Effects of Sunlight, Artificial Light and Oral Vitamin D Supplementation on 25-Hydroxyvitamin D Levels in the African Blackfooted Penguin
Circulating levels of 25-hydroxyvitamin D (25-OH-D) were determined in 24 African blackfooted penguins (Spheniscus demersus)
housed at two separate facilities. Twelve penguins were housed at one facility in an exhibit with daily exposure to ambient sunlight; 12 birds at the
other facility were housed indoors under incandescent lighting. The birds in each environment were subdivided into three groups of four which received
daily oral supplements of 0, 1,000, or 50,000 IU vitamin D over a period of 30 days. The diets of the birds were otherwise standardized, drawing from the
same lot of food fish. Blood samples were collected on day 0 and 30, and serum was harvested for analysis of 25-OH-D using a competitive protein-binding
micro-method assay. Baseline 25-OH-D levels (day 0) for birds housed with exposure to sunlight was 13.02 +/- 9.52 ng/ml but undetectable (less than 2.5
ng/ml) in those housed indoors. Seven of the eight birds housed indoors and receiving oral vitamin D supplements had significant elevations (~5X) in
25-OH-D levels at day 30. All low dose birds housed with exposure to sunlight had significant elevations (~2X) in 25-OHD at day 30 whereas such an effect
was not seen in high dose birds maintained in the same environment. We as yet, have no satisfactory explanation for the lack of change in day 30 25-OH-D
serum levels in high dose supplemented birds maintained in an outdoors exhibit.
This study was partially funded by a grant from Mystic Marinelife Aquarium and the Collins and Aikman Foundation. We thank Heather
Urquhart and the husbandry and laboratory staff at the New England Aquarium and the Mystic Marinelife Aquarium. We also thank the staff of the Boston
University Medical School Vitamin D Research Lab for their laboratory assistance.