A Trinity College research group has discovered "errors" in the bloodlines of international thoroughbred horses. The work points towards mistakes in the recording over centuries of The Stud Book, which details the family trees of pedigree horses. New genetic research at Trinity College Dublin suggests that the bloodlines of pedigree horses may contain a few surprises along the way, writes Dick Ahlstrom.
Knowing the bloodlines of an animal is central to its designation as a thoroughbred, says Dr Emmeline Hill, a former postdoctoral research fellow in the department of genetics at TCD and lead author in a study of thoroughbreds published this month in the journal, Animal Genetics.
"People will pay millions of dollars for a good pedigree," she says. The current record price for a foal, based entirely on the animal's bloodlines, is $13.1 million, paid in the mid-1980s for an unbroken yearling yet to feel the burden of a saddle.
The Trinity research group, which included other teams in Egypt, Turkey, the US and Russia, were therefore surprised to find that the pedigree lines were somewhat clouded by mistakes. Some errors dated back to the establishment of the thoroughbred industry 300 years ago and others to the mid-1800s. The most recent, however, go back only 20 years, explains Hill.
The group looked at 100 animals in 19 "families" of horses. Each family was grouped along female lines, linking daughters to mothers to grandmothers and so on back into the horse's family tree. "What we found in eight of the 19 families was there was at least one individual that didn't match the rest. That means that something happened in the history of the recording of the pedigree," she says.
Thoroughbred horse history is mapped out in The Stud Book, started by James Weatherby more than 200 years ago and still controlled by the Weatherby family. "The Stud Book was established in 1791. It is the bible of thoroughbred pedigrees. If your horse is not registered in Weatherby's, it's not a thoroughbred."
-In the late 1800s an attempt was made to trace all mares then registered in the book back along their family trees to the foundation mares. These were grouped into families, ranked in order by the number of classic race winners the mare's bloodline had produced. Hill and colleagues looked at 19 of these families.
"The problem with The Stud Book and the recording of The Stud Book was that horses, particularly mares, weren't recorded particularly well," Hill said. A horse known by a vendor as The Old Grey Mare might on sale be quickly renamed. Mares were also often named after their sire and over the lifetime of a stallion there would be many of these.
The team decided to follow the female lines by studying mitochondrial DNA, genetic material passed from mother to daughter. Within each family, all females should have the same mitochondrial DNA. "Of the 19 families we looked at, about half of them had errors. Three or four of them are deep-rooted to the early days of The Stud Book when it would have been expected that errors would occur."
For example, family nine is linked to the Old Spot Mare born in 1700. There were 10 modern horses in the sample attributed by The Stud Book to Old Spot Mare, but in fact the majority, six, had the same mitochondrial DNA as horses in family 12, attributed to D'Arcy's Chestnut Arab Mare, also born in 1700.
These findings will provide valuable insights into the earliest days of the throughbred, she believes. The work should also be of interest to the modern industry. "This could have consequences for thoroughbred breeders and buyers who often make million-dollar decisions in the sales ring based on the integrity of these pedigrees," she adds.
"I am not surprised by their findings in view of the fact that there are accidental mixups in the current foal crop," stated Weatherby Ireland's MD, Joe Kiernan. If there are mixups today they were there in the past. Recording errors are impossible since 1986, however, because all foals are DNA tested for parentage.