Scientists at the National Zoo in Washington D.C. confirmed Thursday the giant panda cub born on Aug. 23 is a female and is in good health.
Mei Xiang was artificially inseminated twice on March 30 after multiple unsuccessful attempts to breed her with the Zoo's resident male panda, Tian Tian. Zoo keepers inseminated her with fresh and frozen semen from Tian Tian in the first procedure, and frozen sperm from Tian Tian as well as Gao Gao, the San Diego Zoo's giant panda, in the second.
Paternity tests show that Tian Tian is the father of both the live cub and the second, stillborn cub delivered on Aug. 24. The cubs were fraternal twins.
According to Smithsonian reproductive biologist Pierre Comizzoli, Mei Xiang had never been artificially inseminated with semen from two males before this past breeding season.
Zoologists have had a rocky history with breeding pandas. The first pair of pandas to live in the U.S. tried unsuccessfully to mate for 10 years before they were able to give birth to five cubs, though none lived into adulthood. The National Zoo estimates the mortality rate for female panda cubs born in captivity to be 20 percent in their first year of life and 26 percent for males.
Mei Xiang gave birth to Tai Shan in 2005. This cub, who spent several years at the National Zoo, now lives in China, Mei Xiang had five consecutive false pregnancies between 2007 and 2012. In September 2012, she gave birth to a panda cub that died six days later due to lung and liver problems.
National Zoo panda keeper Nicole MacCorkle told U.S. News last September that although there's nothing specific to pinpoint as to why panda's have such a hard time growing into adulthood, "a lot of it has to do with the fact that they're very small and vulnerable." When born, giant pandas are about the size and weight of a stick of butter.