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New Inbreeding Article



Dog breeding changed my whole attitude and outlook on breeding in general. In dogs, the larger the COI the more likely breeding complications, and fewer puppies in litters.
COI *inbreeding coefficient- of 5% or less was my goal for the PWDs i bred. It was somewhat harder to attain a low COI in Icelandic Sheep but we imported semen and learned how to AI our own sheep. We were not as successful keeping away from related individuals in our Highland Cattle. And i blame the closely bred bull we bought for having a few bottle (dumb) calves.

When i had two oops-bred mares last spring, i was grateful that the mustang stud and mustang mare came from entirely different herds… actually different states (Colorado x Nevada)
And the domestic mare that got accidentally bred, of course was completely removed genetically. Both foals are quite vigorous.


Link to the actual study for those of us who find the Paulick Report’s summary a little lacking:



For the statistical data experts out there-how would one use that information from this report? For example in true nicks- it shows an inbreeding co-efficient to the 10th generation and shows unique ancestors over total ancestors? What is too much in-breeding -if you do not see it in the first 4/5 generations? TIA

Thanks for posting the paper link. It’s an interesting study, not super surprising, though it does have some limitations. Having some correlation between the genomic inbreeding metric that they used and the pedigree inbreeding based calculations others used would be really helpful. Maybe I missed it but they found an increase in the genetic inbreeding metric they used in tissue for mid to late pregnancy loss, but they didn’t look at whether the rate of mid to late pregnancy loss increased with increasing inbreeding. It’s definitely something worth further research and keeping an eye on.

@omare, all horses are going to have some degree of inbreeding, you can’t completely avoid it. I’d worry more about disease or issues from inbreeding that result in a live foal that grows into an adult with issues than the increase in mid to late pregnancy loss this study found.


I hate to see the rise of inbreeding in WBs we are currently seeing. United Touch S is a fantastic specimen of a horse, but it isn’t healthy.

I once owned a highly inbred horse (dad was also damsire). That horse was fine too, but thank God he was gelded.


I’m definitely not encouraging more inbreeding. The issues showing up in some of the Warmblood lines are alarming. Growing up with Arabs I saw varying degrees of line breeding, some of it works, some of it doesn’t. I was always told when it goes well you call it line breeding, when it goes poorly you call it inbreeding.


It’s an interesting study.

Breeders call it linebreeding if it works and inbreeding if it doesn’t work. :rofl: :rofl: