nutrition
Crude protein
How crude protein is measured
Crude protein on a pet food label is derived from the Kjeldahl or Dumas method, which measures total nitrogen and multiplies by 6.25 (because protein is, on average, about 16% nitrogen). The result is reported as a percentage by weight in the Guaranteed Analysis panel.
"Crude" means total, not bioavailable, not digested, not high-quality. The figure doesn't distinguish between protein from chicken muscle and protein from leather scraps; nitrogen is nitrogen to the test.
Why you need dry-matter basis to compare
Dry kibble lists guarantees on an as-fed basis at about 10% moisture; canned food lists them at about 75% moisture. A canned food at 10% crude protein and a kibble at 25% crude protein can have similar dry-matter protein content, about 40% versus about 28%.
Convert to dry-matter basis with: protein% ÷ (100% − moisture%) × 100. This is the only honest way to compare proteins across formats.
Typical ranges
- Adult maintenance dry dog food: roughly 18–30% as-fed
- Puppy/growth and performance dry: roughly 22–35%
- Adult cat dry: roughly 28–42%
- Therapeutic kidney-support diets: deliberately lower, set by the prescribing vet
Why it matters
Crude protein is the number most marketing campaigns inflate or downplay. Knowing what it actually measures, and how to compare across moisture levels, turns label-reading from guesswork into arithmetic. Higher is not automatically better; the right number depends on life stage and health status.
Frequently asked questions
- Is more protein always better?
- No. Healthy adult dogs and cats benefit from adequate, high-quality protein, but excess simply gets metabolized. For animals with kidney disease, the protein level and quality become medically important and should be set by a vet.
- Does crude protein tell me about meat content?
- Indirectly. Two foods at the same crude protein can differ in protein source (animal vs. plant) and in digestibility. The ingredient panel and any feeding-trial AAFCO statement tell you more about quality than the number alone.
- Why is canned food protein percentage so low?
- Moisture. Canned food is mostly water; once you compare on a dry-matter basis, the protein percentage is often as high as or higher than dry food.