Genetic Concentration: Too Much of a Good Thing?

"For years we've taught the industry about reproduction, but we haven't taught about breeding," said Gary Carpenter, executive director of the American Quarter Horse Foundation during a roundtable at the International Equine Summit, held in Lexington, Ky., April 28-29. Fellow horsemen Dan Kenny, owner of Dan Kenny Bloodstock in Lexington, Ky., and Richard Wilcke, director of the Equine Industry Program at the University of Louisville, participated in a discussion with Carpenter on issues surrounding genetic concentration, an overreliance on specific bloodlines in an attempt to reproduce known traits.

Carpenter cited all-around horses (horses that show halter and multiple performance events) in the Quarter Horse industry as an example of a type with ideal genetic concentration. All-around horses, Carpenter said, come from a broader gene pool, a quality that is diminishing in the performance and horse show world. In some cases, bloodlines get saturated with the same names. Quarter Horse breeders are battling the stigma of horses bred for "Western only" and "hunt seat only" events, and this limits their market.

"Specialization was a function of economics," said Wilcke. "It is good, economically, for the industry because it was easier to bring in people that wanted to win pleasure classes and win halter classes," when owners began breeding specifically for these uses.

In the performance horse industry, Carpenter stated that the rise in specialization comes from the saturation of bloodlines and the desire to accentuate certain traits--whether they are negative or positive--and diminish other traits.

"I don't have to tell you that once those traits, once those genes are gone, they're not coming back," Carpenter said. "What's really cumbersome about that is having those negative traits imbedded in those bloodlines, and it's really hard to get away from that."

For example, recent research has shed light on the incidence of polysaccharide storage myopathy (PSSM). A study published in early 2008 showed that one in 10 Quarter Horses were affected by the muscle disorder, and that the muscle disease is more prevalent in certain bloodlines. While this trait, which affects how the horse responds physiologically to sugars in its diet, doesn't have such a negative impact on horses in poor forage conditions, it can be devastating to a highly managed show animal. "Take those same horses and manage them the way we manage them today, and it's more or less a crisis," Carpenter said.

Transporting Genetic Code

Widespread use of artificial insemination with shipped semen has dramatically changed the face of Quarter Horse breeding, allowing genetic variation of the breed in regions of the country that might have once been limited to certain bloodlines because of geography. While Thoroughbred breeders do not utilize artificial insemination because of industry rules, the Quarter Horse industry has accepted it, along with embryo transfers. Today's technology makes it easy for breeders to continually breed to get what they already have.

"We've got plenty of tools, but we're not applying them as wisely as we should." -- Gary Carpenter, American Quarter Horse Foundation
Unfortunately, with the use of this technology, fewer people see their stallion or mare prospect in person. During the discussion, Carpenter showed a photo of a rusty pickup truck and stated that it was a piece of technology that was not being used enough. He cited mare owners posting on Internet forums asking for other people's opinions on what stud to breed to their mare, making mating decisions without ever seeing the stallion, and with the "advisors" never seeing their mare.

"We just need to go look," he said. "We've got plenty of tools, but we're not applying them as wisely as we should.

"In some cases we have a less-educated, less-experienced group of breeders using more powerful tools breeding horses with more identifiable faults, with less observation and less pedigree information, and are breeding mares one, two, or three at a time," Carpenter continued. "In this age of specialization, where breeders are breeding for a certain conformation type and a certain movement, they use the same pedigrees over and over again, risking the exposure to genetic disease. We open ourselves up to being criticized by animal rights activists.

"The danger can occur when we put (technology) in the hands of breeders who are either uninformed or insensitive to the potential repercussions."

About the Author

Megan Arszman

Megan Arszman received a Bachelor of Science In print journalism and equine science from Murray State University in Murray, Ky., and loves combining her love of horses, photography, and writing. In her “free time,” when she’s not busy working as a horse show secretary or riding her American Quarter Horses on her parents’ Indiana farm, she’s training and competing her Pembroke Welsh Corgi and Swedish Vallhund in dog agility and running.

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