Not a bad feed at all. If you choose to they do make a medicated formula. I think it is a mater of preference personally. I do feed the medicated starter to mine. Mine just seem more active on it for some reason.
I am thinking you mean chick crumbles not grit. Grit is the stones they eat to help crush food in the gizzard.
If they are all healthy looking and active why change a good thing?
I have mine on medicated chick crumbles. It does not treat any illness but rather helps to prevent coccidiosis.