I agree with Karrie completely. I have two cats, both ten years old, that I've had since they were about 3 months old. We also have 3 dogs.

In general "kitten" food is much more nutritionally dense so it is much, much better to feed the cat the kitten food, than to feed the kitten any food manufactured for an adult cat, since it is lacking in specific nutrients needed to help the kitten grow.

The same is true for puppy/dog food.