Harness Racing's Effect on Fertility

Every year, countless horses make the transition from a competitive athlete on the harness track to a life as a broodmare or breeding stallion. But will their years on the track and accompanying stresses impact their breeding careers? According to the results of a new study from Finland, it's unlikely that racing has an effect (either positive or negative) on horses' subsequent breeding careers, specifically their fertility.

Jenni Sairanen, MSc, a PhD candidate at the University of Helsinki, and colleagues reviewed the racing and breeding records of more than 60,000 Standardbred and Finnhorse mares and stallions (from 1991 to 2005) to see if and how competitive harness racing careers affected their fertility.

After analyzing foaling outcomes and racing performances, the team found that overall, each mare's racing career had little effect on her future breeding career, and in some cases, some time on the track was beneficial to subsequent pregnancies.

"The mares with a small number of races get all the advantages--conditioning, feeding, and attention--but not too many of the disadvantages, like stress (which can decrease a mare's chances of becoming pregnant)," Sairanen said.

Additionally, the team found that "the mares with the best career racing records had the highest foaling rates." They believe this could be because these mares received "preferential treatment (meaning high-quality nutrition and management, per the study)."

Sairanen suggested, "It would be best to first let the filly concentrate on racing for a couple of years. If she's performed well, have her retire before the breeding season begins (rather than in the midst of the season). The more money the mare can make on track compared to the price of her prospective foals, the longer the racing career can be."

She cautioned, however, "Don't wait too many years; old(er) maiden mares are notoriously difficult to get pregnant," regardless of career type prior to breeding.

The team noted that racing did not appear to have an effect on stallion fertility.

The study "Effects of racing on equine fertility" was published in March in Animal Reproduction Science. The abstract is available on PubMed.

About the Author

Marie Rosenthal, MS

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