Hi all
That's a very interesting theme. Two weeks ago was held in the Zoo of Barcelona a 3 days conference on The Year of The Frog organised by Jersey Zoo, Barcelona Zoo, Fuengirola Zoo, Amphibian Aark, Gerarld Durrell Wildlife, etc. 40 people attended from Spain, Portugal and England with different profiles: biologist, herpetologists, societies, specialised veterinarian (I was stunt about the veterinarian expertise), private breeders, and so on. All veterinarian talk about UVA-UVB, and some did some research along with other specialists around the world. They took different species of wild and captive amphibians (mainly frogs, toads, newts and salamanders), and they X-Ray them. All captive breed animals show BIG BONE DEFICIENCIES OF CALCIUM, even broken bounds on dendrobates species! And non of the wild animals show any problem. The conference was really technical, so unless you were a veterinarian you can hardly follow the presentation. But, to sum up, they basically agreed that low levels of UVA-UVB light was essential for most species (obviously not for cave ones, underground burrows species as a. maculatum, purely aquatic ones, etc ), further research was needed due to huge variations on species. If new captive breed animals were expose to natural light they didn't show the problem any more: F3 generation if was keep outdoors didn't show any calcium deficiency or deformity as they parents do in indoors facilities. Regarding D3, Calcium and other vitamins, they also agreed that a big variety of food along with vitamin supplements were essential too. Research on the amount of each specie vary so they agreed that further research must be done on those issues urgently.
It was very interesting conference, and though all captive animals seem absolutely healthy by bare sight when they X-Ray them the images on the projector compare to wild ones were revelling: huge bone malformations and calcium deficiencies. The main issue is that amphibians without UVA-UVB light can live and breed but those animals are not healthy and can be week as a glass