Hyperlipidemia and reproductive failure in captive-reared alligators: vitamin E, vitamin A, plasma lipids, fatty acids, and steroid hormones

Blood samples were collected from 26 captive-reared alligators (25 females; one male) and 12 (seven females and five males) wild 'nuisance' alligators collected by wildlife personnel in south Louisiana in May 1995. The captiv e alligators, hatched from artificially incubated eggs in 1972-1973, had re ceived vitamin E supplements during the 3 weeks before the blood sample was collected. Each sample was analyzed for vitamin E (alpha -tocopherol), vit amin A (retinol) total lipid, triacylglycerol, phospholipid, cholesterol, c holesteryl ester, free fatty acids, steroid hormones and a standard clinica l blood panel. The fatty acid composition of the plasma lipid fraction was also analyzed. Results indicated that 18 of the captive females and three o f the seven wild females were undergoing vitellogenesis, i.e. had elevated plasma estradiol and elevated plasma calcium. Vitellogenic females had high er vitamin E than non-vitellogenic females (77.4 mug/ml vs. 28.6 mug/ml in captive females, 24.0 mug/ml vs. 21 mug/ml in wild females). Plasma retinol was similar in all groups, ranging from 0.5 to 1.4 mug/ml and close to val ues reported in birds. All lipid fractions. with the exception of cholester yl ester, were higher in captive alligators than in wild alligators. There were also significant differences in the fatty acid composition of wild and captive alligators. Plasma eicosapentaenoic and docasahexaenoic acid were higher in wild than in captive alligators, whereas linoleic was higher in c aptive than in wild. (C) 2001 Elsevier Science Inc. All rights reserved.