First Cloning of Mule Reported

Researchers have cloned a mule, a member of the horse family that results from a cross between a female horse (mare) and a male donkey.

The baby mule was born May 4, 2003, and is the first clone of a hybrid animal. As hybrids, mules are sterile, except in extremely rare cases. The foal has been examined and found to be in good health. The foal's DNA comes from a fetal cell culture established in 1998 at the University of Idaho, the full sibling of a champion racing mule.
Only two horse foals have ever been conceived in a test tube as a result of in vitro fertilization.

For three years, the researchers worked without success. Then in 2001 they began to focus on the calcium levels in the fluid surrounding the eggs during the cloning procedure. They found that adjusting the levels dramatically increased the chances of success. Using mule DNA in 113 attempts, they established 14 pregnancies, of which eight continued to the 40-day stage when heartbeats were detected. Preliminary testing showed that the method used to clone the mule should work equally well with a horse.

The research team was led by Gordon Woods, professor of animal and veterinary sciences at the University of Idaho (Moscow, USA), who is recognized as an expert on cattle cloning. Dr. Woods noted that the horse's basic metabolism is slow compared to humans and many other mammals. He speculated that this difference in cellular activity might play a role in both cancer development and reproduction.




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Univ. of Idaho