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Quarter Horse Bloodlines

As certain populations of the American Quarter Horse lose genetic diversity, Quarter Horse breeders are on the hunt for outcrosses.

By Christine Hamilton
The American Quarter Horse Journal
November 25, 2013

"Looking to Outcross" article in December 2013 American Quarter Horse Journal

In “Looking to Outcross,” respected American Quarter Horse breeders F.E. “Butch” Wise, Greg Whalen, Joe Jeane and Nancy Sue Ryan share their thoughts on the need to outcross in the American Quarter Horse breeding industry. (Journal illustration)

American Quarter Horse breeders tend to think of an “outcross” in two ways:

    1. As what is more correctly termed crossbreeding – breeding two different breeds together, such as a Thoroughbred bred to a Quarter Horse; and
    2. As crossing two largely unrelated bloodlines of horses within the same breed, such as when the King Ranch introduced Mr San Peppy to its Old Sorrel line-bred herd. Even though Mr San Peppy carried one distant cross to Old Sorrel, the rest was unrelated, outcross blood and brought genetic diversity into the bloodline.

Either way you look at it, pockets in the modern American Quarter Horse breed need outcrossing, according to recent American Quarter Horse genetic research supported by the American Quarter Horse Foundation.

The study, conducted by a research team from the University of Minnesota, will soon publish its findings in an upcoming issue of the Journal of Heredity under the title “The American Quarter Horse: Population structure and relationship to the Thoroughbred.” The 2012-13 study was partially funded by the American Quarter Horse Foundation.

“We wanted to delve into understanding the true genetic differences between the Quarter Horse subpopulations, and see what kind of impact the practice of breeding for specialized performance has had on the breed,” explained research team member Dr. Molly McCue, a veterinarian and geneticist at the University of Minnesota College of Veterinary Medicine and a lifelong Quarter Horse enthusiast who grew up with ranch-bred horses.

The research team analyzed six Quarter Horse performance subgroups they identified as halter, western pleasure, reining, working cow, cutting and racing.  

“Within these subpopulations, we’re probably doing a lot of things to limit genetic diversity, and that’s probably especially true over the last 25 to 30 years,” Dr. McCue told The American Quarter Horse Journal. “There is narrowing of the gene pool and evidence of increased inbreeding over time.”

One could say that’s stating the obvious: what we already knew about the American Quarter Horse breed as a whole and the bloodlines of its specialized performers.

However, what we didn’t know was exactly how inbred those population subgroups already are, and the implications of what could happen if current breeding practices and trends don’t change.

“Changing Genetic Landscape” in the December issue of The American Quarter Horse Journal dives into the implications of overly popular American Quarter Horse bloodlines and the findings from the University of Minnesota’s genetic research of the American Quarter Horse.

Another December Journal story, “Looking to Outcross,” features insight from respect American Quarter Horse breeders F.E. “Butch” Wise, Greg Whalen, Joe Jeane and Nancy Sue Ryan. The longtime Quarter Horse breeders share their thoughts on the need to outcross in the American Quarter Horse breeding industry.

Traditionally, the December Journal is the magazine’s annual stallion issue. This year, the December Journal features a multitude of stories for Quarter Horse breeders on both sides of the equation: stallion owners and mare owners.  

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