A new study published in the journal Nature Communications: Biology has identified a critical set of genes linked to successful racehorses. By comparing the genomes of Thoroughbred, Arabian, and Mongolian racehorses to horses bred for other sports or leisure, the experts managed to pinpoint a set of genes which play a significant role in muscle, metabolism, and neurobiology. These genes were clearly different in racing horses, and were common to all racing breeds compared to horses from non-racing breeds.
“Since the discovery of the ‘Speed Gene’ in 2009, we have generated genetic data for thousands of Thoroughbreds and horses from other breeds,” said study senior author Emmeline Hill, a horse geneticist at the University College Dublin (UCD). “This is the first time this set of genes has been linked to the success of racing breeds. Two of the genes were previously identified for performance in Thoroughbreds and Arabians, but the approach we took was to ask what genes were common to all racing breeds and different from non-racing breeds.”
The large variety of horse breeds developed over the last few hundreds of years all over the world have been carefully shaped by selective breeding for different traits, leading to tall horses, small horses, strong draft horses, useful riding horses, and fast racing horses.
“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,” Hill explained.
“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,” added study co-author David MacHugh, a professor of Functional Genomics at UCD.
The scientists compared the genomes of racing horses with those of 21 non-racing breeds – including breeds such as Clydesdale, Connemara pony, Hanoverian, Morgan, Norwegian Fjord, Paint, Shetland, and Shire – and identified seven essential genes for racing. Among the top genes was NTM, which has a major role in brain development and influences learning and memory. This gene was most likely selected during the horse domestication process, and in Thoroughbred racehorses, for instance, it even influences whether a horse ever races or not.
“This finding suggests that equine neurological systems perturbed by natural and artificial selection associated with domestication may overlap with adaptive traits that are required for racing,” said MacHugh.
“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,” Hill concluded.
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