Video: Panda born from frozen sperm

updated 7/24/2009 6:30:13 PM ET 2009-07-24T22:30:13

For the first time, a giant panda cub has been born in China after being conceived using frozen sperm, officials announced Friday — an innovation scientists hope will help the endangered species avoid extinction.

The new cub's birth Thursday means breeders will no longer be forced to rely on semen from China's few virile males, and may even be able to bring in sperm from zoos in San Diego, Mexico City or elsewhere.

That's key to promoting a healthy panda population because too much inbreeding can lead to birth defects that would further threaten the survival of the species.

The new cub, born to You You, a female panda at the Wolong Giant Panda Research Center in southwestern Sichuan, is the tenth born at the breeding facility this year. It was You You's third successful pregnancy.

Just after dawn, the pinkish, hairless cub emerged, and its mother was shown licking the tiny wiggling creature to clean it on footage broadcast by the state television channel CCTV.

Panda researchers said Friday it was the first successful live birth worldwide using frozen panda sperm.

"We did try before but it failed," said Huang Yan, a deputy research technician with the China Panda Preservation Research Center.

He declined to provide specifics but said the Wolong team had improved its thawing techniques, making frozen sperm more viable. Sperm samples are deep-frozen using liquid nitrogen, and in the past, only 20 to 30 percent of the sperm survived. But this time the center managed to raise viability to about 80 percent, he said.

Scientists carried out the artificial insemination in March, and You You was found to be pregnant in June during an ultrasound. The sperm from male panda Lu Lu had been frozen for "a number of years," said Huang.

The sex of the baby panda is not yet clear, so it hasn't been named, Huang said.

Zoo babies

The technique, if it can be replicated, will be a boost for panda conservation efforts, said Matthew Durnin, regional science director in the Asia-Pacific and North Asia for The Nature Conservancy, a U.S.-based conservation organization.

"In the past, they're limited to using semen from a few virile, reproductive males. If you're using only one male at a time, you start to get lower and lower diversity. This can help with issues of genetic diversity among your captive population," he said.

Besides preventing inbreeding, genetically diverse panda populations are generally healthier, meaning they will also have a better chance of thriving if released in the wild, he said.

Dr. Barbara Durrant, a reproductive physiologist at San Diego Zoo, said the success in China opens the way for frozen semen exchanges between zoos. "The ideal situation would be to get semen from every male in captivity and freeze the sperm," she said.

"Exchanging frozen semen between zoos is definitely in the plan," she added, noting this means "much less stress for the animals," than shipping them to other zoos, often thousands of miles away, to mate.

Panda females have only three days a year in which they can conceive — one reason their species is endangered. Ensuring that the male and female pandas are interested and able to mate during that short window is a challenge, and Durrant said some males never succeed at natural breeding.

As a result, artificial insemination has become common practice when breeding captive pandas. In 2006, 34 pandas were born through artificial insemination in China and 30 survived — both record numbers for the endangered species.

The technique has also been used at zoos in the United States, including at the San Diego Zoo, where a female panda, Hua Mei, was born in 1999 using sperm from Shi Shi, a male who was born in the wild in China, said Yadira Galindo, a spokeswoman for the zoo.

Durrant said the zoo has frozen sperm from Shi Shi, who died last year, as well as from its other male, Gao Gao, who was also born in the wild and has sired four offspring naturally. Frozen sperm from pandas born in the wild is especially important to promoting genetic diversity, she said.

Pandas are threatened by loss of habitat, poaching and a low reproduction rate. Females in the wild normally have a cub once every two or three years. The fertility of captive giant pandas is even lower, experts said.

Only about 1,600 pandas live in the wild, mostly in China's southwestern Sichuan province, which was hit by an earthquake last year that killed nearly 70,000 people. An additional 120 are in Chinese breeding facilities and zoos, and about 20 live in zoos outside China.

With so few pandas left, "every female is important, every male is important," Durrant said. "It behooves us to have semen from as many males as possible."

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