i was reading the care sheet on feeding and i think there is a small mistake but i could easily be wrong.
We recommend that you feed mice from the time of birth until the time it becomes a juvenile. Mice are higher in calcium then rats are, and this is important for them during this time of growth. For this reason it is not a wise idea to start them on rats immediately.
it seems like it might be a mistake about the mice being higher in calcium thats why u need to switch to rats???