AAFCO feeding trial vs formulated

AAFCO recognizes two pathways for substantiating nutritional adequacy (Dzanis, J. Nutr. 124:2535S-2539S, 1994; AAFCO Model Regulation PF4): (1) Formulation — the product is formulated so that essential nutrient levels fall within the ranges established by the AAFCO Dog or Cat Food Nutrient Profiles, stated verbatim on the label as "(Name of product) is formulated to meet the nutritional levels established by the AAFCO Dog (or Cat) Food Nutrient Profiles for [life stage]"; and (2) Feeding trial — the product passes an AAFCO-recognized animal feeding protocol, stated as "Animal feeding tests using AAFCO procedures substantiate that (Name of Product) provides complete and balanced nutrition for [life stage]". Products that successfully pass the feeding trials are exempt from having to meet the profiles on paper. Feeding-trial substantiation is generally regarded as the stronger evidence because it demonstrates bioavailability and real-world performance: the AAFCO protocols include defined animal observations and clinical chemistry assessments (the 1994 Dzanis paper notes the addition of serum chemistry analyses such as alkaline phosphatase to the protocols). A third, product-family option allows a claim for a product "comparable in nutritional adequacy to a product which has been substantiated using AAFCO feeding tests". A product meeting neither pathway must bear the statement "This product is intended for intermittent or supplemental feeding only."