Why are meat by-products penalized?
By-products are the parts of an animal not typically used for human food - and while not inherently dangerous, they signal lower ingredient quality and less transparency about what's actually in the food.
"By-product" doesn't automatically mean harmful. Organ meat, for example, is technically a by-product and is actually nutritionally dense. The problem is that the term covers a very wide range - from nutritious organs to low-quality rendered waste - with no way to tell which it is from the label.
What counts as a by-product?
By-products in pet food typically include: organ meat, blood, bone, and other parts excluded from the human food supply. The nutritional value varies enormously depending on what's actually in the batch.
Why does the score penalise them?
"Chicken by-product meal" could mean anything from nutritious liver and kidney to low-value beaks, feet, and undeveloped eggs - all in the same batch, varying from run to run. There's no way to know from the label, and that inconsistency is the core issue.
By-products tend to have a less optimal amino acid profile than whole muscle meat. For cats - obligate carnivores who depend on specific amino acids like taurine and arginine - this matters more than it would for omnivores.
Foods that use named whole muscle meat (e.g. "deboned chicken", "salmon") as primary ingredients consistently show better overall formulation quality than those leading with by-products. The ingredient choice reflects the manufacturer's quality standards across the board.
What to look for instead
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Last updated Feb 18, 2026
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