How old do male mice have to be to breed?

I'm guessing, from what I've read that mice can breed as soon as they are weaned, but I'm wondering about my male mouse.

I guess my female could be pregnant and I just don't know it yet, but I'm starting to wonder.

Maybe I'm just too impatient.

Males can breed as early as 5 weeks...i have heard a few reports that they supposedly bred as early as 3 weeks but the youngest male i had introduced to females started when he was 5 weeks old and 22-23 days later his harem gave birth to their litters so he was obviously fertile

If you are trying to breed I would not set up a male till he is at least 5 weeks old. Honestly I prefer to wait till they are 6 to 8 weeks old. I then introduce them idealy with experianced females. Young males with young females may take longer to breed.

Now as to when they can breed. A male mouse is able to breed as soon as you can see testicals. I have actualy had a 23 day old mouse breed his mother. I now that it was because he was the only male in the litter and the only male in the cage. The doe had babies when the buck was 41 days old. So at the most he was only 23 days old when he bred her. I am just glad I had weaned him right at 4 weeks. Otherwise I have no doubt his sisters would have been bred way to early.

Jeff C.

Got another question along the same lines..only when is it ok to breed a female? The same 6-8 weeks?

When one of my older females gets past breeding age and I retire her, I generally pick the healthiest female fuzzy currently being nursed and just pick around her when feeding days come. That way she grows up with that particular colony and I don't have to let her duke it out on the pecking order.

So far, after a couple of years of doing this I haven't had a problem. The females breed when they can and voila, babies all nice and healthy. The females that have done this don't seem to be showing any health issues related to it at all. Then again, I don't have an x-ray machine nor a veterinary license.

In the beginning I tried to separate the females in a separate tank and let them "age" up a little bit. I used to raise rabbits, and it was hard on young young females to just start out and pop out babies. But I found when they were away from their intended colony for more than a week, re-introductions were rather violent. And it put the new female in such a state, that she wouldn't breed for a month or more.

Maybe I'll try the re-separation thing to see if I can get my females healthier and more prepared and just not worry about the subsequent fights that'll break out.

hmmm people who breed mice for show wait to breed the females until they are about 3-4 sometimes more months old but this is to enable them to be unmarred for showing...

however, i rely more on size if i seperate at all. I , like you would rather avoid the fights and most of my females do not get pregnant until they are ready...it is what would happen in the wild too...and the babies are not any smaller or unhealthy...in fact i notice that my babies are fatter and that my females have less complications...i have never lost a female to birth comlications. waiting too long to breed can cause more complications too, mice age alot fater than we do so a 6 month old female maybe in her prime for breeding but you will probably not get too many litters from her. I just seperate my show quality females for a bit longer than the rest but that is not a problem if you don't breed for show...Hope i helped

First I want to let everyone know that Maxamus's surgery was a huge success. In fact it went so well He only need to spend 1 day in the hospital and not the 3 to 10 we were expecting.

Now to answer your question Misty. I agree 100% with Amy. I have bred both ways and I still do.

My 100% English mice I separate and wait till the does are at least 8 weeks and if they are a little small I wait till 12 weeks to breed them. Since this is a feeder forum I won't go into all the details as to why. I'll just leave it at the English are overall weaker breeder as they have been bred for low production for low production.

As for my feeder colony though I don't leave the female in the colony I set up new colonies at the time I wean. The reason I don't just leave the female is because I generally retire my feeders by colony rather then individuals. I also like to set up new colonies at least 3 months before I plan to retire a colony. This way they will be in full swing to take over before I loose production from the retiring colony.

I also agree with Amy that you will have more problems setting up females to late then to early. This is especially true with Americans bred for feeders and most lab strains. This is because these mice have been bred for production and have a lower metabolism so that they don't unnecessarily burn off calories that could be used by their babies. This, however, causes them to get fat very easily if they are not in production.

Jeff C.