Quote Originally Posted by TripleMoonsExotic View Post
Perhaps it is because you are disrupting your colonies by removing the pregnant females? When I bred rats (gave it up 3 years ago because of hubby), I successfully kept 1.3 groups together at all times and never had moms eatting babies.
I would hesitate to think this has anything to do with it. From my research and from personal experience mom rats tend to do better by themselves to birth and raise a litter, not worse. All of mine have been very tolerant to being moved around at my want and whim, except when housing males together, they tend to pick on each other. I have a maternity rack though, currently has 10 moms in it, and I have yet to see any cannabilism, and some are on their second litters this way. They won't even eat the occasional dead baby.

That said, I have often had trouble with litters of other rodents being killed/eaten when left in with mom for too long, especially boys. I've been weaning between 3 1/2 and 4 weeks old (thanks to the advice here), although they rarely get to a full 4 weeks with mom unless the litter was very large.