What is grit?
Grit is small bits of rock that birds consume. The grit lodges in the gizzard to enable the bird to grind up whole grains.
If the birds are outside, they are finding all the grit they need. If you are feeding them mash, crumbled or pelleted feed, grit is not necessary as the feed
has already been ground. If you do decide to feed grit, do not provide it until the birds are a month old and do not mix it in the feed.
Just provide it in a separate feeder so they can eat what they want.