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Polo Genetics: What is Behind
from Polo Times May 2020
by Edit
Buenos Aires, 2019, La Dolfina claimed the Argentine Polo Open Championship, at Palermo, for the seventh consecutive year and made history. It was indeed a remarkable achievement, that even overwhelmed other historical marks. But what makes Argentine polo so good?
In addition to the extraordinary players, there is a strong focus on horse genetics.
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Polo ponies come from Thoroughbreds (TB) in which myostatin, a gene related with muscle development, has been associated with the performance of a horse. Myostatin (MSTN) is a negative regulator of the muscle development in mammals. A mutation in the gene produces more precocious racehorses which are able to sprint in short flat races [1]. question, we’ve chosen horses ridden in different eras by different teams. A total of 70 horses were tested, including some famous ones: Polo Nevadito (Heguy breeding), Aiken Cura, Dolfina Lapa, Dolfina Cuartetera (all from La Dolfina breeding) and Aguada Anonima (La Aguada breeding). The results are demonstrated in the table (pictured), but all the horse genotypes are available upon request.
The first conclusion is the almost absence (4.3%) of the sprint type compared to the 23.4 % observed in local TB. The comparison is relevant based on their shared background. There is a prevalence of the stamina variety among AP horses with a 2.4 ratio of the stamina to sprint type, compared to 0.81 of TB (P < 1.10-4). This significant difference suggests a functional selection for the MSTN gene in AP horses. They were famous for their stamina, featured in horses that play a complete chukka or more than one per match. Things changed around twenty years ago, when polo players started changing horses – sometimes up to three times – during each chukka. Back then, stamina was less required than before, and horses were not as fast as they used to be and gave advantage to the players that replaced the exhausted horses. According to that and the evolution of the sport, a change in the MSTN might have happened in those top horses. We analyzed the MSTN
Polo Genetics
What is Behind Argentine Polo Ponies? Mario Novillo Corvalán MV got in touch with Polo Times with an article by himself and the Applied Genetics Laboratory of the Livestock Breeders Association, published by the YearBook of the Argentine Polo Pony Breeders Association
There are three types of Thoroughbreds: 1) the “sprint” types, horses carrying the mutation in two copies that are suited to fast, short-distance races; 2) the “stamina” type, horses without the mutation that are less precocious and are best adjusted for racing long distances. 3) horses, with an intermediate genotype, that carry a single copy of the mutation.
MSTN testing has been extended to other horse breeds, like Quarter Horses (Cuarto de Milla), that display the expected sprint type, or Egyptians, with the stamina variety suited to endurance.
Therefore, we wonder what type of variety are applied frequently in top Argentine polo horses (AP). In order to answer the Photograph by ©www.imagesofpolo.com Cuartetera B03 (pictured) is a clone of Dolfina Cuartetera, one of the 70 horses tested Photograph by ©www.imagesofpolo.com
type frequencies with the time measured by the birth date of a horse. As shown in the figure, the stamina type (Stamina/Stamina) decreased steadily from 1982 to 2013 (first and last birth dates recorded), while the Intermediate genotype (Stamina/Sprint) increased inversely. Moreover, there are significant differences between horses from different breedings, such as Heguy and La Dolfina, that represent two different kinds of polo. Nowadays, there is a trend to return to the old style; new leagues, like the All Pro Polo League, suggest that the games are too slow, with much more stop/start and change of direction compared to earlier style of playing. Another issue is the cost associated with breeding and keeping so many horses. Something must change, they said.
We thought that the stamina prevalence in older horses is quite visible within polo tradition in Argentina [2], where polo used to be played just for fun in the estancias in its beginnings, with available Creolo horses, which were known for their endurance. The game likely set up the horse standard when Thoroughbreds were selected for playing in a more professional way. Therefore, we found that mares, such as those from La Aguada, have the stamina phenotype mostly, which is not frequent among local TB. Even when the style of playing has changed, intermediate phenotypes that show sprint are more frequent among modern top polo horses. But stamina is still a required trait as shown by the absence of pure sprint types.
This work helps to understand the evolution of the sport in Argentina, in terms of a gene that regulates the athletic performance, precocity and body mass [1]. This information provides a guide on the issue of breeding and training polo ponies, in the expected direction.
Polo Pureza Polo Bailanta Polo Nevadito Neblina Primavera Manzanita River Slaney Cerecita Aguada Llovizna Aguada Wallabie Aguada Anonima Arroba Nunca Digas Nunca Small Pearson Aiken Cura Dolfina Diosa Dolfina Lapa Dolfina Cuartetera Open Chimento Dolfina Panam Dolfina Peanut Dolfina Nut Heguy Heguy Heguy La Aguada La Aguada La Aguada La Aguada La Aguada La Aguada La Aguada La Aguada La Aguada La Dolfina La Dolfina La Dolfina La Dolfina La Dolfina La Dolfina La Dolfina La Dolfina La Dolfina f f m f f f m f f f f f f m f f f m f f f
Birth of Year
1988 1992 1993 1984 1985 1990 1992 1999 2001 2003 2004 2008 1993 1995 1998 2000 2001 2002 2005 2008 2009
Sprint (+)/ Stamina (-) Genotypes
-/- -/+ -/- -/- -/- -/- -/+ -/- -/+ -/- -/+ +/+ -/+ -/- +/+ -/+ -/+ -/- -/+ -/+ -/+
A summary of the horses tested by polo team, considering their birth dates, gender and myostatin genotypes
References
[1] Hill EW, Gu J, Eivers SS, Fonseca RG, McGivney BA, Govindarajan P, et al. A sequence polymorphism in MSTN predicts sprinting ability and racing stamina in thoroughbred horses. PLoS One. 2010;5:e8645. [2] Laffaye HA. Polo in Argentina: A History: McFarland; 2014.
Acknowledgements
This work was supported by the Sociedad Rural Argentina (Livestock Breeders Association) with own funds. We would like to thank the breeders who own the Polo horses tested in this study. We also thank the Argentine Polo Pony Breeders Association, specially to MV Guillermo Buchanan, for his technical advice.
This work has been published by the Year Book of the Argentine Polo Pony Breeders Association
Temporal variation of MSTN frequencies with AP birth years. Homozygous ”Stamina” type (-/-) decreases while the heterozygous (-/+) with the sprint variant grows with time. The change was significant when frequencies from the earlier and later periods were compared
