Hybrid Vigor and the Three Bars Factor by Larry Thornton



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Hybrid Vigor and the Three Bars Factor by Larry Thornton

(abridged)



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Have you ever heard people say that the world is getting smaller? Even for horsemen, given the global nature of the horse business, this statement is very true. We no longer buy, sell and breed horses just in our own backyard. We buy, sell, and breed horses on a worldwide basis. We export and import horses. We send breeding stallions and frozen semen to other countries halfway around the world. It is truly a shrinking planet.

But this statement may be true in another sense. Not only is the world getting smaller, but also the biodiversity of our planet is getting smaller. We are seeing a shrinking animal and plant population and thus we are losing the genetic material for those lots species. This is becoming a growing concern for the well being of our planet. Thus, we are seeing our world get smaller in the sense as well.

A recent report on “60 minutes” on CBS profiled a plan to save plant varieties by storing seed varieties. This story was about the Svalbard Global Seed Vault located on an island just before you get to North Pole. It is an island off the coast of the northern most edge of Norway. The facility is being used to store thousand of plant varieties that represent everything from wheat to sunflowers. The facility will be home to 1.5 billion different varieties of seeds. This is an effort to save many of the plant varieties that would be lost in the future. Scientists are telling us that we could very well need the genetic diversity these seeds give us to survive on our planet.
The one example that stuck out in my mind was with apples. In the 1800’s, in this country, we had 7,100 varieties of apples. Today, we have only about 300 varieties of apples left. This means that 6800 varieties of apples have become extinct or been lost.
When we start surveying our horse breeds, we see that we have a situation that is going on that is making our breeding world “smaller” when it comes to genetic diversity. We are inbreeding and linebreeding to breed our horses and this is causing our genetic base to shrink. Inbreeding and linebreeding do that because they

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concentrate the genes of the common ancestor or ancestors and this gives us less variety of genes. So, we

are losing our genetic diversity and by losing



genetic diversity, we eventually lose the ability to improve our horses.
The famous King Ranch of Texas is a prime example. The King Ranch is noted for its outstanding line of Quarter Horses that became known as the Old Sorrel Line. They carried on for many years developing some key families within the Old Sorrel Family by linebreeding to this great stallion. They used a good base of Old Sorrel mares and sons of Old Sorrel like Solis, Little Richard, Cardenal, Macanudo, Babe Grande, Tino and Hired Hand to build the Old Sorrel Line of Quarter Horses.
The King Ranch breeding program found that it had reached a plateau in that they were not improving their horses. They had good horses but they still weren’t improving on what they had. So, they started a program to bring in some outcross blood. They used stallions like Otoe, Jackstaw Jr., Blondy’s Dude and Two Eyed Jack as potential outcross sires. They eventually settled on Mr San Peppy and it is through this great stallion that they achieved the outcross needed to instill “hybrid vigor” back into their breeding program.

Hybrid vigor is defined as “the phenomenon that occurs when animals from two different breeds or two unrelated lines within a breed are mated producing offspring with increased vigor over that of the parents.” We often hear the breeder tell the buyer’ this stallion and mare out-produce themselves. Then we can be pretty sure hybrid vigor is a factor. We get this hybrid vigor, also called “heterosis,” by outcrossing (within a breed) or crossbreeding (breed on breed) our horses.

The genetic definition of outcrossing is “the mating of two unrelated individuals from the same breed.” This is the mating of individuals within a breed that show no close-up relatives in the pedigree. We have to remember that many breeds are formed through inbreeding to one or a few common ancestors and that may mean we may eventually get to some common ancestors in the

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pedigree. The King Ranch found its outcross blood in Mr San Peppy, even though he was a Quarter Horse and even though he did carry some Old Sorrel Blood. When we cross two individuals from different breeds, we are crossbreeding. In the Quarter Horse, crossbreeding is commonly achieved by mating with Thoroughbreds.

The role of Three Bars, a Thoroughbred, as a sire of Quarter Horses has been a well documented story that gives us a real life example of how hybrid vigor had a profound effect on the Quarter Horse. Three Bars brought his good looks and speed into the Quarter Horse to become a legendary sire. He was a good racehorse as a stakes winner and a track record holder. He retired to stud duty in the Southwest to become a leading sire of not only racehorses, but also halter horses and performance horses.

The power of Three Bars is still with us today with descendants like Doc Bar, Dash For Cash, Zippo Pat Bars and Impressive as key sires in the industry. All these stallions trace in their sire lines to Three Bars. Doc Bar was sired by Lightning Bar by Three Bars and Dash For Cash was sired by Rocket Wrangler by Rocket Bar by Three Bars. Zippo Pat Bars in his sire line, he was linebred to this great stallion. These stallions have dominated their respective events (cutting, racing, western pleasure and halter) like no other stallions since Three Bars was alive and well.
When we trace the influence of Three Bars back to the beginning of his career as a sire we find that “hybrid vigor” was an interesting topic for early breeders. Bud Warren, the owner of the famed Leo, may have summed it up best. Here is what he had to say about Three Bars and hybrid vigor, “Hybrid Vigor was a favorite subject in our time. Everybody talked about it and nobody really knew much about it, except what some of the beef breeds and what some of the colleges had put out on the value of hybrid vigor in crossbreeding cattle. It just seemed to follow through proving itself every day.”

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He added, “The biggest thing we were getting out of the Thoroughbred was an entirely different bloodline that was crossed on the old foundation Quarter Horses;

Horses that were used to plow the field or pull the buggy to town.”


He continued, “Well, there isn’t any question about it; the first time I ever saw Three Bars was at Albuquerque. We’d heard about him. He had a few colts out. Well, I was a straight Quarter Horse man 100%. But when I saw this horse and he struck me as such a beautiful conformation stallion; as good a lookin’ horse as I had ever seen. I saw him run that day and he lost a rider. He couldn’t run a distance but he had blinding speed and he was a beautiful horse and he crossed with darn near any chunky Quarter Horse that we thought were race horses.”



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