I use Purina Flock Raiser crumbles exclusively. During molt, my hens hit their free choice calcium on a fairly steady basis. They rarely touch it, if ever, at any other time. Another thing I give during molt, is some form of animal protein. While protein may be protein, I find they do much better when they get some additional animal protein. I actually learned to give the animal protein from a few old timers. Does it improve feather quality? Yes, it does.