I have a ton of information about the X factor and I have had Marianna Haun review my horse. This is what she wrote:
My Genius’ Private Secretary
First, let me state that the only way to establish a mare as a double copy is to first measure her and ascertain that she herself expresses a large heart and then to measure a male offspring that looks nothing like her and find another large heart. Her male produce can only receive their X chromosome from their dam and will either express her dominant X or her recessive X chromosome. Because family resemblance follows the expressed X chromosome, you need the son that doesn’t look like his dam to find the recessive. Whenever a mare expresses the X she received from her dam and you know the heart size of her sire, then you can know what is on each of her X chromosomes.
This is always a gift as it can take several years to achieve sons with different Xs. A double copy for the large heart is not a common thing, in any breed. A mare can have a normal heart on one X and a large heart on the other X. This is the more common pattern. Some double copy mares, such as the tiny twin we used in our research, The Last Red, or “Mighty Mouse,” as she is known, had a large heart (heartscore of 130) on one X (her recessive) and a super heart (147-150) on her other X. It is very rare to find a mare with a “super” heart on both Xs.
I’m concerned about the pronouncements of double copy status that are being thrown around the Saddlebred industry. No one can look at a pedigree and firmly state that a mare is a double copy or a stallion has a large heart without measurements. And, in the case of the mare, the recessive is very tricky and can not be determined based upon production or even performance. There is a Saddlebred world champion that I can state has a large heart and that his daughters have all received a copy of this heart on the X chromosome they inherited from their sire. That stallion is Harlem Globetrotter. We measured him and found the Saddlebred equivalent of the super heart found in the Thoroughbred. We were able to measure two sets of full sisters and a grandson and chart the inheritance path of his “super” heart. In his daughters, some expressed his heart and some expressed their mother’s X chromosome. The grandson, out of one of his daughters, had Harlem Globetrotter’s super heart. We have found large and occasionally super hearts in the Saddlebreds we have measured. We have also found normal and small hearts in successful show horses. The stamina influence is helpful in some classes, such as the five-gaited and harness, but is not necessary in other classes. The most important thing for performance Saddlebreds is their conformation and way of traveling.
One of the most interesting things we have learned in the 13 years we have been following the X-linked inheritance for large hearts is the other things that travel on the X chromosome in addition to the heart. We have found that the body type, the front end, the way of traveling, the bone, the air flow, the top line, the nostril, neck, throat latch all follow the expressed X chromosome. Family resemblance follows the expressed X chromosome. Color does not. When a foal hits the ground, look to see who it looks like. If it is a filly, it can look like either the sire or the dam. If it is a colt, it will have the physical characteristics of one side or the other of its dam. The Y chromosome, which is what is passed from father to son, is much smaller than the X chromosome and has few genes on it. Bascially, it is a sex determinant. If the sire throws a Y
chromosome, the resulting foal will be a colt. Muscle mass seems to follow on the Y chromosome. An example of this is Northern Dancer and the way his sons seemed to express his “Quarter Horse” body type in terms of muscle.
In the case of your mare, she has some good possibilities for stamina influences in her pedigree. I like her broodmare sire, Starheart Victory, who is out of the BHF mare High Point Flame. Her dam, Flaming Dawn’s Genius is by champion King’s Genius, who tracks to the Thoroughbred mare, Pekina and Lexington, both of who carried the large heart mutation. Her granddam, Flaming Dawn, also goes to Pekina and Lute Boyd, another stamina influence.
Her sire, Desert’s Supreme Fortune, is out of Lisa Bartlett, whose sire Beau Fortune, is out of BHF Anacacho Princess by Edna May’s King, who also goes to Pekina. Anachacho Princess’s dam, Hazel Simmons is also a BHF with links to Pekina, Eclipse and others. On the bottom of Lisa Bartlett is Mary Bartlett by Noble Kalarama who has links to the large heart mutation. Your mare is inbred to Noble Kalarama with her second dam, Gina Genius by Jovial Genius, who is out of a daughter of Noble Kalarama, High Contente Florence, who is out of a daughter of King Vine, another sire with large heart links. But while there are many indications of the mutation in her pedigree, there is no way to know what she has without measuring her.
There is no way to predict what horses in the past had in terms of heart size. Horses were used for many different purposes and even today they can just be a favorite riding horse or a backyard pet. Different circumstances, money, time and even inclination to develop the talents of a particular horse, can impact their pattern of performance. When we look back historically and try to guess what might have been we look for indications of extraordinary stamina. Horses that were used in four-mile races or who could, like Lute Boyd, cover long distances with little ill effect. There is also the pattern in sires of having better performing daughters than sons like the great Wing Commander. This is a consistent characteristic of a large-hearted sire passing a superior X chromosome to his daughters.
I think one of the easiest ways to try to figure out which X your horse is carrying is to do physical comparisons with parents or grandparents. We have been able to document the heart sizes of long-dead horses based on their descendents with the help of physical resemblance. I’m looking forward to measuring my new mare, Some Chance. She looks very much like her broodmare sire, Cox’s Ridge. When we know what heart size she has, we will know what heart he was passing to his daughters. He is an extraordinary broodmare sire, so it shouldn’t be a small heart. But he is dead, and this is the only way to know what he was passing.
Your mare sounds very interesting and I look forward to seeing her and measuring her heart. Just remember, the heart makes a good genetic marker for what else is being inherited on the X line, which may be even more important in a show horse.
Also, remember that in reading my book, each breed has its own scale of large heartscores. There is approximately a 20 point difference between the Saddlebred heartscore and the Thoroughbred heartscore. In Quarter Horses, their heartscores are between 10-15 points less than they are in a
Thoroughbred. You can’t compare the heartscore found in a Thoroughbred racehorse and a Saddlebred, even though they may track to the same mutation historically. It has been many years since Saddlebred were crossed with Thoroughbreds and their physical conditioning during the formative first three years is different….Marianna Haun
Here's her website:
Here's a link to her book:
I have tried to have a clinic in my area some years back, to have her heart measured but there was just not enough interest. There have been several blogs started on the old trot, you can also look for some things there. I have the book if you have trouble getting it let me kow I will send you my copy. IT IS FASCINATING STUFF!
There are some article in older ASHA magazines about the large heart 3 different articles in the magazines and I have them all I can scan them and send them to you as well.