Thoroughbred Speed Gene

Thoroughbred Racehorses Get Speed from Just a Few Ancestors

Excerpt:

“In 2010, Hill and her colleagues announced they had discovered how variations in the genetic code of thoroughbreds translated to speed. A gene called MSTN, associated with muscle growth, comes in two varieties, or alleles: C and T. Horses with two copies of the C allele are fast, short-distance sprinters. Horses with one C and one T tend to be strong middle-distance runners. And T/T horses have less speed, but greater stamina.”

“In 2010, Hill and her colleagues announced they had discovered how variations in the genetic code of thoroughbreds translated to speed. A gene called MSTN, associated with muscle growth, comes in two varieties, or alleles: C and T. Horses with two copies of the C allele are fast, short-distance sprinters. Horses with one C and one T tend to be strong middle-distance runners. And T/T horses have less speed, but greater stamina.”

“By testing historical samples related to Darley Arabian, the researchers were able to determine that he lacked the C allele.”

Here’s where they lose a large body of data relating to speed in the breed.

“It’s not clear whether the other two stallions (Godolphin and Byerley Turk) had this allele, but their contribution to the gene pool is minimal compared with Darley. That makes it most likely that the C variant entered the thoroughbred line through a single mare bred in the 17th century, right before the thoroughbred population closed off to outbreeding. The results show that the ‘speed gene’ entered the Thoroughbred from a single founder, which was most like a British mare…”

A stallion didn’t need to be prolific in those days in order to change the course of the breed. Could be that the ‘single founder’ was a daughter of Godolphin, or a daughter of the Byerley Turk. Just look at how Godolphin not only changed the breed, but founded a new strain; characterized by speed.

For example: Cade, Matchem, Selima*, Janus5 (imported to the USA – foundation stallion for the fastest breed alive, the American Quarter Horse), Eclipse, Highflyer, Regulus, Blank…

In fact, it didn’t matter which side of the pedigree he was on, either.

The Byerley Turk established several well known lines through his daughters, and contributed significantly to female families 1, 2, 3, 8 (Orville), 17 (Maid of All Work, Sancho, Cowslip, Rachel), 21 (Selima*…), and more. He contributed to male lines as well; Jigg, Herod, Woodpecker, Snap, Sir Peter Teazle…

While Darley was selected because he represented the conformation/type breeders of the day wished to emphasize, and is seen in approximately 90% of today’s sirelines, Godolphin and the Byerley Turk were profoundly influential in both obvious and obscure ways, working prodigally everywhere else in those pedigrees. Personally, since speeds improved when Godolphin offspring arrived on the scene, and since Godolphin had a clear impact on the speed of the earliest Quarter Horses, I’d venture a guess that he was a viable candidate for the ‘C’ factor.

Secretariat had an astounding concentration of Godolphin daughters in his pedigree, especially through the explosive nick established by Lexington and Glencoe, which came through his sire, Bold Ruler. His large heart was attributed to Princequillo, which would have been predominately due to the influence of the Glencoe daughter, Pocahontas (many feel that her x factor came from Eclipse, while there are others who attribute the gene to Godolphin).

Man O War (in the opening of Marguerite Henry’s ‘King of the Wind’) was also a treasure trove of Godolphin blood, having descended directly from him in his sire line, and benefiting from the dispersal of Glencoe daughters throughout his pedigree, one of which (on his dam’s side) was responsible for his large heart expression.

Another significant horse is mentioned in the article, and that is Nearctic.

Interestingly, while Nearctic’s (pedigree here) sire is Nearco, whose damline traces directly to the Lexington/Glencoe mare, Maiden, his direct damline traces directly to Pretty Polly.

Pretty Polly’s pedigree is impressive, however there is an interesting parallel to be noted.

Pretty Polly’s tail female line leads to Wallflower, and then to Daphne, where there is a very interesting turn. From Daphne, the eye goes to Wagtail, through Laurel. Wagtail’s tail female line leads to a mare named ‘Sophia’, a daughter of Godolphin. Sophia has exactly the same grandparents as the great mare Selima* imported to the US in the 18th century. Selima’s influence was incalculable. Without her, horses like Lexington (the fastest 4 miler of his time), and by extension, Spendthrift, the great grandsire of Man O War, wouldn’t have existed.

In fact, Wagtail had a rather large dose of Godolphin and Byerley Turk offspring throughout her pedigree, from her grandsire Sancho, to Sir Peter Teazle, Trumpator and Luna on her sire’s side, to Highflyer, Cantatrice, Eclipse, Brilliant Mare, and Sophia through Sampson mare2 on her damside, all looking dominance, and all deserving their proper place history.

Revisiting the influence of the Godolphin horse, and the Byerley Turk is not only worthwhile, it is very possibly essential in understanding the full capacity and potential of the Thoroughbred horse going into the future.

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