Horses have been selected for athletic characteristics for thousands of years. Traits that first evolved in the wild when horses needed to escape predators and traverse large tracts of land in search of food and shelter have been selectively bred by humans in the pursuit of faster, stronger and more resistant horses – and in doing so, humans have made specific breeds distinct from other horses.
An international team of Equine scientists investigated equine genomes from Asia, Europe, North America, and Ireland and identified a set of distinctive genetic markers associated with muscle, metabolism and neurobiology that set these horses apart from breeds used for sport and leisure where racing isn’t the focus.
UCD Professor Emmeline Hill, the lead scientist on this project and Chief Science Officer at Plusvital, stated, “Since the discovery of the ‘Speed Gene’ in 2009, we have generated genetic data for thousands of Thoroughbreds and horses from other breeds.”
She noted, “This is the first time this specific set of genes has been linked to the success of racing breeds. Two of the identified genes were previously linked with success in Thoroughbreds and Arabians, but what our approach was to uncover was what sets of unique, common genes were different from a group of non-racing breeds.
Horses come in many shapes and sizes, mostly because there has been careful selective breeding for the desired traits of different types of horses. The result is a vast range of breeds that are suitable for different lifestyles. We have discovered a set of genes common to racing horses, but not all horses within a racing breed have the advantageous gene version, so these findings will be useful to identify the most suitable individuals within a breed for racing or for breeding.”
Co-author Professor David MacHugh, commented, “Although racing is a multifactorial trait, with management and training having a considerable influence on the success of a racehorse, this study provides good evidence for major-effect genes shaping the racing trait in horse populations.”
The research, which has been published in an open-access journal from Nature, tested DNA samples of 100 different horses from the Khentii province of Mongolia ( the birthplace of Ghengis Khan) owned by the Ajnai Sharga Horse Racing Team.
The scientists examined these samples, along with those of thoroughbreds and racing Arabians to identify seven genes that make these breeds much more adept for racing compared to 21 other breeds used mainly for sport and leisure including Connemaras, Morgans, Clydsedales, American Paint Horses and Norwegian Fjords.
Among the most important gene findings, was NTM, which impacts brain development and affects how quickly a horse learns and remembers. This gene was first selected at the onset of the domestication process, and in thoroughbred horses, it can influence whether a horse will race during its lifetime.
“This finding suggests that horses’ neurological systems perturbed by natural and artificial selection associated with domestication may overlap with adaptive traits that are required for racing,” said Professor MacHugh.
Dr Haige Han, another project collaborator and first author of the paper, added: “Testing these variants in new sets of hundreds of horses from racing and non-racing breeds identified seven essential genes for racing. These genes have roles in muscle, metabolism, and neurobiological functions, and are central to racing ability among horse breeds.”
The researchers used gene expression data from the skeletal muscles of Thoroughbreds to see if the genes they had identified were related to how well the muscle responds to exercise.
“By integrating these two different data sets we fine-tuned the list of racing genes to those that were most biologically relevant to racing. One of these genes was MYLK2 which is required for muscle contraction. In humans, MYLK2 is associated with exercise-induced muscle damage,” said Professor Hill.
The ability to maximise racing performance is constantly at the forefront of racehorse breeding. Although athletic performance depends on several factors, centuries of selection have led to extreme athletic phenotypes among geographically diverse horse populations that display the influence of protein-coding variants in fundamental exercise-relevant genes.
This research was supported by The National Key R&D Program of China; The National Natural Science Foundation of China; The Science Foundation of Ireland;The US National Institutes of Health and The Royal Agricultural University Cirencester Fund.
The study was performed in collaboration with the UCD School of Agriculture and Food Sciences and UCD Conway Institute, Ireland; the Royal Agricultural University, UK; Inner Mongolia Agricultural University, China; Mongolian Academy of Sciences and Ajnai Sharga Horse Racing Team, Mongolian University of Science and Technology and Mongolian National University of Medical Sciences in Mongolia, the US-based California Institute of Technology and Children’s Hospital Los Angeles’ Saban Research Institute as well as Plusvital Ltd.
Plusvital has been a leader in equine science since its inception in 1975, growing out of Ireland’s well-known racing and sport horse history.
Plusvital acquired Equinome, which provides DNA testing and genomic profiling to predict racing performance potential. Plusvital’s clients include leading trainers, owners, and breeders in all of the major thoroughbred regions worldwide.
The article is titled: ‘Common protein-coding variants influence the racing phenotype in galloping racehorse breeds’ by Haige Han, Beatrice A. McGivney, Lucy Allen, Dongyi Bai, Leanne R. Corduff, Gantulga Davaakhuu, Jargalsaikhan Davaasambuu, Dulguun Dorjgotov, Thomas J. Hall, Andrew J. Hemmings3, Amy R. Holtby, Tuyatsetseg Jambal6, Badarch Jargalsaikhan, Uyasakh Jargalsaikhan, Naveen K. Kadri, David E. MacHugh, Hubert Pausch, Carol Readhead, David Warburton, Manglai Dugarjaviin & Emmeline W. Hill.
The original press relase can be read here.