Do Younger Parents Breed Faster Racehorses?

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Recent research shows that increasing parental age at conception has a detrimental effect on race speed.

By Mark Andrews

When a split-second can separate the horses at the end of the race, the slightest advantage can give the winner the edge. Research from the University of Exeter found that the speed of Thoroughbred horses declines as the age of their parents when they were conceived increases.

Dr. Patrick Sharman and colleagues at the Centre for Ecology and Conservation, University of Exeter, UK, analysed 906,027 racing performances of 101,257 horses — the offspring of 41,107 dams and 2,887 sires. The study included data from almost 25 years of racing results, from 1996-2019, involving meetings across Great Britain. The work is published in Royal Society Open Science.

Dr. Patrick Sharman says, “The fact that parental age affects racehorse speed should be of interest to the horseracing industry. More generally, it adds to an increasing body of evidence which points towards parental ‘state’ at the time of conception having an influence on offspring phenotype. This would have implications well beyond racehorses and the horseracing industry.”

They found a “significant effect” of maternal age on speed, with each additional year of age at conception decreasing the offspring speed by 0.017 yards per second. This may not seem to be very much, but they suggest it could produce a one second difference in a mile-long race between a horse born to a five-year-old mare and one born to a 15-year-old mare.

Also, they found that the paternal age showed a decrease of 0.011 yards per second for every increasing year in stallion age.

Sharman adds: “It is perhaps not surprising that offspring speed declines with increasing maternal age. It is the dams, after all, who care for the foal, first in utero, and then through to around six months of age. 

“What I find fascinating, though, is that increasing paternal age also causes a significant decline in racehorse speed. Thoroughbred stallions play no part whatsoever is raising a foal, so what is behind this decline in speed?”

The authors conclude: “Our analysis identified significant negative within-parent effects of advancing maternal and paternal age on offspring speed. While we had expected to find some evidence of parental age effects, their magnitude is notable, particularly that of the previously undocumented influence of paternal age on offspring speed.”

They hope that their findings will prompt research into the mechanisms by which these parental age influences are transmitted to the offspring.

For more details, see: Evidence of maternal and paternal age effects on speed in thoroughbred racehorses; Patrick Sharman, Andrew J. Young, Alastair J. Wilson; Royal Society Open Science Vol 9, no 10 (2022).

Related: How to Care for Your New Foal

Published with the kind permission of Mark Andrews, Equine Science Update

Photo: Shutterstock/Pfluegler-photo