Pandas are famously picky eaters. They only consume bamboo — a poor quality diet low in fat. But the creatures appear to have evolved to get the most out of what they do eat, according to a new study.
Their gut (肠道) bacteria change in late spring and early summer when bamboo is at its most nutritious — while protein-rich green shoots are coming out. The bacteria make the panda gain more weight and store more fat, which researchers said may compensate for a lack of nutrients later in the year, when bamboo plants have only fibrous leaves to chew.
“We've known these pandas have a different set of gut microbiota during the shoot-eating season for a long time, and it's very obvious that they are chubbier during this time of the year,” said lead study author Guangping Huang, a researcher for the Institute of Zoology at the Chinese Academy of Sciences.
To investigate how the gut bacteria could affect a panda's digestion, the team first collected the wastes of eight wild giant pandas in China's Qinling Mountains during both leaf eating season and shoot-eating season and then examined how the waste samples differed. They found a bacterium called Clostridium butyricum was more abundant in the pandas' guts during the season when they enjoy the fresh bamboo shoots.
To understand whether this bacterium helps the pandas gain and store weight, the researchers put the panda wastes they collected into lab mice. Then they fed the mice for three weeks with a bamboo-based diet that simulated (模仿) what pandas cat. Researchers found the mice Which were transplanted with panda wastes collected during shoot-eating season gained significantly more weight than the ones which were not, despite consuming same amount of food.
“The gut bacteria were the only variable (变量) in this research,” Wei explained. However, Felix Sommer at Christian-Albrechts-University in Kiel, Germany, noted the number of pandas studied was small and that the experiment had only been performed once. Sommer also stressed the researchers had found a link, not a causal relationship between the bacteria and weight gain.
