Not trying to be a smart alec or anything. And yes I agree that our animals deserve the best food and care available. But part of me chuckles sometimes at the great debates about this food or that. They are birds and they spend the day eating bugs, plants, seeds, and whatever else they can find as they wander around. As long as the manmade food offered to them is good quality, it is not something that should keep us up at night worrying. So long as they have healthy environment, clean water, and nutritious food... they'll be fine. Personally, my bigger concerns are keeping them safe from local critters and providing them with a varied diet.
They get lots of veggie scraps. They have layer pellets, grit, and oyster shells available to them at all times. They much prefer roaming our several acres of yard and woods finding their own food. They do LOVE their bugs though. Early this summer when junebugs were everywhere, I'd catch a bunch every night around the porch lights and toss them to the chickens the next morning in lieu of scratch. Talk about some happy chickens.
I use the pellets because it is easier for me. They waste less of it. And, it seems to last longer than the crumbles which sometimes seems more dust than crumble. But it is there more to give them something to nibble at in the mornings while they are waiting to be let out. Once they are out, let the bugs and greens beware.