Sprinter or stayer? ‘Speed gene’ dictates horse’s race potential

A SIGNIFICANT study into horse racing genetics has found that the ‘speed gene’ is the main determinant of why some horses are born sprinters and others stayers.

The new research analysed the genetics and race records of more than 3,000 thoroughbred racehorses to uncover what makes a stayer or sprinter horse.

The horses surveyed raced across the world including in Europe, Australia, South Africa and the USA.

Published this week in ‘Equine Veterinary Journal’, the study found that the myostatin gene, which is also known as the ‘speed gene’, is almost the singular genetic determinant of a horse’s optimum race distance.

The research was led by UCD associate professor of equine science Emmeline Hill, who is also the chief science officer at leading Irish equine science company Plusvital.

While the notion of a single gene being responsible for a performance trait in thoroughbreds has previously been challenged, Prof Hill said that the new study ended any dispute over the central role of the ‘speed gene’.

“We have replicated and validated our original research findings on a massively larger scale,” Prof Hill said.

The power in the numbers has shown the association of the ‘speed gene’ with race distance is as statistically strong as the most highly genetically influenced traits in humans, including eye colour and the probability of an individual going bald, she said.

The study found that in Europe more than 83pc of ‘speed gene’ type C:C (sprint) horses had an optimum race distance of a mile or shorter, while almost 90pc of T:T (staying) horses were at their best running over distances greater than a mile.

The trend was consistent across all race regions but the race pattern influenced the distribution of the ‘speed gene’ types.

In Australia, where there is an emphasis on early two-yearold speed, there were almost twice as many C:C horses among elite race winners in the population when compared to Europe and North America.

And there were almost seven times as many C:Cs as T:Ts within the Australian population.

The main differences between sprinters and staying-type horses has been shown to be caused by a mutation in the ‘speed gene’ that alters the rate of muscle growth and fibre type differences in the muscle.

Although myostatin is the most important gene, the latest research has also identified additional genes which have moderate effects on the staying ability of a horse.