There are two types of cat food, kitten and adult. When your cats first become kittens they should stick to the kitten foods from three months old until their first six months. After six months you can gradually switch them over to the adult cat food as a treat or a small amount daily. Over time it is best for both of you if your kitty stays on only one type of food. But make sure that you check with your vet before continuing any change in diet!