Buckpasser in the X

[DDT]

Stan

I am a little confused by some of your statements. When you say that broodmares transmit about 50% of their X Chromosome to each foal do you actually mean that each broodmare has a 50% chance of passing on one of her recombined X Chromosomes, the one received from her sire and the one received from her dam? You have stated this before and I never received a clear answer from you, or I missed it.

This discussion centers around your statements that the X chromosome is important to broodmare success. I do not believe that any response to that has indicated that the X chromosome is not important to the foal. The majority of responses disagree with you as to the primary influence of the X going to broodmare success.


DDT

[Patuxet]

Stan:

I found the 88 elite SWs (winners of two or more Grade I races) using the pedigree program called "G1 Goldmine".

My edition of the program identified 44 elite SWs sired by stallions whose dams were by Buckpasser and another 44 by stallions whose dams were by Secretariat. Coincidentally each group included 17 fillies.

[stancaris]

DDT: A broodmare sire transmits nearly 100% of his X chromosome to all his daughters. His daughters receive two X chromosomes, one from the broodmare sire and one from her dam. She in turn transmits one of her recombined Xs to each of her offspring.

In the specific case of Buckpasser--- he passes on 100% of his X to all his daughters. They in turn will transmit around 50% of that X to all their progeny. This is an average percentage and it may be more than 50% or less than 50% of Buckpasser's original X chromosome.

Answer: A broodmare will transmit only one of her X chromosomes to her offspring and that X will be recombined with her other X chromosome so that there is no way of knowing exactly what percentage of the original X is carried on the recombined X. The recombined X she transmits to her foals could be as high as 65% of Buckpasser's X chromosome or as low as 35% of that original X carried by Buckpasser. On the average however, the foal will receive around 50% of Buckpasser's original X.

Pan Zareta has continually stated that the X chromosome at best plays a minor role in broodmare sire success. I do not believe that the X plays a minor role toward that success. It plays an important role.

[DDT]

Stan

You are not considering the fact that DNA from 3 X Chromosomes are involved in the recombination process, each egg produced by the mare carries an X Chromosome unique to that egg and the percentages are determined by chance. It is absolutely possible, in this case, that Buckpasser could be the broodmare sire but donate very little DNA from his X Chromosome, and that is one of the reasons that the DNA carried on the X Chromosome is not a primary factor for broodmare sire success.

DDT

[stancaris]

DDT: The mare has two X chromosomes not three. Explain how 3 X chromosomes are involved in the recombination process. Where do these three X chromosomes come from? etc.

[DDT]

Stan

Okay, Seeking the Gold received an X Chromosome from his dam, Con Game. Con Game's recombined X has DNA from Broadway and Flitabout and Busanda, do you disagree with that?

DDT

[Pan Zareta]

Pan Zareta has continually stated that the X chromosome at best plays a minor role in broodmare sire success. I do not believe that the X plays a minor role toward that success. It plays an important role.

Why is it necessary to keep reminding you that you were first informed of the X's comparatively minor role in elite performance and therefore broodmare sire success, as defined by genome-based evidence, not by myself but by an industry professional whose conclusions were drawn from analysis of full genome scans of hundreds of TBs and are consistent with the findings of other researchers looking at same?

I might add that, unlike you, none of those people have any emotional investment in which chromosomes are most/more influential to broodmare sire or any other kind of success. Their stake is in accurate identification of the ones that are.

You are inexplicably obsessed with the fact that a sire passes along his only X, unrecombined, to his daughters. Big whoop. He also passes along a recombined haploid set of 31 other chromosomes that account for the vast majority of total DNA he's transmitting and that's where the variables most/more influential to superior performance are. Hardly surprising since the X is non-recombinant in males and there are far fewer of them than females in the breeding population of the domestic horse as a whole and the TB in particular. In such an environment X variability is quite likely diminished relative to the fully recombinant autosomes, at least in comparison with less polygamous species.

[Jeff]

Genomic evidence does not prove that the X plays a minor role in broodmare sire success.

If you want to deny what the TB genome-based evidence proves and pretend that it can in any way be refuted by cherrypicked stats that's your problem. Just don't expect that your claims will go unchallenged or be regarded as credible within an industry that's slowly but inexorably shifting from pedigree-based to genome-based analysis.

And yes, when the only 'support' cited for your idea that the X is of any more than minor importance to broodmare sire success is based solely upon scrutiny of the top 10 North American broodmare sires 2009-2012 and 2013 to date, those stats are most certainly cherrypicked. Try something along the lines of the model Dink used in this recent analyis. In an examination of a wider scope of the population the X didn't look all that 'powerful'.

Since Dink's study of 2007 auction horses tail female to Primcequillo, Blue Larkspur, War Admiral and Mahoud does not include those offspring that were privately held and did not make it to public auction; that makes it an unscientific study; lacking merit and lacking authority. A real dink of a study.

[Jeff]

http://www.pedigreequery.com/kittens+joy

Here's this week's #1 sire per BloodHorse.

Look at the War Admiral/ Buckpasser/ Princequillo lining the bottom of the pedigree. Stan's the Man!

[DDT]

Jeff

Princequillo and Buckpasser do not count because they are represented in the pedigree by sons and did not receive a super X from them, War Admiral does qualify according to Stan's rationale, but he is not talking about Princequillo or War Admiral.

DDT

[Jeff]

DDT,
Obviously the best of the X was somehow passed along. Kittens Joy is #1 and these superior broodmare sires that pass on the X are well represented in the bottom of his pedigree.

[DDT]

Jeff

Kitten's Joy is a leading sire because of his entire genetic makeup and the support of Mr. Ramsey. You are missing the point here, the X is not passed sire to son, these outstanding broodmare sires, with the exception of War Admiral, did not pass any part of their X chromosomes on in the pedigree, and that is a scientific fact that cannot be refuted by argument.

DDT

[Pan Zareta]

Obviously the best of the X was somehow passed along. Kittens Joy is #1 and these superior broodmare sires that pass on the X are well represented in the bottom of his pedigree.

If L'Enjoleur had received an X chromosome from Buckpasser he'd have been a she. Doesn't mean Buckpasser's best didn't get passed along though. Just means it wasn't on the X.

[stancaris]

Pan Zareta: You keep bringing up Byron Rogers quotes about genomic research as proof that the X chromosome plays only a minor role in broodmare sire success and even go on to say that any conclusions he draws is a valid conclusion and therefore would definitely not be biased at all because these conclusive statements mentioned by him were only based on genomic research of the the SNP scans of variants discovered by his company.

Rogers is selling performance genetics to people who want to buy a potential champion thoroughbred and are willing to spend big bucks for that chance. He certainly wants to push the findings of his researchers as the most important discoveries that lead to the making of an elite runner.

In several of Brogers posts he mentions that the X chromosome carries variants that relate to elite performance and then goes on to say that these variants just have nothing to do at all with heart size. He also states that Haun's X Factor hypothesis has done more harm to the breeding industry than any other theory in recent years. He is biased toward his company and wants his company to be the most successful in this competitive industry.

Since Haun published her books on the X factor and the large heart there has been a significant movement toward buying horses that carry the great War Admiral in the X passing position and also horses that were inbred to War Admiral.

Competing companies certainly want to play down the importance of the X chromosome while at the same time pushing their own agendas which involve research on autosomes. They certainly would not want to discover any major variants on the X chromosome because that would only give another boost to the already great amount of interest in the so called superlative X.

[DDT]

Stan

So I guess Haun published her ideas with the intent of informing owners and breeders of her theory without regard to personal gain, she has not and does not give her books away. She has attempted to prove her theory first hand by breeding but has thus far failed to do so. You should brush up on basic genetics, an area that Haun gave little attention to.

Breeders utilized War Admiral long before Haun published. I do not know what makes you think that her theory generated an upswing in War Admiral's appearance in pedigrees considering the fact that he was foaled in 1934, more than 50 years before Haun formulated her theory.

The X Factor theory is pure bunk, no ifs, ands or buttttttts.

DDT