BEIJING (Reuters) - An eight-year-old giant panda in southwestern China recently gave birth to her second cub after being artificially inseminated in March, the official Xinhua news agency said. The mother panda, named „No. 28,“ and her cub were both in good condition at the Giant Panda Protection and Research Centre in the Wolong reserve in southwestern Sichuan province, Xinhua said. Pandas rarely become pregnant in artificial environments, with more than 90 percent of male pandas in zoos or breeding centres unable to mate and a pregnancy rate in females of only 24 percent, state media have said. Since the research centre was established in 1991, it had helped breed 21 pandas, 15 of which survived, it said. China has fewer than 1,000 giant pandas, which are under constant threat from poachers and human development that has encroached on their forest homes. In a separate report, Xinhua said a Siberian tiger gave birth on July 3 to three cubs at a zoo in Changchun, capital of the northeastern province of Jilin. The 13-year-old mother, Yan Chun, had miscarried a fourth cub but the three others were in good condition, weighing more than 1.0 kilogram (2.2 lb) each. There are only about 300 Siberian tigers surviving in the world, and about 20 in the wild in China.