The AAFCO definition and what it allows
Per AAFCO Official Publication 2024, animal by-product meal is defined as “the rendered product from mammal tissues, exclusive of any added blood, hair, hoof, horn, hide trimmings, manure, stomach and rumen contents.” The definition specifies what must be excluded but does not specify what must be included. The rendered material can come from any mammalian source — cattle, swine, sheep, deer, or mixed lots — and the species composition can vary batch-to-batch based on supplier availability. Per AAFCO Official Publication 2024 ingredient labeling rules, the species of origin does not need to be declared on the pet food label.
The functional reason for this category exists. Rendering plants receive raw material from many sources — meat-packing operations, restaurant fat collection, dead-stock disposal — and the species composition naturally varies. Creating a single “animal by-product meal” category allows the renderer to mix sources and provide a consistent specification (typical 50-60% crude protein, 12-15% fat, 25-35% ash) without separating each species into its own line. The trade-off is the species-anonymity that consumers see on the label.
The species-named alternative — what changes when the label says “chicken meal”
Per AAFCO Official Publication 2024 separately defined ingredient categories, species-named meals (chicken meal, lamb meal, salmon meal, herring meal, beef meal) require the species of origin to be specified. Chicken meal must come from chickens; salmon meal from salmon. The supply chain becomes traceable: the renderer must source from documented species processors, the manufacturer can verify the source, and the consumer reading the label knows which protein their dog is consuming.
The traceability matters in three concrete ways. First, dogs with documented adverse food reactions (food allergies) need to identify and avoid specific protein sources — species-named meals enable that, generic by-product meal does not. Second, manufacturers building premium brand identity prefer species-named ingredients to support marketing claims about ingredient quality. Third, consumers researching their pet’s diet can match ingredient panels against known dietary tolerance — a benefit that disappears under species-anonymous categories. See our chicken meal explainer, salmon meal explainer, and lamb meal explainer for the species-named context.
Animal by-product meal vs meat-and-bone meal — AAFCO category distinctions
Per AAFCO Official Publication 2024, “meat-and-bone meal” is a separate category that overlaps with but is not identical to animal by-product meal. The AAFCO meat-and-bone meal definition is “the rendered product from mammal tissues, including bone, exclusive of blood, hair, hoof, horn, hide trimmings, manure, stomach and rumen contents.” The required difference: meat-and-bone meal must contain bone, with minimum calcium 4.0% and minimum phosphorus 2.0%. Animal by-product meal may or may not contain bone.
Per the FDA Bovine Spongiform Encephalopathy Compliance Policy Guide 690.300, animal-source rendered products are also subject to FDA ruminant feed bans designed to prevent transmissible spongiform encephalopathy (the bovine prion disease that prompted the 1997 BSE Feed Ban under 21 CFR 589). The relevant restriction: protein from ruminant tissue cannot be fed back to ruminants. Pet food (cat and dog) is not subject to the BSE feed ban directly — cats and dogs are not ruminants — but the rendering plant’s overall species sourcing affects the supply chain’s overall safety profile.
Quality signal in the manufacturer-quality framework
Per WSAVA 2018 Global Nutrition Toolkit, ingredient quality is one of several manufacturer-level signals consumers can use to evaluate pet food. The WSAVA 2018 framework includes: full-time veterinary nutritionist on staff, AAFCO Feeding Trial substantiation (vs Formulated-to-Meet shortcut), documented quality control protocols, batch testing for nutrient verification, and ingredient sourcing transparency. Species-named meals correlate with manufacturers investing in the broader WSAVA 2018 framework; generic animal by-product meal correlates with minimum-cost formulation.
The correlation is not deterministic. Some major commercial brands (including some Purina Pro Plan and Hill’s Science Diet variants) use species-named ingredients in some lines and generic categories in others, depending on the formulation target and price point. The WSAVA 2018 Toolkit emphasizes that ingredient quality should be evaluated alongside the other manufacturer signals, not in isolation.
The “by-product” vocabulary problem
Per the AAFCO Official Publication 2024 separate definition of “chicken by-product meal” (covered in our dedicated chicken by-product meal explainer), the term “by-product” in pet food regulatory language refers to the secondary tissues from a primary processing operation — necks, feet, undeveloped eggs, organs — and does not have the negative connotation it carries in casual English usage. “Generic animal by-product meal” combines two separate concerns: the by-product source (which is functionally normal for animal protein rendering) and the species-anonymous designation (which is the actual quality signal). Conflating them creates confusion. Species-named by-product meals (chicken by-product meal, lamb by-product meal) are functionally normal pet food ingredients; generic mixed-mammalian by-product meal is the lower-traceability category.
How KibbleIQ scores animal by-product meal
The KibbleIQ Dry Kibble Rubric v15 awards partial credit to animal by-product meal as an animal protein source, but applies a documented penalty for species anonymity relative to species-named meal alternatives. The penalty reflects the WSAVA 2018 ingredient-quality framework rather than a toxicity or nutritional concern. A formula with chicken meal at position 2 will score higher than an otherwise-identical formula with animal by-product meal at position 2. The same logic applies to meat-and-bone meal — partial credit, with the species-anonymous penalty. See our chicken by-product meal explainer for the species-named comparison case. To check what your dog’s food declares, paste the ingredient list into the KibbleIQ analyzer.