Yangyang, a female goat cloned from an adult by Chinese scientists in 2000, celebrated her fourth birthday on Tuesday.

She is full grown, healthy and has no sign of premature senility, a complication that zoologists say might affect cloned mammals, according to scientists with the sheep-breeding base of the China Science and Technology University for Agriculture and Forestry in Xi'an, capital of northwest China's Shaanxi Province.

Yangyang is now the happy great-grandmother in a four-generation family. She is living with her daughter, three-year-old Qingqing, granddaughter Tiantian, 16 months old, and great-granddaughter Xiaoxiao who was born on Feb. 6 this year.

"Her booming family prove goats cloned from somatic cells and embryos can cross-fertilize and reproduce in the same way as ordinary goats," said Zhang Yong, an expert on animal embryo engineering who cloned Yangyang.

Yangyang was the second goat cloned from somatic cells at the base. The first one, Yuanyuan, also a female, died from respiratory failure stemming from undeveloped lungs 36 hours after she was born.

Over 1 million people from all walks of life have visited Yangyang at the base over the past four years.

Scientists at the base are closely watching Yangyang's overall condition. "It's still too early to say whether she might suffer from premature senility or other complications later on," said Prof. Zhang Yong.

Dolly the sheep, the world's first mammal cloned from an adult, died an early death last year after being diagnosed with progressive lung disease. Dolly was six, while sheep can normally live to 11 or 12 years.

(Xinhua News Agency June 22, 2004)