Encouraging a female mouse to accept a male mouse for breeding

Question
QUESTION: I have 1 male and 3 female mice. I am trying to breed them and have done tons of research and not had problems in the past. How ever, I have a fresh set of mice and my females do not seem to be willing to allow the male to breed with them. The male has his own tank and the females have a separate one together. The female are happy together but will not let the male anywhere near them when they are introduced. I have always introduce the females to the males space and never had a problem like this. What are your thoughts and suggestions please? I look forward to hearing back from you soon and thank you for your time!

ANSWER: Hi Eileen,

Sometimes this problem is a result of the females, and sometimes it's on the male's side.  Have you bred that particular male in the past?  Not all bucks woo their ladies the same way - some can be too aggressive and overly stress the females or even injure them, and some aren't pushy enough.  On the other hand, sometimes females are over-anxious and can injure a buck who is trying to mate them.  While this doesn't always prevent pregnancy, it's a little dangerous to risk and may be passed on to the offspring.  It could also be a result of introducing the females as a group, where they may have more confidence together or potentially intimidate the male.  I've used that method in the past, but sometimes it yields better results to cycle the females through one at a time (the male will be able to focus on just one doe, with more attempted matings, yielding better odds).

If it were me, I'd try and figure out which gender is causing the mismatch.  If you think the male is being too forceful, try placing him in the doe cage, which will make him feel less at home until he scents everything.  It may take him a couple of days before he mates in this case, but may reduce aggression.  If you think he isn't being forceful enough, and if the females are not actively showing aggression toward him (but are instead simply evading him), try placing only one female in his cage at a time and cycling them out each 7-14 days.  Lastly, if you think it's the females causing the problem, try and figure out why.  It may be anxiety, in which case keeping them together and adding hiding places to his cage is just about your only hope of keeping them somewhat comfortable, or it may be a group problem, in which case you may want to separate and cycle them through like I mentioned before.

In the end, some mice are simply not compatible.  You can try a different buck, but if the problem is on the female side, it might not be a good idea to breed the females anyways.  Best of luck!

-Tam

---------- FOLLOW-UP ----------

QUESTION: i do only run the females through one at a time bc i do not want him to be overly 'distracted'... but i did not think about the anxiety and over aggression on either ones part... will have to watch them more closely... and this is the 'first' time i have attempted to breed this particular group as none of them have reproduced yet... i am going to give them more time and watch the reactions... other then gaining weight, what would be another good sign that the females have 'taken'... any thoughts would be greatly appreciated... thank you again for your time and knowledge!!!

Answer
You can sometimes notice the widening out sooner by gently holding the tail just long enough for the female in question to stretch forward - as soon as she pulls let go!  This will emphasize the belly region and let you notice pregnancy a little bit sooner than if you waited her to look like she swallowed a golf ball.  Weighing them each day on a gram scale (like a food scale, pretty inexpensive) could also help you catch that weight gain a little sooner.

You can also look for a plug soon after mating, or in this case each morning, but that is only a sign of mating and not necessarily of successful pregnancy.  A plug is hardened fluids from the male that solidify in the vagina of the female to prevent other males from mating with her for up to 12 hours after mating ( http://ko.cwru.edu/services/musfrming.html#plug ).  This is the only other way I know of to check for a successful mating (though like I mentioned it may not lead to pregnancy), but might be a little hard to do at home.  I would NOT recommend probing like the link mentions - it would be far too easy to injure her.  When I breed I don't bother checking for plugs, I just wait two weeks after first putting them together and then check her tummy region.  Remember if you feel her belly not to squeeze!  :)  The link also mentions some troubleshooting for mice that aren't inclined to breed, so I'd definitely give it a look (though it's kind of technical - it's written for laboratories).  It mentions adding a little fat to the female's diet (a few more seeds would do the trick), providing ample privacy, keeping the light cycles in the room steady, and it doesn't mention it but I would also recommend putting some of the male's bedding in the female's cage when they are not breeding.  His scent will keep their cycles going and may make them more interested in mating when they are placed in with him.

Best of luck!
-Tam