Olderchckens and oyster shell and grit

[the girls club]

Sorry
Forgot to say these chickens are in a coop and run only

 

[ChickenCanoe]

So, what is your question?
All chickens need insoluble grit.
Birds that are actively building egg shells need extra calcium - either in the form of layer feed or supplemental crushed oyster shell.

 

[farmgirllvo]

Put the oyster shells in a container that they can always get to, and than mix scratch grains and oyster shells and toss them in their run, they will love scratching for them.