Will DNA Profiling Create The Perfect Thoroughbred? Hold Your Horses, Experts Say

A new clause began showing up in the breeding contract of at least one major Central Kentucky stud farm this winter: language informing mare owners that by signing, they are giving permission to stallion farms to collect broodmares’ hair samples for identity confirmation and possibly genetic analysis.

From the stallion owner’s perspective, building a cache of genetic data would seem to be a good potential marketing tool or even a high-tech way to engineer a super horse. But how close are we to using DNA data to predict a horse’s likelihood of reaching the Kentucky Derby gates? And should mare owners be concerned about privacy when it comes to the medical data of their breeding stock?

The answers, like much in the breeding business, are anything but simple.

What DNA can tell us

Equine genetics made headlines in 2012 when mainstream media picked up on the “Speed Gene Test.” Research by genomics scientists at University College Dublin and the University of Cambridge looked into the impacts of myostatin, a gene group which can be marked for a preference toward long or short distance.

Dr. David Lambert, president of Equine Analysis Systems in Midway, Ky., said the myostatin test remains popular among his clientele.

“I don’t know what other people do but in our company we’ve seen fit to combine it with other tests that we do to try to give our clients a better overall understanding of a particular individual or a possibility for a mating,” said Lambert.

Since the equine genome was completely sequenced in 2006, researchers have also located the mutation that causes spotting in Appaloosa and found a link between that mutation and night blindness.

For the most part, development of testing for anything performance-related has stopped with myostatin. Diseases with a genetic link are more attractive to academic institutions, which rely on grant money to fund their projects and are more likely to get a study funded if it has wide-reaching applications.

Lambert’s company offers clients analysis and consultation on bloodstock based on the traditional criteria like conformation and training, as well as more advanced technologies like echocardiography and general genetic analysis.

Although DNA analysis is a piece of the formula he uses to size up a horse, Lambert doesn’t foresee the business of testing for individual genes going much further.

Dr. Ernie Bailey, immunogenetics and genomics researcher at the University of Kentucky’s Gluck Equine Research Center, agreed. Bailey said information collection will continue to be the name of the game in the equine world.

“This type of work has been done very successfully by cattle breeding companies using large amounts of data.  Data is limited for horses. And the phenotype — racing at different distances on different tracks with different jockeys and different trainers — is arguably more complex,” said Bailey. “Therefore, it is very important for the companies doing the work to continue to collect data and learn more about the genetics of racing. Furthermore, as time goes on, selection can change the genetic profile of the population and this requires continuing testing for comparison. The success of the activity requires that the data be collected, archived and reanalyzed.”

At this point, though, genetic testing can be useful in testing some assumptions about the bloodstock business. A foal gets half its genetic material from each parent, but there’s no way to reliably predict which half of which parent’s chromosome ends up in the foal.

Lambert’s research supports some of the notions horsemen have relied on for years, such as sires “stamping” a majority of offspring with a particular shoulder or hip consistently. He says other things, like inbreeding, don’t hold up under DNA scrutiny. He studied DNA of individuals and compared them against the inbreeding visible in their pedigrees to gauge similarities to the horses with which they were inbred.

“We found there was no correlation,” said Lambert. “The amount of inbreeding in the pedigree page was not reflected in their actual DNA. A pedigree page, while generally probably indicating what’s going on, could for an individual be totally misleading.”

What DNA can’t tell us

Even if researchers engineered new tests for single genes impacting racing performance, genetics is only part of the picture.

“I think in the horse business people are still imagining this is going to be super dramatic and change everything, but it isn’t, because a race is such an unbelievably complicated event,” said Lambert. “The things that are going on that make up a race are so many and so varied, to be able to genetically identify the animals who have got it and those who haven’t got it is virtually impossible.”

Just the process of trying to isolate a gene or group of genes common to an elite group like Grade 1 winners is a statistical headache.

“Let’s say you’re trying to sort out Grade 1 winners. How many are there every year? [Then] once you break them up into their different groups (grass/dirt, sprint/milers, fillies/colts), there might only be a handful,” Lambert said. “You can’t do an experiment on a handful. You need at least 100 if it’s a simple trait, and if it’s a complicated trait you need 1,000.”

Always Dreaming (Bodemeister) wins the Kentucky Derby at Churchill Downs on 5.6.2017.

For example, there have only been 143 Kentucky Derby winners, many with different running styles and only a small number of which are living.

When Lambert sits down with owners and breeders, he stresses the same concepts: his measurements, genetic analysis — all of it is only part of the picture. He prefers working with owners whose trainers are open to hearing his findings and interested in providing him feedback based on their observations of the horse. Often, he says a trainer will have tried a few changes and made some progress but not quite advanced the horse to its total potential. Together, Lambert believes the team can sometimes piece together a puzzle, using reports and practical observations to better identify running style, distance, surface, or conditioning changes.

Ultimately though, this approach is only helpful for the owners and breeders willing to invest the money in the analysis itself, and the extra bills that may come with the time a trainer takes to try a new strategy.

What should owners be thinking about?

Regardless of what DNA will or won’t be used for in the future, sample collection at the time of a shed appointment is almost certainly not designed to benefit the mare owner. Analysis will obviously not give either stallion or mare owner information about the suitability of a mating since the mating will certainly have taken place by the time any information could come back.

According to Bailey, there is potential for this type of collection to be used against a mare – especially if samples are easily identified.

“Horse owners should retain control over the information about their horses,” he said. “They should control who has access.  They should have assurances of anonymity for their horse if the data is used in larger, presumably randomized studies.  The worst situation would be for someone to publish damaging descriptions about a horse because of information gained through this activity.”

Then, a mare owner might consider the use of that data. In the human realm, companies like 23andme and AncestryDNA offer to provide customers a percentage breakdown of their geographical heritage. Several companies provide a breed analysis based on dogs’ DNA. Sometimes, the results don’t quite ring true when people open the envelopes, which may be thanks to algorithms. Each company develops its own formula for determining a human or canine genetic origin based on certain DNA markers. That means the results aren’t foolproof and also that two different companies might offer somewhat different printouts based on the same sample.

The same is likely true of current and future analysts of equine DNA – results will only be as good as the database on which they’re based, and those results could be swayed by the composition of that database.

That’s why Bailey believes owners ought to take an active interest in this type of DNA collection.

“Horse owners should receive copies of the raw data for DNA testing. There are a relatively small number of platforms used for genomic testing of horses,” he said. “Currently the most popular is the SNP70 from a company called Geneseek in Lincoln, Neb. Many researchers are accustomed to working with this data. It might be appropriate for horse owners to ask for copies of the raw data and be prepared to share it with other scientists to confirm claims.”

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