Coming up with the recommended levels of different nutrients for dogs at their various life stages — pregnancy and lactation included — is something of a two-step process. It begins with the National Research Council, which is an arm of the National Academy of Sciences. Every 10 years or so, the National Research Council combs the literature for the latest crop of studies on nutrition and writes up the vitamin and mineral requirements according to the accumulated body of evidence. They do this not just for dogs but for other animals, too.
The Association of American Feed Control Officials — AAFCO — takes it from there. Where the National Research Council handles the science of nutrition, AAFCO, made up of at least one feed control official from each state, handles the regulatory component — translating the science into realistic recommendations for what needs to be in commercial pet foods.
Interestingly, the National Research Council divides life stages for dogs into growth (puppies’ nutrient needs), gestation and lactation, and adult maintenance. But AAFCO takes the data for puppies and the reproductive stages of a bitch’s life and lumps them together, perhaps taking the higher of the two values for each nutrient to insure adequate nutrition in each case.