Calcium is not the only thing they need to produce eggs. Phosphorus, manganese, vitamins A,D,E, protein, plenty of water, as well as other micro nutrients. In other words, a complete feed. Even if you give them a layers feed that contains all needed nutrients, if they don't eat enough, because...
You want maximum egg production and quality. No treats of any kind. No scratch grains. No cracked corn. No whole corn. No fruits. No vegetables. No kitchen scraps. No table scraps.
Feeding anything but chicken feed, as in layers feed, all-flock feed, or an 18% start & grow type will affect...