Our first cloned sheep found dead

Matilda, Australia's first cloned sheep, has died of unknown causes, according to the South Australian Research and Development Institute (SARDI).

"Basically she looked healthy at 3pm on Saturday when she was fed, then was found dead at 10am on Sunday," said SARDI executive director Rob Lewis.

By the time the sheep was found, Lewis said, the summer conditions meant that deterioration had set in. "She was autopsied, but due to the extent of deterioration, we were unable to determine the cause of death," he said.

"Our scientists' feeling is that while this is unfortunate, it appears to be a natural death, but it could be an impact of the cloning."

Three-year-old Matilda was the first clone produced by SARDI scientists, and while no longer an active part of the cloning and in vitro technologies program, she represented the proof of concept.

"It showed that we could perfect the technique," Lewis said. Aside from Matilda, the organisation still has two cloned ewes and a cloned ram, all of which appear healthy.

In the last couple of years, premature ageing has been flagged as a potential concern for cloned animals, with original sheep clone Dolly apparently suffering from early-onset arthritis. Experts postulate that cloning from an older animal means that the clone has 'older' cells and therefore starts to exhibit signs of ageing earlier.

But Lewis said that in the case of Matilda, premature ageing did not appear to be a significant factor in her death, and in any case, she was cloned from a very young animal.

SARDI is continuing to develop cloning technology, along with other reproductive in vitro technologies.

"Cloning is not the only part of the technology -- our IVF work is just as important," Lewis said.

While cloning might be useful for rescuing valuable animals, for example, Lewis said there was still a long way to go before the technology was cost-effective.