The Association of American Feed Control Official (AAFCO) formed the Canine (1990-1991) and Feline (1991-1992) Nutrition Expert Subcommittees to update the requirements for substantiation of "complete and balanced" claims for pet foods sold in the United States. There are two means by which a company may substantiate nutritional adequacy for a dog or cat food. The first means is by formulating the food so that nutrient levels fall within the ranges as established in the AAFCO Dog and Cat Food Nutrient Profiles. These profiles replace the National Research Council recommendations as the recognized authority in the United States as that term is applied to AAFCO regulations. Levels of nutrients are based on practical formulations of pet foods with adjustments to account for bioavailability of nutrients in commonly used ingredients. Separate profiles for adult maintenance and growth and reproduction are set, and maximum levels of some nutrients are also established. The second means of substantiation is through the conduct of feeding trials following AAFCO protocols.