Scientists investigating why giant pandas have to spend 14 hours a day eating have finally found an answer.
As it turns out, giant pandas only digest approximately 17% of the bamboo that they swallow, because their gut does not contain bacteria which are effective in breaking down plant material. Giant panda guts are in fact better suited to a diet of meat, writes Sarah Knapton for The Telegraph.
Panda gut similar to carnivorous bears
Research published in the journal mBio claims that the gut of a giant panda is actually similar to that of a carnivorous animal. Scientists claim that the giant panda in fact struggles to properly digest its food.
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There are only 1,600 pandas left in the wild, making the species one of the most endangered on Earth. Study lead author Zhihe Zhang, director of the Chengdu Research Base of Giant Panda Breeding in China, said: “Unlike other plant-eating animals that have successfully evolved, anatomically specialized digestive systems to efficiently deconstruct fibrous plant matter, the giant panda still retains a gastrointestinal tract typical of carnivores.”
Zhang says that the animals “also do not have the genes for plant-digesting enzymes in their own genome. This combined scenario may have increased their risk for extinction.”
Doctor Xiaoyan Pang, co-author of the study and an associate professor in the School of Life Sciences and Biotechnology at Shanghai Jiao Tong University, said: “This result is unexpected and quite interesting, because it implies the giant panda’s gut microbiota may not have well adapted to its unique diet, and places pandas at an evolutionary dilemma.”
Sequencing shows ill-adapted gut
According to the researchers, giant pandas are evolved from bears that ate a mixed diet, while pandas switched to an exclusive diet of bamboo around 2 million years ago.
Despite the fact that they spend 14 hours a day eating up to 12.5 kilos of bamboo, pandas only digest 17% of that. The majority of material in their stools is in fact undigested bamboo fragments.
In order to evaluate the gut microbiota of pandas, scientists used a lab technique known as 16S rRNA sequencing on 121 fecal samples from 45 giant pandas. Findings showed that the giant pandas had extremely low gut microbiota diversity, and the overall structure of the gut was similar to carnivorous and omnivorous bears.
No evidence was found of plant-degrading bacteria like Ruminococcaceae and Bacteroides which are commonly found in other herbivores. The fact that gut microbiota varied by season could be explained by the lack of bamboo shoots in late autumn, and a follow-up study is being planned.