The Mares in Great Sires

[vineyridge]

Is the same level of analysis on the X factor being done on European horses?

It's pretty definite that none of the four stallions that stancaris refers to have much of a presence in the European breeding pool--at least not comparatively.

They might have just been great breeders whose genes "clicked" with the US mare base or the mares/genes in other European stallions.

Would you postulate Galopin/Merry Gal/White Eagle/Quick Thought/Cosquilla
Or Miss Matty/Papyrus? For Princequillo

For War Admiral
Canterbury Pilgrim/Harry of Hereford/Annette K/Brush Up? Or Spearmint/Bathing Girl/Annette K/Brushup? Or Pink Domino/Sweep/Brushup?

Fact is that all of those mare are from superlative dam lines.

[DDT]

Stan

In my opinion, in the case of Mr. Prospector and Sadler's Wells I believe it is more a function of quality and quantity of representation that carried these two stallions to the top of the broodmare sire lists rather than an X factor at work. These two stallions also sired many good sons, not just daughters.

DDT

[Georgerz]

I read sometime ago that Mr. Prospedtor was found, upon physical inspection, to have a normal (not large) size heart. How, then, could he pass a large gene, if he didn't have it himself?

[aethervox]

I would like to point out that it was researchers in Australia that linked foal heart size to dam heart size. They weren't willing to state whether it was genetic or maternal effect, but there was a very high statistical correlation between heart size of the dam and heart size of foals, with the highest correlation between dams and colts.

Have any other scientific studies been done on thoroughbred heart size and heritability?

[xfactor fan]

According to historical record, Eclipse had a large heart. This is supposed to be the source of many of the later X factor horses. So the X factor should be well represented in European Horses.

And it was the Australians investigating the large heart the their national racing hero Phar Lap that started looking into this. Phar Lap's 14 pound preserved heart is on display.

http://www.nma.gov.au/collections/pharlaps_heart/

stancaris, which heart line do you attribute to Giants Causeway?

[stancaris]

X Factor Fan:

Giants Causeway's broodmare sire is Rahy whose maternal grandsire is Halo who carries Mahmoud and also Blue Larkspur in the X passing position. In addition Rahy's dam, Glorious Song traces to Swaps in the X passing position and Swaps has War Admiral in the X passing position. So, one can say that Giants Causeway's broodmare sire has 3 out of the 4 major stallions in the X passing position. Haun has not listed Giants Causeway under any of the 4 big hearted stallions in either of her first two books. Your guess is as good as mine on the above but nevertheless it sure is likely that Giants Causeway carries Blue Larkspur's X chromosome or War Admirals X chromosome. Haun identified Halo as a carrier of Blue Larkspur's X.

[xfactor fan]

Two things about classic X factor stallions. Daughters are better than sons. And there tends to be a resemblance between the stallions that carry the same heart.

All of the Mahmoud heart line stallions tend to be small, around 15h. Mamhoud, Halo, Rahy, all are about that size.

Giant's Causeway is 16.1 according to his stallion page. I"d be more inclined to look at Roberto's X.

http://www.sporthorse-data.com/d?i=621401


Giant's Causeway

http://www.sporthorse-data.com/d?i=10005811

And the ears seem to be similar.


And going back a bit more, take a look at Bull Lea

http://www.sporthorse-data.com/d?i=10347149


I took a quick look at the earnings listed for Roberto offspring, and based on the data here in PQ earnings seem to be split between his colts and fillies, with maybe a few more colts.

Could you take a better look at how the two stallions compare?

And a question for PZ.

Do you know what the testing is looking for? Are they looking for variations? Or can the test pick up duplications of the same gene?

Thanks

[Pan Zareta]

And a question for PZ.

Do you know what the testing is looking for? Are they looking for variations? Or can the test pick up duplications of the same gene?

Thanks

The test uses a chip (microarray) to examine ~70,000 known SNPs (single nucleotide polymorphisms) spread throughout the entire equine genome. Yes, they're looking for variants (polymorphisms), in this case specifically for those which correlate with aptitude and/or performance. If by "duplication of the same gene" you mean homozygosity I believe the answer to that question would also be yes.

[vineyridge]

Just because a heart is large doesn't necessarily mean it's genetic and goes with athletic performance. It might be an enlarged heart with size enhanced by athletic performance or caused by heart disease and/or athletic performance.

Agree with Brogers that the spleen is underestimated.

Chicken and the egg, anyone?

[stancaris]

X Factor Fan: You could be correct. Here is another point I want to make. Earlier I posted a list of the last 29 broodmare sire leaders and I made a mistake. Mr. Prospector has Nashua as his broodmare sire and Blue Larkspur is Mr. Prospector's fourth damsire. I stated that Blue Larkspur was found in the X passing position of Mr. Prospectors broodmare sire. That is not true. However, Nashua, the broodmare sire of Mr. Prospector has Sir Gallahad in the X passing position. Whats so intriguing about this is that Sir Gallahad led the broodmare sire list 11 times, more than any other broodmare sire since around 1940. It is quite possible that Mr. Prospector carries Sir Gallahads X chromosome and many of the fine traits that are carried on his X which allowed Sir Gallahad to become a champion broodmare sire for 11 years. Interestingly, Mr. Prospector, who could have Sir Gallahads X also led the broodmare sire list very often (9 times). The X chromosome is vital to the overall success of a racehorse and in particular is a key factor in allowing a horse to become a great broodmare sire. Horses like Buckpasser, Princequillo, Sir Gallahad, Nijinsky, War Admiral etc transmitted superlative X chromosomes to ALL their daughters and none of their sons. Furthermore, all the daughters of a great broodmare sire transmit his superlative X chromosome to 50% of their offspring. Hence, we can account for Mr. Prospector's great success as a broodmare sire. He could have transmitted Sir Gallahad's X chromosome to all his daughters (assuming he inherited that X from his dam, Gold Digger). That same X chromosome was a key factor in allowing Sir Gallahad to lead the broodmare sire list 11 times and similarly could have been a key part of why Mr. Prospector led the list 9 times. The transmission could be figured out as follows: Sir Gallahad must give his X chromosome to his daughter La France. She has a 50% chance at giving that X to her son Johnstown who must give that X to his daughter, Segula. If Segula got that X she has a 50% chance of giving that X to her son, Nashua. Now Nashua had a huge racing career. It is logical that he received a superlative X from Segula and that X has a pretty fair chance of being Sir Gallahad's. Assuming that Nashua has Sir Gallahads X one can say that Mr. Prospector had a 50% chance of getting Nashua's X from his dam, Gold Digger. Sir Gallahad and Mr. Prospector were both fantastic broodmare sires. Isn't it likely that they both carried the same X chromosome?

Assuming the X chromosome does not carry a gene for Heart size as Byron Rogers professes. It still is a powerful carrier of super genes because it is the super genes on the X that make a broodmare sire successful in getting superlative daughters who in turn get well above average sons and daughters. The X chromosome is the only chromosome that is transmitted by a sire ONLY to his daughters.

Another possible explanation is that the X chromosome carries genes that dictated the production of a very efficient heart. Not big, not small, just great. Mr. Prospector himself, probably had too many sprinter genes and never won a race beyond a mile or a mile and a sixteenth. However, his X chromosome was superior and he transmitted that X to all his daughters and they in turn to 50% of their sons and daughters. You don't lead the broodmare sire list 9 times by transmitting a mediocre X to your daughters.

Don't get me wrong, the X chromosome is not the sure road to success but it sure is important. It is vital to a racehorse and also vital to humans. Humans born with one X chromosome survive.(Turners Syndrome). Humans that inherit two Y chromosomes and no X never develop. X marks the spot for great broodmare siredom.

[DDT]

Stan

I think most everybody agrees that the X chromosome is special and there is somethings to learn yet, however as to multiple broodmare champion sires I think it would be wise to take into account that Princequillo, Buckpasser, Nijinsky II, Mr. Prospector and Sir Gallahad all stood at Claiborne during the time span when Claiborne was and still is a leader in breeding and Bull Lea stood at Calumet, another noted for solid breeding, hence, they had wonderful opportunity and were bred to top mares for most of their careers. Now don't get me wrong here, I still believe that the X chromosome plays a major role in broodmare sire success, however, opportunity does also.

DDT

[xfactor fan]

PZ,

Thanks for the answer, however the question is slightly different.

Would the testing pick up a duplication of a region on one chromosome. Lets say during re-combination instead of making the splice in the same spot in the DNA strand, an error is made and one chromosome gets an extra piece and one chromosome is missing a bit.

I've wondered if there is a region that controls replication. For example a developing heart has to know when to stop growing--other wise with unlimited growth the Chicken Heart that Ate New York City could be a reality, not just a bad joke.

An error is this region (if it exists) could increase the number of replication cycles leading to a larger heart --or any other organ for that matter.

Thinking about equine evolution, there has to be a mechanism where heart size is increased. Theres no way a heart that powered Eohippus, could work in a modern horse of any breed.

Dogs are a good example of this. Mostly dogs have the same size heart, the bigger the dog, the shorter the lifespan. The heart just isn't powerful enough to support a large dog body.

Back to the X factor theory.

Did anyone ever test Mr Prospector and see what kind of heart score he actually had? I've seen folks claiming he had a large heart, and others claiming he had a normal size heart. Evidence would be nice.

Also anyone know what kind of heart Northern Dancer had?






Interestingly enough, Greyhounds that have been selected for racing, exhibit more variation in heart size than other dogs. And overall they have a life expectancy a bit longer than other breeds of the same size,

[aethervox]

Just because a heart is large doesn't necessarily mean it's genetic and goes with athletic performance. It might be an enlarged heart with size enhanced by athletic performance or caused by heart disease and/or athletic performance.

As I understand it the measurements took into consideration the enlargement caused or enhanced by exercise, and there was no evidence of heart disease.

In her second book, Haun mentions that Dr. Fregin noticed differences in QRS traces between the different 'heart' lines, which does suggest that the trait is genetic, not environmental. Unfortunately no one has really studied the EKG strips that Dr. Fregin has compiled -- no funding, of course.

I, too, think that there's another factor or two that, along with a larger than normal heart, makes a 'super horse'. Spleen makes sense, and I think lung capacity plays a role.

[Pan Zareta]

PZ,

Thanks for the answer, however the question is slightly different.

Would the testing pick up a duplication of a region on one chromosome. Lets say during re-combination instead of making the splice in the same spot in the DNA strand, an error is made and one chromosome gets an extra piece and one chromosome is missing a bit.

A translocation. Whether this testing would pick up a balanced translocation, I don't know. Unbalanced translocations are seldom viable.

I've wondered if there is a region that controls replication. For example a developing heart has to know when to stop growing--other wise with unlimited growth the Chicken Heart that Ate New York City could be a reality, not just a bad joke.

An error is this region (if it exists) could increase the number of replication cycles leading to a larger heart --or any other organ for that matter.

Thinking about equine evolution, there has to be a mechanism where heart size is increased. Theres no way a heart that powered Eohippus, could work in a modern horse of any breed.

Dogs are a good example of this. Mostly dogs have the same size heart, the bigger the dog, the shorter the lifespan. The heart just isn't powerful enough to support a large dog body.

Have you read any of the published reports re. the myostatin gene? Compared the canine and equine findings? Myostatin is an inhibitor of muscle cell proliferation.

Back to the X factor theory.

Did anyone ever test Mr Prospector and see what kind of heart score he actually had? I've seen folks claiming he had a large heart, and others claiming he had a normal size heart. Evidence would be nice.

I don't know whether he was ever tested, but seem to recall reading that post-mortem examination revealed that he had a normal size heart. (So did Bold Ruler.)

Also anyone know what kind of heart Northern Dancer had?

I don't know, but according to Jeff Seder (EQB) Northern Dancer & his sons tend to get large-hearted foals. Otoh, Dynaformer doesn't, but his foals tend to have thick septal walls (a good thing). Another less than shocking factoid from the same source, some of the largest hearts relative to age and gender are found in fillies at "high-end" private breeding farms, fillies that are seldom found in the sale ring (I believe sale stock was the main source for Seder's database).

[xfactor fan]

What started me thinking along the lines of duplicated segments was a report on one of the science programs about the "risk" gene in humans, Most folks have a copy. Folks with multiple copies (unbalanced trans-locations) Tend to indulge in high risk behaviors. The example profiled was a Japanese Skydiver. Not a sport that has taken hold in Japan.

The fact that most trans-locations aren't viable might explain why evolution takes such a long time. The change has to happen, it has to be viable through breeding age, and it has to have some pro-survival effect.

I doubt the simple theory that Haun put forth in her books is the entire answer. It may very well be that there are multiple factors that come into play. It would be nice to sort out the genetics so that breeders can load the dice in their favor.