Zoo Atlanta announced that its 15-year-old giant panda Lun Lun gave birth to twins on Monday, July 15, 2013. The first baby arrived at 6:21 p.m., and its twin followed at 6:23 p.m. The cubs are the first giant pandas to be born in the U.S. in 2013 and the first twins to be born in the U.S. since 1987.

Western University of Health Sciences’ College of Veterinary Medicine Assistant Professor of Physiology David Kersey, PhD, played a key role in the artificial insemination (AI) of Lun Lun.

“The first twins born in the U.S. since 1987 are something to celebrate,” Kersey said. “Although giant pandas have a biological tendency to give birth to twins – 48 percent of historic captive births have been twins – this event has been rare in the U.S. Now we have to be alert to the well-being of both cubs. At Zoo Atlanta now is a scientist from the Chengdu Breeding Base in China, and he is an expert in hand-rearing cubs. I think the cubs are in good hands.”

In February 2013, Kersey, a giant panda reproduction expert since 2001 who has been consulting with Zoo Atlanta, began receiving Lun Lun’s urine sample to track hormonal changes that would indicate fertility.

In March, Kersey detected the hormonal changes he was looking for and traveled to Atlanta to provide on-site analysis. On March 21 he detected ovulation, at which time he and colleagues performed an AI procedure. They performed another one on March 22.

AI was done within eight hours of each other. Zoo Atlanta used frozen semen that was on reserve for the first AI and followed that up with fresh semen before the 40-hour window ended.

Zoo Atlanta Members and guests can expect to meet the cubs in late fall. The newborns’ father, 15-year-old Yang Yang, and older brothers Xi Lan, 4, and Po, 2, remain on exhibit and will not be housed with Lun Lun or the cubs. This separation is normal for giant pandas, which are solitary in the wild, according to Zoo Atlanta.

Click here to view Zoo Atlanta’s birth announcement.