Embryonic Development
Monday, October 12, 2009 - By Nicole Kraft, executive editor, Hoof Beats

An audible buzz went through the Fasig-Tipton auction ring the evening of Oct. 4, 2007, when hip number 162 strode into the ring.

There was virtually nothing to dislike about the bright bay colt with a star on his forehead. An impeccably bred son of hot freshman sire Cantab Hall and Miss Marita-dam of champion Passionate Glide and Hambletonian Oaks winner Marita's Victory-he was a near-perfect physical specimen, well-crafted in body, bright of eye and smart in expression. Bidding on the Brittany Farms-bred Mr Cantab started swiftly and ended at a sale-topping $350,000.

There were, however, those in the audience who gave barely a glance at the colt's pedigree in the catalog-and simply turned the page. When he went through the ring, they were looking at another consignment, getting a drink, talking with friends, or just watching quietly. For no matter how perfect he appeared on paper and in presence, Mr Cantab had one intangible chink in his armor that still proves a non-negotiable deal-breaker for some yearling buyers.

He was the product of embryo transfer.

The idea behind embryo transfer is simple: breed a mare to a stallion and, after she has grown her embryo for mere days, it is flushed from its natural mother and placed in the uterus of a surrogate mare. The alternate mother grows the embryo and births the foal that will, optimistically, become a future champion.

To some, embryo transfer is a revolutionary science that gives reproductive hope for those who had none. For others, however, it borders on Frankenstein-like manipulation with the end result never quite measuring up to nature. It is, however, here to stay, as breeders and buyers alike continue to debate the merits and myths surrounding the procedure.

"The perception among some in the marketplace is that those horses would not be equal to one born naturally," admitted Bob Brady of Kentuckiana Farms. "Not everyone holds that opinion. It's been our opinion that genetically, those foals can compete as any other naturally bred and carried foal can, but we know there are those out there who disagree."

 

 New Image Media Photo

Invitro is the richest embryo transfer foal, having earned $1,983,077 over a six-year career.

It was the late 19th century when the science of embryo transfer was launched-in rabbits, despite their well-known proclivity for reproduction. Horses jumped into the fray in the early 1970s when the first equine transfer was accomplished in Japan, according to Keith J. Betteridge's "A History of Farm Animal Embryo Transfer and Some Associated Techniques," published through the University of Guelph's Department of Biomedical Sciences.

The process expanded during the 1980s and has continued to grow into the 21st century; it is a common procedure in humans who suffer fertility issues.

With equine embryo transfer, a sterile solution flowed into the uterus and flushed back out, carries with it the microscopic embryo. Once isolated, the embryo is transferred into a recipient mare's uterus, and she carries it to foaling, before raising it as her own.


"There is a four- to five-day 'window' of time in which a recipient is capable of accepting the transferred embryo," said Dr. John Hurtgen of Nandi Farm. "Once the recipient mare is determined to be pregnant, she is managed and treated like any other pregnant mare."

The USTA approved the registration of ET foals effective with the crop of 1998, and since then 929 foals have been produced through the procedure. Of those, 416 were pacers and 513 were trotters. The numbers peaked in 2004 with 135 registrations, though only 80 were recorded in 2008.

All ET foals are marked with "*embryo transfer*" on their registration papers, and only one foal per donor mare- the first one born-may be registered each year.

An expert in equine theriogenology, Hurtgen is arguably the Standardbred breed's most respected embryo transfer expert-and one of its strongest advocates. He has a hard time understanding why anyone would be prejudiced toward ET foals. Hurtgen stressed that the blood and circulatory system of the developing embryo is its own, and does not come from the host mare. The genetics of the foal-be it an ET or conventional pregnancy-are established at fertilization and are not altered by the surrogate mare.

"Some breeders are concerned about the ET foal acquiring the habits and instincts of the recipient mare instead of those of its genetic mother," said Hurtgen. "I raise about 45 to 50 ET foals at my farm each year. The behavior of the ET foals is most like their genetic mothers. A donor mare that produces 'crazy' or hyperactive foals will continue to have foals of this behavior type, even if the surrogate mare is a draft horse. 

"I know of no research that suggests that the surrogate mare alters the foal's inherited characteristics. If the foal is genetically predisposed to offset knees, umbilical hernia, cryptorchidism, OCD, or speed, these conditions are not altered by the transfer process itself, or by the surrogate. It is crucial to remember that certain factors can modify those conditions, including nutrition of the mare during pregnancy, nutrition of the growing foal, trainer, training methods, racetrack surface, and the list goes on. 
 

USTA Photos

One of the Standardbred breed's most respected embryo transfer experts, Dr. John Hurtgen, is a strong advocate for embryo transfer.

"If the speed of horses wasn't influenced by so many factors beside genetics, we could all be very smart breeders and yearling buyers."

Hurtgen puts his money where his mouth is. From his band of 35 mares, 13 are ET donors. 

"Without ET, two or three foals would result from these 13 mares each year," he said. "With ET, they will produce 10 or 11 foals. Without ET, these mares would probably be culled."

Science and practicality aside, however, the prejudice against ET foals by some horsemen remains a real part of the buying and selling process. Trond Smedshammer, who won the Trotting Triple Crown with Windsong's Legacy and the Kentucky Futurity with Strong Yankee, was adamant in his position on ET foals: "I don't even look at them."

"There are a lot of things we don't know about ET, and in general I am against it," he said. "If I am against something, why support and buy them as a yearling?

"There have been a few good foals, but I don't know if we know enough about them to get a good reading on them in general, as compared to regular horses. It's easier for me to walk away and turn the page."

Smedshammer admitted examining Mr Cantab and found him to be "an impressive-looking yearling," but he never entertained the idea of buying the horse because he has ongoing concerns about the impact the birth mare has on the resulting foal.

"There are still a lot of other things that you don't know how they affect the foal," he said. "The upbringing, the immune system-there are too many unknowns."

A similar hesitance was expressed by Bob Glazer, owner of such champions as 2003 Horse of the Year No Pan Intended, Meadowlands Pace winner The Panderosa and divisional champion Mystical Maddy. His reasoning, however, is more economical.

Despite the fact Glazer utilized embryo transfer with Mystical Maddy, the limitations on ET foals make it so he would "not go out of my way to produce or buy" an embryo transfer.

"Initially when it came along, I thought the process was OK, and for mares that have had some problem pregnancies, it gives you an alternative to sitting out a year," he said. "But there was an incredible statistical run that was detailing a lack of success of the embryo transfer foals. And the New Jersey Sire Stakes made ET foals ineligible. In my mind, those are definitely factors."

Even those who have used it successfully, like Brittany Farms, admit it is not a breeding tool they use easily or quickly. The cost of the procedure and the existence of buyer hesitancy for ET foals mean Brittany will only transfer embryos for highest-caliber mares who suffer issues related to age or reproductive health.

"It doesn't make economic sense to do it with a $25,000 or $30,000 yearling," said farm manager Art Zubrod. "Some people are also prejudiced toward a surrogate mare raising the foal, and I don't disagree."

Zubrod admitted the on-track statistics for ET foals are "not great," a fact he attributes to the use of the procedure on mares who are either too young to prove themselves worthy of such an endeavor, or too old to throw consistent quality performers. His view is shared by Brady, who said Kentuckiana's ET efforts are focused primarily on mares of significant breeding or bloodline acumen that are "reproductively compromised."

Since enough buyers shy away from an ET to compromise its sale success, Brady said that Kentuckiana must feel the potential foal would be "pretty special" to make ET worth the effort.

"Perception, on the average one, is that people just don't want them," he said. "They sold significantly well last year, but that was an exception. You have to spend $6,000 or $7,000 just to get one, and that doesn't count the stud fee. With a filly it might be worth it to keep good bloodlines going, but you have to be producing an exceptional colt when you are starting with that kind of expense.

 
Embryo transfer is given a negative reputation by many buyers due to concerns regarding the horses' health and performance.
"If you have a mediocre 20-year-old mare, and you got a colt, and have $6,000 in cost right off the bat, and some buyers are not even going to look at it, you are already handicapping yourself as far as what you'll get for the yearling."

But if mare, stallion and surrogate combine to produce a winner, it can thrill any breeder.

"Mr Cantab was always bigger and stronger than any other yearling we had," he said. "Think of what he would have sold for if he had not been an ET. He was gorgeous. We sold an Intercontinental [ET] colt (Cantabcontinental by Cantab Hall), and he was the best-looking foal that mare's had since [1996 Horse of the Year] Continentalvictory. We were hoping to get $100,000 and he brought $120,000."

And Mr Cantab has thus far proved a worthy investment. Now 3, the Erv Miller trainee won six of his first nine lifetime starts and took his 1:53.3 mark this year at the Meadowlands. He finished fifth in his Hambletonian elimination but failed to make the final. Conversely, Cantabcontinental has won only once in his 12 lifetime starts, taking a 1:57.4 mark at 2 and earning just over $10,000.

Other ET foals, however, have enjoyed their share of success. Thirty-five ET foals have earned at least $100,000, led by two foals of 2001, millionaire-and aptly named-Invitro p,4,1:50s ($1,983,077), and the ill-fated divisional champion Forever Starlet 2,1:55.4 ($690,717).

Canadian conditioner James Dean, who gained fame with pint-sized champion Doonbeg, has been fortunate to train two of the best ET foals in $750,000-winner Domitian Hanover and Shake That Junk p,3,1:52.3h ($376,773). He says he has "no qualms" about buying or training a product of embryo transfer.

"With Shake That Junk, I didn't even know he was an embryo transfer," Dean said with a laugh. "It does not bother me one bit. I have no idea why it bothers other people."

Dean acknowledged, however, that others' ET bias likely helped him get a good bargain with both his pacers. Domitian Hanover cost just $30,000, and Shake That Junk was a $72,000 purchase. In fact, of the ET foals to win more than $100,000, only two-Duca p,1:51.2f ($337,550) and Western Mac p,1:50 ($189,112)-cost six figures, selling for $320,000 and $305,000, respectively. Nineteen top ET performers sold for less than $50,000, and nine sold for less than $20,000.

"It's never entered in my thoughts, but I can tell a lot of other people are thinking about it-and not bidding," he said. "Me, I don't know a whole lot about reproduction. I thought it was the egg or semen where traits come from."

Hurtgen said it is just such success that makes him so disappointed about the bias against ET yearlings, and he simply can't understand the reasoning behind it.

"Some owners and trainers will not inspect and evaluate ET yearlings; I'm not sure why," he said. "There is also a bias against chestnut horses. I have not seen this bias against chestnut Thoroughbred yearlings. Why Standardbreds? There doesn't seem to be a similar bias against ET foals in other disciplines such as polo, cutting, reining or dressage.

"It seems odd to me that, in the Standardbred industry, embryo transfer is viewed with a jaundiced eye. The technology of embryo transfer is a method of dealing with fertility problems in what the owner perceives as a genetically valuable mare. There may be many issues  facing the Standardbred breeding and racing industry, but the value of ET foals and their race performance shouldn't even be an issue."

***

Mommy Dearest

A surrogate mare can be of any breed, though many ET breeders have utilized draft mares for their even temperament and physical constitution. Those who do the procedure enough may keep their own band of surrogate mares, while others may rent a mare or use one supplied by a veterinary service. 

"We have our own band here, which has been moderately successful, and we use mares from Hagyard-Davidson-McGee, which put [its] own band together," said Art Zubrod of Brittany Farms.

Zubrod acknowledged some people do not like the idea of a surrogate raising the foal of a top mare, and he agreed he would like that champion to have the chance to impart her qualities on her foal. But that is not always the case-and hasn't been in history either.

"If you go back in the years before semen transport, 50 percent of foals in Kentucky got put on nurse mares when their dams went out to be bred," he said. "What's the difference? Then people didn't like to ship foals when they shipped mares to breed in New Jersey, Pennsylvania or New York, and you had no choice."
 
Many embryo transfer concerns revolve around whether foals are raised properly with a surrogate mare.

Brittany looks for surrogates who prove themselves maternal and social to give the foal the best and most natural nurturing opportunities, although Zubrod admitted such planning is a "crap shoot."

"If you have a good mare who mixes in, it's no problem," he said. "If you have a mare that some horses can't get along with, that can be a problem. We want mares that are good mothers and good at socializing. If they are not good at socializing, we won't keep them."

Bob Brady of Kentuckiana said he recognizes some horsemen question the impact a surrogate mare will have on the foal they raise, but he said a good mother is a good mother.

"If you have a good surrogate mother and the foal is raised properly, it's the same environmental factors as the other foal," he said. "They ought to have the same chance to compete. It all goes back to genetics. If the foal has the pedigree, if he or she is bred to compete, they have an equal opportunity. Some ET foals competed at the very top level."

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Babies making babies

Embryo transfer makes viable breeding a mare that previously could not carry her foal-for whatever reason. But breeders say cultivating embryos from a horse that is still racing-or even too young to start racing-is another, sometimes controversial, use of the procedure.

"We've watched other people flush a 2-year-old mare and then try and train and race her, but that is not the objective," said Bob Brady, whose Kentuckiana Farm was a catalyst pushing for passage of the embryo transfer rule. "We encouraged its passage based on the grounds of a mare not being reproductively capable."

Dr. John Hurtgen said the process of doing embryo transfer on a racing mare does not, per se, have a negative impact on the mare's race performance, but he said such circumstances make the procedure more difficult.

 
Performing embryo transfer on racing mares does not affect their performance but it does make the process more difficult.
"The negative aspect could come into play if the mare needs to be taken out of training, or if the training schedule is altered," he said. "Many training centers do not have reproductive specialists available to follow the mare's heat cycle closely enough to breed the mare at the optimum time and determine days of ovulation. Most training centers are also not set up to stimulate the mare to cycle early in February or March by using a lighting program that should begin in early December.

"It is difficult, logistically, to maximize the mare's training schedule and breeding program, but it can be done."

Hurtgen said embryo transfer has been attempted on such prominent racing mares as Windylane Hanover and Day For Night. Though the process didn't seem to have an impact on their racing performance, it also was not successful, despite multiple attempts. 

That did not, however, stop Hurtgen from giving it a shot.

"I have done ET on a young filly that I was racing," he said. "The filly [Radical Missy] needed to have OCD surgery. So, during her three-month recuperation, she was bred [to Windsong's Legacy], and the resulting embryo was transferred to a recipient."

That embryo resulted in the 2009 yearling colt Rebel Windsong. Radical Missy made just one fruitless 2008 start and has since been bred conventionally to Tom Ridge.

Though Brittany Farms shies away from breeding such young mares, Art Zubrod stressed there is no question embryo transfer, in all its forms, is here to stay.

"I understand-you pay $200,000 or $300,000 for a yearling filly, and you want as big and quick a return as possible," said Zubrod. "I don't have the science to say an embryo out of a 2-year-old is not as good as an embryo out of a 5-year-old. If it's a tool, it's a tool, and people are going to use it."

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