Body and Soul: The Ten Commandments of Stallion Selection

By Robert D. Fierro

We know what you’re thinking: Whatever in the world would possess someone to talk about stallion selection just before the breeding season officially ends? While some might accuse your correspondent of being somewhat possessed, in some ways, there is a logical reason for exploring this subject at this time: Everybody starts thinking about next year when the breeding shed doors close up for the season.

Stallion managers start looking more closely at prospects for the next season. Sometimes they look to stay on a roll of success after breeders stormed the doors for a newbie or freshmen sires burst out in style. Sometimes they need to assuage the frustration of a newbie failing to attract much interest, or those with a couple of crops failing to show much competence or class.

Breeders conjure up similar thoughts, especially those who booked to stallions whose first or second crops sold like hotcakes at the yearling or 2-year-old sales, but have demonstrably proven their shortcomings a week or so after their mare has been bred to one of them.

Guilt trips travel over various routes.

Below we present a check list of factors that might raise an eyebrow or two as to what we have referred to as the “Ten Commandments of Stallion Selection” (no apostacy intended, and we even phrased most of them as questions rather than dictates). While it is more geared toward the breeder than the stallion manager, there might be a nugget or two for all to find interesting, if not helpful.

[I] How Did He Run? The best sire prospects–even among sprinters–gain early position and have the cruising power, stride length, and thrust (kick from behind through hocks and quarters), to outlast the rest at the end. These horses are more efficient. On the other hand, deep closers–including closing sprinters–may be less efficient due to biomechanical issues which force them to settle, get into rhythm, and then win on momentum. It’s an axiom of genetic probability that the more efficient body will have the best chance of replicating itself in a population of mares where the majority are closer to being reasonably efficient.

[II] How did he move? Did he move as to give an appearance of running with his nose to the ground–like Danzig, Deputy Minister, A.P. Indy, for example? Did he run with his neck extended straight ahead and move in a rhythmic motion with his shoulder extension–like Affirmed and Alydar? Did he run with his head up, floating along like a ballet dancer–such as Montjeu? Which style defined your mare, and do you want to match it or blend it with another style?

[III] Where, and on what surface, did he run? The majority of leading sires in Kentucky–and in most major breeding states–raced successfully in New York, and by extension on the major circuit which includes Churchill Downs, Keeneland, Gulfstream, Santa Anita and Del Mar. Some may have done well overseas before racing here, but for the most part you want domesticity in a race record.

[IV] Is he a square, a rectangle, or a trapezoid? This is an assessment of body set and takes some eye adjustment. A square body will include equal front and rear leg length and relatively short body length–you see a square. Rectangle would include those with legs that might be the same length as those on a square body, but the length of the back and body would be long, so you see a rectangle. A trapezoid would be a body set that is to the eye either square or rectangular, but the body itself is lower or higher at the elbow or flank thereby generating either a downhill or an uphill trajectory.

[V] Is he Derek Jeter, Wilson Kipsang, or Tom Brady? Now, move around to the front and, still keeping your eyes above the knees, try to get a handle on this guy’s girth–i.e. how wide or how narrow he is. Jeter is agile and versatile, Kipsang is lanky and long-winded, Brady is as balanced as Jeter but not as agile. Think of the athlete you are viewing and determine what kind of athlete you are looking to breed.

[VI] Is he a “sport?” Biologically speaking, a “sport” is “an organism that has characteristics resulting from chromosomal alteration–a living thing that has (or can develop) the ability to act or function independently.” In the vernacular, that refers to a person or animal who appears to be completely different than what was expected, but manages to establish itself as a success. In racing, that could mean success on the racetrack, and either success or failure at stud. California Chrome is a bit of a sport.

[VII] Kick the tires. It is much easier to breed for one trait than two, and heaven forbid a stallion has bad front wheels as well as being very short in those legs. You might want to send a long legged, correct, mare to him, but you might not get a correction for both factors unless the rest of their physical traits are close. Try to do your genetic homework here–find out if bad front wheels are a trait of the sire’s pedigree, or whether the wheels were an environmental accident, e.g., awkward position in-utero, nutrition as a foal, etc.

[VIII] Who’s his daddy? Line or branch founders are generally consistent in siring the type of individual who helps establish that offshoot. Fappiano’s branch of Mr. Prospector’s line is far different than Gone West’s, Smart Strike’s and Forty Niner’s in many key aspects–each branch is quite consistent in expressing the founder’s size, aptitude, or personality, for example

[IX] What stock did his momma come from-and who was her daddy? You can quickly eliminate a stallion from consideration on the strength of the broodmare sire and his sire-line. Check the list of leading sires over the past 10 years and note which were produced by mares whose sires and maternal grandsires made no lasting impression on the breed–love that phrase, memorize it. Look at the six-cross pedigree of the stallion prospect and ask yourself, “Does this work?”

[X] Be wary of a stallion prospect whose name you cannot pronounce or spell. Years ago a breeder asked whether we thought of a new stallion, whose name he pronounced “Abajoenee.” Puzzled, we asked other pertinent questions but finally asked how the name was spelled. He spelled it and we then informed him that the name was pronounced “A-bag-in-one” (he was by Devil’s Bag). The man preferred his pronunciation and eschewed breeding to that horse.

Abaginone notwithstanding, such is the way of the world, and our game.

Bob Fierro is a partner with Jay Kilgore and Frank Mitchell in DataTrack International, biomechanical consultants and developers of BreezeFigs. He can be reached at