By Edwin AnthonySpeed. Acceleration. Brilliance. These words draw attention and make the heart race. Speed is especially important in stallion prospects, which is why breeders are always on the lookout for horses with that elusive "turn of foot." A horse might power to the lead from the gate and set eye-popping fractions, or rally with an explosive move on the final turn. Either way, speed wins races.More importantly, speed is often a deciding factor in stallion success. Consider that there are a number of successful sires and broodmare sires, but far fewer successful sires-of-sires. After years of research, I've come to the conclusion that speed is the single most important factor in determining a horse's chances to succeed as a sire of sires. The speed merchants Blushing Groom, Danzig, Icecapade, In Reality, Mr. Prospector, Seattle Slew, and Storm Cat are continually changing the face of the industry through their descendants.Speed influences the outcome of important stakes races and shapes the results of yearling and 2-year-old auctions. In an increasingly commercial market, velocity and precocity are always in fashion. The foundation provided by classic influences is as important now as ever, but speed is a very important part of the evolution of the Thoroughbred.Not long ago, sprinters (restricted to six furlongs) were frowned upon as stallions. If a colt couldn't win a graded stakes at a mile (or farther), breeders and yearling buyers weren't particularly interested. The success at stud of sprinters like Belong to Me, Carson City, Mt. Livermore, and Phone Trick has changed a lot of stubborn minds.Pure speed is sometimes seen as a negative, because of the tendency of the sport's fastest runners to suffer injuries. An Indy 500 car needs more tune-ups and pit stops than your average car, so you can expect some wear and tear with the fleetest Thoroughbreds. Speed is a necessary element in pedigrees, and works quite well, as long as it is utilized properly. If tempered with the stamina and good bone provided by classic influences in pedigrees (Buckpasser, Fappiano, Nijinsky II, Ribot, Roberto, Secretariat, etc.), a runner sired by a sprinter or miler can win quality route races and stay sound.Many stakes winners are able to grind out victories with sustained moves over long distances, but these plodders are not the kind of colts that normally find success at stud. Some classic distance runners are able to succeed as stallions because they also have the speed to win at shorter distances. While Unbridled won the Kentucky Derby (gr. I) and Breeders' Cup Classic (gr. I), he also beat champion sprinter Housebuster at seven furlongs -- a noteworthy achievement. Many other classic winners and champions have been capable of winning at shorter distances as well.The owners of horses with enough stamina to win stakes races at nine or 10 furlongs will logically campaign their horses in those events. The purse structure for two-turn stakes events is significantly better than it is for sprints. Most horses have a limited number of starts in them, and economic choices must be made.At the same time, owners would greatly enhance their horse's residual value by allowing it to flash speed from time to time, even in a workout. Forty Niner (as an example) was a popular stallion because he was capable of winning at the classic distance of 10 furlongs, but also set a track record at one mile and was 2-year-old champion. Versatility is definitely a plus in the eyes of breeders.Pure sprinters seem to have a distinctive build. An overly muscular shoulder and hind end, a wide chest, and a short-coupled body are the conformational hallmarks of a speed type, although good horses come in all shapes and sizes. Phalaris was one of the first sprinters to find success at stud, and he was a horse with size and scope -- the antithesis of the modern sprinter.Mares with speed have had a profound impact on the breed as well. Crimson Saint (dam of Royal Academy, second dam of Storm Cat), Gold Beauty (dam of Dayjur, second dam of Sky Beauty), and Mumtaz Mahal (foundation mare of the Nasrullah, Mahmoud, Royal Charger, and Abernant families) were renowned speedballs during their racing careers. These mares prove that the time-honored practice of crossing speedy stallions and stamina-laden mares can work in reverse (stamina stallions over mares with speed).The old handicapping adage says, "Pace makes the race." In that same vein, you can say that speed drives the breeding industry.