Scientists have unravelled the inner workings of the so-called “speed gene” in horses, which directly affects skeletal muscle growth and, in turn, race distance ability.
Their work, reported in the open-access journal PLOS ONE, has pinpointed the genetic basis that explains why some thoroughbreds are better equipped to race over sprint distances and others over longer distances.
Thoroughbreds are finely tuned athletes with a high aerobic capacity relative to their skeletal muscle mass, which can be attributed to centuries of genetic selection for speed and stamina.
Non-genetic factors such as variation in training schedule can also influence how racehorse distance aptitudes and preferences develop.
But Professor Emmeline Hill, from University College Dublin, demonstrated that different versions of the myostatin gene, a pronounced inhibitor of skeletal muscle growth, was a major factor in the gene-based race-distance aptitude of racehorses.
This discovery earned the myostatin gene the moniker of “speed gene”. Horses with “CC” copies tend to develop into sprinters; those with “CT” copies tend to develop into middle-distance performers; and those with “TT” copies tend to be best equipped for long distances.
However, until now, scientists did not know which elements of the gene held the secrets to understanding the all-important racing distance preference.
In their new study, the scientists pinpointed the specific non-coding section of the “speed gene” that is exclusively responsible for limiting myostatin protein production in thoroughbreds which, in turn, affects skeletal muscle development and race-distance aptitude.
“Our data provides the first mechanistic evidence as to the specific element of the ‘speed gene’ that acts as the sole protagonist in dictating its expression in the Thoroughbred,” said Richard Porter, associate professor in biochemistry at Trinity College Dublin.
“As a result, this element is the key genetic factor in determining distance aptitude in Thoroughbred horses.
“This knowledge is extremely valuable to thoroughbred breeders and trainers, in what is a multi-billion dollar industry,” said Porter, who was senior author of the journal article.
The research was collaborative, involving research scientist Mary Rooney and Associate Professor Vincent Kelly from Trinity, together with Hill from the University College Dublin School of Agriculture and Food Science.