Horse Genetics Continuedfrompage42......
“I learned a lot from studying the King Ranch and their early inbreeding and line breeding program to Old Sorrel,” Larry says.
“As their herd progressed, Old Sorrel
wasn’t close up (in the pedigrees). He might have been three or four generations back, but their horses still had a percent of blood of around 50 percent for Old Sorrel, because of the multiple crosses to him. “But they were very strict about
ensuring that only the best individuals were carried on to the next generation,” he says.
“That’s something that people don’t
understand today. Someone will call and ask me, ‘I have a great stallion, and I want to breed one of his daughters back to him. What am I going to get?’ Well, you can get both the good and the bad.” “You have to be prepared, because
there is a downside to inbreeding,” Larry says. “It’s going to be unsuccessful more than it’s going to be successful. “King Ranch carried through
inbreeding and line breeding to Old Sorrel and brought about great horses,” he says. “But they culled and got rid of the ones that didn’t work. That’s important to under- stand.
“If you’re going to have an inbreed-
ing program, you need to have high num- bers to make it work. King Ranch had those numbers: lots of individuals, lots of horses. “It was the same with Hank
Wiescamp. Hank had a lot of horses, and that allowed him to do what he wanted to do with his line breeding program. “That’s largely why inbreeding is
difficult for us to do today: We don’t typi- cally have the ability to have hundreds of horses and maintain them and get rid of the individuals that don’t work.”
The Ultimate Goal “Inbreeding a line of horses is only
the path you take to get to where you can outcross that line,” Larry says. In his opinion, the real “magic” to a
successful breeding program is not reach- ing a high percent of blood for a particular great ancestor. It’s in knowing when to introduce the right amount of genetic diversity to a family of horses through an outcross. “You don’t have true genetic
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improvement until you introduce hybrid vigor,” he says. “Introducing that outcross blood at strategic times to give you that hybrid vigor boost, that’s the key to it all. That’s the process that produces the better individuals. “Hank Wiescamp was a genius at introducing outside blood at key times,”
Larry says. “Bar Mount was one example. He also loved the mare Lena’s Bar (TB), the mother of Easy Jet, and he ended up using Double Dancer as an outcross because of her. “King Ranch is another good exam-
ple,” he says. “They came to the point in their program where they had a lot of great line bred mares to Old Sorrel, but there was no hybrid vigor when they crossed them back on their own stallions. They hit a plateau and leveled out. “That’s when Mr San Peppy came in.
He carried the King Ranch bloodlines, so he tied back into the mares, but he also had other outcross blood that put genetic diver- sity back into the King Ranch horses. “Line breeding reaches a point where
if the horses are going to continue to improve, you’ve got to outcross.”
Just One Tool “The most important thing is to never use percent of blood without looking at the individual,” Larry says. “There are some people that go out and breed by pedigree alone, and that’s a mistake. “Using percent of blood and pedi-
grees is only a part of what we do as breed- ers,” he says.
“Conformation is so important, and
performance and disposition. “We have to remember that pedigree
is only one of our selection tools.”
Correct ‘Crosses’ Cross-breed: When you cross two
different breeds, as in breeding a Quarter Horse mare to a Thoroughbred stallion or vice versa. Outcross: Crossing two unrelated
individuals within the same breed. Line cross: A type of outcross where you cross two specific families of horses. Example: If you took a mare line bred to King and bred her to a stallion line bred to Wimpy.
Approximate Percent Blood Influence per Generation In pedigrees, the first generation is an indi- vidual’s parents. If the ancestor appears in the ____ genera- tion, then it contributes ____ blood to an individual first generation = 50.00 percent second generation = 25.00 percent third generation = 12.50 percent fourth generation = 6.25 percent fifth generation = 3.125 percent sixth generation = 1.5625 percent seventh generation = 0.78125 percent eighth generation = 0.390625 percent
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