Title

Retinol and alpha-tocopherol utilization by captive pinnipeds

Date of Completion

January 1994

Keywords

Biology, Zoology|Agriculture, Animal Culture and Nutrition|Biology, Veterinary Science

Degree

Ph.D.

Abstract

This dissertation contains three studies designed to establish more consistent vitamin A and vitamin E supplementation practices among institutions maintaining captive pinnipeds and to aid in developing vitamin tolerance ranges and recommended daily allowances for captive pinnipeds. Blood was collected from pinnipeds maintained at Mystic Marinelife Aquarium, Mystic, CT. Serum was analyzed for vitamin A, vitamin E, and lipid content.^ In Study 1 blood was collected from 4 species of pinnipeds during routine physical examinations. Serum retinol, tocopherol, and cholesterol concentrations were compared using a one way ANOVA and significant species differences observed. Post hoc analysis using Scheffe's multiple comparison procedure showed that for retinol and tocopherol/cholesterol ratios the differences appeared to be between the 2 pinniped families (phocids: harbor and grey seals vs. otariids: fur seals and sea lions). There was also a significant positive correlation between serum tocopherol and cholesterol in otariids that was not observed in phocids.^ Studies 2 and 3 looked at vitamin A kinetics and vitamin A-vitamin E interactions in adult female northern fur seals. The mean sojourn time (average time a molecule of vitamin A spends in the body before being lost) was 40 days for one animal and 73 days for another. From the disposal rate, a daily vitamin A requirement of 0.32 to 0.64 umol was estimated for the two animals. The presumed upper safe level was calculated to be 1.3 to 6.4 umol vitamin A/day. From dietary analyses, appears that vitamin A requirements of northern fur seals can be met by diet without additional supplementation. In addition we found that high vitamin A supplementation (50,000 IU/day) caused a decrease in serum vitamin E concentrations after 30 days of supplementation. However, there was no change in mean sojourn time or disposal rate and there were no clinical signs of vitamin A toxicity or vitamin E deficiency.^ Through these studies we conclude that vitamin supplementation practices of some aquariums and zoos are unnecessarily high in vitamin A, at least for northern fur seals, and that there appears from our limited data to be differences in vitamin A and vitamin E utilization among phocid and otariid seals. ^