The death of your birds due to hypervitaminosis D is not an uncommon problem. Oversupplimentation of certain vitamins, especially the fat soluble vitamins such as A, D, and E can result in potentially toxic levels of these vitamins in animals bodies. This is a problem that we see more commonly in birds than other species. Commonly the cause is just as you described, adding vitamin suppliments to a pelleted or formulated diet that has already been made to be nutritionally complete. (ie. adding the Zupreem supliment to the Kaytee food.) The same results could have happened if you had put Prime vitamin suppliment over his food. We don't see this problem in mammals as much because nutritional studies have been completed on these animals and people don't often suppliment dog and cat foods with extra vitamins. HOWEVER, in these days of extra suppliments and nutritional additives I suspect we will start to see a reoccurance of these common nutrtional diseases in all pets. In fact with the number of ferrets that are recieving ferritone, pet tinic, lixotinic, ect. I am suprized that we have not seen more of this problem in our ferret populations. As for ferret food I reccomend a good quality high protein (>28%) food such as totally ferret. Marshals is an acceptable second choice. Zupreem is also an excellent choice but it tends to make ferrets fat! As an aside it was probably both the liver and kidney that were involved since vitamin overload affects both organs. The Animal Medical Center Avian and Exotic Pet Medicine ABVP(Avian) Resident 510 East 62nd St. New York, NY 10021-8302 [log in to unmask] (212)329-8714 [Posted in FML issue 3113]