I start hatchlings on rat fuzzies or small mice. The rat eaters get 2-3 meals of fuzzies, then I move right up to pups/chubs.

I haven't experienced any mousers taking longer to grow up than rat eaters here. I only had one female that wouldn't eat rats so I fed her strictly mice for over a year. She is currently my largest and heaviest '06 female. Now she'll eat anything, so she usually gets a small rat followed by a mouse. You just have to feed enough mice to equal the weight of an appropriately sized rat.

I also had a bunch of snakes stop eating rats and only eat mice when I started breeding mice in my snake room. It must have been the scent in the room. I now feed about half and half, and my mousers are growing like weeds. I feed them one mouse at a time until they've had 2-4 each, depending on the snake's size, or until they don't eat it within a few minutes. Most of the time it's the former.