A lot of foods have by-products which are usually heads, necks, stomach contents, organs, etc. That turns some people off though I've yet to see a dog not eat that stuff if they come across a carcass in a field. Frankly, to me its everything people feeding their dogs a raw diet would give and I don't see the big deal if say, chicken by-product meal, is included in a dog food's ingredients. Watch a nature program with wild dogs and wolves and you'll see them eating these parts of the animal. I would make sure the by-product meal was specific such as chicken or lamb by-product meal and not just listed as "poultry", "meat" or "animal" by-product meal.
...I read this somewhere and thought it described by-products perfectly:
It's not meat, but the organ matter from the chicken, the guts, liver, heart, brains, intestines, stomach etc. I think this is a human thing, because those organs are always the first to be eaten by wild canids, wild felines, and pretty much any other. They don't go for the 'meaty haunch', they go for the gut and pull out all that gooey stuff and eat it.
Meat byproducts in dog food by law do not include hair, horn, teeth or hooves, feathers or manure. It does include organs, including the lungs, spleen, intestines, brains, kidneys and liver, and in the case of chicken byproducts will include the head and feet. About 50 percent of a slaughtered cow will not go for human use, most of this leftover goes into the pet food industry, not because it's unhealthy. How many of us rush out to the grocery store to eat a daily meal with tripe (stomach), chitlins (intestines), and scrambled brains? Believe it or not, while organ meats are gross to think of eating to humans, they are also extremely high in natural vitamins and minerals.[/b]