Two female giant pandas have been artificially fertilized with semen from a 21-year-old panda, the equivalent of 60 in human years, said experts at a giant panda breeding base in northwest China's Shaanxi Province on Wednesday.

Xiaoming, a 21-year-old panda, the equivalent of 60 in human years, was taken care of at a giant panda breeding base in northwest China's Shaanxi Province on June 16, 2009. [Xinhua]

The senior panda, Xiaoming, was a wild panda rescued by wild animal preservationists in Shaanxi in 2007. He was blind from cataracts and suffered from nephritis. He became the second giant panda to receive the cataract surgery in China last December, which helped restore his eyesight.

"Xiaoming has been in good health and had become sexually frisky since spring. We found 390 million sperm per milliliter of his semen, with 60 percent of the sperm active for fertility," said Ma Qingyi, head of the veterinary hospital with the Shaanxi Research Center of Rare Wild Animal Rescue and Breeding.

Ma said Xiaoming's sperm vitality is as good as young pandas.

"Using sperm from a wild panda can be conducive in avoiding close breeding among pandas in captivity," he said.

The expert said the fertilization rate of giant pandas is very low, which is part of the reason for the animal's risk of extinction.

If the two female pandas, nine-year-old Zhu Zhu and six-year-old Yang Yang, become pregnant, they could be expected to give birth in autumn, as pandas' pregnancy lasts from 83 to 185 days.