How To Read Your Horse's Test Results: Speed (Myostatin)

Does your horse have a need for speed, or are they built to go the distance? The answer may lie in the extraordinary world of myostatin (MSTN), also known as the “speed” gene. Beyond racing, where the MSTN gene was first researched in horses, discover how this genetic insight can help you set your horse up for career success in jumping, barrel racing, dressage, and more. Your horse's DNA is the key to unlocking their full potential in any equestrian adventure.

With a DNA test from Etalon Equine Genetics, you can unveil whether your horse carries specific variants that influence their unique brand of speed, whether that be a predisposition to sprint, for endurance, or a mix of both. Join us for a lap around the track to learn more about the MSTN gene and its impact on your horse's performance!

Understanding the Speed Gene MSTN

Myostatin (MSTN) is a protein that plays a crucial role in regulating muscle growth. It acts as a negative regulator, meaning it inhibits the development of muscle tissue. Mutations in the MSTN gene can lead to changes in the production or function of myostatin, resulting in alterations in muscle mass.

One notable example of MSTN mutations causing significant effects is observed in Belgian Blue cattle. These cattle exhibit a condition known as double muscling, characterized by a substantial increase in muscle mass. This trait is highly desirable in the beef industry because it leads to a higher meat-to-bone ratio. The double muscling phenotype is a result of natural mutations in the MSTN gene, which disrupt the normal function of myostatin, allowing for uncontrolled muscle growth.

In the context of dogs, particularly the whippet breed, there is a variant in the MSTN gene associated with racing performance.¹ Racing performance in whippets heavily depends on their muscular strength and agility. The specific mutation in whippets is located within a non-coding portion of the MSTN gene, suggesting that it may influence the regulation of myostatin expression rather than altering the structure of the protein itself.

It's worth noting that the mutation associated with racing performance in whippets is found in a non-coding region, highlighting the complexity of genetic regulation. Non-coding regions, once thought to be less important, are now recognized for their potential to play a role in the regulation of gene expression.

However, despite this association with racing performance, it currently stands that no variants with a stronger association have been found. This indicates that while there is a known association between MSTN and speed, the genetic factors influencing racing performance in whippets, and by extension in horses, are likely multifaceted and involve a combination of various genes and environmental factors. The study of such genetic variations not only provides insights into the biology of muscle development but also has practical applications in the horse breeding industry for specific speed or stamina-related traits.

The MSTN Gene and Its Influence on Performance

Thoroughbred horses are renowned for their speed and agility, crucial attributes in horse racing. The knowledge gained from studying the correlation between racing distances in Thoroughbreds and specific MSTN gene variants provides valuable insights into the genetic basis of athletic performance. This information can be leveraged to enhance the overall well-being and performance of horses in various equestrian disciplines, extending beyond just racing.

Thoroughbred races encompass various distances, and individual racehorses typically exhibit preferences for specific ranges. Some research suggests that horses specializing in sprints, covering distances less than 6 furlongs (2/3rds of a mile), tend to be more compact and muscular compared to their counterparts in longer-distance races.

The genetic aspect of this preference has been traced back to the MSTN gene, which forms the correlation between specific MSTN gene variants and racing distances among elite Thoroughbreds. Dr. Emmeline Hill, an Irish equine geneticist who is credited with discovering the myostatin gene in horses, described MSTN as “the most powerful genetic marker for prediction of race distance aptitude in Thoroughbreds.”²

Horses with the C/C genotype (Sprint/Sprint) excel in races of 8 furlongs or less, showcasing their prowess in shorter sprints. On the other hand, those with the T/T genotype (Endurance/Endurance) are more prevalent in races spanning 9 furlongs or more, emphasizing their endurance capabilities. Horses carrying one copy of each allele, C/T (Sprint/Endurance), have demonstrated success across all distances. This genetic combination appears to provide a horse with a versatile advantage, allowing them to perform competitively in both sprint and endurance races.³ ⁴

Using the genotype and performance results demonstrated in Thoroughbred studies, Etalon can test your horse for the MSTN gene and reasonably predict their aptitude for speed, endurance, or a mix of both. Each of our comprehensive genetic testing panels includes insights into whether your horse is a speed or endurance athlete. This can help you make the best career decisions for your equine partner so that they can excel in whatever discipline aligns best with their DNA.

There are three possible genotype results for the MSTN speed gene. Your horse’s Etalon DNA results will be one of the following possible combinations:

• Sprint = Sprint type; horse may accel at short distances, quick bursts of speed over endurance type activity.
• Mid-Distance = Mid-distance type; horse may have multidistance capabilities including sprint and endurance.
• Endurance = Endurance type; horse may accel at longer distance travel versus short distance sprint type activity.

If you have a specific discipline in mind for your future partner, evaluating their speed-related genetics can offer a leg-up. One example of this that we have observed is in exceptional show jumpers who have one sprint-type gene variant and one endurance-type variant. These elite horses, such as Flexible and Banba who are half-siblings sired by Cruising, all fall into this category. They have the endurance to complete a course plus the speed necessary to put up consistently fast times. We also see similarities in speed-related genetics reflected in top eventing and dressage horses, such as Tsetserleg TSF and Qredit. We often see that horses who excel in these disciplines regularly carry two copies of the endurance-type variant.

The genetic landscape of horse performance is intricate, with the myostatin gene playing a role in shaping the physical attributes of horses specialized for specific disciplines. These insights contribute to the ongoing efforts to refine breeding strategies and optimize career performance based on the genetic factors influencing the speed, stamina, and muscular characteristics of not only Thoroughbred racehorses but of any competitive horse.

The Final Lap

As we reflect on the intricate dance between genes and performance, the MSTN gene emerges as a powerful tool for breeders, trainers, and horse enthusiasts alike. From exceptional show jumpers to top dressage and eventing horses, the influence of genetic combinations is undeniable.

Whether your equine companion is destined for speed, endurance, or a versatile mix, unlocking their full potential begins with understanding their genetic makeup. With testing by Etalon Equine Genetics, you have the power to get to know your horse down to the DNA. From sprinters to endurance champions and those balancing both, each genetic profile offers a roadmap to either breeding horses best suited for your chosen discipline or setting your current horse up for career success.

As you embark on this genetically inspired horsemanship journey, armed with insights from Etalon, you're not just exploring the DNA of your horse; you're unlocking a future where each ride is a testament to the extraordinary genetic potential that makes your horse one of a kind.

References

¹ Mosher, D. S., Quignon, P., Bustamante, C. D., Sutter, N. B., Mellersh, C. S., Parker, H. G., & Ostrander, E. A. (2007). A mutation in the myostatin gene increases muscle mass and enhances racing performance in heterozygote dogs. PLoS genetics, 3(5), e79. https://doi.org/10.1371/journal.pgen.0030079

² Hill, E. W., McGivney, B. A., Gu, J., Whiston, R., & Machugh, D. E. (2010). A genome-wide SNP-association study confirms a sequence variant (g.66493737C>T) in the equine myostatin (MSTN) gene as the most powerful predictor of optimum racing distance for Thoroughbred racehorses. BMC genomics, 11, 552. https://doi.org/10.1186/1471-2164-11-552

³ Hill, E. W., Gu, J., Eivers, S. S., Fonseca, R. G., McGivney, B. A., Govindarajan, P., Orr, N., Katz, L. M., & MacHugh, D. E. (2010). A sequence polymorphism in MSTN predicts sprinting ability and racing stamina in thoroughbred horses. PloS one, 5(1), e8645. https://doi.org/10.1371/journal.pone.0008645

⁴ Hill, E. W., Fonseca, R. G., McGivney, B. A., Gu, J., MacHugh, D. E., & Katz, L. M. (2012). MSTN genotype (g.66493737C/T) association with speed indices in Thoroughbred racehorses. Journal of applied physiology (Bethesda, Md. : 1985), 112(1), 86–90. https://doi.org/10.1152/japplphysiol.00793.2011