Starting today, Scot Gillies' blog at The Bloodhorse will be featuring a series of mares for sale at the upcoming Keeneland November Sales. He's looking for reader input, and one of the questions he asked in regards to today's feature mare is 'what do you think of unraced mares'.
I'll give my opinion on that here. Most horses, regardless of breeding are relatively unsuccessful on the racetrack. Certainly most are not successful enough to warrant much interest as broodmares. So statistically, you have to go on the assumption that most unraced mares would not have been good enough to be worth much for breeding. This is even more true once you consider that they may have remained unraced due to soundness issues that they could potentially pass along to their offspring. No matter how well bred, I would assume an unraced broodmare should be a cheap broodmare.
An obviously extension of this line of thinking is that an unraced stallion is NEVER worth trying out. I don't care that he's a son of Storm Cat out of a top mare. The odds that he would have been successful enough to warrant a career at stud are incredibly low...certainly never high enough to justify an expensive breeding experiment.