I'm afraid I don't.
I feed pellet or crumble and only know about the problem with whole grain feed from members here who have had problems with it and shared the warning with the community.
Whole grain feeds are intended to be fed wet or fermented. The vitamins are in the powdery part (or in a pellet depending on the brand), and the chickens WILL end up deficient if it's not fed in a way that prevents them from picking their favorites from the mix. :)