Researchers have discovered the inner workings of a known speed gene in Thoroughbred racehorses which directly affects skeletal muscle growth and, in turn, race distance aptitude. | Photo: iStock

Researchers have pinpointed the genetic basis that explains why some Thoroughbreds are better equipped to race over sprint distances and others over longer distances. The scientists from Trinity College Dublin and University College Dublin (UCD), both in Ireland, have discovered the inner workings of a known “speed gene” in Thoroughbred racehorses, which directly affects skeletal muscle growth and, in turn, race distance aptitude.

Thoroughbred horses are finely-tuned athletes with a high aerobic capacity relative to their skeletal muscle mass, which can be attributed to centuries of genetic selection for speed and stamina. Nongenetic factors, such as training schedule variations, can also influence how racehorse distance aptitudes and preferences develop. However, prior work by UCD professor Emmeline Hill, PhD, had demonstrated that different versions (polymorphisms) of the myostatin gene, a pronounced inhibitor of skeletal muscle growth, almost singularly account for gene-based race distance aptitude in racehorses.

This prior discovery earned the myostatin gene the speed gene moniker. Horses with CC copies tend to develop into sprinters, those with CT copies generally develop into middle-distance performers, and those with TT copies are typically best equipped for long distances