# overpopulation



## bitterblue (Oct 24, 2016)

i have a question that keeps popping up in my head for awhile now, please bear with me  so i just wanted to ask what do you guys do to keep the number of mice in your colonies at a manageable level. I know about culling but that doesn't seem like enough. What i mean is about 4-5 pups about every 4 weeks (not counting rests) about half from the litter are male (and a few girls that are undesirable), and none are going to be useful for further breeding... do you keep them (and house them separately, and they take up space), or do you sell them, or maybe dispatch them. please tell me your thoughts, and forgive my ignorance


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## Lilly (Nov 21, 2015)

In an actual colony situation mice don't tend to breed constantly every 4 weeks, they will have rest periods and you will only have a few pregnant at a time, at least from talking to people that keep them.

What is probably more common than a colony with males/females/babies together though is having a breeding male or two separate and putting him in with females when you want to breed so that way you are in control of numbers somewhat.

As for half in a litter being males, unless I need males my cull order for a litter is runts/unhealthy > males > color i don't want so that keeps down the numbers somewhat and makes it easier to manage since females can be housed in a big group. Unwanted females will go to other people/breeders or kept as pets or in some cases culled but this is generally when there is some health/temperament issue with them (some can be very aggressive to other mice for example, or may be unhealthy and go downhill without a lot of supplementation)


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## bitterblue (Oct 24, 2016)

ok, thanks!


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## WoodWitch (Oct 18, 2009)

Most people would not use colony breeding unless a firm plan was in place for numbers (ie, culling). I don't use colony breeding.


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## PPVallhunds (Jul 26, 2010)

The people I know who collaney breed are the ones who breed for food, so they want huge numbers to cull off for freezing and later feeding.

I breed alot but bring litters down to about 4-6 sexes depending on which I'm after but if I'm after both I prefur to keep 1-2 bucks then the rest does. Once 8 weeks one's deemed unsutible to go back Into the line for me end up as frozen food.
When I first started in mice I tried to rehome or keep the ones who wernt good enough and just ended up with too many and not having the space to carry on the line.


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## Amtma Mousery (Jan 29, 2015)

Only in one specific situation, I may choose to colony breed. I choose this tactic when one of my lines do not have a specifically outstanding buck. I choose to breed the top best 3 bucks to all the does within that line. I often will select the two best does (if any) to out cross them into another line.

Although, I often have 2 colonies for each specific breeding group. I then separate the females pups to one colony, the male pups to the other colony. If you breed Siamese and Black (like me), have one colony dedicated to black, the other Siamese. Then you will be able to tell which pups came from which colony. <--- Best tactic, if you keep detailed genetic records. It helps a lot in the long-run.

What I stated above, is close inbreeding- sisters to brothers... expect a lot of culling and runts. But you'll benefit in the long-run, you will have a better understanding of the recessive genetics within that line and have some pretty durable offspring after this.

After the offspring of the colony breeding has matured, I suggest returning back to line-breeding.

How I cull:
Runts > faults > weight > unwanted color

More than often, I choose to keep pups regardless of gender because you may be culling a really nice stud. If you want to increase your odds, have one nursery dedicated to females pups, one for male pups. I have viewed this as one of the best ways to go about breeding.

If you want to get even more efficient and disregard morals/ethics, breed an alternative doe(s) the same time or a few days before breeding your main doe(s). Then when the litters are born, cull all the pups for the alternative doe(s) and split the litter(s) between the main and alternative does. Basically, you get all the offspring without having to cull any of your viable stock and without jeopardizing developments.
Additionally, I suggest fostering the pups that you care less about in case of cannibalism.

This is how I did it for my mice... and I started with runty 20 gram petshop mice. 3 years later, 40g-50g Siamese. 

Good luck!


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