Protein quality vs quantity — why the % is only half the story

What "crude protein" actually measures

The protein line on the guaranteed analysis comes from a nitrogen assay: measure nitrogen, multiply by 6.25, call it protein. It is a fine estimate of _how much_ protein-like material is present and completely silent on _what_ it is. Feather meal, corn gluten, and chicken breast all register. The infamous 2007 adulteration scandal worked precisely because the industry's protein number is really a nitrogen number — melamine is nitrogen-rich, so spiking with it faked a higher protein reading.

Compare quantity fairly, or not at all

Two protein percentages are only comparable on the same moisture basis. A wet food at 10% protein can out-protein a kibble at 30% once the water is removed — dry-matter basis is the two-minute math that makes the comparison honest. Species matters too: cats need substantially more protein than dogs, so "high protein" is a claim relative to who is eating it, not an absolute.

Where quality actually lives

Quality is on the ingredient list, and it mostly comes down to naming and form:

• Named species beat anonymous sources. "Chicken", "salmon meal", "beef" are accountable; "meat meal", "poultry meal", and "animal digest" name nothing and can change contents batch to batch.
• Meals are honest about their weight. Fresh meat is weighed with its water, so it ranks higher on the label than it lands in the kibble; a rendered meal's rank reflects real contribution. "Meal" is a format, not a downgrade — the distinction that matters is named versus unnamed.
• Plant protein raises the number, not the story. Corn gluten meal, wheat gluten, and pea protein all lift the guaranteed-analysis percentage. They are legitimate ingredients — but a label that needs them to hit its protein claim is telling you where the animal protein isn't.

How Bowlmark scores it

The engine treats quantity and quality as different questions, exactly as this guide does. Adequacy is the nutrition pillar's job, checked against the AAFCO life-stage profiles. Sourcing is the ingredient-quality pillar's job, and the rules are public: a named fresh protein leading the label earns 15 points, a named meal leading earns 12, a named meal in the second or third slot earns 8. Unnamed mammal and poultry sources take a single 20-point deduction; unnamed fish terms take a 10-point one. No rule rewards a bigger protein percentage for its own sake — the methodology is versioned and public, so you can check the math behind any score.

At the shelf

Read the first five ingredients before you read the protein number. If the protein claim is carried by named animal ingredients in the top slots, quantity and quality agree and the number means what it implies. If the top of the list is grain and the protein arrives via gluten and concentrates further down, the number is real but the story is not the one on the front of the bag.