Cat food nutrition is regulated by a set of standards presented by the Association of American Feed Control Officials (AAFCO). Cat foods labeled "Complete and balanced" must adhere to these standards. There are two different profiles for cat food nutrition. One was created specifically for kitten nutrition, and the other applies to adult cat nutrition maintenance. Adult cats tend to require a smaller amount of protein, vitamins and minerals than do kittens and younger, more energetic cats.
AAFCO has methods in place for determining if cat food is approved for consumption based upon its standards. The first of the two procedures requires that the food be tested in AAFCO's laboratory to ensure that it meets the minimum required levels of protein, fat, vitamins and minerals. The second requires at least one product from the family of foods offered to be tested for at least six months, on a set number of cats, to determine if the product provides the proper amount of nutrition. Once either of these tests has been passed, the company has permission to list "formulated to meet AAFCO's nutrient requirement," or "Complete and balanced" on its cat food label.
All cat foods are a certain percentage moisture, and a certain percentage dry matter. As you would imagine, canned cat food has a much higher moisture percentage than dry food. In order to properly understand the charts and minimum levels listed for cat food nutrition, one must understand the formula for dry matter. The standards are calculated based on a dry matter basis, whereas levels listed on cat food labels are generally expressed on an as fed basis. A simple calculation must be made to determine if AAFCO standards for cat food nutrition are being met, and to compare crude protein and fat levels between brands.
If the cat food label lists 10% moisture, that leaves 90% of dry matter. If protein level is listed at 20%, simply divide 20% by 90% to get 22% protein on a dry matter basis. This calculation can be performed for each of the listed levels and compared with the AAFCO standards. It may be necessary to use this formula when determining your selection for cat food nutrition. When the amount of moisture differs from brand to brand, it will be helpful to know this formula to properly determine actual protein and fat percentages.
The term "Guaranteed analysis" is listed on many cat food labels. This is a requirement by the AAFCO. Guaranteed analysis lists, either maximum or minimum, crude protein, crude fiber, crude fat and moisture percentages. Minimum levels listed may contain much more, and maximum levels may contain much less than the stated percentage. While this is important information to have when comparing cat foods, nutritional information cannot be determined by these numbers. In order to properly compare nutrient and energy levels, it is necessary to contact the manufacturer.