2 out of 5 of our leghorns have started laying, I gave them some fine crushed egg shells. I may give them oyster shells too. I have them on grower/finisher and they free range almost all day. Is layer feed really necessary?
I'm not sure what all is in layer that makes it a necessary feed...but I think it goes beyond just being high in calcium. I've always used it, figuring smarter minds than mine must know what they're doing. But when you think about it, old time chicken keepers threw a couple handfuls of scratch on the ground and the birds were on their own!
Lots of folks use a grower or all-flock feed and offer calcium on the side. There is nothing wrong with that. The benefit of layer feed is convenience -- complete nutrition in one feed. I use it myself. Unless I have juveniles in the coop. Then it's back to grower for all until the youngsters are laying.