Does Harness Racing Effect Horses' Fertility?

According to an old adage, the most successful race horses "leave their best on the track." This means that horses that were winners on the track often weren't winners when it came to the breeding shed. But a major study of 60,000 Standardbred and Finnhorse harness racing horses suggests that races have no substantial effect on an individual horse's fertility.

Finnhorses, the second most popular harness racing breed in Finland have lower fertility rates than Standardbreds. The Finnhorse has an aging population, especially among mares. It is normal for mares to become barren as they get into their 20s '" no matter what their breed. But what about barrenness in mares at the prime of their lives?

Stallions and Mares

This study, undertaken by University of Helsinki PhD candidate Jenni Sairanen, MSc, looked at short-term and long-term fertility records of 60,000 harness racing horses that took up a second career in the breeding shed. Stallions and colts sperm seemed unaffected by light or heavy racing careers. But for mares, there was a slightly different story, but perhaps not enough to truly make a major impact on reducing the numbers of fillies and mares in harness racing.

However, mares should be retired to the breeding shed before their age hits double digits. No matter what their racing record, older maiden (virgin) mares have great difficulty getting pregnant.

Racing After Mating

The study also looked at the foaling records of mares that went back to the track after they had been bred. Pregnant mares are often raced during their first six months. Their foaling percentage decreased slightly if they raced more than 10 times in a year. But the percentage raised slightly if the mare raced 1 to 5 times in a year before going to foal.

Sairenen recommended that fillies and mares have light racing campaigns after mating, so their bodies get toned and healthy. Pregnant mares may also get preferential treatment by getting good nutrition and personal attention denied from unbred mares raced every week for years. Fit but not fat mares become pregnant and can carry the foal to term.

Harness Racing in Finland

Harness racing is big business in Scandinavian countries. Race wins make headline news, just after the hockey scores. Although there are questions about how ethical the sport is and how retired racers are treated, for the moment Scandinavia is committed to keeping the sport going.

Drugs that plague American race tracks are rarely seen in Finland, so they did not factor into the study. Some drugs, such as steroids, can reduce fertility in horses. The study did acknowledge that a horse's particular genes can affect fertility. More studies need to be done to determine what can be done to better increase fertility in Finnhorses, especially the mares.

Resources

"Harness Racing's Effect on Fertility." Marie Rosenthal, MS. The Horse. August 2011.

"Effects of racing on equine fertility." J Sairanen, et al. Animal Reproduction Science. March 2011.

"A 15-year survey of reproductive efficiency of Standardbred and Finnhorse trotters in Finland--descriptive results." T Katila, et al. Atca Veterinaria Scandinavica. June 14, 2010. http://www.ncbi.nlm.nih.gov/pubmed/20546559