Cloned Foal Romps Into Record Books

Prometea the Halflinger foal is little more than three months old, but already has a place in the record books as the first horse to be cloned. It is also the first cloned mammal born to its genetic mother.

It could show the way to a new generation of champion jumpers or show horses - and give great geldings of the past the chance to pass on their bloodlines.

Researchers so far have cloned sheep, mice, pigs, cattle, rabbits, cats and even a mule. But Prometea, born on May 28 and announced in Nature today by the Laboratory of Reproductive Technology at Cremona in Italy, is the first horse to step into the stud books without benefit of a stallion.

It is also the first clone to be born to its genetic donor: it was cloned from a cell taken from the mare that was also to become the birth mother.

This in itself is a surprise: normal offspring are genetically different from their mothers, and the theory has been that the parental immune system reacts to the foetal "stranger" in the womb in a way that influences the baby's wellbeing.

Halflingers take their name from a village in the Tyrolean Alps, and are descended from a cross between an Arab stallion and a mountain pony. There are Halflinger breeders the world over.

Philip Freedman of the Thoroughbred Breeders Association told the Press Association yesterday that the development would be of no benefit to the racing community - which forbids even the use of artificial insemination - and the authorities would strongly oppose it.

But it was theoretically possible that the fertility technology could be used to replicate show jumpers.

The technology that took Prometea from laboratory dish to gambolling foal is likely to awaken dreams of "bringing back" legendary horses such as Red Rum, Shergar, Mill Reef and so on, if only to explore the roles of genetic traits and training in making them sporting legends.

Thoroughbred racing seems to be at a genetic standstill, and a number of classic race times have stood unmatched for decades. So there will be huge interest in the experiment within the racing world.

"For one thing, you could use it to work out whether your trainers are any good. You could send them identical clones and see which turned out a winner," said an unnamed expert.

But if Prometea is a symbol of hope, the foal is also a lesson in the uncertainty of the technique.

The Italian team, led by Cesare Galli, cultured 513 reconstructed embryos from the skin of an Arabian thoroughbred male, and 328 from the Halflinger mare, using eggs from horses sent to the abattoir.

Of these, eight male embryos and 14 female embryos went on to the blastocyst stage, at which they could be implanted in surrogate mothers. The researchers put eight male and nine female embryos into nine mares, one of which was a donor. They used ultrasound 21 days later to discover that only four had developed. Two of these were lost shortly afterwards and a third aborted after 187 days.

Only Prometea survived to full term and was born after 336 days.

"The remarkable birth of a live foal from its genetically identical recipient is at odds with the idea that maintenance of gestation depends on immunological recognition of the pregnancy by the mother, based on the evidence that abortion can result from inadequate recognition of foetal antigens," the scientists report.

"Furthermore, our result adds the horse to the list of mammals that have so far been cloned from an adult somatic cell. In principle, cloning could enable gelding champions to contribute their genotype to future generations, as well as opening up an opportunity to verify the reproducibility of traits such as character and sporting performance."