Not Doing What Comes Naturally

Mei Xiang and Tian Tian Fail to Mate, So Scientists Step In for a Third Time

Scientists at the National Zoo said they artificially inseminated the giant panda Mei Xiang yesterday after she and her partner, Tian Tian, unsuccessfully tried to mate Tuesday.

Whether the procedure will result in a panda birth won't be known for a few months. Mei Xiang gave birth to a cub, Tai Shan, in 2005 after being artificially inseminated. But a similar procedure last year was unsuccessful.

The yearly breeding period for pandas lasts only a day or two, and for Mei Xiang, 9, and Tian Tian, 10, it began Tuesday, specialists said at a news conference.

After monitoring Mei Xiang's hormones and waiting for the big moment, "we saw the earliest onset of very strong estrous behavior" Tuesday, said Suzan Murray, the zoo's chief veterinarian.

"The estrous behavior we were looking for specifically," Murray said, "was her backing up and directing her tail end toward the male panda, and obviously we were looking for comparable interest on the part of our male."

Tian Tian, weighing in at 275 pounds or so, and Mei Xiang, about 230 pounds, got together for six hours Tuesday, scientists said. But things didn't work out.

"Unfortunately, although there was great interest on the part of our pandas, their orientation wasn't the greatest," Murray said. "Our female still doesn't assume a classic breeding position, which makes it very hard on the male, in terms of getting his alignment and positioning correct."

Scientists used Tian Tian's sperm to impregnate Mei Xiang in April 2005, resulting in Tai Shan's birth three months later. Last year, in the interest of genetic diversity, they used sperm from a different panda, Gao Gao of the San Diego Zoo. But it didn't take.

The National Zoo had wanted to use Gao Gao's sperm again this year. However, because Gao Gao is being monitored for recent physical discomfort that is possibly related to arthritis, scientists in San Diego did not want to anesthetize him for sperm collection.

So Tian Tian, who came to the zoo with Mei Xiang from China in December 2000, gets another chance to be a father. Mei Xiang did not mate in 2006 because she was still nursing Tai Shan.

Yesterday, after anesthetizing Tian Tian, specialists drew sperm from him and implanted it in the anesthetized Mei Xiang.

"We ended up putting about 1.7 milliliters of diluted semen in her uterus," said Jo Gayle Howard, a reproduction scientist. "The quality was good. Good motility. Good forward progression. The number of sperm was excellent. We put over 500 million in her, so surely that should do it."

If the artificial insemination works, "it could be anywhere between three and six months before a birth," Murray said.

The giant panda is an endangered species. Only about 1,600 live in the wild, and a little more than 200 are in zoos.

"From a veterinary point of view, a birth is . . . exhilarating beyond belief," Murray said.

At 170 pounds, Tai Shan, now almost 3, is apparently a frisky panda. The zoo said he scratched one of his keepers Tuesday in his outdoor habitat. The keeper, who suffered a minor leg cut, was treated at a hospital and then went home.

"The keeper had brought Tai Shan indoors for a routine feeding," the zoo said in a statement. "The door separating Tai Shan from the outdoor yard apparently was not secured, and Tai Shan went back outside and made physical contact with the keeper."