X-factor help, please

Understanding pedigrees, inbreeding, dosage, etc.

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barbfool
Yearling
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Joined: Thu Apr 20, 2006 7:22 pm

X-factor help, please

Postby barbfool » Sat Oct 27, 2007 8:05 pm

Consider the pedigree of Jonathan's Gold. His dam received the x-factor from her sire, Ridan. How can you be sure, one way or the other, weather or not Jonathan received it from his dam?

xfactor fan
Breeder's Cup Winner
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Postby xfactor fan » Mon Oct 29, 2007 8:36 am

You can't, unless you have someone do a heart score for your horse, and you have the heart score for Ridan. If they are the same, then it is likely that Jonathon's Gold got the Ridan X from Goldian.

Are you sure that Ridan has one of the large heart X's? And what is the source of this information? Does Johanthon's Gold look like his sire or his broodmare sire? Not color but conformation.
Other things to look at is the stud career of Ridan. Are his fillies better overall than his colts? Is he a great broodmare sire, but not so hot as a sire of sires?

The genetics behind this theory is that there is a complex of genes on the X chromosome that give extra cardio capacity. Mares have two X's but only express one. They give one of their X's to each foal, 50/50 chance each time which X is passed on. Colts only have one X so it is expressed and you can see if they have the extra cardio. Fillies may express it, or may not, again 50/50 chance which X they show.

Mares by a X factor stallion will have one copy of the large heart X from their sire, but may not express it.

Hope this helps.