Great horses by design

The King Ranch pioneered selective breeding practices, steeped in science, that still provide the surest path to producing superior horses.

The King Ranch pioneered selective breeding practices, steeped in science, that still provide the surest path to producing superior horses.

Upon his father’s death in 1932, Robert J. Kleberg, Jr. became manager of King Ranch and was named its president three years later when it was incorporated. For the next 50 years, “Mr. Bob” was the prime mover behind King Ranch horse and cattle breeding programs and he deserves major credit for designing a scientific and highly effective breeding system.

Gritty, persistent, indomitable and highly knowledgeable, Kleberg famously summed up his philosophy when he told his daughter, “You must have a dream first. Then work like hell to make it come true.” The King Ranch program contains valuable lessons for anyone interested in breeding horses, whether their operation is large or small.

As King Ranch enterprises grew to become multi national after 1940, Bob Kleberg’s nephew Richard Kleberg, Jr. (“Mr. Dick”), took over most aspects of running the Quarter Horse breeding program. Taking full advantage of enormous resources in terms of money, quality breeding stock, acreage and manpower, the Klebergs were able to “fix” the type of the horses and cattle bred on the King Ranch in a remarkably short span of time. According to breed historian Robert Denhardt, they would have gone on to establish a unique

King Ranch horse breed had it not been for the incorporation of the American Quarter Horse Association (AQHA) in 1940, just as the breeding program Bob Kleberg had started in 1921 was coming to fruition. The Klebergs’ reasons for throwing in with the association instead of carrying on independently were both financially wise and, as we will see, highly laudable in terms of the long-term benefit to the breed.

THE OLD SORREL

The Old Sorrel is the foundational King Ranch Quarter Horse stallion, but he did not enter the picture immediately. As early as 1854, ranch founder Captain Richard King began buying good “American” horses (bred east of the Mississippi) and bred them for both sale and use on the ranch. When the U.S. Government remount breeding program came into existence in the first decades of the 20th century, his successor and son-in-law, Robert Kleberg, Sr., took advantage of the opportunity to introduce some quality Thoroughbred blood. Thus from its earliest days, King Ranch cowboys had ridden a mixture of types including Cayuses, Mustangs, part-Thoroughbreds, Morgans and Mountain Horses (the ancestors of American Saddlebreds in the same way that the Billy-Rondo is the ancestor of the Quarter Horse; see “Mountain Horses: America’s Hidden Treasure,” EQUUS 489). Derived from colonial-era easy-gaited Thoroughbreds, Mountain Horses were known for toughness and stamina and were widely used for ranch work (see “America’s Major Horse Breeds Emerge,” EQUUS 473). Kleberg, like King before him, was after size, strength, easy saddling qualities, soundness, handsome appearance, good-mindedness and smooth gaits.

Sometime about 1910, however, the senior Mr. Kleberg discovered Billys. Neighbor George Clegg bred and loved this type of horse and had purchased the stallion Hickory Bill, the Old Sorrel’s sire, at the Sam Watkins estate dispersal sale (see “Quarter Horses Adapt to a New Century,” EQUUS

495). At this early date the ranch did not breed Quarter Horses---no such breed existed at the time. Texas Billys and Missouri Rondos, the immediate ancestors of registered Quarter Horses, are the source of what we now regard as Quarter Horse physical type but they were bred and used for short-track racing. Kleberg was not interested in racing and, in fact, refused gifts of Thoroughbred bloodstock on more than one occasion. But the sorrel colt brought over by Clegg for inspection on a summer day in 1915 represented an intermediate: His mother was Thoroughbred and his sire, Hickory Bill, was a Billy with considerable Thoroughbred ancestry. Mixtures of this kind interested Kleberg because they made good ranch horses.

Considered superior because of a combination of sweet temperament, soundness, stamina, conformation and aptitude for cattle work, Old Sorrel became the King Ranch foundation stallion almost in hindsight. After Kleberg purchased him and his dam for $125, the colt was allowed to grow up in a King Ranch pasture. He was broke to ride and eventually given a few mares to cover. He was also tried out personally by the Kleberg family. Bob Kleberg averred that Old Sorrel was the best cowhorse he had ever ridden, while J.K. Northway, DVM, longtime staff veterinarian at the King Ranch reported, “I saw [Dick] Kleberg and George Clegg rope off him and ride him all morning and then race him in the afternoon. You could rope, cut, or do any other ranch work on him and he was not just adequate---he was superior in all his actions.” Old Sorrel was also the choice of the ranch’s most trusted employees---excellent riders and expert stock-handlers, vaqueros of Mexican heritage who called themselves Kineños--- but by the time Bob Kleberg began his breeding program in 1921, the colt that the Kineños had always called “El Alazán” had become “El Alazán Viejo”---The Old Sorrel.

SCIENTIFIC HORSE BREEDING

At the age of 19, Bob Kleberg enrolled as a biology and agriculture major at the University of Wisconsin. Due to his father’s failing health, however, he returned to the ranch in 1916 after only a little more than a year at University---but not before being exposed to the latest ideas in animal breeding then being published by pioneering geneticist and population biologist Sewall Wright of the University of Chicago. This area of science was controversial, because most researchers at the time did not believe that the experiments of Gregor Mendel applied to animals (Mendel’s experiments, which showed that offspring inherit their characteristics not by blending or “averaging” parental characteristics but by the recombination of discrete particles called genes, were carried out on plants). Most scientists at the beginning of the 20th century also thought that Mendel’s “particulate inheritance” had nothing to do with Charles Darwin’s theory of evolution; the so-called “modern synthesis” of these ideas into a single mathematical framework was not completed until the 1940s (and debate on some points continues to this day).

Sewall Wright was one of the first geneticists to develop and apply mathematical formulas to increase the efficiency of livestock breeding.

Sewall Wright was one of the first geneticists to develop and apply mathematical formulas for the purpose of increasing the efficiency of livestock breeding. Developed between 1905 and 1925, his formulas for calculating degree of relatedness of individuals whose names appear in pedigrees, and for calculating related aspects of population structure and dynamics, are by any measure daunting. Most require the development of actuarial tables---and computers that make this arduous task easier were not, of course, available at the time, so that in proverbial Einsteinian fashion a Sewall Wright lecture would typically cover several chalkboards with mathematical scrawlings. One year is not enough to master this discipline but while he was at University Kleberg saw enough to get

the essential outline and to appreciate one central fact---that for ultimate success the breeder must not just “breed the best to the best to get the best,” but employ a systematic method for matching mares to stallions, generation after generation, over the long term.

The breeding system that Kleberg utilized is today called “purging selection.” It involves alternation between tight inbreeding---sire/ daughter, uncle/niece, half-siblings or first cousins---and outcrossing to unrelated but conformationally and behaviorally complementary horses. This method is highly efficient at exposing recessive alleles which are deleterious (and also dominant alleles which may also be deleterious). There is no room in this article for a complete review of genetics, but the accompanying glossary and sidebars may be of help if you feel a little rusty on genetic concepts and terminology.

SOUND BREEDING PRACTICES AND PROCEDURE

By the early 1940s, Kleberg’s King Ranch horse breeding program had moved into the third and fourth generation downstream from Old Sorrel. Kleberg’s “experiment” met theoretical ideals in terms of numbers, for it incorporated 10 stallions and approximately 400 mares in its first 10 years, and by 1970 the total broodmare band had grown to some 2,000 head. When Bob Kleberg began the program, all of the stallions (partbreds later registered as Quarter Horses) as well as 10 percent of the mares were descendants of Old Sorrel. Today, all horses on the King Ranch are descendants of Old Sorrel but the

blood of many “outside”---less related or unrelated---stallions and mares has also been incorporated.

The Klebergs were acutely aware that excessive inbreeding is dangerous. Breed historian Robert Denhardt reported in 1970, “[Data from the

King Ranch] indicate a fair amount of inbreeding. Yet Bob Kleberg did not inbreed Quarter Horses as much as he did the Santa Gertrudis cattle. The uncertain [but crucially important] factors represented by temperament, action and endurance made all-out inbreeding in horses too dangerous.

His plan was to maintain a relationship to Old Sorrel but to skip a generation by mating uncles to nieces, not fathers to daughters. Outcrosses were made with some regularity…in order to halt the spread of any deleterious tendencies in the breeding bands.”

Concerned because the AQHA was embroiled in debate over whether to close its registry, in 1946 Kleberg decided to use the prestigious and authoritative Journal of Heredity to report his results to the world. Professor A. O. Rhoad, Chief of Animal Husbandry at the Inter-American Institute of Agricultural Sciences in Costa Rica, assisted Kleberg in preparing the paper, and his primary contribution was to perform Sewall Wright-style “path analyses” of pedigrees supplied by Kleberg. However, while Kleberg presents a series of diagrams illustrating relationships between King Ranch horses, the analyses themselves were never published. As a result, the paper was almost entirely written by Kleberg, whose main purpose was to outline his breeding scheme and highlight the King Ranch stallions involved. A system of purging selection can be summarized in eight phases:

• Step 1. Select a foundation sire. Selection of foundation sire is best done by testing that probes all important areas, including conformation, hardiness, stamina, soundness, temperament, trainability and willingness. Testing of Old Sorrel (and all the horses in the King Ranch program) was performed by Kineños and both Klebergs in the context of ranch work that they would have done every day in any case, including breaking-in, basic training, herding, cutting, penning, sorting, branding, roping and trekking over moderately long distances to check fence or survey calving cows (see “Meaningful Testing,” page 106). Days were long and the work was hard, and the Klebergs were especially interested in finding horses that would not go lame, tire out or quit.

• Step 2. Identify a remuda of mares to breed to the foundation stallion. In order to guarantee the largest possible starting gene pool,

these females should be unrelated to the sire and to each other. And, Kleberg avers, “Always the plan was to employ only such matings as would complement as to disposition, conformation and the great variety of characters which make up any living creature.”

Initially at the King Ranch, these were the Dr. Rose, Lucky Mose, and Lazarus mares (see “The Rise of An Empire,” EQUUS 499), believed to be pure or near-pure Thoroughbreds. Also included in the foundation manada were other Thoroughbred mares with known sires such as Chicaro and Martin’s Best. Still others were Billys sired by Little Joe, Harmon Baker, Cotton-Eyed Joe or Hickory Bill; some were Cayuses of part-Mustang heritage; a few were Morgans, and one was an Arabian.

Many studies of both natural and domestic herds have shown that the larger the foundation herd, the better because a large and diverse gene pool increases the chance of creating fortuitous combinations or “good nicks,” while avoiding the potentially disastrous effects of genetic drift

(see “Genetic Terms Explained,” page 90 and “Genetic Principles,” page

92). Contrary to the belief of many breeders, periodic outcrossing is vitally necessary because genetic recombination is an important source of novel combinations and heterozygous individuals are more resilient physically, physiologically, and psychologically.

Another point to highlight is sheer numbers: No domestic horse breed founded on fewer than 400 broodmares has ever persisted beyond a few generations. The King Ranch is one of only a few examples which could be cited worldwide of a single breeding operation with enough economic clout to purchase, raise, manage and maintain the number of broodmares necessary to found a viable breed. While anyone can, at any time, designate a stallion as a “foundation sire,” and can establish the legal entity---the registry---that keeps track of pedigrees and issues “papers,” this does not mean that the strain will breed true. One reason I have prepared this report is to show why it is important for horse buyers to beware of “papers that are mere papers.”

• Step 3. Cull the first-generation foal crop. Because they are all outcrosses, foals resulting from the mating of sire with the foundation herd of mares will show great variety in all characteristics. The most important task of the breeder at this point is culling, which means the permanent elimination of inferior produce from the breeding program, either by euthanatizing foals or by spaying