Hi Links and welcome to BYC.
I have only a little knowledge of using whole grain feeding. A long time ago, I tried to get my little flock of hens thru Winter on a diet based on wheat. They promptly quit laying.
Much more knowledgeable people (ag scientists) say that it can be done and even,
"can be an easy method of feeding small flocks of laying hens . . . As long as you give them the opportunity to make clear, easy nutritional choices, the hens will be healthy and productive." That sounds darn positive
!
Feed is given free choice and the birds sort it out. The problem here is that a specially formulated, 25% to 40% protein, supplement is recommended with the whole grain. Perhaps (?),
Fertrell supplements would "fill the bill" but you'd better do some careful reading and you are likely to need the additional protein ingredient. Fertrell says, "Poultry Nutri-Balancer is to be mixed with grains and
protein sources at a rate 60 LB per Ton" etc. etc. By the time you purchase and mix these ingredients . . . "free grain" may not look so free anymore.
Still, free grain looks real good at the moment. Perhaps (?), keeping the birds on starter with grain and oyster shell as they mature would work. Game bird starter is especially high in protein and would fall within the range recommended.
Just a few thoughts . . .
Steve