There are several posts here on that...
I dont... treats will cause them to eat less of the nutritionally balanced feed they need...
Personally I feed mine from day one live culture yogurt free choice (for the probiotics) and mix some wheatgermoil through their basic feed. That is it . They start freeranging the yard with mama when they are around 4-5 weeks old and I make sure they have a source of grit available to them.