A) I'm not really out to change anyone's feeding religion, but just so all the anti-byproduct folks know, wonderful nutritious vitamin-rich stuff like liver, lungs, hearts, and kidneys (that a dog would actually be eating if it were out killing and/or scavenging its own meals) are "byproducts" according to AAFCO, which is the independent regulatory body that governs things like definitions of animal feed ingredients. So foods that contain organ meats *cannot* be labeled "no byproducts." And conversely, any food that wants to jump on the "no byproducts" marketing bandwagon is going to have to add more artificial/chemical supplementation, because the muscle meat you're paying extra for is pretty deficient in an awful lot of nutrients. On the other hand, "chicken byproduct meal" can actually be a very complete high-quality source of nutrition, despite the unappetizing name. Kinda ironic, no?
I am a whole prey model raw feeder (and I also feed about 20% super premium commercial canned, especially on days when I have a test the next morning). I try to recreate the carcass of the animal, so for instance, I buy whole roaster chickens (with giblets when I can find them) and feed organ meat as well (mostly a bit of liver, some gizzards and hearts, etc). I also have raw feeding friends that raise their own rabbits for this purpose (perhaps if I get a fence up this spring, I'll raise my own chickens). I also feed ground green cow tripe (along with a lot of other things, but anyways). As you correctly point out, by-products in and of themselves are not bad, especially when I can buy them locally from local farmers and support local sustainable agriculture where I know the animals have been raised humanely. These are all human grade meats, except for the green cow tripe, which technically cannot be sold for human consumption until it has been scalded and bleached.
However, as should be
abundantly clear from the numerous pet food recalls as well as the recalls of the beef from downed cows, these huge multi billion dollar companies look for the very cheapest of the cheap in terms of ingredients. If your average bag of Purina Dog Chow costs the consumer $0.30 a pound at Sam's Club, do you really think they are using high quality ingredients, including by-products? It doesn't take an MBA to realize that the bottom line of finding cheap sources of ingredients for these mass produced foods is more important than ensuring quality. How many times have I heard "it's
just dog food" as if we humans should exist on a higher plane of nutrition than dogs.
As the Whole Dog Journal commented in their February 2008 issue on dry pet foods:
We reject any food containing meat by-products or poultry by-products. It's just about impossible to ascertain the quality of by-products used by a a food manufacturer. We've spoken to representatives who swore they used only the finest sources of by-products, but when asked, they all say that! The fact is, there is a much wider range of quality in the by-products available for pet food manufacturing than there is for whole meats. Whole meats are expensive, and because they are expensive, dog food makers insist on their quality to an extent that is unreasonable when buying bargain-basement by-products.
B) One of our nutrition profs made a point about the use of corn in pet foods. It's true, a dog "in the wild" would not eat corn. But that doesn't mean that the dog's digestive system cannot extract good nutrition from corn and other grains. When it comes right down to it, whatever you put in the gut is broken down and actually gets absorbed as monosaccharides, amino acids, fatty acids... So as long as the food you're putting in has the right balance of building blocks, with good bioavailability for the particular species you're feeding, the source is really not critical to overall nutrition.
In your nutrition class, did you cover the chart which discusses bioavailablity and digestibility of various ingredients used for protein sources? It's the one where egg protein is the most digestible. Then we have various animal proteins and then on down the list, we have various plant proteins. I'm sure you learned that plant proteins are less digestible than animal proteins, as we covered that numerous times. I can't access the notes from that class or that particular chart, but corn was quite a ways down the list, below rice and soy, if I recall. So all those cheap calories (as that's what they are as by-products of the agricultural industry) can go in one end and out the other if it's not highly digestible like animal protein is. How do you know how digestible it is? Take a look at the fecal volume output of a dog on Science Diet, Purina Dog Chow, Beneful, Ol' Roy, compared to Canidae, Chicken Soup, Evo, Wellness, etc. and it's pretty obvious which is more digestible. If they can't digest it well, it ain't gonna be doing much good.
I am not one of the folks who thinks that all dog food should contain no grain at all. I realize that there has to be a way to bind together the kibble, either with something like potato, tapioca, rice, etc. I also realize that in the wild, wolves, pariah dogs, etc would be eating small rodents and rabbits pretty much whole and they would likely be eating a small amount of grasses and grains when eating those animals whole, especially seed and grain eaters like mice and voles. However, there is absolutely no need for all these foods to contain loads of corn, soy, wheat, sorghum, etc. that many of them do. A small amount is permissible. But animal nutritionists (and the companies they work for) spend huge amounts of money trying to see what they can get away with feeding to save money. It's just good business to them. And all that junk is for the most part just cheap calories, nothing more.
So the crux of it is, which I've asked on VIN multiple times and to which I have never got a single straight answer from any of the diplomates of the American College of Veterinary Nutrition is this: not
can dogs and cats eat grain heavy foods (as obviously they can with varying results), but
should they? As someone who wants to eventually do a nutrition residency (especially on the holistic side of things), I would resoundingly say
NO. They are not species appropriate ingredients in the levels that they are commonly found at. It is for human economics and for convenience that these grain heavy ingredients are used, nothing more.
