Is corn really well digested an dutilized by dogs and cats? Everywhere else I've read when looking at discussions of dog foods have said that corn is not easily digested.
That's what I was taught in school. So then I went to the vet forum and did a bit more reading - basically it comes down to (as far as I can tell): Cooked ground corn is a good source of protein and carbohydrates. It is not quite as good a source of protein as meat. But it's a lot cheaper so it gets used a lot. Some animals develop sensitivities to it, but beef, wheat, egg, chicken, fish are more likely to cause allergies (or more accurately, be a target for allergies). Some animals do better on a low or no corn/grain diet. Some animals do just fine on a regular corn/grain diet. Some vets have great success in putting an itchy dog on a no-grain diet... but they also do some other things at the same time, and it might not necessarily be the no grain, but something else about the diet that's helping. Whole or uncooked corn would not be very well used. But when cooked and ground up, all the useful bits are now easily exposed to the gut for absorption, so it works. Might not be the best ingredient to be the top one or two, but probably not bad if it's a little further down the list. Just like lots of other things. Dry foods need something to hold them together - once you get above a certain percentage of protein, a) it doesn't hold together and b) it becomes less palatable. That's why canned foods typically have less grains than dry foods.
There are more and more vets out there who are advocating more "alternative" diets. Holistic vets are especially at the forefront of this movement. But most vets are a little older, so they know and are comfortable with the foods they've always used. I personally tell people that if their pet is healthy, happy, not itchy, active, and has a good coat, it's probably working. If one or more of the above is not true for a particular pet, then we might talk about diet choice. I tell people to read the ingredients, not to be afraid of meals or by products (one means the ingredient is ground up, the other means that it's an animal part a human might not normally eat - and the legal definition does not allow nondigestible parts get called a byproduct). I tell them that there are plenty of good diets out there, that the big companies have the most research behind them, but the smaller ones are probably using information published by the big companies. The brand new little companies don't have as much time behind their diets... but the big companies also reformulate their diets from time to time. I tell people that what they feed is a personal choice (though I do try to say something to discourage them from feeding whatever is cheapest) and if they're going to go with a particular company that has multiple lines of food (e.g., Purina has the Chows, the Ones and the ProPlans), to go with the highest quality of that brand's food (in this case, the ProPlan, which happens to be what I feed my cat). I tell people who are home cooking or raw feeding that I strongly recommend they talk to a nutritionist to make sure it's balanced and offer to get them phone numbers (most of these people decline...), and to be very careful with the handling of the food. I don't generally tell them not to do it (though I might if the animal had immune problems or had an illness where that diet wasn't a good idea - e.g., a pancreatitis dog who was getting a lot of fatty meat). I tell people who don't seem to have done much research into home cooking that it's probably better for their dog to feed a formulated diet, especially if these people don't seem interested in learning. But "it's doing fine" and/or "my parents fed their farm dogs like this for years and they always did ok." *sigh*
My favorite two would be the client who feeds their chihuahua a combination of kitten food and table scraps because he won't eat anything else (maybe because he knows they'll give in and give him the tastier stuff?) and the Scottish deerhound who gets forcefed three times a day a variety of rather interesting things (whole boiled eggs, raw and cooked ground meat, yoghurt, fish oil, "super fat balls" (which ingredients I never did figure out), rotisserie chicken, PetTabs among other things...) because he didn't eat well on his own (would you if you were forcefed three times a day?)... and the breeder she got the dog from is a Nationally Renowed Deerhound Nutrition Expert and Says That This Diet Is Fine, so referral to a veterinary nutritionist isn't necessary...
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