Need some insight on Feeding.

[The Coop-D-etat]

I appreciate everyone getting in depth with this matter. It helps out alot

 

[Chris2018]

The eggshell is the perfect indicator for the body's calcium needs. If the hen isn't getting enough calcium, the shell of her egg will suffer before her bones do. So no need to worry about her depleting her bone calcium if her shells are hard. And if they are hard, then there's no problem. If they are soft or brittle, supply another source of calcium (or a larger quantity of what you already provide).

Not exactly correct.
CaCO3 is extracted from the Medullary Bone and as the Medullary Bone reserves become depleted, the bird uses the Cortical Bone as a source of calcium for the eggshell.

--Medullary bone is a specialized woven bone which serves as a calcium reserve for the demands of egg shell formation. Easily created and resorbed, medullary bone is ideally the first source mobilized when more calcium is required.

--Cortical bone is the hard outer surface of the round bones, such as the femur or the humerus, and the flat bones, such as the skull or the pelvis.

The Merck Veterinary Manual, Hy-Line and Hendrix Genetics just to name a few has some good information on the subject.