Chance, a Brahman bull, died earlier this year, but scientists at Texas A&M University, US, have created a clone using skin cells taken shortly before he died. The floppy-eared calf is called Second Chance.

Second Chance is being looked after by its surrogate mother

The feat could indicate that cloning can be done using cells of any age and could have important implications for livestock breeding. However, it took 189 attempts at transferring Chance's DNA into eggs to produce Second Chance.

"What is the limit?" asked researcher Mark Westhusin. "Do the cells reach a certain age where you can't clone them anymore or does that ever happen?"

Old age bull

Professor Westhusin said Chance was chronologically equivalent to an 88-year-old human when he died of old age. He was owned by Ralph and Sandra Fisher of La Grange, Texas who used him in their photography and television business, allowing people to be pictured riding bulls.

On seeing Second Chance, Mr Fisher said: "The hair stood up on the back of my neck - he has the same markings as Chance."

Another team member, Jonathan Hill said: "The Fishers wanted to have their prized bull cloned because of his unusually gentle nature, and they considered the cloning effort a good opportunity to see if an identical copy of Chance might also have such an easy going disposition."

Chance was unable to reproduce naturally because of the removal of both diseased testicles two years ago.

Old timer

Second Chance, born three weeks ago, will stay at Texas A&M until he is weaned in another six months and then go join the Fishers' photography business. However, scientists will continue to keep a close watch for any signs of premature ageing.

Dolly: old before her time?

Last spring, scientists revealed that the DNA of Dolly, the first cloned sheep, had some characteristics of the older cells that were used to generate her.

"The chromosomes, which package the animal's DNA, have some special DNA at their tips called telomeres," Dr Hill explained. "These small pieces of DNA help to protect chromosomes from damage.

"Very young animals have long telomeres, but as the animal ages, the telomeres are worn away. We should know in a month or so if the telomeres of Second Chance are like those of the 21-year-old bull used as the source of the cells for the cloning process, or if they are more like those of a normal new-born calf."

Second Chance, like previously cloned calves, displayed some early symptoms similar to those seen in premature human babies. However, Second Chance is now in good health, Dr Hill said.

Dog clone

Professor Westhusin also leads the Missyplicity Project which is attempting to produce the first cloned dog. The anonymous sponsors of the project have invested $2.3 million to produce a clone of their pet dog, Missy, a mixed-breed border collie.

The cloning of Second Chance was funded by the Texas Co-ordinating Board of Higher Education's Advanced Research Program and by Ultimate Genetics in Franklin, Texas.