Last time, in Part One of this series, we looked at a few of the imponderables that influence thoroughbred breeding and the offspring of some very fine racing mares. In Part Two, we’re going to look at some of the inherited traits carried on the X chromosome and how these might influence Rachel’s, Rags’ and Zenyatta’s offspring, just as they have influenced thoroughbreds from as far back as 200 years ago.
But before we get started, a couple of “truths” must be kept in mind. First and foremost is that there is no fail-proof recipe for breeding a thoroughbred champion. There are, of course, any number of breeding beliefs. But to produce a champion, many factors have to be taken into account, from pedigree to race records and from soundness to training.
Secondly, every thoroughbred is a completely unique, unrepeatable individual. So that, while our three exceptional ladies will undoubtedly have fine offspring, they can never reproduce themselves, simply because it is the design of genes, chromosomes and DNA that each of them inherited from their parents that made them who they are. Rachel, Rags and Zenyatta are all originals in that sense — and there will never again be another thoroughbred just like them. Anymore than there could ever be an exact replica of you or of me!
(NOTE: For anyone who needs it, there’s a definition of gene, chromosome and DNA at the end of this article. Just scroll down to the end.)
To begin: there are many reasons that pedigree experts may decide to match a particular stallion with a specific mare. Typically, the choice of a stallion for Rachel, Rags and Zenyatta will involve looking at what each individual brings to the mating through studying sire lines and family (mare’s side), as well as racing performance data over a number of generations and the stallion’s record at stud. This, together with a focus on the characteristics the breeder is looking to breed into a potential offspring, completes the picture. If a mare, or a stallion, has lots of speed, a breeder might look for a stamina influence. Soundness and conformation might be another important consideration. Or a breeder might be looking for offspring with lots of heart room, favouring individuals with this type of conformation, such as Bernardini (2003) or Giant’s Causeway (1997) or Zenyatta or Rags to Riches. A breeder who is looking to breed a dirt horse who is good under most track conditions is looking for a mare/sire combination that favours this kind of adaptability. In this instance, a son of Mr. Prospector (1970) like Smart Strike (1992), or a grandson like Curlin (2004), might be favoured for a mare like Rachel Alexandra, who demonstrated so dramatically that she could win in the mud or in the sunshine.
Regardless of the rationale for pairing a certain stallion and mare, whether or not the qualities being sought come to fruition in the foal is as much a matter of genetics as it is related to the environment in which the foal is raised and trained. The genetic influence begins with the difference between the X and Y chromosomes. The mare carries a pair of X chromosomes (XX) — an X from her sire and another X from her dam. The stallion carries a different pair: a Y from his sire and an X from his dam (XY). This means that, in the case of a filly foal (XX), the stallion contributes the X chromosome he received from his dam. But because a mare has two X chromosomes, she will contribute either the one she received from her sire OR the one she received from her dam, depending on which one is dominant. In the case of a colt foal (XY), the stallion contributes the Y he received from his sire, while the mare provides the X, making it the stallion who determines the sex of a foal. However, neither the sex of a foal nor which of the two X’s the dam expresses to it can be pre-determined.
While the stallion has the role of determining the foal’s sex, it is the X chromosome that carries far more genetic potential (whether it comes from the stallion or the mare). On the X chromosome are factors that influence sound build, temperament, speed and stamina. These are called “X-linked traits.” But the sex-related chromosomes are not the only genetic inheritance a foal receives from its parents. There are 62 other chromosomes, arrayed in 31 pairs, that influence everything else about the foal’s physiology, conformation, coat colour, temperament, racing prowess and so forth. Each pair of chromosomes is composed of inherited genetic traits from both the sire and the dam. In other words, a foal inherits a bunch of important characteristics, including speed and stamina traits, from both its parents.
So although the X chromosome carries more genetic material than the Y, who contributes what as far as the other 31 pairs of chromosomes are concerned has to do with dominant and recessive genes. As they combine into the “code of life” that will become a foal, these dominant and recessive genes — themselves the inheritance of the sire and dam’s ancestors — dance themselves into a pattern that is completely unique to this still unborn thoroughbred. And depending on how the chromosomes that carry the genes arrange themselves, certain traits will dominate over others. So, for example, if Rachel Alexandra expresses a dominant stamina influence via her genes they might well dominate a speed influence from a prospective stallion to whom she is bred. In this case, she will likely produce a foal who needs a longer distance and who may quite honestly be (genetically) disadvantaged in a sprint. This is why, when you open the progeny list for a mare or a stallion, even the successful ones, you usually find everything from soup to nuts! Those pesky genes combine in ways that can advantage — or seriously disadvantage — a champion’s offspring.
In any mating, the hope is for a talented, healthy youngster and breeders base much of that optimism on the performance abilities of its sire and dam. But it’s the genes, chromosomes and DNA that always hold the best hand — and they keep their secrets pretty much hidden until that foal becomes a yearling and goes into training.
There is still another factor that’s loaded with potential, depending on whether or not it occurs in a thoroughbred’s pedigree. It’s quite literally called the “X-factor” because it’s a sex-linked trait. It’s “sex-linked” because it involves the inheritance of a large heart gene that is only carried on the X chromosome — the sire’s single X that is expressed only to his daughters and the dam’s two X’s, one of which she will express to her foal, whether a filly or a colt. And that large heart gene has been found to be a solid indicator of racing performance in standardbreds, thoroughbreds and quarter horses.
Research over the last 20 years in the UK, Australia and the USA has uncovered an inherited pattern for the large heart gene, as far back as the first known instance recorded of a large heart, which was that of the great Eclipse (1764). Now it appears that Eclipse passed on this trait. Over several generations, this large heart gene was passed from sire to daughter and from that daughter to her son, until we arrive at the most influential broodmare in thoroughbred history: Pocahontas (1837). A descendant of Eclipse, Pocahontas was a great producer during her lifetime, her most famous sons being Stockwell(1849), Rataplan (1850), and King Tom (1851) . She also produced five very good daughters, out of a total of 15 foals. Stockwell became the most important of her three sons and appears in the pedigrees of the outstanding individuals Phalaris (1913), Nearco (1935), and Native Dancer (1950). How influential was Pocahontas? Just look at the number of crosses back to her found among these remarkable thoroughbreds: The Tetrarch (7), Man O’ War (9), Nearco (37), Raise A Native (175), Secretariat (249), Northern Dancer (272) and Mr. Prospector (353). Too, in Pocahontas’ pedigree are 13 crosses to the immortal Eclipse — suggesting to large heart X researchers that this trait may well be Eclipse’s permanent gift to the breed.
It was upon the death of the immortal one, Secretariat (1970), that X-factor research was given the impetus it needed to move forward. It was discovered during his autopsy that Secretariat had a huge heart, weighing approximately 22 lbs. (An average thoroughbred heart weighs about 8.5 lbs.) Despite its size, Secretariat’s heart was normal in every other aspect. It was just that the champion turned “running on heart” from a metaphor into a statement of biological fact. In an industry that had focused almost exclusively on the sire, it turns out that the dam is as reliable a transmitter of this gene as the sire. As you might perhaps expect, a mare more reliably passes this gene on to a son. And, as the stallion is only able to transmit the large heart gene on his X chromosome to a daughter, his reliability lies there. In Secretariat’s case, it was Somethingroyal (1952) who expressed her large-heart gene to him, and not Bold Ruler (1954), his sire (who had to donate the Y for Secretariat to become a colt.)
In an almost poetically beautiful turn of events, we now know that Secretariat’s great heart is literally living on, through the progeny of four of his daughters: Weekend Surprise (1980), Terlingua (1976), Secrettame ( 1978) and Betty’s Secret (1977). We know this because the ongoing research into the large heart X has shown that to carry this sex-linked trait to an offspring, a thoroughbred needs to descend directly from at least one of four sire lines: War Admiral (1934), Mahmoud (1933), Blue Larkspur (1926) and Princequillo (1940). Each of these sire lines, in turn, trace directly back to the British mare, Pocahontas.
Today, the large heart principle, or “X-factor” is used as one source of breeding information, in combination with more traditional breeding theories.
As indicated above, the large heart X gene descends, in a zigzag pattern, from a sire to his daughter and from that daughter to her sons. However, not all stallions have this X-linked trait to pass on to their daughters. Only those who trace back to the four heart line sires named above can accomplish the deed. If a mare inherits her X from a sire who descends from at least one of the large heart sire lines, she is called a “single copy” mare. This means that she has a 50/50 chance of passing the large heart on to her son(s) or daughter(s), depending upon which X is dominant. So, even though the large heart gene is an important trait, it isn’t necessarily the dominant X in a mare’s genetic profile. In other words, a mare may be a carrier of the X-factor but never be able to pass it on to her offspring.
If a mare inherits the X-linked large heart from both her sire and her dam, she is called a “double copy” mare. All of Secretariat’s four large-heart daughters are double copy mares. This means that both of their X chromosomes carry the large heart X, making it twice as likely that they will be able to give it to either a son or a daughter.
For example, Weekend Surprise likely expressed the large heart X to her sons, A.P. Indy (1989) and Summer Squall (1987). However, these sires can only pass it on to their daughters. As an example, a filly by Seattle Slew (1974) ex. Weekend Surprise inherits an X from Slew that carries the large heart trait PLUS another large heart X from Weekend Surprise, who, being a double copy mare is more likely to pass the trait on with some consistency to her offspring. In any case, this filly would have 3 out of 3 chances to inherit the large heart gene from one of her parents.
Now, let’s take a look at the pedigrees of our three outstanding ladies, and the gentlemen in their lives, to see whether or not the large heart gene is present in these mating combinations and, if it is, what its chances are of being inherited by a foal from these matings.
Rags To Riches
Rags’ sire, A.P. Indy carries the large heart X which he received from his dam, Weekend Surprise (who had both Princequillo AND War Admiral large heart sire lines). Given his success on the track and at stud, it is reasonable to say that A.P. Indy passed the large heart gene on to Rags, just as he appears to have done with other female offspring. However, Rags’ dam, the excellent Better Than Honour (1996), does not link back (in that zigzag pattern) to a large-hearted sire line. So Rags is very likely a single copy mare, with a 50/50 chance of passing this trait on to a son. (The 50/50 ratio drops in the case of a filly, since both parents contribute an X and one of those X’s will be more dominant than the other.)
Although she is now in Ireland and in foal to Galileo (1998), Rags’ first foal, a filly by Giant’s Causeway, was born in the USA. A chestnut who seems to hold an uncanny resemblance to her dam, the filly’s training has been postponed because of an injury to her sesamoid following a gallop (Thoroughbred Times, 09-06-2011). Interestingly, Giant’s Causeway has two potential sources of the large heart gene in his pedigree, only one of which is active since his sire, Storm Cat (1983), could only give him a Y chromosome. So it is the X he received from his dam, Mariah’s Storm (1991), that he will pass down to a daughter. This means that Rags’ first foal, a filly, had two opportunities to inherit the large heart gene — one from her dam and the other from her sire. If the “X-factor” theory holds true, Rags’ firstborn has an excellent chance of inheriting the large heart gene from Giant’s Causeway.
Rags’ second foal, a colt, is by Henrythenavigator (2005) and the little fellow is reportedly a beautiful individual. This stallion has no connection to any of the four heart line sires in his pedigree. This means that Rags may have expressed the large heart gene on the one X in her pedigree that carries it. Or maybe not. The chances remain about 50/50 because only one of her X’s carries the large heart gene.
Galileo was a great race horse and is proving to be an outstanding sire. He carries the large heart gene from his dam, Urban Sea (1989), who is also the dam of his half-brother, the brilliant Sea The Stars (2006). Urban Sea inherits the gene through her sire, Miswaki (1978), a son of Mr. Prospector who traces back to War Admiral. This bodes well for Rags’ third offspring — if a filly, it will certainly receive the large heart gene on Galileo’s X; if a colt, it has a 50/50 chance of inheriting Rags’ large heart gene.
“Hooves crossed,” wonder- full Rags!
Rachel Alexandra
Rachel’s sire, Medaglia d’Oro (1999) does not descend from one of the four heart line stallions in a pattern that allowed him to receive the large heart gene, even though his sire is El Prado (1989), who descends from Northern Dancer and, therefore, the Mahmoud heart line. (El Prado expressed the Y chromosome to Medaglia d’Oro.) Still, no-one could doubt that this stallion isn’t sending great genetic material to his daughters when we think of Rachel’s brilliance, as well as the exploits of Champagne d’Oro (1997), Gabby’s Golden Gal (2006), Tasty Temptation (2006), Payton d’Oro (2006), Plum Pretty (2008) and Vision in Gold (2009).
Rachel’s dam, Lotta Kim (2001), traces back to Pocahontas through her sire, Roar (1993), but not to one of the heart line sires along the way. However, through her broodmare sire, Cure the Blues (1978), Lotta Kim traces back to War Admiral. In other words, Rachel’s dam is likely a single copy mare and, if so, has a 50/50 chance of expressing the large heart gene to her offspring. Curlin, Rachel’s first beau, does not trace back to the large heart sire lines, although through his dam, Sherriffs Deputy (1994), Curlin does trace back to Eclipse.
This adds up to mean that Rachel might be a carrier of the large heart gene, but only if it was passed on to her by her dam. If she is — and it would appear to be a strong possibility, given her amazing racing abilities — Rachel would also be a single copy mare, with a 50/50 chance of expressing this trait to a son or a daughter. As we know that Rachel is expecting a colt, it will be interesting to see whether or not he exhibits this trait.
“Hooves crossed,” beautiful girl!
Zenyatta
Although Zenyatta’s sire, Street Cry (1998), traces back to Pocahontas in a zigzag pattern (sire to daughter to daughter’s son), he does not trace back to heart line sires through his dam. And it is Street Cry’s dam that would need to express the large heart gene, first to him and then from him to Zenyatta. However, Zenny’s dam, Vertigineux (1995), descends from the Princequillo heart sire line, making Zenyatta — like both Rags to Riches and Rachel Alexandra — a potential single copy mare.
Bernardini, her first suitor, traces back to the War Admiral and Mahmoud heart sire lines through his dam, Cara Rafaela (1993), making her a double copy X mare. This means that Zenyatta’s foal — if it’s a filly — has three possible chances of inheriting the large heart gene, one from Zenny and the other on the X from Bernardini, which must carry the large heart X . As we have seen, the A. P. Indy sire line boasts a goodly number of outstanding fillies, making it quite interesting to see — X aside — what a filly foal from this pair will be like in terms of racing performance. If the foal is a colt, Zenny becomes the only potential source of the large-heart X, a 50/50 proposition.
However, Vertigineux has also produced other accomplished daughters in Balance (2003) by Thunder Gulch (who traces back to Eclipse through his dam), as well as Where’s Bailey (2002) by Aljabr (who does not trace back to the heart line sires). Her son, Souper Spectacular ( 2007) by Giant’s Causeway is a promising turf performer, having most recently won three in a row over distances from a mile to a mile and a quarter. All of which bodes well for Zenyatta, since it would suggest that Vertigineux tends to express her large heart gene to her offspring fairly consistently, possibly because the gene is a dominant X. (Note: Eblouissante, another Vertigineux daughter, is still in training, so was not mentioned at this time.)
“Hooves crossed,” big girl!
Of course, it must be stressed that these sex-related influences are only one dimension of a much larger “genetic collage.” When one looks carefully at the pedigrees of Rachel, Rags and Zenyatta, as well as the stallions to whom they have been bred, it really is an impressive array of great, great thoroughbred bloodlines. Other influences these bloodlines favour will form part of the final article (part three) in this series.
One thing’s for certain: Rachel, Rags and Zenyatta all gave astounding testimonials to their stamina, courage and heart each and every time they raced. As broodmares, there is absolutely no reason to doubt their potency and the gifts it will bring to their respective offspring!
(P.S. Special thanks to zenyatta.com for inventing the expression “Hooves crossed” that was re-cycled here.)
NEXT TIME: Here’s another genetic trait that these ladies share where dominance has absolutely nothing to do with it. Join us at THE VAULT as we conclude our series with a look at the power of mitochondrial DNA, as well as other influences on the offspring of Rachel, Rags and Zenyatta.
DEFINITION OF TERMS
Gene: a segment of DNA. Genes are the basic biological unit of heredity. What a filly or colt is like, in every way, is its genetic inheritance from its sire and its dam.
DNA: Genes are made up of DNA, a molecule that looks like a double helix or spiral. Each thoroughbred has literally thousands of genes that determine their individual characteristics, or genetic traits.
Chromosomes: Genes, carrying DNA, are arranged along 32 pairs of chromosomes in thoroughbreds. So thoroughbreds all have 64 chromosomes. Each pair of chromosomes represents one chromosome from the sire and one chromosome from the dam. It is these pairings that make every thoroughbred completely unique. In fact, there are over 12 million different chromosomal variations possible in horses!!!!!
Abigail, you’ve again produced an outstanding piece of work, CONGRATULATIONS!!! Not only have you linked the three best mares of the present day, you’ve written about three of the best loved horses and demonstrated why they were so great. I particularly enjoyed the links to our love Secretariat and our Canadian champ The Dancer. Next month, when I am at Claiborne, I intend to leave a little mint on Secretariat’s headstone in your name, as well as one from me. I received an e-mail from Claiborne yesterday and all are safe and sound after the scary weather.
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Brenda: I SO appreciate your feedback! It was truly very tough to take the language of genetics and write it so that perfectly intelligent, non-geneticists could enjoy the information and find it a good read. And you’re going to leave a mint on Secretariat’s grave for me???? Oh, thank you a million times over, Brenda. I have never visited Kentucky but intend to do that now that I’m only working small contracts, rather than full-time education. But I was so moved that you would remember me to my great love. I don’t know what else to say — too emotional. But from the bottom of my heart, thank you. Please tell Big Red that Abigail loves him forever and ever.
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Thank you, Abigail, for another wonderful blog entry lesson! I love learning about the large heart gene and did not realize it had been traced all the way back to Eclipse. How amazing! Ordinarily I get thoroughly confused on discussions of genetics, but you made it clear enough to penetrate some of the cobwebs in my brain! Thank you also for sharing the wonderful photos. I always look forward to your new entries to the blog.
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Celeste — lovely, as always, to hear from you and I’m very pleased to know that part 2 proved a good read. It took me ages to translate the genetics into the kind of language that speaks to intelligent — even gifted! — non-geneticists. So it’s gratifying to know that sleeping with the X-factor was worth it!!!!! Take good care now, Abigail XXX000
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Dear Abigail
Really lovely well written article. I am a medical person
So terms are familiar but complicated. You superbly
Made it sooo understandable. Loved the descriptions of the links to the
“men” in their lives. Did not realize big heart gene was actual size of the heart. 22 lbs for “big red’s” WOW.
Look forward to part 3. Thanks again
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Sign: Thanks for your supportive comments. I never tire of hearing back from you! So you’re a “medical person” — tell me more! Fond regards, as always, Abigail
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Yeah!!! The filly won the Queens Plate. An by quite (5?) lenghts. I have been a little naive as to all of the racing and breeding and everything else that goes on with horses to only the US. Thanks so much for expanding horizons. It is truely all over the world.
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Hi there “Sign.” Sorry to take so long to respond. I’ve been busy working on part 3 of The Power of X. Whew! I screamed myself hoarse watching Inglorious. What a great filly! And you are so right — it is truly all over the world. There are many great thoroughbreds out there and, given the continued loss of interest in horse racing (even in Australia!) we all need to do our part to keep fans interested and to attract new enthusiasts. Hope you’re well. It’s always so nice to hear from you. Abigail
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Abigail, I am in awe of your knowledge and talent to be able to make it all understandable. I have just scratched the surface in my learning about the very complex and intricate subject of pedigrees. I had come across the large heart gene and “X” factor, but until now, I had not made much sense of it all. You stitched it all together quite nicely, and a light bulb went on as I was reading through this piece for the first time. It will require quite a few readings for me to feel conversant in this piece of the pedigree puzzle, but I am a willing and eager student.
Would love for you to submit this series to Steve Haskin for him to use as a guest column, like he did with your response to his column, “I Lied”. You are so talented and your knowledge is so vast on this subject, you deserve a wider audience, and the audience would indeed be blessed to have you as their guide for the fascinating journey through the pedigree maize! Like a 1,000 piece jigsaw puzzle or like the scene in The Bishop’s Wife where Cary Grant has offered to organize the card file, he throws the cards up in the air and they all fall down into the right order. That’s kind of what I think you do with this subject, except I know it took you longer to make all the pieces understandable to us “amateurs”!
Good luck with your picks for the Queen’s Plate. I’m pulling for the filly — surprise, surprise!! — Inglorious! She certainly has a shot. By the way, a racing question: Are Canada’s Triple Crown races the only ones where the horse entered has to have been foaled in Canada? I was surprised to notice that when I was doing my latest blog on the races for the weekend to see that as a requirement. I’m not that familiar with other countries’ TC races. Best wishes, Abigail.
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Ann Maree: Thank you so very much for this fantastic “review.” It means a lot to get such praise from you. I’m just glad that I could pull this one off — it was very hard to translate some of these ideas from genetics-speak to a language that is inclusive, that any intelligent person could read & enjoy. (In general, I lose patience with any person or discipline that excludes everyone else from the dialogue, except specialists in the field, so it was a translation job right up my alley!) I listened to Steve Haskin today on Talkin’ Horses where he spoke about how you make a name in the field and he pointed out that you must write your stories with passion. He also suggested that one submit an article to the Blood-Horse that they could publish for free — he did this many times when he was getting started. Steve did so much to get me started and has said that he would contact me for a guest blog again. But he added that he needed to be careful about doing this, since his editors would squawk if he wasn’t writing on his own blog @ least 97% of the time. What I may do is go from blog to website, since this could lead to even wider exposure and perhaps a little income, which would be great. But thanks for the suggestion, Ann Maree. RE: Queen’s Plate — it’s actually one of North America’s oldest races, did you know that? And it’s inception was about encouraging Canadian thoroughbred breeders, giving them a showcase, so to speak. Remember that, big as Canada is geographically, we’re a tiny population compared to the USA (34, 278, 00 vs. over 310 million in the USA), so the Queen’s Plate allows Canadian breeders a rare opportunity to run solely against other Canadian-breds. Looking forward to the Queen’s Plate today and I’m also pulling for the filly!!!!
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Abigail, I took the liberty of suggesting to Jason Shandler with BloodHorse that you would make a good guest blogger while he’s on vacation from mid-to-end of July! Hope you don’t mind! I sent him a link to this Part 2, so, just in case, wanted to give you a “heads up”!!
Well, our filly won, and I was so excited at how brilliantly she did it! Her jockey ran a perfect race, and I guess she did have some “racing luck”, but I don’t think there ever has been a better trip or better jockey judgment! There’s some talk she might come back here to race, maybe even the Breeders Cup??? If she comes back here to race, it really will be a “ladies year” again this year, with all the Older Females and even the 3 Year Old Fillies doing so well! I’m so proud of these two divisions for providing the consistency that the others have been so lacking this year!! I guess we still have a lot of racing coming up, and with some Europeans getting more ink here, this could be the year when a “foreign” horse/filly/mare has a shot at the big Eclipse honors.
Abigail, I’m wondering if you have given thought to writing a book? My guess is your only problem would be picking a particular horse or subject because your interests are so far and wide!
Best wishes, and let me know if you hear from Jason.
Ann Maree
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Ann Maree: I can’t believe you did that…..THANK YOU SO MUCH! I don’t know what to say. I’m really touched that you would think of me. Inglorious — that would be GREAT if she raced in the USA. Maybe they’ll even bring her to Saratoga. I mean, her owners are American, I believe, so they might be seriously thinking about it!!!!
I have thought about writing a book, yes. But as you wisely point out, I can’t say that I’ve centred on a topic. But I am thinking about it!
I will most definitely let you know if I hear from Jason. It would be a very exciting opportunity. Hooves crossed, right?
Hugs,
Abigail
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Dear Abigail: A must-read effort. Don`t be surprised to find it requested at teaching levels across a wide spectrum. Not merely instructive, but luminous, Thank you.
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Kathryn: Thanks so much for the positive feedback! I’m just thrilled to know that part 2 was both instructive and compelling, since it was quite the challenge to write. I’ve been following X-related research for many years now, but it’s quite another thing to write about it in a fashion that engages a non-geneticist!
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Abigail- this is the first time I have completely understood the “x-factor”. What a great article! I can’t wait to see all three of these mares’ foals race, especially Zenyatta’s 🙂 FYI, according to Rags To Riches’ FB page, her third foal is a colt. I think he would be about 2-3 months old now. Thank you so much! (Susan in TN)
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Susan: Thanks for writing such a super commentary. It’s always great to hear from you! And thanks for the info on Rags’ Galileo colt. I checked her FB page but didn’t see this posted. And it’s murder trying to get info on her thru an internet search. Last time, I wrote directly to Ashford and they very kindly responded. I’d LOVE to see a photo of this lad. HOW EXCITING! I can’t wait for her babies to run either. Ditto for Rachel’s colt & Zenny’s foal!!!!!
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Absolutely wonderful information. I love both Zenyatta and Rachel and axiously await their offspring.
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Mary Margaret: Thank you so much for the wonderful feedback! It feels just wonderful each & every time I hear back from a reader. I appreciate the contact and your interest. Stay tuned for part 3…part of the reason it took me so long to respond to your kind comments!
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A wonderful article Abigail, and I stumbled on it on Z’s fb page. I love your use of CW Anderson’s wonderful illustrations. I LOVED his books when I was young, and he inspired me to buy my own #2 pencils (soft lead, so one could use them for shading, just like CW 🙂 and I drew a lot – mostly horses. I’m a fan of all these mares, but I must admit that Z was the one who inspired me to finally travel to see a race in person. We are going again this fall, and I’m back in riding lessons – pretty much because of that fabulous big-hearted gal. I used to ride so much when I was young, and following her exploits reminded me of how much I missed having horses in my life. I would expect that some day far in the future, they will find she has a huge heart. She ran like it and her physical beauty in person is stunning. Thanks again for a very interesting and understandable read. I, too, look forward to seeing the babies of these wonderful mares on the track one day.
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Sue: What a great post! Like you, I was also crazy about CW Anderson’s books and just loved his drawings. Like you, I was also inspired to draw (horses mostly) and still do some of that now, although when I was working full-time, I found it hard to work seriously on a drawing. I also rode as a kid but doubt I could take it up again because I have an “old” back for a woman my age and pretty bad arthritis in my hands. I DO however intend to start visiting places like Saratoga & Kentucky — to drink in a culture that I adore. I was “kidnapped” into the sport by Secretariat, Northern Dancer, Sec’s daughter, Terlingua (whom I wrote about earlier), Nijinsky and Dance Smartly. But although I loved Rachel, it was also Zenny who made my heart sing! I would add the great Sea The Stars as well, although it was only Zenny (because of her amazing Team Z) who you could get so close to, it almost felt as though you knew her. Don’t you agree? I’m also certain that she has indeed a large heart….how could she not? Her stride is longer than Secretariat’s & I read that it would only take Zenny 12 strides to cover the length of a typical football field. Imagine that!
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Hi Abigail,
I just love the photos of Rags you have in these blogs on fillies and mares.
Did you see Steve Haskins is looking for some articles while he is gone
in July? He is asking for volunteers. This filly/mare series would be great.
Hope you have a great 4th. Had the opportunity to ride a canadian sport horse that was actually purchased by our barn owner. Very much like a TB
spirited and spooky. Really loved her.
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Hi “Sign” — Yeah, those are great shots by Amber Chalfin, mostly. She’s just a SUPER photographer! I did NOT see the Haskin call for volunteers. I checked the Blood-Horse site & couldn’t seem to find it….. I know there’s a Jason Shandler who’s looking for volunteers….are you sure you’re not thinking of him? Abigail
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I will check for you.
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I just discovered your blog and I am so impressed! You do some fantastic work, I learned so much just from reading this post, and I have a hard time following the language of genetics. Excellent blog, thank you for sharing your vast knowledge of thoroughbred bloodlines and genetics.
Would it be alright if I added your blog to my links?
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Hi Brian. How great to hear from a new reader and thank you for taking the time to comment. I welcome links. Be my guest!!!!
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You’ve done your work, but the large heart gene is only a theory. It hasn’t been proved, and right now it seems to be a mostly North America proposition. The Europeans don’t seem to believe in it nearly as much as Haun disciples here.
The day the genome researchers actually find a sex linked large heart gene is the day that it will cease to be a mere hypothesis and become a theory that can be proved or disproved.
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I certainly agree with your point about Haun’s work. In any case, even if she were dead right, Harrison et al.’s work on mtDNA would cause her to go back to the drawing board, don’t you agree? I am awaiting the arrival of Tony Morris’ book on breeding theories and am certain that it will give me an excellent insight into the European perspective. Thanks very much for taking the time to comment. I appreciated your viewpoint1
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Has Zenyatta been able to birth a foal?
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Northern Dancer had a heart that weighed 15 pounds but got beat in the Belmont by quadrangle who had a heart weighing 16 pounds California Chrome has a heart weighing 15 pounds but got beat in the Belmont by Tonalist who has a heart of 17 pounds Zenyatta has a heart of 17 pounds the foal Zenyatta is carrying will have a 17 pound heart
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Harold: Thanks for taking the time to comment! Abigail
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I was digging around in War Admiral’s pedigree, and I can’t find Pocahontas on Brushup’s side. Am I just blind? I see Eclipse twice, but in both cases behind sons, so that can’t be the source of War Admiral’s gene, right?
Thanks in advance for your help. I find this completely fascinating, just trying to figure out where I’m going wrong in understanding.
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Becky: I share your fascination with the big heart theory, although it does have its flaws! Abigail
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Never mind! I found Pocahontas. I needed to go back one more generation than I had. As you were.
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Becky: Glad you found it! Pocahontos’ influence is really quite astounding as regards the numbers of outstanding individuals that come down from her directly or on her tail female. Abigail
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When checking Medaglia De Oro’s pedigree i believe he could’ve inherited the large heart from the mare Risk who was by Sir Galahad out of Plucky Leige
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Patricia: Yes, he may well have as long as it follows the mother to son to daughter to son pattern. But he certainly has several large heart influences in his first 5 generations!!!! Abigail
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Hi, I’ve just brought a yearling filly whose 2nd dam was Summer Voyage a daughter of Summer Squall. Summer Voyage was mated with Cherokee Run producing an unraced daughter, Voyage Out. Voyage Out was sent to Australia and has been mated with the stallion Longhorn, a son of Danehill. I have just purchased their yearling filly (as yet unnamed). According to your article, Summer Voyage will have inherited a large heart gene from Summer Squall. What are the chances my filly may have inherited the gene.
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Hi John: Well, it’s not a sure-fire thing that she did inherit the large heart gene. But she has at least a 50-50 chance of doing so! Abigail
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