Tuesday, 3 April 2012

Unearthing the genetics beneath the Thoroughbred’s success

(Odyssey 2010)

The Sport of Kings has been popular among the masses for centuries and, despite the demise of the horse as a daily necessity, this sport is still going strong. Over the last three centuries, horses of Arab, Barb and Turk as well as British descent have been selectively bred for the purpose of creating the ultimate racehorse (Bower et al. 2012). In the past, the selection of horses for racing and breeding has relied on their conformation and athleticism as well as the assumption that these traits would be passed on to offspring, however, recent advances in equine genetics are forming the basis for a new method of bloodline management, this time based on genetic traits (Bower et al. 2012).

Scientific journal Nature Communications recently published an article on the detection of the ‘speed gene’ that makes Thoroughbred horses so good at racing.

With the sequencing of the entire equine genome has come the discovery of the genetic factors that contribute to the athletic abilities of the thoroughbred horse. In 2009 the University College Dublin established Equinome, a biotech company, in order to implement research into the equine genome led by scientist Emmeline Hill and Mr Jim Bolger, one of Ireland’s well known thoroughbred trainer and breeder (Science Daily 2010). This research allowed them to identify the locus on the equine chromosome that plays a significant role in determining the speed and stamina of Thoroughbred horses (Bower et al. 2012). The discovery of this gene was made by analysing DNA obtained from several living and deceased equines including 22 breeds of Eurasian and North American descent, museum specimens from twelve historically influential stallions, 330 successful modern thoroughbreds, as well as 40 donkeys and two zebras (O’Connell 2012). Research was also conducted into the genetics of the Quarter Horse, a breed named after its ability to sprint a quarter mile at record speed (Bower et al. 2012). This ‘speed gene’ is a variation of C or T alleles on the myostatin gene which has been found to be partially responsible for muscle development in many species of mammal (Bower et al. 2012). Thoroughbreds who had two copies of the C allele were found to be best suited to sprint races requiring more speed and less stamina; heterozygous thoroughbreds possessing both the C allele and the T allele were found to run well in medium distances, and those possessing two copies of the T allele were those who ran best in long distances races requiring more stamina (O’Connell 2012). This deeper understanding of the equine genome will help to improve breeding in the racing industry as well as other areas of equestrian sports.

Edward Gal and Moorlands Totilas. © 2008 Ken Braddick/dressage-news.com

In the future, new knowledge of the equine genome may also hold the key to the early detection and management of Equine Metabolic Syndrome and resulting Laminitis, a common disorder known to arise from a combination of genetic and environmental factors (McCue, 2011).

Ideally, this new knowledge of the equine genome and the specific performance-influencing genes in it will lead to improved breeding and further development of the thoroughbred horse as genotypes are considered over phenotypes. This newfound knowledge may also help in the management of diseases such as Equine Metabolic Syndrome. Such a discovery as the identification of the specific genes responsible for performance traits is sure to revolutionise not only the multibillion dollar racing industry, but the entire equestrian world.

1. Bower, MA, McGivney, BA, Campana, MG, Gu, J, Andersson, LS, Barrett, E, Davis, CR, Mikko, S, Stock, F, Voronkova, V, Bradley, DG, Fahey, AG, Lindgren, G, MacHugh, DE, Sulimova, G, Hill, EW 2012, ‘The genetic origin and history of speed in the Thoroughbred racehorse’ Nature Communications, vol. 3, article no. 643

2. O’Connell, C 2012, Origin of ‘speed gene’ in horses, The Irish Times, viewed 16 March 2012, <http://www.irishtimes.com/newspaper/sciencetoday/2012/0126/1224310755727.html>

3. Science Daily 2010, Genetic Test for ‘Speed Gene’ in Thoroughbred Horses, viewed 15 March 2012, <http://www.sciencedaily.com/releases/2010/02/100202144204.htm>

4. McCue, M 2011, Advances in Equine Genetics, viewed 13 March 2012, < http://myhorseuniversity.com/resources/webcasts/july_2011>

Braddick, KJ 2008, Exquis World Dressage Masters CDI5* Starts at Hickstead Friday, CDI3* Starts Thursday, Dressage-News.com < http://www.dressage-news.com/?p=2408>
6. Odyssey 2010, Equine Research, viewed 15 March 2012, <http://www.research.uky.edu/odyssey/fall10/equine.html>

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