Abstract

Vitamin D is essential for the maintenance of calcium and bone metabolism in vertebrates, and deficiency can contribute to a variety of forms of metabolic bone disease (MBD) including osteomalacia/rickets, osteoporosis, and secondary nutritional hyperparathyroidism.^1,2 Metabolic bone disease has been documented in various species of birds (primarily domestic seed-eaters),³ but also in Humboldt penguins managed under human care⁴. After the diagnosis of metabolic bone disease in a 6 year old female African penguin, an investigation into the vitamin D status of the collection was undertaken. Serum was collected from 56 African penguins ranging in age from 4 months to 28 years who were housed indoors (without full-spectrum UVA/UVB lighting) and fed a diet of comprised of herring, capelin, silversides, and/or squid. Serum samples were submitted to Hartland Assays for total calcium, 25-hydroxyvitamin D (25(OH)D), 1,25-dihydroxyvitamin D (1,25(OH)₂D), vitamin D₂ and D₃ testing. Prey samples were simultaneously sent for vitamin D₂ and D₃ testing. Mean serum 25(OH)D levels in the African penguins in this study were higher than those reported in healthy Humboldt penguins,⁴ although different analytical labs were utilized. Serum lab results identified four penguins (ages 6, 7, 23 and 28 years) with low 25(OH)D and vitamin D₃ levels compared with conspecifics. These four individuals routinely consume a diet comprised almost exclusively of capelin, which also tested low in 25(OH)D and vitamin D₃ compared with the other fish species. Oral supplementation with vitamin D₃ (300 IU, with 500 mg of calcium) TIW was started, and the birds were re-tested 3–4 months later with little improvement in 25(OH)D, the analyte most indicative of overall vitamin D status. Oral vitamin D₃ supplementation doses have been increased, and serum samples will be analyzed in the coming weeks to determine if 25(OH)D levels have increased. This on-going study will continue to monitor vitamin D levels in the entire Georgia Aquarium penguin collection with more frequent monitoring occurring in the individuals receiving vitamin D₃ supplementation in response to suspected deficiency.

Acknowledgements

The authors wish to the thank both the Department of Animal Health and the Zoological Operations, Mammal and Bird teams at the Georgia Aquarium for their assistance in animal handling and sampling.

* Presenting author

Literature Cited

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