I'm not against any of those organs, but from what I've read they use all the sick birds in it. And after seeing photos of battery hens, even the healthy ones look rather sick.I don't tend to shy away from by-products as much as I used to in dry or canned foods. Lungs, spleen, and liver sound gross to us but if your cat catches a mouse, or when they catch fish from the river, they will more than likely consume those parts.
Maybe I'm very wrong, but my impression was anything they thought was too nasty for people to eat, they put in dog and cat food.
Am I wrong? I would like to be!