Hand Feeding
At 6 or 7 weeks of age, hand-fed babies can be removed from the brooder and put into a small cage. You can put the chick back into the brooder at night for sleeping. When you move the chicks to a cage, you can still hand feed them at regular times but you should also start attempting to wean the chicks. Foods that should be introduced and put into a bowl include crumbled corn muffins, soft whole-wheat breads, cooked corn, spray millet, pellet foods, oats and sunflower seeds. Take away any food that isn't eaten.
When You Don't Pull Chicks
If you don't pull the chicks early on, the time to start weaning them is when they become ambulatory and are moving around inside the brooder box. One way to do this is to suspend a spray of millet from the cover of the box which they can pick at. They won't eat much, but they do come to understand that there is a purpose for their beaks other than holding them open and being fed.
Types of Food
Young chicks can be fed commercial hand-feeding formulas that are comparable to a heavy cream. As the chick gets older, lessen the amount of water that is in the formula until its consistency is that of cake batter. This formula should be put in a container filled with hot water so that it stays at 105 degrees. After the chick eats, clean it up because the formula is glue-like when it dries. You can also use a high-protein baby cereal mixed with some pureed vegetables if you don't have access to a commercial formula.
Older Chicks
When a cockatiel is 4 weeks old you can start giving it millet seeds as well as steamed vegetables, carrots and corn peas. Babies that have been fed by their parents will be ready to leave the nest box at 4 or 5 weeks of age because they're ready to fly. However, they are still dependent on their parents for food, so they opt to stay with their mom and dad until they are taught how to eat weaning foods. At that point the mother stops feeding her babies.