Athletic ability in both humans and horses is largely genetic, so understanding the genetic make-up of a racehorse is a priceless skill. Before the recent advent of genetic testing in the laboratory, there were essentially three ways to estimate the genetic make-up of a thoroughbred racehorse:  pedigree, conformation and racing performance. The latter two are visible to the naked eye, but estimating the strength of a pedigree has traditionally been more of an art than a science.

Top Racehorses Not Always Best

Having two parents who were outstanding racehorses has usually been considered the mark of a fine pedigree, but many top racehorses do not become successful breeding horses, while some rather modest racehorses go on to become excellent breeding horses. This is particularly true of broodmare prospects, since almost all stallion prospects enjoyed considerable success on the racetrack. The old adage of “Breed the best to the best, and hope for the best” is simply not an ideal breeding strategy.

On the other hand, it has been recognized by agricultural breeders across the livestock kingdom that certain bloodlines combine or “nick” consistently well, even when these bloodlines are relatively modest in their own right. To use a simple analogy, steak and caviar may not combine very well, but peanut-butter and jelly surely do. In the thoroughbred world, we saw that Northern Dancer thrived dramatically with mares loaded with Teddy blood, producing champions such as Nijinsky II, El Gran Senor, and Storm Bird, etc. Nijinsky II in turn produced an incredible 37 per cent stakes winners from mares by Round Table, yet only eight per cent stakes winners from mares by Buckpasser — the premiere broodmare-sire of his era. So a genetic compatibility between a sire and dam is a fundamental ingredient for success.

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