We have two groups of chicks. Our older chicks are about 13 or 14 weeks old and our younger ones were hatched 12/15, 12/25 and 12/30. The older have an enclosed pen (about the size of a garage) and the younger ones are in a very big dog crate. The bottom in the crate is dirt. How much grit should each group be getting? Should I put it on the ground or mix it into their food? Im not sure if it makes much of a difference, the older ones eat the crumble and the younger eat mash. Hubby is sectioning off the coup tomorrow and I wanted to be able to start giving treats to them. Ive given treats to the bigger birds but its pretty limited because I didnt have grit.