Haha...I usually like the female to be around 3 years old and a healthy 6 foot minimum. Although, if a female is over 2 1/2 years and already a sound 6 foot and eating jumbo rats...I'll give her a go and see how she reacts. It's just always a good thing to wait the full 3 to 3 1/2 years and produce a bigger litter...not to mention the much healthier mom after the birth.