At What Age....

Figured this would do better as a poll. I wait until a mouse is at least 12 weeks old before breeding them for the first time, though I've seen other mouse breeders begin breeding at different ages. So when do you begin introducing a male to your female mice? You can also include when you begin breeding a male. (I'm sure this is considerably younger)

8 to 10 weeks and I retire them after 5 litters.

It was always recommended to me to wait until they were 12 weeks old. Is there a reason for this? I retire after 6 litters. Of course that is my rule but I have never had a breeder colony long enough for that.

Like Deborah, I usually wait until they are about 8 to 10 weeks of age to introduce them to the male. I think if you go any earlier than that, you might cause the female more grief than she can take...which in turn could cause her to eat her young. Then again, most new mothers end up eating at least some of their first offspring, or so has been my experience. It took me a few months to get a good, solid colony going, but now they're doing great. I always retire mine after their fifth or sixth litter, which is easy to do as their offspring work great in taking their place. ;)

Forgot to mention that I breed the male as early as 6 weeks, so long as he's capable of doing the job. If it's a smaller male, I might wait another couple of weeks, but usually by that age, they are ready to go.

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Originally Posted by Jay_Bunny

It was always recommended to me to wait until they were 12 weeks old. Is there a reason for this? I retire after 6 litters. Of course that is my rule but I have never had a breeder colony long enough for that.

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Well those are guidelines but I pretty much go my my own guidelines based on what work with my colony.

I have been breeding rats and mice for a few years and have try various thing and 8 to 10 weeks with my colony seems to work perfectly, I have tried younger but they tend to have smaller litters and more prone to cannibalism.

At 8/10 week they average 12 to 16 babies even as first timer :O and they never eat their first litter.

I guess I could wait a little more but let's face it the breeding lifespan of mice is already very short so 8 to 10 is what I go by.

I always do 12 weeks with mice and 16 weeks with rats.

Its only a pain in the butt in the beginning when you are growing up your first breeders. After you have a good rotation in place it doesn't hold you back to wait until they are 12 weeks old.

So, I personally would wait until they are 12 weeks old.

Thanks everyone for your replies. :D

I start breeding females at 28 days. At this point they are sexually mature and will begin to cycle. If you think you are gaining anything by waiting you're not.

28 days is waaaaay to soon for a female mouse to begin breeding. Sure they are ABLE physically to conceive but that does not mean her body is READY for that kind of task. I mean, technically a 13 year old can conceive, but I bet you her body would not be able to handle it and she'd have all sorts of problems. I say ABSOLUTE minimum is 6 weeks. I have four does that are 6 weeks old tomorrow. They are not as big as their mothers, maybe only 25g at most. To me, they are not ready. I will wait another two weeks and then weigh them again.

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Originally Posted by Jay_Bunny

28 days is waaaaay to soon for a female mouse to begin breeding. Sure they are ABLE physically to conceive but that does not mean her body is READY for that kind of task. I mean, technically a 13 year old can conceive, but I bet you her body would not be able to handle it and she'd have all sorts of problems. I say ABSOLUTE minimum is 6 weeks. I have four does that are 6 weeks old tomorrow. They are not as big as their mothers, maybe only 25g at most. To me, they are not ready. I will wait another two weeks and then weigh them again.

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You need to get a better strain of mouse then. The mice I used to breed were 25 grams at 4 weeks old. If they are ovulating and breeding, they are ready. I bred mice for 15 years and have friends that have been for 25+ years. Our females were always introduced at 28 days. You will see litters in 21-25 days. Mice and humans are apples and oranges. Keep waiting and limit your production.

If you know EXACTLY what age to breed them, why even ask people their opinion? I know it worked for me for many years, but you absolutely refuse to take my advice. It's not waaaay too early if it's been proven successful for many many years. You say the ABSOLUTE minimun is 6 weeks, I say it's 28 days.