I have a 1.4 colony set up, and they simply have not produced one single litter for me since I got them. Probably been about 2 months now, if not a bit longer.

I got out of breeding ASFs and switched to regular hooded rats when a guy I know decided to get rid of his. He basically said, come get them and they're yours. So we went and picked them up, but at the time all the breeders were split into bins, and we only had 2 big shipping totes to bring them home in. So when I got home, I separated them into male and female, and then put them into mixed up 1.4 colonies. (Didn't keep their previous groupings)

Anyways, because of this I have no idea how old the male is, nor the females. I figure it's just the male that is a dud, because I've seen him/heard him trying to mount the females but there just haven't been any pregnancies.

Should I try to replace the current male with a new, younger one? Or should I just euthanize the entire colony and start from scratch?