After reading Omnivore's Dilemma awhile back, I have been scrutinizing the diets of domestic and farm animals whenever the subject arises.  Michael Pollan, the author of the aforementioned book, discusses in depth how we are feeding animals an unnatural diet in order to make them bigger, fatter, and in a hurry.  "Unnatural" here refers to one of the basic definitions of the term: Contrived or constrained; artificial.  Is your beef corn fed?  It shouldn't be.  Cows, Pollan argues (and after no small amount of research on his part), are suited, built, designed, etc. to eat and digest grass.  For poultry, it's a combination of grass and bugs, yet we feed these corn as well and dupe people by saying, "At least it's an organic diet!"

I'm not here to talk about this, though. Just read his book; it's very good.

Often I see a commercial for dog or cat food that is similarly duping people into buying it.  They lure us in with the real chunks of chicken or tuna, and then seal the deal with a few whole grains.  Because humans recognize this as a balanced diet (albeit, FOR HUMANS), many assume it is for our pets as well.  I promise you that if you plop down a selection of foods before a cat--meat, rice, corn, soybeans--the cat will dive into the meet and maybe lick at the others before deciding not to eat them.  Dogs, at least the ones I know, will eat everything you put in front of them, except for medication.  Those, of course, always wind up suspiciously untouched at the bottom of the bowl.

My real gripe here is with the bizarre "flavor" combinations cat food companies devise.  The worst, most gag-inducing one we feed my cat is "Flakes of tuna & egg bits."  Let it be known that the egg bits aren't even technically egg, and the finished product looks like a product my cat just finished vomiting onto the floor.