I’d provide grit. Well, I always provide it anyway. Since they don’t have teeth they use small bits of rock to grind their food up in their gizzard. I don’t know what kind of bugs those were but they are probably OK without grit, but it’s a good precaution.
You can provide grit a lot of different ways. Most feed stores carry “Chick Grit”. That’s small pieces of granite waste from granite quarries sorted and sold for that purpose. At their age make sure it is chick grit and not regular grit. The regular grit is too big for those chicks.
You can collect coarse sand from a stream or riverbed. That works great. You don’t want the real fine sugar sand but the stuff with larger particles. If it is an ocean beach you need to rinse it to get rid of most of the salt. Too much salt is bad for them. Or you can buy a coarse sand, like construction sand. Play sand is too fine. It just passes on through their system.
You can collect dirt from your yard and feed that to them. They will love the dirt itself as a treat and will find grit sized grains in it. Some people cut chinks of sod from their yard, grass, roots and all, and put that in the brooder. They’ll love tearing it apart and eating it. Or scrape up some small gravel from a gravel road or driveway.
Or take them out on grass or dirt and let them peck around for a while. They will find their own grit. It’s instinctive.
