The best size for breeder rats is 3-4 months of age. They can breed when smaller but not quite as efficient at it. Research local feed or seed stores for bedding and rodent chow, seems to be alot cheaper at these type of facilities. Dont use the plastic drawer sytems because they can chew out of them. I have a thread in the feeder section for a rat rack I built. This works very good. I have 20 or so snakes and breeding my own is more cost effective, plus I will soon be having a surplus that I can sell locally to get back some of my investment. Good Luck!!

Here is link to thread.

Bill