All of my thirteen girls get free demand oyster shell. They eat Layena pellets mixed in with flock grower since they adore flock grower, and will eat Layena as long as they can have the flock grower.
They also get daily fresh raw veggies, occasional yogurt, hot oatmeal and raisins on sub-zero mornings, and a small ration of scratch grain. They eat better than I do.
This egg was laid two weeks ago, and all eggs since have been normal, I'm relieved to report.