An investigation in to the relationship between fluctuating asymmetry and performance in Polo ponies.

  • McDonald, K. (Speaker)
  • S. Measom (Speaker)
  • K. Baddeley (Speaker)

Activity: Talk or presentation typesOral presentation at Conference


Introduction: Symmetry of biological bilateral traits is the optimal aim during growth and development of an organism (Manning and Pickup 1998) and has been suggested to act as an indicator of phenotypic quality within a number of species (Manning et al., 1996). The symmetry of bilateral morphological traits has been linked to superior athletic function in humans (Manning and Pickup 1998), racehorses (Manning and Ockenden 1998) and event horses (McDonald and Dumbell 2007). The relationship between asymmetry and performance within other disciplines has yet to be investigated and may act as an indicator of performance potential in young stock if found to be a cross-discipline performance characteristic.Methods: Direct measurements of 13 bilateral traits were taken from 30 low goal polo horses of mixed age and gender. The ponies were based at two different yards, had been bred for, and had competed successfully at low goal. Nostril and pinna length and width, cheekbone length, fore and hind proximal phalanx width, third metacarpal and third metatarsal length and width and carpal and tarsal width were measured via Silverline® 300mm digital callipers (0.01mm accuracy). Anatomical landmarks were confirmed as giving repeatable measurements during a pilot study. Three repeated measurements were taken by the same operators and the mean calculated. Directional asymmetry was calculated by subtracting the right from the left measurement, and fluctuating asymmetry by subtracting the smaller measurement from the corresponding larger measurement. Directional bias was identified through Chi-Squared analysis and Mann Whitney U (limb traits) and T-test (facial traits) analysis identified differences between the asymmetry score and the ideal of zero.Results: With the exception of nostril length and cheekbone length facial traits demonstrated propensity to be larger to the right whereas limb traits were all larger to the left; however significance levels varied between each bilateral trait. All facial traits showed a very highly significant difference from the ideal of zero (P<0.001). Discussion and Conclusion: The results reinforce previous research findings indicating a directional bias of trait asymmetry within the polo ponies studies however some of the directionality does differ slightly; particularly when considering the forelimb. Many of the results are thought to reflect anatomical compensations through scar tissue formation as a result of discipline specific demands. These findings could be used to identify an association with injury prevalence and therefore potential adaptations to training to prevent injury occurrence. References: Manning, J.T., Scutt, D., Whitehouse, G.H., Leinster, S.J. & Walton, J.M. (1996) Asymmetry & the menstrual cycle in women. Ethol Sociobiol 17: 129-143Manning, J.T. & Pickup, L.J. (1998) Symmetry and Performance in Middle Distance Runners. International Journal of sports Medicine 19: 205-209Manning, J. & Ockenden, J. (1994) Fluctuating asymmetry in racehorses Nature 370:185-186McDonald, K. and Dumbell, L. (2008) The Relationship Between Fluctuating Asymmetry and Performance in Event Horses In: 6th International Conference on Equine Locomotion Book of Abstracts June 16th – 19th 2008 Cabourg, Normandy pp 60
Period20 Apr 2011
Event title1st Alltech-Hartpury Student Conference
Event typeConference
Conference number1
LocationGloucestershire, United KingdomShow on map