A group of Chinese and US scientists improved the technology of frozen semen and successfully increased the pregnancy rate of giant pandas reared by man.

The Research Center for Giant Panda Breeding in Chengdu, capital of southwest China's Sichuan Province, has bred 11 giant pandas with the new technology over the past three years.

Chinese scientists of the research center and experts from the United States and World Conservation Union jointly started a research in 1997 to improve the artificial collection of semen and the semen freezing and conservation technology.

Giant pandas are considered to be one of the world's most endangered species. Only about 1,000 are known to exist, most of which inhabit Sichuan. Sterility of giant pandas has been a long time problem plaguing scientists with an aim to protect the animal from extinction.

Statistics show that only one-third of the artificial feeding female giant pandas in the world have given birth, and only a dozen male pandas have the ability of natural mating.

Chinese scientists began to tackle this problem with frozen semen technology as early as the end of 1970's. However, the quality of the frozen semen was not high enough to make the female pandas conceive.

Experts say the newly improved technology will greatly increase the chance of the female giant pandas of becoming pregnant after receiving artificial fertilization.