# How much inbreeding ?



## pauly (Feb 21, 2013)

I am sure people know of the old saying : It's line breeding when it works, it's inbreeding when it doesn't. I'd be interested to hear what plans breeders are following, particularly SarahY, whose article in the Febuary NMC news , I found very interesting.

I started thinking about this as I'm trying to get some foundation stock over to Ireland, & as it won't be easy to obtain an outcross when I want one, how close & for how long is it advisable to closely breed.

Would it be a good to idea to bring over two separate lines from two different breeders ?


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## SarahC (Oct 3, 2008)

you could keep two complimentary varieties and outcross when necessary.PEW'S and creams,fawns and champagne tans,reds and cinnamon and agouti etc.Alternatively does that have been mated in advance to bucks that are unrelated to the ones that you aquire with them or as you say 2 trios of entirely unrelated stock.


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## onionpencil (Jan 6, 2013)

pauly there's no cut and dried rule that i know of. you can inbreed until you get problems- could happen early, might never happen. it depends on luck and what's lurking in your stock's gene pool. the bigger question might be- what will you do if you develop issues? who will you breed to if/when you need outside blood? sarahc's idea of running 2 lines might help- you'd have less related mice to breed to in your own stock. good luck!


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## pro-petz (Nov 14, 2012)

I personally go for 3 separate unrelated lines per variety thus enabling both inbreedig and line breeding to be done with the chances of actually requiring outside outcrosses to a minimum unless one spots that super mouse that has so many faults in the way of excessive to desired standard. Otherwise any outcross must excell in feature required yet be of equal quality or better than current stock.

They say 20 times inbred is a pure strain, but in doing so may also lose desired features or size, harsh culling and selection is a must in this scenario.

It would be interesting to know if any studies have been done as to determine which sex fixes the various features required for show stock.

eg bucks increase size, type
does ears, tail set

these are just examples and by no means are actual indicators

Knowing which sex produces and fixes features may help in line breeding the various lines so that with three lines running of the same variety outcrosses with desirable features will always be at hand


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## Seafolly (Mar 13, 2012)

I don't know how off topic this is but I'm curious if there have been studies done based on whether buck or doe influences the genetic component of personality more. I am inbreeding, but am considering an outcross to a lesser typed doe but is leagues better in terms of docile and friendly.


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## Lyra (Mar 1, 2013)

From what I have seen in my area, most of the mice that are bred here (excluding those from feeder breeders) all are outcrossed. After hearing many times "you shall not inbreed" lectures I was outcrossing myself, but I have some plans considering linebreeding. I've read a lot about it, and yet I'm still a little unsure how to maintain the traits I want without making my mice less fertile and healthy&#8230; 
About inheriting personality, I was quite disappointed when two of my best tempered mice, full of love for humanity, gave me a litter in which only 2 are like parents, 4 are rather friendly (but not much interested) and 3 are totally not interested in any interaction with humans.


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## Seafolly (Mar 13, 2012)

If I had the luxury of choice I'd line breed but mouse selection here is very poor and I got very lucky with my foundation buck. I've been offered a black, long haired buck but everything about him looks feeder bin. However, he apparently loves to ride shoulders so I have been tempted to add yet more friendly genes into the mix. My lovely pet line errs on the side of skittish. My foundation doe is the friendliest of my line, but no other female is as laid back. It baffles me.


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## Sizzlea89 (Jan 19, 2013)

I have 4 separate family groups all unrelated in any way, 3 banded groups and one Siamese trio. I have in total 3 adult bucks in their own cages. The family groups are mothers, sisters and daughters. I find borrowing bucks from others helps keep lines going if you breed them in every 2nd generation to give fresh genes. Interesting genes have shown up in a few of mine and its fascinating me. Just thought this might be of some use lol. I know there are plenty of people that would do differently but I find this avoids a lot of health issues and short life spans


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## Seafolly (Mar 13, 2012)

Inbreeding will only cause health issues if there's a bad recessive to be exposed. Health issues are just as likely to pop up in outcrossed lines. It completely depends on the mice you're pairing.


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