Conventional wisdom in Thoroughbred racing and breeding states that a horse born earlier in the foaling season is going to be more physically mature than one born near the end of it when they meet on the racetrack and are considered to be the same age in the eyes of The Jockey Club.
A study by British and Canadian researchers affirmed that axiom, concluding that runners born earlier in the foaling season made more money during their 2-year-old and 3-year-old racing seasons in the U.K. and Ireland than those born later in the year.
The study also found that runners who sold for more money at auction tended to race less often during those first two years on the track than their less expensive counterparts, but they earned more prize money, both in total and per start.
The study involved 28,282 horses, encompassing all horses born in the U.K. and Ireland during the 2014 and 2015 foaling seasons.
Of the horses that raced at least once by age three, the study found that 34 percent had not earned any prize money by the end of their 2-year-old season, and 19 percent had no prize money by the end of their sophomore campaign.
The decline in average prize earnings for foals born later in the season was significant. For 2-year-olds, both total earnings and earnings per start fell by three percent for every week after Jan. 1 that a horse was born, and the chances of making no money on the year increased by three percent per week. Three-year-olds saw a two percent drop in earnings per week born after Jan. 1, and the chances of earning no money rose by three percent per week.
Among sale graduates in the study, just 17 percent of those sold as weanlings made back their purchase price on the racetrack through their 3-year-old season, while 13 percent of horses sold as yearlings surpassed their sale price after their sophomore campaign.
Yearlings that brought 6,666 guineas or less, the study’s lowest price bracket, made an average of 7.8 starts through the end of their 3-year-old seasons and earned an average of £5,241 (US$5,846) in that timespan, with an average of £588 (US$656) per start.
On the other side of the spectrum, yearlings that sold for 48,000 guineas, the study’s highest bracket, average 6.9 starts through their sophomore season, for average total earnings of £15,462 (US$17,250) and per-start earnings of £2,065 (US$2,303).
To view the full study, click here.