Horse Breeding

A Century of Breeding Horses

September 13, 2013

Follow the techniques of King Ranch to set yourself up for horse-breeding success.

Old Sorrel is one of the many influential Quarter Horse sires that came from the King Ranch breeding program. Photo courtesy of the American Quarter Horse Hall of Fame and Museum.

Old Sorrel is one of the many influential Quarter Horse sires that came from the King Ranch breeding program. Photo courtesy of the American Quarter Horse Hall of Fame & Museum.

From The American Quarter Horse Journal

Nearly 100 years ago, the King Ranch in South Texas began an ambitious breeding program to develop a superior line of ranch horses. The program involved line breeding to concentrate genes for desired traits from outstanding animals.

However, it was line breeding accompanied with meticulous selection and ruthless culling that was the master stroke of the program.

How It Began

In 1915, Old Sorrel was foaled, the nameless horse destined to become the foundation sire of the King Ranch line of American Quarter Horses. At the time, his paternal grandsire, Peter McCue, and his sire, Hickory Bill, were the most influential sires in the line of American Quarter Horses going back to the Colonial period.

Early accounts attest that Old Sorrel was a truly remarkable horse with respect to beauty, disposition, intelligence, cow sense, agility, stamina and speed, so the ranch decided to design a line breeding program to highlight this amazing ranch horse.

For example, Solis, a son of Old Sorrel, was mated to daughters of Old Sorrel. Wimpy P-1, who had Old Sorrel on the top and bottom sides of his pedigree, was likewise often mated to daughters of Old Sorrel.

Many of Old Sorrel’s offspring and grand offspring were as exceptional as he was. Direct descendants of Old sorrel include sires Babe Grande, Macanudo, Peppy, Solis and Wimpy P-1.

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A Texas A&M University-Kingsville study aimed to determine historic ancestry and to find genetic relationships and inbreeding for the current King Ranch breeding population of Quarter Horses (based on extensive pedigree information) so the results could be considered to maintain the integrity of the King Ranch line of Quarter Horses for future generations.

Early Influences

The Thoroughbred influence was reported in early breedings of the Quarter Horse to contribute genes for body size and speed that the early Quarter Horse lacked. As many as 97 percent of the horse pedigrees analyzed for the King Ranch traced back to at least one Thoroughbred ancestor.

Old Sorrel was at least 56 percent Thoroughbred, and King Ranch breeders weren’t afraid to keep the Thoroughbred influence in the early breeding program.

On the King Ranch, horses with Thoroughbred blood have been preferred roping horses because of their larger body size and speed, helpful for roping larger calves, cows or bulls on the 825,000-acre ranch. The Thoroughbred influence for King Ranch Quarter Horses born between 1941 and 1942 was determined to be 65.8 percent Thoroughbred and 34 percent registered Quarter Horse.

A 1983 study (MacCluer et al.) examined pedigrees on Standardbreds and stated that genes from superior animals can be maintained by line breeding. If used properly, line breeding ensures that desired traits of common ancestors will not be lost through time.

Line breeding is a mild form of inbreeding. Geneticists tend to call inbred those animals resulting from parent-offspring matings or full brother-full sister matings. Opinions vary, but when inbreeding values get above 15 percent, that is leaving line breeding and approaching inbreeding.

Through planning, culling and careful use of line breeding – and minimizing inbreeding – the King Ranch had outstanding results.

Genetic Relationships

The study was based on eight-generation pedigrees of 16 stallions and 74 mares that were used for breeding on the King Ranch in 2007, allowing the researcher to trace breeding lines to Hickory Bill and examine more than 100 years of breeding practices.

The study found the genetic relationships of King Ranch stallions and mares to the foundation sire Old Sorrel, and also to American Quarter Horse Hall of Fame stallions Mr San Peppy and his son, Peppy San Badger. The study also looked at the relationships of Doc Bar and Three Bars (TB) to the King Ranch breeding bands.

“The King Ranch can use this information to retain relationships to our most-famous cow-minded lines of horses,” says Scott Moore, an area manager on the King Ranch.

The folks at the King Ranch were primarily interested in learning the average inbreeding values for the horses, because when inbreeding gets to certain levels (around 25 percent), it can for example, decrease fertility in offspring and lead to increased abortion rates in mares. Scott thinks the information from the study “will enable us to continue breeding our genetics for years to come without attaining high levels of inbreeding.”

Scott and the King Ranch were surprised to see that the average inbreeding for the ranch’s horses was lower than expected, ranking an average of 1.61 percent for the stallions and 3.49 percent for the mares. It is important to note that these inbreeding values are based solely on ancestry by Old Sorrel or Hickory Bill within the King Ranch line, and are not referring to total inbreeding found across all common ancestry lines in the herd – different lines bring in different genetics. In general, these results suggest only a mild degree of inbreeding, implying low genetic relationships between parents.

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Genetic relationships can be used to help maintain genetics to horses that a breeding program is known for. For the King Ranch, these lines primarily trace back to Peppy San Badger, Mr San Peppy and Old Sorrel.

King Ranch can use information on genetic relationships among stallions to plan future matings.

The study showed, for example, that Taquito Sugar, a King Ranch stallion, possesses the highest genetic relationship to Old Sorrel (14.8 percent) among the ranch’s stallions and is related to Mr San Peppy and Peppy San Badger by 14.2 and 25 percent, respectively. Despite these high relationships, Taquito Sugar has an inbreeding value of only 1.9 percent.

The King Ranch can use Taquito Sugar as a stallion to almost any mare on the ranch because although he does possess some relationship to Mr San Peppy and Peppy San Badger, he will not create offspring with high inbreeding. For instance, if a breeder wanted to breed Taquito Sugar to Peppys Sweet Sister (see hypothetical pedigree) the foal would have low inbreeding value but maintain a high genetic relationship.

In contrast to stallions, average genetic relationships of mares were consistently higher to Old Sorrel, Mr San Peppy and Peppy San Badger. Most of the mares were born on King Ranch and were selected first for conformation, then ability under the saddle and third on pedigree.

Stallions tended to be chosen for pedigree more than performance records and to a lesser extent on the basis of their extended pedigree.

The relationships and genetics in King Ranch horses can primarily be found in mares and to a smaller extend in stallions.

Using King Ranch Techniques

How can horse breeders ensure the use of a good breeding program? There are many different ways to maintain a well-planned line breeding program, which makes it possible to achieve low inbreeding levels, while maintaining high genetic relationships to outstanding ancestors.

To demonstrate one way, the inbreeding level is low in Peppys Sweet Sister, despite being double-bred to Mr San Peppy, because the influence of Mr San Peppy has been allowed to decrease. Breeders can practice this same breeding by looking at a pedigree and seeing where common ancestors occur, like what was done with Old Sorrel and his offspring in early matings of the King Ranch line.

Choosing the proper sire and dam mating is also important when trying to minimize inbreeding in herds. For example, if a mare was chosen with an inbreeding value of 16 percent and was mated to Taquito Sugar (with no close relationship to each other), the inbreeding of the foal would be low, not because of the inbreeding levels of the parents, but because the parents were not closely related. Breeders should be aware of the inbreeding levels of both potential parents to ensure that proper inbreeding levels are maintained.

A second way would be allowing outside sources to bring in new genetics into the herd. Outbreeding can also produce these low inbreeding coefficients through the periodic purchase and/or lease of outside stallions and mares from somewhat different genetic lines. The King Ranch has been able to do this and create an open population that has infused new genes for desired traits (i.e., show earnings for cutting ability) into their bloodlines.

Any breeder can be successful in creating a breeding program. The main focus should be on maintaining relationships, or bloodlines, that the breeder is known for and keeping inbreeding low. The King Ranch has been able to do this for the past 100 years. With the information from the Kingsville study, the King Ranch can continue “to maintain historic, foundation, excellent cow-sense pedigrees while reaching toward the future” for many years to come.

AQHA Member Benefits

Did you know that AQHA members get FREE admission to the American Quarter Horse Hall of Fame & Museum in Amarillo? Walk among legends like Old Sorrel, enjoy artwork and memorabilia from our Hall of Fame inductees and purchase merchandise from our store.  This is just one of the many benefits of being an AQHA member. Purchase your membership today and reap the fantastic rewards!