Then there are claims about "USDA approved" ingredients, "human grade" ingredients and ingredients purchased right out of the meat counter at the grocery store. Again, at first glance - and superficiality is what marketers like to deal with - it may seem that such foods would have merit over others. But such labels only create a perception of quality. People would not consider the food pets are designed for in the wild - whole, raw prey and carrion - "human grade" or "USDA approved." Because something is not "human grade" does not mean it is not healthy or nutritious. For example, chicken viscera is not "human grade" but carries more nutritional value than a clean white chicken breast. Americans think that chicken feet would not be fit for human consumption but many far eastern countries relish them. On the other hand, "human grade" beef steaks fed to pets could cause serious nutritional imbalances and disease if fed exclusively. Pet foods that create the superficial perception of quality (USDA, human grade, etc.) with the intent of getting pet owners to feed a particular food exclusively is not what health is about.
There are also the larger concerns of the Earth's dwindling food resources and swelling population. Should "human grade" food products be taken out of the mouths of people and fed to pets with all of the excellent nutritional non-"human grade" ingredients put in the garbage?
Are By-Products Bad?
From a nutritional as well as ethical standpoint, the benefits of incorporating by-products into pet foods cannot be denied.
The Whole Dog Journal advises pet owners to reject any by-products and instead seek “whole meats.” This demonstrates their lack of understanding of the nutritional merits of the various parts of food animals. Whole Dog and others in the pet food marketplace pushing the "no by-products" claim seem unaware of the fact that “by-product” is a mere word invention. It creates a negative connotation, but has nothing to do with health or nutrition. Pet health and nutrition are not about superficial impressions created by word labels. Feeding just muscle meats to pets is a serious error since no carnivore in the wild eats such a diet. If they did, they would become diseased from doing so
while it relates to a different list this site perpetuates many of the same myths
Critique Of Internet 'Rate Your Dog Food' List