Makin’ Babies: The Influence of Breeding Technologies, Part III

by Kristin Berkery

go to part IV | part I | part II

The previous I and II installments of Makin’ Babies examined how artificial insemination, transported semen, and embryo transfer can influence breed trends.

Pieraz, the first horse to be cloned.

There’s one breeding technology that isn’t approved by registries in the U.S. but has been used in Quarter Horses, Arabians, and Warmblood breeds — cloning.

One of the first horses to be cloned was an Arabian, the accomplished endurance racing gelding, Pieraz. Because Pieraz can’t be used for breeding, he was cloned so his genes could be passed on to the next generation. Pieraz’s clone, called “Pieraz Cryozootech Stallion,” stands at stud in France. The stallion clone was registered by the Anglo European Studbook, an organization that registers performance horses for competition.

LD Pistal, the double National Champion Senior Stallion who was cloned. Photo by Kelly Campbell

In 2007 a colt who was a clone of the 2006 and 2008 U.S. National Champion Senior Arabian Stallion, LD Pistal, was born.

Horse clones are produced through somatic cell nuclear transfer (SCNT), a process that involves taking a tissue sample from a horse, extracting the DNA from it, and inserting the DNA into an egg cell that has had the nucleus removed. The egg is stimulated to start dividing into a blastocyst, or early embryo, and then implanted in a surrogate mare who carries it to term.

The donor eggs used in the cloning process are usually from ovaries harvested from slaughtered mares. The horses are not slaughtered specifically for their ovaries; the harvested ovaries are a by-product of processing the animals. Since horse slaughter has been banned in the U.S., cloning facilities must get their donor eggs from other countries. One cloning company, ViaGen, built a facility close to a Canadian slaughterhouse to lower the cost of obtaining donor eggs.

A diagram of SCNT cloning. Therapeutic cloning means the resulting somatic cell is used for regenerative medicine, i.e. growing tissue for burn victims. Diagram by Dr. Jürgen Groth. Click the image for a larger view.

The reason LD Pistal was cloned was because he is subfertile and his clone would replace him in the breeding barn. There is one major roadblock: The Arabian Horse Association doesn’t allow clones to be registered or used for breeding registered horses. After the foal was born, its owner, Jeff Sloan, requested to meet with the registration committee to discuss whether cloning might be permitted by the AHA in the near future. The meeting was not held however, as LD Pistal and his clone were sold as a package to a new owner, Felix Cantu. Sloan chose not to pursue the issue any further, leaving it to Cantu to advocate for clone registrations.

It’s popular to say that a clone is “genetically identical” to the “parent” that donated its DNA to the “child,” but this isn’t actually true in the case of SCNT. According to Wikipedia:

In SCNT, not all of the donor cell’s genetic information is transferred, as the donor cell’s mitochondria that contain their own mitochondrial DNA are left behind. The resulting hybrid cells retain those mitochondrial structures which originally belonged to the egg. As a consequence, clones such as Dolly [the sheep] that are born from SCNT are not perfect copies of the donor of the nucleus.

Mitochondrial DNA is only passed from mother to child, and since there’s not actually a “mother” contributing her DNA to the foal, that missing genetic information is being pulled from the egg that was used in the cloning process. According to studies done on sheep cloned through SCNT, no mitochrondrial DNA from the donor (the animal that was cloned) was present in the resulting cloned offspring. This means the offspring obtained through SCNT cannot be genetically identical to the animal that was cloned.

Dolly the sheep.

The first successfully cloned animal, Dolly the sheep, died at the age of seven after a respiratory infection. (Sheep life expectancy is about 10 to 12 years.) In a report published in Human Molecular Genetics, studies have shown human mitochondrial DNA that has mutated tends to give rise to respiratory defects and age-related disorders, suggesting that SCNT clones will not live as long or be as healthy as their donor “parent.” The subject is not completely understood by scientists, but these studies serve as a warning that when mitochrondrial DNA becomes mutated, the resulting cloned animal may have health issues.

Pieraz clone horse

Pieraz’s clone. Photo from The Horse Magazine.

Not only are SCNT clones not genetically identical to their donor “parent,” they’re also not physically identical. Just like identical twins, there are small traits like white markings that appear different on a clone, which is a result of various cells migrating during gestation.

Should registries allow cloned animals to be registered for breeding purposes? There’s one immediate argument against it: Clones obtained through SCNT are not genetically identical to the original animal. With stallion clones used for breeding, they don’t pass on their mitochondrial DNA because the mares they’re bred to contribute their own mitochondrial DNA, essentially cancelling out the “foreign” mitochondrial DNA that comes from the donor egg during the cloning process.

Compare the markings on show jumper ET (left) with his clone (right).

But mare clones will not “breed true” — since their mitochondrial DNA comes from the donor egg during cloning, mare clones will pass on “foreign” mitochondrial DNA to their foals. The only way around this issue is to use a donor egg in the cloning process that comes from the same mare being cloned, but that requires the donor mare to be alive and still producing eggs. This work-around would also add to the cost of the procedure since it’s more complicated to harvest viable donor eggs from a living horse.

The point of a registering authority is to keep accurate records of all horses’ pedigrees, but how can parentage be determined of a horse that wasn’t the product of conception and carries the genetic material of an unknown donor? A great emphasis is placed on “purity” in Arabians, and the issue of SCNT introduces more purity questions.

read more in part IV | part I | part II

(You may leave your comments on part IV.)

Makin’ Babies: The Influence of Breeding Technologies, Part IV

by Kristin Berkery

return to part III | part I | part II

There are other ethical concerns with using cloned animals for breeding purposes. Natural selection, in this case subfertility, would normally determine that LD Pistal’s genetic influence on the breed would be limited. Cloning might be warranted if he has physical traits or rare bloodlines that would be hard to find elsewhere, but that’s not the case with LD Pistal. His sire, Magnum Psyche, has sired more than 1,500 foals as of May 2011 and his dam, Halana, has produced five registered foals, three of which were sired by Padrons Psyche, his son Magnum Psyche, and another Padrons Psyche son, FS Ritz. Two of Halana’s foals were donated to the Salem Children’s Home in Flanagan, Illinois. (Thank you to Arlene Magid for researching Halana’s production record.)

On paper, LD Pistal doesn’t look particularly uncommon. LD Pistal’s pedigree is a popular “recipe” of Russian, Spanish, Polish, Egyptian, and American bloodlines. Conformationally, LD Pistal also resembles the majority of Arabian halter horses today.

In the case of showjumping Warmblood gelding ET, he was cloned so his athletic genes could continue into the next generation. But when he was a youngster, his light body type wasn’t desireable for the Hanoverian studbook in the 1980s and he was gelded. For the first time in history, we can geld good horses without the concern that their genes will be lost forever. But does that justify the possible complications of cloning?

Smart Little Lena clones

Smart Little Lena and his five clones. Image created by Nature Biotechnology

In 2005 five clones were created of Quarter Horse cutting champion Smart Little Lena, who was no longer breeding. There are still frozen straws of his semen available, but his syndicate owners wanted to stretch Smart Little Lena’s influence well into the future. This certainly raises questions about how much of an impact any one horse should have on a breed, especially when clones can be produced indefinitely in the future, and how much profit motives should drive the decision to clone.

The clones triggered ongoing conflicts in the Smart Little Lena syndicate, spawning lawsuits and a major shakeup in management. In the meantime, one of the clones died of cancer and two were found to be infertile, with one having undescended testicles. The four living clones were sold at auction in December 2010.

You may be thinking it won’t matter that Smart Little Lena’s clones will be available for breeding in the near future since the American Quarter Horse Association won’t register clones or the offspring of clones. However, horses that compete at National Cutting Horse Association shows are not required to be registered, only age-verified by a veterinarian, and the NCHA has said it will allow clones to compete. So expect to see clones in cutting competition.

Magnum Psyche, sire of LD Pistal. Photo by Luiz Rocco

As more clones are produced, there is the issue of ensuring cloned horses receive good care. Let’s say a stallion is found to be subfertile and his clone is used to sire his foals, but the original stallion’s fertility is restored (which can happen) — what about the clone? Is it automatically gelded? Should it continue to breed on behalf of its “parent”? What if a clone is found to be unsuitable for breeding? If it’s gelded and consequently devalued, will it be sold to an appropriate home where it will be cared for — or will it be dumped on the market, or worse, sold at a killer auction?

Texas A&M University reports that they have a 26% live foal rate per cloned embryo transferred, meaning there are many embryos that die in utero and a few foals that die after birth. While future technology may improve the success rate, is it ethical to be willing to lose that many foals in the pursuit of profits and extending a horse’s breeding influence? These clones are, after all, living, breathing animals with feelings and we live in a compassionate nation where many people try to buy products marked “Not tested on animals.”

Even more questions come to mind. Should a horse be cloned multiple times in order to increase its influence on a breed? Should a horse’s genes be available many years into the future, well past a horse’s natural lifetime, or past the time frozen semen is considered viable?

Since SCNT clones are not genetically identical to their “parent,” how would this affect DNA typing during the registration process? Perhaps most importantly, do financially-challenged horse breed registries have the manpower and the funds to investigate all these issues and then govern them? It’s quite a Pandora’s box.

Cloning is a hot topic in Quarter Horses – learn more about it at Quarter Horse News. The American Quarter Horse Journal published a very thorough article on the subject. Leave your opinions below.

return to part III | part I | part II

Makin’ Babies: The Influence of Breeding Technologies, Part II

by Kristin Berkery

part I | part II | part III | part IV

The first installment of Makin’ Babies examined how breeding technologies could improve the Thoroughbred breed and how artificial insemination (AI) and transported semen have affected the Arabian breed over the last 30+ years.

An Arabian mare and foal. Photo by B. Wahler

Another significant technology approved for Arabians is embryo transfer. With this procedure, a mare is bred (typically through AI) and the resulting embryo is removed from her uterus around day 7. Then it’s frozen for future use or implanted in the uterus of a surrogate mare who delivers and nurtures the foal. This frees the dam to be used in competition or bred again, and it can allow previously infertile mares to produce foals.

In 2002, the Arabian Horse Association registry removed the limit of one foal per dam, per year via embryo transfer. Currently, only the cost of the procedure limits how many times it’s done on a mare.

There’s one question that’s lingered since the early days of artificial insemination: Is it a good idea to use technology to get foals from mares who are subfertile? For mares who struggle to produce good quality eggs or carry a foal to term, AI and embryo transfer allows them another opportunity to contribute to the gene pool. But those mares may pass on their reproductive faults to their foals, which may make AI and embryo transfer necessary for their offspring to reproduce as well. Over the long term, we may find a growing number of horses that are unable to reproduce without costly human intervention — and if you put that into evolutionary terms, those horses would become extinct in nature.

But in the case of those older, valuable mares who are past their breeding prime, embryo transfer could mean preserving their influence longer than ever before.

Since dams are now able to produce multiple foals a year through embryo transfer, a mare has the opportunity to have a greater impact on bloodlines than in the past. Of course there is always the risk that those additional foals will flood the market, especially if the dam’s bloodlines are common or her quality is less desirable.

A horse in the Canterbury Farms seizure by the Humane Society in April 2011.

A horse from the Canterbury Farms seizure by the Humane Society in April 2011. 140 horses were rescued and the owner faced 35 counts of animal cruelty. The owner has continued to breed horses. From a Humane Society video.

Certain conditions need to be in place for a horse market to be “flooded.” First, horse owners are stressed by challenging economic conditions (like we have currently) and they struggle to cover the growing costs of vet bills, feed bills, board, and training. As a result, many owners try to sell excess horses to recoup their costs, but the high price of ownership makes it difficult for new buyers to enter the market. Sellers lower their prices more and more until they become close to killer market prices. Some send their horses to auctions and cross their fingers that they’ll find loving homes rather than a feedlot buyer. In the saddest cases, sellers abandon or neglect their herds and the horses end up being euthanized after suffering, or are very slowly (and expensively) rehabilitated by rescue programs.

If you’ve been a long-time horse lover, you’ve no doubt heard of or seen desperately sad situations where horses were severely neglected by owners who could no longer afford to keep them.

With all these risks in a depressed horse market like we’re currently facing, why would a registry allow multiple foals a year from one mare? For one thing, registries also feel the money crunch and they depend on fees from registrations and AI, transported semen, and embryo transfer certificates. The more foals bred, the more revenue for the registry. In addition, breed popularity is often measured by how many horses are registered in a given year, so registries rely on greater numbers of registrations to make the breed look more desirable to newcomers.

>So how can embryo transfer be used to benefit the Arabian breed over the long haul? Most importantly, profits should be moved farther down the list of priorities. Breeders need to take an objective look at whether a mare’s impact on the breed is truly beneficial. Is her pedigree available from many other sources? Or is her breeding harder to find? Is her conformation good for a specific use, other than standing in a halter class and looking pretty? Ideally, a mare with quality, athletic conformation and a pedigree that’s not “trendy” or common is the best candidate for embryo transfer. Her foals stand less of a chance of flooding the market. (Of course the same ideals apply to breeding stallions as well.)

Just as with AI and transported semen, there is a chance of breeding fraud with embryo transfer. To prevent incorrect parentage assignments, registries that permit breeding technologies also require DNA testing of all breeding horses and their foals. Registries have staff members that handle and investigate DNA records, which takes time and money. And it’s not foolproof.

RWR Sonora, who was registered as a purebred but had her papers pulled after blood typing was done.

One very surprising example of incorrect parentage that managed to slip by the Arabian Horse Association’s purebred registry is the mare RWR Sonora, who was registered as a 2005 bay purebred Arabian mare, registration number 627880. In the photo shown here, she’s clearly a tobiano — which is not possible in purebred Arabians. Allegedly DNA typing was done on the mare and no questions were raised, but the registry later requested to have her blood typed. The results of the blood typing led the registry to cancel the mare’s purebred papers and ban her from the Half-Arabian registry for suspected fraud.

RWR Sonora's recorded markings, which clearly do not match her actual markings.

RWR Sonora's recorded markings, which clearly do not match her actual markings.

How did this happen? The registry doesn’t require photos of horses during the registration process, which would have revealed a discrepancy from the very beginning, but photos of another horse could have been substituted by an unethical breeder. As stated in the previous installment of this article, DNA typing is accurate about 96% of the time in Arabians. So either RWR Sonora’s DNA was mishandled, falsified, or DNA typing didn’t work correctly, and her complete markings were not recorded accurately either. Seen at right, her body markings are clearly missing from her registration papers. Even more surprising, the owner who registered her is a former regional director and breeding committee member of the American Shagya-Arabian Verband (registry and breed association).

Regardless of whether RWR Sonora was a product of natural service, AI, transported semen, or embryo transfer, the situation shows how it’s possible to defeat safeguards in an effort to cheat the system.

In the next installment, let’s discuss the advent of cloning horses for breeding purposes. It sounds like an oxymoron, but it’s already been done once before in the Arabian breed.

part I | part II | part III | part IV

Makin’ Babies: The Influence of Breeding Technologies, Part I

by Kristin Berkery

part I | part II | part III | part IV

Technology lets us do amazing things, even in the horse business. Thanks to artificial insemination, transported semen, and embryo transfer, it’s possible to have two or more foals from a single mare who’s never been in the same state — or country — as the sire.

There are all kinds of pros and cons to these developments. The theory behind artificial insemination (or AI) and transported semen is that it can diversify the gene pool by giving stallions the chance to sire foals in far-off locations. Embryo transfer allows mares to prove themselves in competition at the same time they are producing foals. In The Nature of Horses, author Stephen Budiansky argues that in the milk cattle business,

“The widespread availability of AI services enormously increased competition among potential breeding stock… with AI the offspring of any given bull were now available to anyone. The cachet of pedigree was undermined, and in its place came hard-headed demands to see the bottom line on performance… Not surprisingly, this change has led to a rapid improvement in the average milk output of dairy cattle.”

Equine artificial insemination. Photo by the Haras National Suisse

I won’t pretend to be an expert on cattle breeding, but there is the obvious risk that most breeders will only want to use the few bulls who sire the top milk-producing cows — resulting in a more limited gene pool over time. To ensure diversity, breeders must have the foresight to use “less popular” sires who are still very good quality, although that might mean slightly lower sale prices and milk production in the short term.

But the goals of horse breeding are different than in milk cattle breeding. Budiansky explains that AI could radically improve the Thoroughbred breed, allowing mares and stallions to prove themselves on the track while also producing foals, which could lengthen those horses’ racing careers and allow breeders to judge the horses’ abilities objectively when making breeding decisions.

Today’s Thoroughbreds generally have short racing careers, which some would argue is a result of breeding horses more prone to breaking down. If the registering authority for the Thoroughbred breed in the U.S. and Canada, the Jockey Club (JC), allowed AI, perhaps breeders might start producing horses that are proven to remain sound longer. If embryo transfer was approved by the JC, maybe we’d see more mares racing against stallions and geldings instead of being retired to the broodmare barn. These developments could improve the breed’s quality over time.


*Bask, sire of 1,046 purebred Arabians

But how have AI, transported semen, and embryo transfer affected other breeds? Without a doubt, AI changed the face of the Arabian breed by allowing stallions to breed multiple mares with just one semen collection. *Bask became the first Arabian stallion to sire more than 1,000 purebred foals, due in part to the approval of AI by the American registry in 1977.

Older stallions who had trouble mounting a mare could now be collected and used for breeding. Horses with busy competition schedules could be collected and the semen frozen or cooled for later use. Valuable stallions could also avoid being injured during breeding by never coming into contact with mares. Even stallions who had died could still sire foals from stored semen.

The Arabian stallion Huckleberry Bey, who sired foals after his death in 1992 thanks to artificial insemination and frozen semen.

Of course AI opened a new door to the possibility of fraud, because now another stallion’s semen could be substituted and the mare owner would never know — or semen could be implanted in a different mare than the one listed on the breeding certificate. Blood typing was used as a solution: After a foal was born, its blood type would be determined and compared to the blood types of its parents. If a foal’s blood type couldn’t possibly be the product of a specific stallion or mare, then the registry could reject the application for possible fraud. Blood typing was not foolproof, but it worked about 96% of the time in Arabians, according to geneticist Ann T. Bowling.

In 2000, DNA typing became a requirement in Arabians, which made the process of identifying parentage more reliable than blood typing.

When transported semen was approved in Arabians in 1995, some breeders were excited about the potential of new diversity in the breed. Previously, different regions of the country were known for their concentrations of specific bloodlines because of the stallions standing at stud in those areas. For example, there was a large population of straight Egyptian Arabians in Texas thanks to some well-financed Egyptian breeding farms, and Crabbet-Maynesboro-Kellogg horses were easy to find in California because of the Kellogg Ranch program that dated from the 1920s. With transported semen, stallions in more isolated areas or with rarer bloodlines were now accessible to anyone, potentially increasing their influence on the breed.

The Kellogg Ranch in Pomona, California.

So transported semen made it possible to produce foals in one part of the country by a stallion who lived elsewhere. Did it diversify the breed by “spreading out” bloodlines in different locales? There are valid arguments that it hasn’t worked out that way. Instead, transported semen has inadvertently turned breeding decisions into global popularity contests. Previously breeders would choose a stallion that was geographically close to them because they had to transport their mares to the stallions’ locations, but now anyone can pick a stallion anywhere in the world without moving their mare.

Part of the reason transported semen has turned Arabian breeding decisions into popularity contests is because most of the high-dollar sales are of horses shown at or qualified for regional and national shows in performance or, most often, halter (or breeding) classes. These competitions are judged subjectively by opinionated humans, unlike in Thoroughbred racing where the impartial clock is the deciding factor. A judge at an Arabian show can favor a particular horse or bloodline, making it more popular with breeders. Under most current show rules, there is no unbiased way to assess the quality of a show horse as long as humans are deciding who should win.

Nowadays, a breeder may make a breeding decision based on a promotional video and without ever seeing a stallion in the flesh. This allows slick marketing, instead of in-person scrutiny, to influence breeding trends. It also allows more breeders to focus on fewer bloodlines in the quest to create marketable offspring, which can result in less diversity overall. And the reliance on transported semen favors stallions with semen that handles freezing or cooling well — but it’s a disadvantage for stallions with average fertility whose semen does not remain viable during transport.

In the next installment of Makin’ Babies, we’ll examine some of the effects of embryo transfer, the necessary safeguards against breeding fraud, and the possible future of the Arabian breed as a result of these new technologies.

part I | part II | part III | part IV