# Does the size of a mouse affect their ability to breed?



## mauser (Sep 9, 2013)

Hope I've posted this in the right section! Although this is a question about breeding, it is more aimed at the health of the mouse.

I have a gorgeous pink eyed white female who I have been planning to breed for a while now. She is roughly 3-4 months old, and I have heard that for a first time litter, 3-4 months is the best time to breed them - is this true?

Anyhow, what I am concerned with is that she is slightly smaller than the average mouse - is this simply because she is a pink eyed white? Or is that totally unrelated? Do smaller mice have less chance of having a large litter? What is the approx. size of a mouse's first time litter?

I will not breed her if I think her own health and welfare is at risk. I'd just like a bit of guidance. Although I have bred before, I do not kid myself that I am fully experienced, I'd like some honest opinions.

Thank you very much 

**EDIT** I have just weighed Phoebe, she is 26-28 grams.


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## Serena (Dec 29, 2011)

Size is not related to the colour. there are gorgeous PEWs out there that are huge.
It is hard to tell if she's too small to breed. What's her weight? 
If she's otherwise healthy and not too small there shouldn't be a big problem. Just don't use your largest buck on her 
The size of first litters vary. Everything between 4 and 20 is possible. It is said that they are smaller the first time, but I don't know if it's true. Mine always have relatively large litters.


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## Laigaie (Mar 7, 2011)

I've seen teeny-tiny does get through birth just fine, and gigantic show does birth a whole litter of stillborn pups. Size is relevant, but you mostly need to know whether she's fully-grown, and whether she is healthy. If the line she's from tends to produce small mice, then she may well be just fine. If she's from a line of large mice, you probably shouldn't breed her. As a rule, most try to make sure their does are nearly full-grown before starting to breed them, as this gives the pups and the mother their best bet. If she is tiny, culling the litter down to a more manageable size may make it easier on her and the pups.

Also, I've found that pink-eyed and c-diluted mice are generally larger than black-eyed mice. Something about the nutrient cost of pigment is my best guess as to why, but she's certainly not tiny because of being a pew.


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## mauser (Sep 9, 2013)

Laigaie said:


> I've seen teeny-tiny does get through birth just fine, and gigantic show does birth a whole litter of stillborn pups. Size is relevant, but you mostly need to know whether she's fully-grown, and whether she is healthy. If the line she's from tends to produce small mice, then she may well be just fine. If she's from a line of large mice, you probably shouldn't breed her. As a rule, most try to make sure their does are nearly full-grown before starting to breed them, as this gives the pups and the mother their best bet. If she is tiny, culling the litter down to a more manageable size may make it easier on her and the pups.
> 
> Also, I've found that pink-eyed and c-diluted mice are generally larger than black-eyed mice. Something about the nutrient cost of pigment is my best guess as to why, but she's certainly not tiny because of being a pew.


Thank you Someone said that the best time for a mouse to have her first litter is between 3-4 months, is that correct? Because Phoebe is roughly 4 months old now, if not a few days older, would that be considered 'too old'?


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## Serena (Dec 29, 2011)

4 months is fine. I know breeders that even wait until 6 months. because of that you don't have to worry.


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## mauser (Sep 9, 2013)

I just weighed her, she is between 26-28 grams - would you say that is an acceptable weight to breed her? Or would you advise against it?


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## Serena (Dec 29, 2011)

It's a little on the smaller side, but doesn't sound too bad to me. 
As long as you don't you a really big buck she shouldn't be at too high risk for complications (there's always a chance for complications)


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## mauser (Sep 9, 2013)

Serena said:


> It's a little on the smaller side, but doesn't sound too bad to me.
> As long as you don't you a really big buck she shouldn't be at too high risk for complications (there's always a chance for complications)


I have just weight the buck I plan to breed her with and he is 34g - does this sound too big to you?


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## Serena (Dec 29, 2011)

no, doesn't sound too big for me. By big I was thinking more of sth around 50-60g ^^


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## mauser (Sep 9, 2013)

Serena said:


> no, doesn't sound too big for me. By big I was thinking more of sth around 50-60g ^^


Thank you very much n.n


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## Laigaie (Mar 7, 2011)

As for needing to have the first litter by a certain age, that's hogwash. There is no biological reason that a 3month old mouse is more fit to be a first-time Mom than a 6mo mouse, and many lines do equally well at 9mo. Breeding your doe early helps you get longer breaks between litters, and thus healthier babies and moms when you're breeding several litters, but that's more of a scheduling thing than a biological thing.


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