggest that these fish contain a heat-labile antimetabolite which reduces iron absorption, resulting in anaemia, decreased growth rates and increased mortality (Helgebostad & Martinsons 1958;Stout, Oldfield & Adair 1960).…”