I have 5 chicks, now 4 weeks old, and they seem to be doing fine. They are in the brooder during the night, but during the day they live outside in a temporary pen we move around the garden so they can scratch around. They love that, and in Australia the temperature during the day now is quite warm. They get lettuce a few times during the day, a few meal worms, but other than what they scratch up in the garden they're mainly on starter crumbles. For a "treat" I add water to turn it into a mash, which they go crazy for. So crazy in fact that one chick, a light Sussex, will eat like she's never seen food before, she pushes all the other birds out the way and eats to the point it feels like her crop is going to explode! I give them about half a table spoon of crumbles like this 4-6 times a day, especially before bed when they're in their brooder, but they also have the same feed (sans added water) available all the time in a feeder. She's now starting to grown larger than the other birds, unremarkably considering how much she eats! Is this ever a problem and can chicks ever over eat? On the other hand is this all just a good thing and lucky that she's eating so well? They are all feathering out now.