By-Products on a Cat Food Label: Are They Really Bad?
By-products are a common sight on cat food labels: 11.3% of the cat food lines in our catalog (6 of 53) list a by-product as the 1st ingredient — a broader cut, considering the first three ingredients, reaches 30.2% (16 of 53) . That frequency says nothing about quality on its own — "by-product" is not a synonym for a bad ingredient. The AAFCO defines animal by-product as clean, non-rendered parts of the slaughtered animal other than meat — lung, spleen, kidney, liver, blood, partially defatted bones — as long as the species of origin is identified on the label.
The real point of attention is not the word "by-product" in isolation, but the absence of the species of origin. "Poultry by-product" identifies the species; a generic "animal by-product" with no species is the warning sign — because it hides which animal the ingredient came from and makes it harder to trace quality and possible allergies.
Is by-product in cat food a sign of poor quality?
Not in isolation. The AAFCO defines by-product as a nutritionally usable ingredient — liver, kidney and spleen have a high density of vitamins and minerals, often higher than pure muscle meat. The problem arises when the term appears without species identification (generic "animal by-product").
Foods that declare "poultry by-product meal" or "chicken by-product" meet the traceability requirement — the owner knows exactly which animal the ingredient came from. It is that transparency, not the presence of by-product itself, that separates a reliable formulation from an evasive label.
What is the difference between "by-product" and "by-product meal"?
Technically they are close categories: by-product meal is the by-product already dehydrated and concentrated, with the water weight removed — which increases the real proportion of protein per gram compared with fresh meat, which loses weight in extrusion because it contains up to 70% water before drying.
In practice, "poultry by-product meal" tends to be seen as more transparent than "animal by-product" only because of the more specific nomenclature used by manufacturers — both can be nutritionally equivalent if the species is identified in both cases.
What AAFCO defines as a by-product
| Label term | AAFCO definition | Level of transparency |
|---|---|---|
| "Chicken/poultry by-product" | Non-muscle parts of slaughtered poultry, species identified | High — traceable |
| "Poultry by-product meal" | Dehydrated, concentrated by-product, species identified | High — traceable |
| "Animal by-product" (generic) | Mix of unidentified species | Low — avoid when possible |
| "Meat and bone meal" | Mixed by-product, often without a single species | Medium-low — check the full label |
When the alert is real
- The label uses "animal by-product" or "meat and bone meal" without naming the species — here it is worth questioning the manufacturer or preferring another line.
- Generic by-product appears in the first 3 ingredients of an entry-level food, together with multiple fractionated corn derivatives ("ingredient splitting") — a combined sign of a cheap formulation.
- The same cat has a recurrent allergic reaction and the owner cannot identify the causative protein because the label does not name the species of by-product used.
Frequently asked questions
Is cat food with by-products banned or irregular?
No. It is a legal ingredient as long as the species of origin appears on the label. The AAFCO defines the term — the AAFCO details the full definition of by-products and the requirement to identify the species on the label — while the FDA and state feed regulators enforce pet food labeling.
Does by-product meal have less protein than fresh meat?
On the contrary: by-product meal is already dehydrated, concentrating protein per gram. Fresh meat contains up to 70% water, which is removed during extrusion — the final weight of protein drops proportionally. Always compare by the declared crude protein guarantee level, not by the order of the terms on the label.
How do I know whether the by-product in my cat's food is good quality?
Check that the species is identified ("chicken by-product", not generic "animal by-product") and that the manufacturer declares feeding trials or a confidence level from a public source. Manufacturers that hide the species of origin tend to use lower-cost ingredients that vary between batches.
See the ranking of cat foods with an identified protein source →
To learn how to read the rest of the label, see the complete guide to reading your cat's food label.
Picked by score from our overall cat ranking, not by the topic of this article. To get it right for your pet — age, weight, spayed or neutered — take the quiz and get a list made for them. A pet with a diagnosed condition needs a diet prescribed by a veterinarian.
