Lisa M. Mazzaro; J. Lawrence Dunn; Harold C. Furr; Neal A Overstrom; Richard M. Clark
University of Connecticut, Storrs, CT; Mystic Marine life Aquarium, Mystic, CT
A survey of twenty North American institutions which maintain captive pinnipeds finds most institutions provide vitamin A and E supplementation to their pinnipeds; however, there is wide variation in the amounts of vitamin A and E supplemented Vitamin A supplementation ranged from zero to 49,000 lU/day (14,700 ug/day) and vitamin E supplementation ranged from 50 to 4000 IU/day (34 to 2685 ug/day). The most common amounts being administered were 5000 IU vitamin A/day and 400 IU vitamin E/day.
Several researchers have demonstrated that high concentrations of vitamin A in the diet increase vitamin E requirements in rats, chickens, and cattle. It appears that vitamin A interferes with vitamin E in the gut. This study shows that this interaction may also take place in the northern fur seal and that some current vitamin A supplementation practices may be high enough to result in decreased serum vitamin E concentrations. In this study adult female fur seals (n=9) were given a vitamin A (retinol palmitate) supplement of 51,760 IU/day, for two months, (approximately 10 times their usual vitamin A supplement and 4 times their total daily retinol intake). Supplements were administered orally in capsules placed into the food fish. Blood samples were drawn from the hind flipper after zero, 30, and 60 days of vitamin A supplementation. Serum was analyzed for retinol, alpha-tocopherol (Toc), and phospholipid (PL).
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Prestudy
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30 Days
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60 Days
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Retinol (ug/ml)
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0.67
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0.69
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0.70
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Tocopherol (ug/ml)
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13.06
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11.61*
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13.19
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Phospholipid (mg/ml)
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3.90
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3.91
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4.27
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Toc/PL (ug/mg)
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3.41
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3.04*
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3.20*
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* significant difference (p<0.05) from prestudy levels.
Vitamin E in the blood is carried by lipoproteins and is affected by the intake of vitamin E and by blood lipid levels. For these reasons vitamin E is usually reported as E/lipid ratio. In a previous study with these pinnipeds a significant correlation was found between serum tocopherol and serum phospholipid and hence we chose to report vitamin E levels in this format.
Vitamin A supplementation was associated with a decrease in serum tocopherol levels at one month followed by a recovery to prestudy levels by two months. There was no noticeable change in serum retinol concentrations. More information is needed about the absorption, metabolism, and interactions between these two vitamins in pinnipeds in order to determine the amount of supplementation necessary to maintain these animals in the best possible nutritional status. (Supported by the Sea Research Foundation.)