The relevent passages:
6. Since we are still in the topics of nutrition, what is your standing on the necessity of supplementing a preformed vitamin A VS beta-carotene?
I went through a period where I gut-loaded crickets with carrots but deprived them of preformed vitamin A and the chameleons developed vitamin A deficiency. This was surprising because humans can use beta-carotene for our vitamin A needs. So, I recommend using preformed vitamin A either as a direct supplement or in insect feeds.
7. Are you familiar with the reason why they cannot convert beta-carotene into Vitamin A? Also, how is it in the wild, they satisfy their need of Retinol? As a chameleon keeper, this topic seems to be controversial among people. Is there a more thorough study that addresses this matter?
I don’t know why the carotene in carrots couldn’t be converted. It could be that other carotenes in the guts of wild plant-eating insects can be. It could also be why panthers sometimes occasionally eat lizards and nestling birds, which should be a good source of retinol. I think it is a good idea to feed panthers large pinkies or small lizards, such as anoles, occasionally, if they will eat them. There indeed needs to be more study on this subject.