Your kitten will probably have been already weaned when he or she first arrives at your house, and, hopefully, will be eating a high-quality food designed for kittens. If so, it will probably be best to continue him on the food he is accustomed to, to avoid the inevitable tummy upsets of a quick food change. If not - if your kitten has been eating a lesser-quality (grocery store) food, you'll need to convert him over to a more appropriate kitten food gradually. Start by adding a small amount of premium kitten food to his existing food, then gradually increase the amount each day. You will likely find that once your kitten tastes the higher quality food, he will nose through the kibble to find those morsels. At that point, you can make the switch complete.
Dry Food Versus Canned
We'll start with dry food first, simply because of its convenience, and because many cat "parents" continue to feed dry food. However, for a longer, fuller life, you should try to convert your kitten over to canned food as quickly as possible, with dry food given only as "snacks" or "treats." More information on dry vs canned foods can be found in my article, Canned Food - the Real Staple for Cats.
Unlike adult cats, kittens will eat only as much food as they need for adequate nutrition, so free-feeding of dry kitten foods will work, if that is what you need for your own household.
Here are my Top Picks of Premium Dry Kitten Foods.
What About Adult Cat Food?
Kittens are not just miniature cats. Kittens' growth and development need extra protein, fat, vitamins, and minerals to get the right start in life. The extra protein is needed for growth and development of strong muscles and supporting tissue; fat is essential for fatty acids, as a carrier for fat-soluble vitamins, and for the additional calories for energy, according to this excellent article from PetEducation.com. Minerals, of course, are needed for the development of strong teeth and bones.
While adult cat food will not "hurt" your kitten in the short term, it is selling him short on the extra nutrients he needs for active growth, which takes place throughout the first year of his life. Save the adult cat food for your big guys, and give your kitten what he needs: kitten food, for his first year.
Here are my Top Picks of Canned Premium Kitten Foods.