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compared to any of the other breeds studied. The research teams also found that
many of the original foundation stallions carried the T gene or were TT for the genotype for stamina or long distance running. The three stallions they refer to are the Darley Arabian, the Godolphin Arabian, and the Byerly Turk. This verifies the purpose of these early racehorses to
run long distances, which was the goal of King Charles II and his pursuit of more stamina in the breed that became the Thoroughbred. These early Thoroughbreds would run multiple four-mile heats on the same day to improve the stamina needed for the British Army. The researchers found that the “T” gene has 11 different variants while there is only one variant of the “C” gene, giving rise to the theory that this “C” gene came from one individual.
The early efforts to breed for stamina proved successful, but as time went on, they found that the interest for more speed and less stamina was taking effect. This is shown in how Eclipse was undefeated as a racehorse, and then he became a great sire who today is a key individual in the Darley Arabian sire line. His entry into the scheme of things tells us that
he signals the turning point of this desire to breed for stamina and how that transferred to breeding for less stamina and more speed.
The research teams of Hill and Bower also saw a marked increase in the presence of the “C” gene in the population from the success of Northern Dancer and
his sire Nearctic as sires in the modern Thoroughbred. I found this interesting in that Nearco, the sire of Nearctic, wasn’t included in this information. Nearco is also the sire of Nasrullah, who is the sire of horses like Bold Ruler and the grandsire of Secretariat. Bold Ruler and his success as a sire was noted for speed.
The revelation of the origin of the speed gene being related back to a “native British mare” takes us back to the Irish Hobby and where speed in the modern Thoroughbred and Quarter Horse comes from. Then, we add in where many of these early mares like Piping Peg’s Dam and Old Bald Peg could have
been related gives us some interesting food
for thought about the origin of speed in our racehorses and that one “native British mare.”
Author’s Note: The term “speed gene” can be misleading since the working of the myostatin gene does not guarantee the horse will be fast. The speed gene is one of a number of factors that go into making the horse run fast. Although it is a key factor in that, without the speed gene sending the right signal for the development of the right kind of muscle fiber, we wouldn’t have the opportunity to get that speed.
Scientists studying the Speed Gene found that the Shetland Pony had a higher percentage of the “C” gene than any of the other breeds studied. The “C” gene was found to be accountable for an increase in muscle mass.
Nasrullah
Bold Ruler
...theIrishHobbycanbe considered a part of the foundation of the American Thoroughbred and the American Quarter Horse.
A marked increase
in the “C” gene was found in the modern Thoroughbred line of Northern Dancer and his sire Nearctic, who is sired by Nearco. Nearco is also the sire of Nasrullah, who in turn is the sire of successful sire Bold Ruler.
SPEEDHORSE, July 2016 43
SPEEDLINES