No offense to the OP but this sounds like a bad idea on many levels. If you want to figure out what to feed deer, ask your state's Fish and Game/Wildlife biologists or wardens. Chances are they will tell you not to do it or that it's not legal, etc. If they do give you the go ahead, they should be able to recommend something that is healthy for deer. Instead of having tourists hand feeds the deer, you might consider a food plot. Another thought is what will happen when more predators come around, especially with sickly deer and start eating the deer? That probably won't go over well with your guests.