Looking for some advice on diet for my girls. I have
2 - 7mth old Bielefelder - I have found a broken soft shelled egg on the

2 - 7mth old Red Sex Link / Bielefelder cross - one lays almost daily normal dark brown egg; One has laid a few paper soft eggs just outside the nesting box. (I saw her in the nesting box and later found the egg)
2 - 2yr old Light Sussex laying light brown normal eggs almost daily
I feed them layer crumb from my local feed store and have oyster shell available in a separate feeder. They free range (9am - 7pm on a 1 acre country lot) most days.
Are the soft shelled eggs just immaturity since the Bielefelder is slow to mature or should I be adding something more to their diet?
Thank you in advance for your advice