I feed day old chicks with mature Meal Worms and when available farm raised crickets of even adult size. The chases they have are the mechanism used to break such items down into smaller pieces. By the time they are a week old that start pecking at tender greens although consumption does not start until about two weeks. At about 2 weeks I have grit available. Consumption rate of greens does not really pick up until chicks become juveniles at about 5 weeks. Tender new growth and seedlings are what I would present. Be careful with added moisture around a brooder as that can set stage for health issues stemming from infections. Brooder best all dry except for waterer.