I'm a little confused.... do the oyster shells provide some necessary calcium for new chicks? Or does it act just as a grit. I have some regular stone grit that I give to my adults, but it kinda looks like it's too big for them? Also, any tricks for giving my chicks a good headstart? I think I'm gonna give them some vitamin drops, but is there anything else? Should I buy medicated feed? Sorry for all the questions, but thanks for any help you can give!!!