Some heavily inbred horses have a marker that makes them less likely to race.

Horses have been bred for hundreds of years to produce champion racers, but a new study has found that horses with higher levels of inbreeding may never set foot on the racetrack.

A team of scientists led by University College Dublin has identified a single genetic marker that reduces a horse’s chances of racing by almost a third.

The genetic marker negatively affects the development and repair of the animal’s bones, and the inheritance of the marker from both parents reduces the likelihood of racing by up to 32 percent.

Approximately one in six stallions are carriers, as well as over 10 percent of all Thoroughbreds.

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A team of scientists led by University College Dublin has identified a single genetic marker that reduces a horse’s chances of racing by almost a third.

The genetic markers are a haplotype that overlaps with the EFNA5 candidate gene, which is highly expressed in cartilage.

And damage to EFNA5 is one of the most common causes of catastrophic musculoskeletal injury in racehorses.

In the study, researchers quantified inbreeding in 6,128 horses born in Europe and Australia, of which 13.2 percent were non-racing — a negative genetic marker was found in one percent of the samples.

The data shows that a 10 percent increase in inbreeding, based on inbreeding rates, is associated with a 7 percent decrease in likelihood to race.

The genetic marker negatively affects the development and repair of the animal's bones, and the inheritance of the marker from both parents reduces the likelihood of racing by up to 32 percent.

The genetic marker negatively affects the development and repair of the animal’s bones, and the inheritance of the marker from both parents reduces the likelihood of racing by up to 32 percent.

This was stated by the lead researcher, Professor Emmeline Hill from the School of Agriculture and Food Sciences, University College Dublin (UCD). statement: “The identification of a single genetic marker with a strong negative effect is good news, because it means that it can be manipulated.

“If the ‘carrier’ status of the mare and stallion is known, this information can be used to avoid producing foals with two copies of the genetic marker. The immediate benefits of this will be economic benefits for racehorse breeders and owners, as well as improved animal welfare.

“Knowing this genetic marker will allow testing to reduce the negative impact of inbreeding in order to increase the number of foals born in this race.”

Thoroughbreds were bred in 17th century England in an attempt to create horses that could race and jump, and 80 percent of Thoroughbreds today can be traced back to a small number of founders.

Thoroughbreds were bred in 17th century England in an attempt to create horses that could race and jump, and 80 percent of Thoroughbreds today can be traced back to a small number of founders.  Photograph of Byerley Turk

Thoroughbreds were bred in 17th century England in an attempt to create horses that could race and jump, and 80 percent of Thoroughbreds today can be traced back to a small number of founders. Photograph of Byerley Turk

During the reigns of James I and Charles I, 34 mares, called royal mares, were brought into England and bred with Arabian stallions.

This started the Common Stud Book, which included only those horses that could be traced back to royal mares in a straight line, or to one of three other horses imported into England.

Imported horses were Byerley Turk in 1689, Darley Arabian after 1700, and Godolphin Barb around 1730.

Since then, the Thoroughbred has been introduced to most countries where it is bred for racing or used to improve local breeds.

However, breeders bred the animals heavily, resulting in a high level of inbreeding among racehorses.

Co-author Professor Josephine Pemberton of the University of Edinburgh, said in a statement: “The effects of inbreeding that we have observed are certainly not new, but have only been discovered through genomic data for many of the purebred animals that are contained in these data. installed.

“These results are a warning sign of a growing trend of inbreeding among purebreds.”

Inbreeding of Thoroughbred racehorses is on the rise, raising concerns about the future health of the population.

However, the identification of this new genetic marker and the possibility of introducing genetic screening means that breeding decisions can be better made to improve the health and welfare of these valuable animals.

“It still needs to be studied whether this marker is associated with injury risk, but the data points in that direction,” Hill said.

“This may seem like a small number of horses, but it has a significant impact on the population as a whole. In the long term, the occurrence of this marker in a breed could be reduced if a whole breed testing program is implemented.

“This will have a positive long-term effect on the genetic health of the population and will not discriminate against the use of any stallion as it also depends on mares.”

Genetic diversity can be used as a marker of the health of a species.

An animal group that is more genetically diverse is more likely to be able to cope with threats such as disease, as individuals will carry slightly different versions of the same genes, some of which may help them fight disease.

But species with low genetic diversity could potentially be at higher risk.

If their genes make them more susceptible to the virus, for example, one outbreak could wipe out a large number of people, further reducing diversity and tightening the loop.

In the study, the researchers showed that species and populations in areas outside the tropics and in areas that are more affected by humans, such as urban areas and croplands, have reduced genetic diversity.

“However, we don’t yet know if a reduction in genetic diversity is putting them at risk of extinction,” Dr. Andrea Miraldo, a researcher at the University of Copenhagen, told MailOnline.

“Populations and species can be sustained even at low genetic diversity, although the higher the genetic diversity, the more resilient the species to environmental changes.”