x chromosome

[ZiaLand]

I'd like to see that info, x factor.

[xfactor fan]

Which bits?

The fact that Eclipse had a very large heart is pretty well documented. As is the Secretariat large heart.

The heart score/race performance mostly comes from Australian sources, and some from Finland measuring trotters.

The Australians started investigating the large heart because of their national hero Phar Lap, who also had a large heart-that one is preserved in a jar.

[jacksontyger]

Tell us more

[ZiaLand]

I meant I'd like to see that extended post, x factor.

Which horse was documented to have the largest heart? Was it Phar Lap or Secretariat? (Or another horse entirely.)

[stancaris]

sec had the largest heart ever at around 22 pounds.

[Tim]

I have read all the posts with interest. This is a fun portion of pedigree research. My question is this: how can you tell if your horse has the LHX and how do you tell from whom it came? And is there a test to find out whether or not any horse actually has the LHX?
I have heard that the way to quickly "see" if a horse has the LHX is to put your fist into the throatlatch of the horse. If it fits into that groove,the horse has it. The theory being that the LHX comes with enlarged airway passages as well.I don't know the validity to such a claim but have observed many indivuals doing this to horses at the Keeneland sales.
In trying to make sense of my questions,I will give you a for instance. My filly has the War Admiral LHX through her sire Cahill Road. I believe it is through Buckpasser,which is War Admiral. Her mother is by Rahy,so she received the Mahmoud from him. Now there is a possibility that my filly is a double X copy. How do I find out if she is or she isn't?And how will I know which LHX to concentrate further breedings for her?

[xfactor fan]

I'm going to assume that you don't want to weight your fillies heart after she's dead. There are outfits that will hook a EKG up to your horse, and measure the results, and then produce a "heart score".

Females are more complicated than males, so depending on a huge number of factors including X chromosome inactivations, your filly most likely will only express one X in her heart score.

Depending on how much you believe Haun's theory, you could try looking at your filly. How close is she in conformation and height to:
1) her sire,
2) her broodmare sire
3) anyone else upstream on the female side of the pedigree.


You know for a fact that she is going to have one X from her sire. No choice in that, the trick is in figuring out what and where the other X comes from.


First are you sure that Cahill Road has the War Admiral X?, if so, then she will carry this X. Which again according to Haun should give you a well balanced smallish horse- around 15 hands or so.

The dam by Rahy will carry the Rahy X, but also another X from her dam. And there is no telling which X she gave your filly.

You might try looking at the ear of your filly--Are they very round when viewed from the front? If so she might be carrying the Mahmoud X.

Would you be willing to post a photo, and her name? I'd love to take a look and make a guess.

Hope this helps.

[katydid]

Could you take a look at my mare? I put a face pic up on her pedigree, her conformation is very similar to that of her sires "Personal Hope". She's got a wonderful heartgirth, her neck ties in kinda low with a large low hanging windpipe. I have wondered if she carries the x-factor gene but I don't know enough about it (she didn't do well at the track--so I don't think she'd produce very marketable race-prospects).

clicke here (she's the bay in the pic =D)

conformation

[xfactor fan]

If she's the one with the small star, take a look at her ears. They appear to be very round. This could be a marker for the Mahmoud X.
How big is she?
And how big is Personal Hope?

Take a look at Rare Perfume, and see if you can see a family "look" shared with Personal Hope.


A horse can be an X factor horse, and not be a great racehorse.

[katydid]

She's approx. 16H not sure how tall Personal Hope was though it appears he was in the 16-16.1H range as well. I see resemblances on both sides of her family, but it is hard to tell from pictures =D


It seems that most modern day TB's would posses the x-factor gene, or are there are lot of x-factor inactivators? Interesting stuff nonetheless =D I had heard that possession of a large heart only accounted for like 10% increase in athletic performance so it just can't be heart size that made those greats "great". Ultimately, one would think that it is near to impossible to duplicate it was a genetic jackpot.

[stancaris]

the evidence is strong that the large heart gene or genes is carried on the x chromosome. it is a sex linked trait. the pattern of inheritence is fom a father to all his daughters. proof of the pattern follows; 50 percent of secs daughters show his large heart---none of his sons get that heart. if the trait was autosomal one would expect 50 percent of secs sons to get that large heart and this is not the case. in all of Hahn's research this pattern repeats itself with hundreds of horses.

the gene or genes for a large heart are carried on the X chromosome--that is irrefutable in light of the evidence at this time and Hahn's two books strongly support this view WITH FACTUAL EVIDENCE.

[Mahubah]

Stan, is there anything on Man o' War's heart size in the literature? He has a potential heartline path back to Pocahontas via St. Simon and ranked among the top ten American broodmare sires 22 times though he never led the list.

[stancaris]

Mahuba: Hauhn states that Man O War carried a large heart. However, in modern derby winners his heartline is not as frequent as War Admiral, Mahmoud, Princequillo, Blue larkspur etc. Every so often Man O War does appear in the X passing position and one notable star that had Man O War in the X passing position was Sunday Silence.

[xfactor fan]

One of my gripes about the X factor books is that Haun is not consistant in her nomenclature.

There are several large heart lines that she talks about:

War Admiral/Sweep/Domino

Secretariat/Princequillo

Mahmoud

Blue Larkspur

Man O War/Rock Sand

The Man O War heart is large but not as large as the other hearts.

Stan would you check the pedigree of Suday Silence to see if someone has been messing with it? I don't see Man O War along any of the X chromosome lines but via a son up in Wishing Well's pedigree.

[Mahubah]

Sunday Silence does have a possible heartline path to Man o' War. His dam is by Understanding, so has Understanding's X chromosome. Understanding is out of a mare by Stymie, so has a 50% chance of having Stymie's X chromosome (the other 50% is that the X is from his maternal granddam). Stymie is out of Stop Watch, whose dam Sunset Gun is by Man o' War, so Stymie could have inherited the Man o' War X.