By the time a young kitten gets to be around 4 months old, their growth rate slows, but their activity levels skyrocket. With a developing immune system, growing bones and muscles, emerging adult teeth, and that skyrocketing energy level, older kittens need nutrition with more protein than a younger baby cat. ..While it may seem like a kittens nutritional needs are complicated, Royal Canin Thin Slices in Gravy makes it simple to feed their magnificence from the start.