I have several OFA'd dogs that have started on a 31/21 blend from the get-go. The adult food I feed is, in my opinion, the best available...why would I feed my developing pups anything else. Further, I excercise my pups along side the adults. I have two 8 month old pups now that can hang with any three-five year old in my kennel in terms of swimming or running and stamina!
Skip the propaganda...feed a quality food, excercise them very hard, and monitor the waste...the best three nutritional tips I have.