For kittens from 4 to 12 months of age A kitten's growth can be segmented into two distinct stages, with very different nutritional requirements. The first stage is from weaning until 4 months. The second stage is from 4 until 12 months. During the second stage, a kitten's growth rate actually slows, and energy requirements are different. At the same time, it is increasingly important to provide the right nutrient balance for optimal development.