Most stallions within breeding programmes are expected to breed and compete concurrently. The exercising of stallions with regards to training regimes during the breeding season is a controversial subject. Daily exercise at low intensities is important for the mental and reproductive well-being of the stallion, however higher intensities of exercise, as seen in competing stallions, may have detrimental effects on seminal quality. To calculate if competition does affect semen quality, this study investigated the effect that equestrian discipline and timing of competition had on a range of stallion semen characteristics. This was a retrospective study that evaluated the seminal data of 1130 stallion semen collections from two UK based stud farms between 2009 and 2016. Competing stallion semen quality was significantly lower with regards to concentration (p < 0.05) and progressive motility (p < 0.05) than non-competing stallions. Semen volume was higher in competing stallions (p < 0.05) than non-competing stallions. There was a significant difference in seminal attributes among disciplines and competition levels (p < 0.05). The difference in semen quality among competing and non-competing stallions, as well as the difference among disciplines suggests endocrinological and physiological changes occur in relation to training intensity and competition.

Rationale: Artificial insemination allows sport horse stallions within breeding programmes to breed and compete concurrently. The level of exercise of stallions complete during the breeding season is a controversial subject. Daily exercise at low intensities is important for the mental and reproductive well-being of the stallion, however higher intensities of exercise, as seen in competing stallions, may have detrimental effects on seminal quality. The purpose of this study was to gain a greater understanding into the effects of competition and discipline on equid stallion semen through analysis of seminal parameters. The identification of optimal competition management for breeding stallions may lead to increased stallion fertility and economic gain. Methods:This retrospective study evaluated the seminal data of 1130 stallion collections from two UK based stud farms between 2009 and 2015. Seminal volume, concentration and progressive motility were analysed for differences between competing and non-competing stallions, then for differences between stallion disciplines. Results:Competing stallion semen concentration and progressive motility was significantly lower than noncompeting stallions (p<0.05). Semen volume was significantly higher in competing stallions (p<0.05) than noncompeting stallions. Non-competing stallion semen count was significantly higher than that of competing stallions (p<0.05). Conclusion:The difference in semen quality between competing and non-competing stallions, as well as the difference between disciplines suggests endocrinological and physiological changes occur in relation to training intensity and competition. Further research into semen quality considering exercise and competition will allow for contextualisation as to why these differences occurred.

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