Here's a link that shows the AAFCO requirements.
AAFCO Puppy Food Standards & Requirements The minimum for puppies is 21% protein and 8% fat (dry matter basis). I interpret these guidelines much like the RDA for humans in that these levels are the minimum required to prevent a deficiency rather than the optimum levels to promote health. The food I feed my dogs (puppies and adults) has 36% protein and 18% fat.