AAFCO stands for Association of American Feed Control Officials. They are in charge of many things in relationship to ingredients required in pet and livestock feed but their certification should never be assumed to reflect quality of the food.
AAFCO defines what ingredients are, and nutritional requirements for pets.
So they might define what by-products are and how much protein a pet of a certain type might need in their food. They do not regulate where the protein (for example) comes from which is why so many lower quality pet foods use corn as a protein source, even though corn is hard to digest and low in nutrition otherwise. As mentioned in another article, cats are carnivores, so why is there corn in some cat food?
So if a food contains a label saying it is AAFCO approved it only means that the food meets certain minimum or maximum standards for the amount of protein, and so forth.
In a study done to educate the public into being cautious in regards to assuming the AAFCO requirements mean a pet food is good quality a theoretical dog food was made using leather boots (protein), motor oil (fat) and sawdust (fiber) and that under the rules for percentages, such a food could be approved and labeled “Nutritionally Balanced” by the AAFCO.
All pet owners should become more familiar with the definitions of the ingredients in their pets food and the ingredient list is really the first thing they should look at when selecting a pet food. For example here is the AAFCO description of meat by products.
“Meat By-Products – the non rendered, clean parts, other than meat, derived from slaughtered mammals. It includes, but is not limited to, lungs, spleen, kidneys, brain, livers, blood, bone, partially defatted low-temperature fatty tissue and stomachs and intestines freed of their contents. It does not include hair, horns, teeth and hooves.”
What you do not see is that meat by-products can be meat from any animal, and in the past many pet foods did use euthanized cats and dogs. A huge study triggered by animal shelter veterinarians noticing that it was taking more and more medication to euthanize pets and theorizing that these pets had built up an immunity of sorts to the drugs sent this into the spot light years ago and many companies discontinued the practice. Currently there is no rule against the use of euthanized cats, dogs, or livestock, in pet food and the EPA has documents indicating such.
By-products can include cancerous tumors and so forth, and worse still is that by-products are preserved with a chemical pesticide (Ethoxyquin) which is highly regulated in livestock feed and banned for human use, and is considered so vile that some countries (such as Japan) forbid it altogether).
In order to find a good quality pet food pet owners can look for hints such as “All Natural” and “Human Grade Ingredients” but these terms are not highly regulated. As a general rule though any pet food with by-products, should be held suspect as being of low quality as by-products (among what was mentioned earlier) are really nothing more than cheap filler.
There are many other questionable ingredients used in pet foods including color dyes (linked to behavior problems, also pets are colorblind to red so these dyes have no value as far as the pet is concerned), BHA, and BHT (cheap preservatives), corn gluten meal (filler), and so forth.
Other Reading on Pets and Feeding