Nutrition of tortoises and other reptiles (Merck): calcium:phosphorus, vitamin D3, UVB
Source: Merck Veterinary Manual article "Nutritional, Metabolic, and Endocrine Diseases of Reptiles" (first-hand, retrieved 2026-07-29 via curl, HTML stripped to plain text). All bullets are exact verbatim substrings of the cited source_file and C1-substring verified.
Calcium, vitamin D3 and UVB for herbivorous chelonians
nutritional hyperparathyroidism is the most common bone disease encountered in reptile practice. It is caused by poor diet (low calcium:phosphorus ratio, vitamin D 3 deficiency) or poor husbandry (lack of UVB light, inadequate thermal provision)herbivorous and insectivorous lizards and chelonians.