My trainer, rears pups on his farm. Always has sensational looking pups with plenty of leg underneath them. I've been up there a few time while his feeding. I have observed -

Pre Breakfast - Vitamins & very fresh Minced Mutton
Breakfast - Cooked in a stew Rice, vegies, Mutton, vitamins
Lunch - Puppy Kibble, Beef mince, with water.
Tea - As lunch or breakfast

Other things fed pasta, chicken necks, bones. And plenty of vitamins. Pretty secretive about which vitamins they use.

They have a 90 sq meter galloping paddock, which the pups love to burn around in. They also have different size yards for different ages.
So it's good feeding, and plenty of galloping.