Feed your babies only starter feed. These starter feeds are formulated with all the right nutritional content, and it is just the right size for the babies to eat. Chicks need a chick starter. Ducklings and geese a waterfowl or duckling starter. Turkeys, guineas, and other game birds need a turkey or game bird starter.
Please read the back of the bag of feed that you purchase to find out when that manufacturer recommends you switch to the next type of feed, which is usually a grower/developer feed.