I have caught many rabbits with Tape Worm cysts in them, some really infested some with a few. I'm absolutely sure if you fed them fresh you could pass those worms on to the ferrets. Also ferret need fat in their diet I think its 20% but don't hold me to that, rabbits sometimes don't have much fat, so a bit of extra fat would not go a miss. Some odd things can kill a ferret like Chewing gum I think its the sweetener in it know there others but can't remember them all, I know you guys would not feed them deliberately, but a bit of discarded gum could be a problem. Have a look at the bottom of