When you see the word by-product on a pet food label, it means the food contains protein derived from meat-processing leftovers like chicken feet and beef intestines. These tasty morsels are tossed in a pot, simmered into a slurry, and baked to yield a concentrated dried protein known as by-product or meal.
When by-products are identified by the animal they come from (i.e.: beef, chicken, or turkey), they earn a pet-food grade level and perfectly safe (if not fancy). But read carefully: meat or animal by-products are graded less stringently and can legally include road kill, poultry that arrived dead at the processing plant, even deceased zoo animals. Because there’s no way of knowing how long that flattened possum baked on the highway or whether the zoo animal died from disease, the quality of generic by-product meal is much lower.
According to Dog Food Advisor, our go-to source for independent pet-food product reviews, if the word by-product turns up on a pet-food label, make sure the type of meat is specified, but know that it’s a cheap protein source—and don’t pay top dollar for it.