Grit with oyster shells for chicks?!

[chwoey]

I bought grit from the pet store (its for some kind of pet bird, i forget the type). But now that I read the ingredients I saw there was oyster shells in it!
Is this bad for my baby chicks? (they are 4 weeks old)

 

[Nemo]

Could be... Excessive calcium can be bad for chicks kidneys. That's why it's not in chick feed.