I bought a bag of OS at TS yesterday. It says it is Grit, and on the top says Crushed Granite. The brand is Nutri Source. On the back, it says "to develop healthy nutrition in chicks." The #1 ing. is Oyster Shell. It has 10% calcium. I want to make sure it is okay to feed this to my hens, as it says to feed to chicks up to 10 weeks of age. Plus my roo will have access to it, although I don't know that he would eat it. Thanks for all replies!