Actually, I did. I changed their feed from layer pellets to high protein game bird feed. they also increased egg production on the higher protein feed. They had oyster shells anyway to nibble at will. After months of loosing chicks in the shell, they came popping out.
I did also lower the brooder temp 2 degrees at the recomendation of a friend, but I feel that the feed made the difference here.
The girls run is all sand (Florida) and I cut down bushes and give them stuff out of garden for fresh greens. They love broccoli, corn and collards