If they are of laying age, they should be on layer feed. It's usually 16 or 18% protein.
I have read where people say that their bantams can't eat pellets (vs. crumbles), but let me tell you the tiny little finches and sparrows that get into my coop have no problem at all eating pellets.
I actually have a wild sparrow that stays with my flock full-time. He or she roosts with them and eats their pelleted feed.