Thanks guys, good to some input into the thread. It's a difficult subject and the scientific studies are limited. There is never going to be funding to produce a scientific study pertaining to the UVB requirements of every species in the hobby sadly so we have to work with what is available. When a study shows that dietary supplement of D3 is inefficient and that UVB is not it is reasonable to take that as sound for the reasons stated rather than right it off because it isn't the exact animal you're dealing with. The mechanisms within the body are the same.

I think it's time to simplify things. The purpose of this thread is to discuss a very important part of correctly caring for captive animals and was prompted by seeing people new to the hobby asking about UVB and being given the answer that 'UVB isn't needed for frogs as we supplement with calcium' Apart from being incorrect, this advice disregards one of the most important biological requirements for captive animals that does need to be provided, (Vitamin D3) in order to avoid calcium deficiency.

So, can we all agree that D3 needs to be provided as without it calcium isn't utilised in the body? Or is the provision of D3 at all in question?

If we can agree, then we know that there are two ways to provide D3 in captivity. I promote UVB as it is the way that the animal has evolved to 'manufacture' D3 within it's own body in the wild and also offer many other benefits to the captive animal. With UVB the production of D3 is 'self-regulated' by the animal to produce the correct amount. It does need to be used correctly (placement, intensity and adequate cover all need to be addressed) and it does cost (although 20 bucks once a year shouldn't be beyond reach of anyone keeping animals, if it is that person shouldn't be keeping them).

The alternative method is oral D3 supplementation. I don't like this method because it has been shown to be inefficient, impossible to dose correctly and when overdosed (which is easy enough to do as it can't be dosed correctly) can slowly kill the animal through hypervitaminosis d and does not offer any of the other observed benefits of natural sunlight exposure.

I think at the very least new keepers asking the question should be told about the two alternative ways of providing D3.

For those who prefer to supplement instead of using UVB, could you explain how you work out the dosing for each of your species and how you administer that dose?