You sid..."I worry about vitamin A because its one of the important vitamins that ties in with calcium and MBD prevention. I did not want to go through the prEformed vitamin A because I was scared of it being too toxic"...calcium, D3, phos. and vitamin A are all important players in bone health and need to be in balance....but the vitamin A is antagonistic somewhat to the D3 which I think is the main reason for even mentioning it/bringing it into the balance. Vitamin A (as well as the other nutrients) also serves other purposes in the body as well.
The reason I always use the vitamin with beta carotene is that it can not build up in the system because it can only serve a purpose if its converted...and it leaves the chameleon's owner to control the amount of prEformed vitamin A given to the chameleon, if any.
As far as insects and vitamin A...they should all have some retinyl in their eyes...but I can't find anything that says they have it other places...but I suspect that at least some of them store it in a different manner than reptiles or mammals do. I keep working on finding this out...but have very little concrete information so far.
This site explains some of it...
http://web.archive.org/web/20060502...rnals.com/vet/index.php?show=5.Vitamin.A.html
http://web.archive.org/web/20060421.../index.php?show=6.Vitamin.D3.and.Calcium.html
You said..."I feed my cham Kale and that's a good source of vitamin A"...the vitamin A in kale and other greens and veggies is prOformed though and has to be converted....so if the chameleon can not convert vitamin A then it wouldn't do it any good. (And I'm not saying that chameleons can or can't convert it...I'm just pointing it out.)
I can tell you that I use only Rep-cal with and without D3 and Herptivite (as described by me many times on this forum) and I gutload/feed the crickets, etc. with a wide assortment of greens and veggies as I've described many times on here. I have also mentioned that I have no control over what the insects are fed before they come to me so I can not be sure how much prEformed vitamin A they would have or retain after I've gutloaded/fed them. Keeping my veileds, for example, the way I do most of the females live to be over 6 and the males even longer. If they were lacking nutrients or over-supplemented, I would have thought that it would be showing up.
Sorry I can't give you any more concrete answers than this.
