Outcross Possibilities: Breeding for Speed

Outcross Possibilities: Breeding for Speed

Knowing what horses to cross takes special knowledge. Here we examine conformation, hybrid vigor and muscle fiber types.

A palomino mare named Bets Topaz photographed in conformation profile is held by a man wearing western clothes, including a red Four Sixes shirt. PHOTO: Andrea Caudill

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From the Quarter Racing Journal

Equine  veterinarian,  breeder and former president of the Florida Quarter Horse Racing Association Dr. Steve Fisch knows the importance of the outcross in his breeding practices. After scanning and dissecting pedigrees for possible breeding, Steve will go see the horses in person.

“We cull 90-95 percent of possible breedings based on conformation alone,” Dr. Fisch says. “We are looking down the road for soundness – that mare or stallion (in our program) is going to be producing generations of babies for the track or in the arena, and they have to be able to perform for the long haul.”

Dr. Fisch stands several stallions, and while his main focus is breeding for Quarter Horse racing, his secondary goal is to have good barrel racing horses that come from his stallions.

As a veterinarian, Dr. Fisch knows more about biology than most and goes as far as talking about slow- and fast-twitch muscles, and how those muscles affect the running speed of the offspring. Knowing that outcrosses are essential for the health and well-being of a line of horses is one thing; knowing which horses to cross is something else.

Crossing for Hybrid Vigor

“Your first outcross is your best hybrid-vigor foal and is going to be a superior performer in most cases, but they don’t breed as true since they are crossbred,” Dr. Fisch says. “That is the general rule, but there will be a small percentage that will pass on their genetic makeup, so that a percentage of that second and third generation will have and pass on their performance ability. That is when you get a superior breeding animal.”

It can take years and years of dedicated breeding to even produce one superior animal as a broodmare or stallion, and it can take four to 12 years to see how their get produce and whether they are consistent, Dr. Fisch says. Not only that, he mentioned, but if you don’t have a good cross, you can very well end up back at the drawing board.

Thoroughbred horses, for one, have a different type of muscle fiber than a foundation-bred Quarter Horse.

Type 1 slow-twitch fiber horses: work off of aerobic metabolism. That’s how they produce their energy. They are a highly oxidative type of horse.

Type 2 fast-twitch fiber horses: are further divided into fast twitch types 2A and 2B, and are low-oxidative fibers.

If you are breeding for speed, but want that hybrid vigor, as well, then you could choose your Thoroughbred based on how well he did in sprint races and how far ahead he ran. You’d want a fast, early speed Thoroughbred to cross on your Quarter Horse so that you end up with early speed and hybrid vigor from outcrossing.

Breeding for Speed

Clearly, this is a simplistic explanation of a complicated process, and Dr. Fisch says it’s even possible that while trying to produce a speedier Quarter Horse, you could end up slowing him down through the breeding process. So it’s imperative to know the full ins and outs of breeding before producing more horses.

“There is some science to it,” Dr. Fisch says. “When you are looking to produce the whole package, start with a pedigree of fast horses, not just one generation that produced a superstar. What you want is a long line of generation after generation producing speed horses. And if you are looking to have the soundness in there, you have to look for great conformation, bone makeup, strength, size of their feet – the whole body phenotype that can not only produce speed, but a horse in which the body stays together.”