THE proportion of the world’s thoroughbreds who are genetically suited to long-distance races appears to have fallen dramatically.

The claim was made this week by Professor Emmeline Hill (below) of UCD, also chief science officer at leading Irish equine science company Plusvital.

Professor Hill made her observation following publication of research findings which analysed the genetics and race records of over 3,000 thoroughbreds which raced in Europe, Australia, South Africa and the USA.

This latest research represented an advancement of Professor Hill’s 2012 discovery of the ‘speed gene’, a DNA profiling system which indicates whether a horse is predisposed to sprinting or staying races.

The notion of a single gene, named myostatin, being responsible for a performance trait in thoroughbreds has previously been challenged. However, Professor Hill said the new study ended any dispute over the central role played by the ‘speed gene’.

“We have replicated and validated our original research findings on a massively larger scale,” Professor Hill said. “The power in the numbers has shown that 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.”

The study found that in Europe more than 83% of ‘speed gene’ type C:C (sprint) horses had an optimum race distance of a mile or shorter, while more than 89% of T:T (staying) horses ran best 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-year old speed, there were almost twice as many C:C horses among elite race winners in the population compared to Europe and North America (46% compared to 26% and 28%) and there were almost seven times as many C:Cs as T:Ts within the Australian population.

CONCERN FOR STAYERS

Addressing the apparent drop in the number of stayers, Professor Hill said: “Since there is just one gene that is a major player in the sprinting versus staying stakes, it is extremely vulnerable to selection pressures.

“This has been recognised by the concern in the industry over the potential reduction in genetic diversity by favouring precocious, commercially attractive horses.

“This concern is well justified, the staying type is at serious threat of extinction in the global population. T:T (staying) types make up less than 17% of elite race winners in Britain and Ireland and less than 7% of the Australian elite winning population. This is a complete reversal from the picture of genetics of the thoroughbred 150 years ago.

“We do not operate our testing services in the sales environment which could further accelerate this trend. However, it is essential that the industry incentivises the breeding and racing of stayers to reduce the pressure to breed for the sales ring.”