Influence of dietary vitamins A and E on serum alpha- and gamma-tocopherols, retinol, retinyl palmitate and carotenoid concentrations in Humboldt penguins (Spheniscus humboldti)

Serum retinol, retinyl palmitate, beta-carotene, cryptoxanthin, lutein, alp ha-tocopherol and gamma-tocopherol were measured in 18 captive Humboldt pen guins (Spheniscus humboldti) prior to and following the removal of Columbia River (CR) smelt (Thaleichthys pacificus) from the diet. Dietary vitamin A was reduced from 9.8 to 13. IU g(-1) (dry matter basis) when CR smelt was removed from the diet. Minimal changes were noted in dietary vitamin E. Ser um samples Without-CR smelt had significantly lower circulating retinol (1. 19 +/- 0.09 vs. 1.94 +/- 0.05 mu g ml(-1)) and retinyl palmitate (0.033 +/- 0.012 vs. 0.012 vs. 0.105 +/- 0.004 mu g ml(-1)) compared to samples With- CR. The Without-CR smelt diet resulted in increased serum alpha-tocopherol from 26.4 +/- 0.94 to 39.1 +/- 3.72 mu g ml(-1). More serum samples taken W ithout-CR smelt had detectable levels of gamma-tocopherol than those With-C R smelt. Serum lutein was higher for the samples taken Without versus With- CR smelt. Serum cryptoxanthin did not differ. beta-Carotene was not detecte d. Data indicate that high levels of dietary vitamin A can affect circulati ng levels of retinol, retinyl palmitate and vitamin E. Thus, dietary vitami n A and the interrelationship between vitamins A and E should be considered when assessing captive penguins. (C) 1998 Elsevier Science Inc. All rights reserved.