I really should start researching and stop guessing and assuming. I just was reading about Nutrena feed on their website. I just read that scratch grain is only supposed to be 10% of the chickens diet at the most. It has been the main feed for my flock for a whole year. I supply meatbird, all flock, and layer, but they hardly eat anything but scratch.
They have probably been eating enough of the other feeds to get by on nutrition. Brace yourself for a reluctance to eat for a while when you remove the scratch; it's a bit like candy to a kid is. They'll eat when they are hungry enough. In the "old days," people fed a few handfuls of scratch or cracked corn and maybe some table scraps (if they didn't go to pigs,) and the chickens foraged. They probably weren't usually as healthy as they are on a balanced feed, but they got by.
