Zoo

Photo by PoPville flickr user Mr. T in DC

From the National Zoo:

Dr. Pierre Comizzoli is a reproductive cryobiologist at the Smithsonian Conservation Biology Institute. In this giant panda update he explains how the Zoo stores semen for endangered wildlife, which can be used for procedures like artificial inseminations.

The team of people at the Zoo who study and research giant panda reproduction includes keepers, veterinarians and scientists. I am one of the scientists on that team, specifically a reproductive cryobiologist. That means that I am a specialist in the preservation of sperm cells, eggs and gonadal tissues of endangered species at freezing temperatures.

By freezing semen samples of endangered species we preserve them for long periods of time and can suspend the life of sperm for decades. At the Zoo we store frozen semen of giant pandas and other species in the sperm bank. It is critical to create frozen sperm banks because the genes from endangered deceased individuals can be used to produce offspring long after their death. This is really important for the sustainability of small populations and it is integrated with other conservation efforts. When we need the frozen sperm cells, we thaw them and then they can be used for assisted reproduction (like an artificial insemination). The Zoo’s sperm bank contains more than 2,000 semen samples from more than 100 species. Sixty of those samples are giant panda semen from five males.

Our two pandas at the Zoo, Mei Xiang and Tian Tian, have never successfully bred on their own. For a critically endangered species like the giant panda – that presents a challenge for conservation efforts, which is why we perform artificial inseminations on Mei Xiang when natural breeding does not occur.

I have been involved with performing giant panda artificial inseminations at the Zoo every year since 2004 – except in 2006 when Mei Xiang was nursing Tai Shan. For some artificial inseminations we have used frozen sperm, which is stored in the Zoo’s sperm bank.

We only freeze semen from endangered species that is high-quality. The process for freezing samples is very specific to ensure that the samples are the highest quality possible. First, the semen has to be mixed with a solution that prevents pH variations, otherwise those variations would kill the small and fragile cells. Then, an ‘anti-freeze’ agent (glycerol) is added to the diluted semen to protect the cells before being exposed to decreasing temperatures. Ideally the semen is first cooled to 4°C, which is the temperature of a refrigerator, in a couple of hours. The cold semen suspension is then loaded in small plastic straws that hold less than 1/4mL of semen. All of the straws hold the same concentration of semen. Finally, the straws are exposed for several minutes to liquid nitrogen vapors at a temperature of about -100°C, before being plunged in the liquid nitrogen (-196°C).

Photo by PoPville flickr user ashleykalena

From the National Zoo:

Our pathologists have finished the final necropsy on Mei’s cub, and the panda team shared the results this morning. The initial necropsy, which was performed on September 23, showed that the week-old female cub had fluid in her abdomen and her liver was hard in places. There were no signs of internal or external trauma. The final necropsy determined that lung and liver damage ultimately caused the cub’s death. Her lungs were poorly developed and likely caused her to have insufficient oxygen, which would be consistent with the changes in the liver. The mortality rate for pandas in their first year in captivity is estimated to be 26 percent for males and 20 percent for females. Some early mortality rates may be underestimated.

We are working with our colleagues in China to answer questions about giant pandas that will ensure the best care in captivity and that will help bolster the species’ numbers in the wild. The information about how this cub died will add to the scientific body of knowledge about giant pandas. The Zoo will continue to work closely with its Chinese colleagues and share the information it has learned about giant panda reproduction and cub health.

Many of you have been asking about what our plans are for Mei and Tian. No decision has been made about their future. Our current agreement with China lasts through December 5, 2015 and stipulates that the Zoo will conduct research in the areas of breeding and cub behavior. Panda fans can still watch Mei and Tian on the panda cams, which are going to slowly convert to high-definition digital cameras thanks to a donation from the Ford Motor Company Fund, every day.

We are happy to report that Mei is almost completely back to her old self! Her hormones have returned to normal levels, as has her behavior. Mei is choosing to go outside in the mornings. In the afternoons she can usually be found napping on her indoor rockwork. Mei’s appetite has also returned, and she is eating almost all of her bamboo and all of her leaf eater biscuits and produce. The David M. Rubenstein Family Giant Panda Habitat is open, and visitors can see Tian Tian and Mei Xiang outdoors and indoors, though the area directly around Mei’s den is still closed. The panda team expects that the entire David M. Rubenstein Family Giant Panda Habitat will be open soon, as Mei has not shown any sensitivity to noise lately.

Keepers cleaned the bamboo out of Mei’s den on Wednesday since she no longer spends much time there. Months ago, we installed a time-lapse camera in Mei’s den before she started building her nest in hopes that for the first time, we would have a visual record of how she built her nest. We retrieved it from the den this week. Unfortunately, we had some technical difficulties so it did not work out exactly as planned.Even though the progression is not as detailed as we would have liked, the photos still show some of Mei’s nesting. You can watch the time-lapse video made from the photos on our YouTube page.