Do they have access to soil to peck at when foraging? If so, they're probably getting their phosphorus and potassium.
Calcium metabolism issues seem to be the mineral to be concerned about, and the required vitamin D to let calcium do its job.
@U_Stormcrow , do you have any idea of required vit D amounts for laying hens? It's fat-soluble, therefore retained in the body, so you don't want to go crazy with it. In the third pic, it says it contains 0.01 mg per mg. The others (the ones that have vit D) list the accursed IUs (international units.)