Kittens need large amounts of energy--about two to three times that of an adult cat. Food for your kitten should contain at least 30% protein. Make sure the food you offer is specifically formulated for kittens.
How Often Should a Kitten Eat?
The following is a general eating schedule for newborns and young cats:
Newborn kittens may nurse about every 1-2 hours.
At about three to four weeks old, they can be offered milk replacer from a bowl and then small amounts of moistened kitten food four to six times a day.
Kittens from six to 12 weeks old should be fed four times a day as you gradually decrease their access to milk replacer.
Kittens from three to six months old should be fed three times a day.
http://pets.webmd.com/cats/guide/newborn-kitten-care?page=2