Balls are much easier to deal with when they are on rats. I have had some mousers in the past that would not eat more then one at a feeding. So one mouse every other or third day. Took forever to one of my girls to size. Once she got to size and laid she finally swapped to rats and became an awesome eater. Male mousers aren't as big of a pain. They are easy to maintain with their smaller size instead of trying to get weight on them. I don't know how anyone can say a mouser would not be smaller then a rat eater. I have many girls over 25000. I even have a girl over 4000. How many mice would they need to eat a week to maintain? How many mice would it take to get weight back on after laying?