i have two female rats--both about 5 months old or so. i have a male that i saved back from a batch of feeders i picked up--he's maybe about 8 weeks old. my question is, how close in size does the male need to be to the females before i can safely breed them? right now he is only about a third of their size--looks like he might make a tasty morsel for them if they decide they don't like him.