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Are Angus the new terminal breed?
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MiradaAcres
Posted 6/4/2019 17:32 (#7541262 - in reply to #7541088)
Subject: RE: Wow, I'm all in it's a moneyball!



scmn

I don't really think there is enough genetic diversity left in the north american Holstein herd to enable those kind of changes but I would love to be proven wrong and genomic testing just might enable the finding of what would be the 175 percentile (or greater) outliers - - - -but I think the would be very very very rare.

I think this is 100% true.  I have had several discussions with other Holstein breeders about merits of genomic tests.  My understanding is that stud companies will not buy a bull that is not genomic tested (they want to know what they are getting); I have also herd that if you have a bull tested and the stud companies are interested that they will contact you before you get the results back from the genomic test.  The stud companies know before you do because the genomic data is uploaded to the CDCB database; the stud companies query the database using filters to find specific genomic profiles that they are interested in.

I can not seem to find the query now but there is a query were you can see the marker value of every chromosome contributed by the sire and the dam for each genomic tested heifer.  With 29 chromosomes and 4 possibilities per chromosome (a or b from sire and A or B from dam) that is 288 quadrillion combinations per mating (sire/dam and 1 offspring).  The likelihood of propagating any given maker on a chromosome is still 50% (either they get it A or B from parent for each marker).  The likelihood of eliminating any marker is still quite low since there are several non-preferred markers in every animal that is selected to stay on for another round of breeding and if every animal breeds to produce 2 offspring in theory one of each marker should always be passed along.

The saving grace of the situation is that there is always a producer that is going a different direction than the majority of the breed because it works for them and when the breed as a whole needed to change directions, the stud companies will find those individual animals by evaluating their genomic profile.  Genomic may vary well help keep the diversity as much as limit it.  I have several heifers that show low inbreeding when mating to bulls based on parental averages, but show high levels of inbreeding because they picked up the common genetics from dam and sire.

Edit to add:
I should add that we have Ayrshires and Milking Shorthorns also and limiting inbreeding is more difficult there since there population is lower and there are less bulls in stud making the breed less diverse quicker than the Holsteins.  One thing that brings in fresh cross is Milking Shorthorn has a grade up program were we can cross to another breed and grade up in 3-4 generations so long as the Milking Shorthorn characteristics are preserved (black is not allowed to enter Full Herd Book or EXP status so multiple generations can sit at GE2 status until red coat is attained.



Edited by MiradaAcres 6/4/2019 17:38
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