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Mule Joins List of Cloned Animals

Scientists in Idaho have produced the world's first cloned mule. So far, the mule, born May 4, is the only member of the horse family to be successfully cloned. The project took almost five years and millions of dollars, but as NPR's Joe Palca reports, scientific interest wasn't the only motivation.

Every Memorial Day weekend, a mule festival takes over the town of Bishop, California. There are mule shoeing contests, mule driving demonstrations, and mule racing. Don Jacklin was a stranger to mules until he visited the mule festival in the 1970s.

"I just plain got hooked on mule racing," says Jacklin. "Came home, and bred a mare for the purpose of mule racing, and went down and entered a few years later myself. Excuse the pun of the term, but I got my ass kicked."

But Jacklin is no quitter. A few years later, he produced the first of a series of winners. But he wanted to go a step further.

Mating a female horse with a male donkey produces a mule. As hybrid animals, mules are sterile. Jacklin wondered if it was possible to clone a mule -- preferably one of his champion racers.

He contacted Gordon Woods at the University of Idaho, who was working on horse reproduction. Woods agreed to turn his attention to mules.

To make a clone, researchers remove cells from the animal to be cloned, and put them into eggs from which the DNA has been removed. A surrogate mother carries the resulting embryo to term.

The University of Idaho project to clone a mule began in 1998. By 2002, Woods and his team had worked out the details on a method that resulted in the world's first mule clone, Idaho Gem. His birth was announced in the online edition of the journal Science.

He was cloned from cells taken from a mule fetus produced by the same parents that produced Jacklin's champion racer Taz. Idaho Gem's two siblings are expected to be born later this year.

Woods says 33 hours after birth, Idaho Gem was already showing a racer's spirit when they let him out of the barn.

"He darted around like a rabbit," says Woods. "It took six of us to kind of corner him in and get him back into the stall because he is really vital and vibrant."

Even though his interest is in mule racing, both Woods and Jacklin know the big money is in horse racing, and they're hoping that what worked for cloning a mule will work for cloning a horse.

Jacklin says many champion horses can't reproduce -- such as Funny Cide, the winner of this year's Preakness and Kentucky Derby races.

"[Funny Cide] is a gelding, so he can't reproduce, so how do you ever continue his blood line and his strength in the future?" Jacklin asks. He predicts the answer is through cloning.

That may be, although horse racing is slow to allow new reproductive technologies to be used to produce race horses.

And cloning researcher Michael Roberts at the University of Missouri says many cloned animals have developed health problems either shortly after birth, or even later in life. Roberts says there's no reason to think the same won't happen with cloned mules like Idaho Gem.

"Whether this mule will turn out to have racing potential or normal health is I think questionable at the moment," Roberts says.

Copyright 2022 NPR. To see more, visit https://www.npr.org.

Joe Palca is a science correspondent for NPR. Since joining NPR in 1992, Palca has covered a range of science topics — everything from biomedical research to astronomy. He is currently focused on the eponymous series, "Joe's Big Idea." Stories in the series explore the minds and motivations of scientists and inventors. Palca is also the founder of NPR Scicommers – A science communication collective.