Preliminary observations on the relationship of calcium ingestion to vitamin D status in the green iguana (Iguana iguana)
✍ Scribed by Olav T. Oftedal; Tai C. Chen; Jay Schulkin
- Publisher
- John Wiley and Sons
- Year
- 1997
- Tongue
- English
- Weight
- 48 KB
- Volume
- 16
- Category
- Article
- ISSN
- 0733-3188
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✦ Synopsis
We hypothesized that vitamin D-deficient green iguanas with depleted calcium stores would seek to augment calcium intake by self-selection of a high calcium source. Eight green iguanas were offered free-choice ground oystershell in addition to their regular diet. Of these, two had not been exposed to ultraviolet (UV-B) radiation for > 5 years and were demonstrated to be vitamin D-deficient by low circulating levels of the principal vitamin D metabolite, calcidiol (25-hydroxy-cholecalciferol). The six others had been exposed to a UV-B emitting bulb for the previous 3 years and had high circulating calcidiol levels. Average daily food intake (expressed as dry matter per kg body mass) did not differ between the Low-D and High-D iguanas. The daily oystershell intake of the Low-D iguanas (0.02-0.03 g/kg) was lower than that of the High-D iguanas (0.06-0.70 g/ kg), leading to a significant difference in calcium intake. The failure of iguanas to increase calcium intake in response to vitamin D-deficiency was puzzling and suggests that vitamin D, as a steroid hormone, may play some role in the expression of calcium appetite. Zoo Biol 16:201-207, 1997.