My chickens are 9 weeks old and we have started giving them treats (leftovers, vegetables, scratch) so I went out today to buy some grit for them. The only grit that I could find was a 5 lb. bag of crushed granite grit. I was wondering about the calcium content in the grit, because I know that young chickens aren't supposed to have too much. The grit has a minimum of 11% calcium and a maximum of 13.2%. They are getting started on grower crumbles tonight. Would it be ok to let them have this grit, or do I need to look for some more? Thanks!