I don't mix the food - Jamie gets a different kind every day. He's almost 4, and he's never had trouble with an upset stomach, diarrhea or vomiting. Of course, he might just have an "ironclad stomach". All the different brands were his idea, i.e. at his insistence, not mine. It is more expensive than buying just one or two brands, since I have to stick to small bags/cans, but I don't feel it's hurting him in any way. It's also sometimes hard to keep track of his weekly menu, though if I make a mistake he tells me about it. His idea of heaven is lots of little sample bags of premium dry foods. I hesitated about going along with it, but then I thought about what cats eat outside - not just mice and rats, but moles, garter snakes, butterflies, fish, dragonflies, birds, spiders, etc., in other words, a variety of things.
