Panda bears are known for their appetite for bamboo. These creatures spend up to 14 hours a day eating as much as 27 pounds of this grass.

New research, however, suggests why these cuddly animals munch too much bamboo: they are not good at digesting it.

In a new study published in the journal mBio on May 19, researchers have found that pandas have microbes that are more similar to those of omnivores and carnivores than those of herbivores.

The animal, in fact, lacks the particular bacteria associated with breaking down cellulose, a component of the cells of plants that makes plant materials difficult for omnivores to break down. The scientists calculated that despite the amount of bamboo that pandas consume, they can only digest about 17 percent of what they eat.

For the study, researchers in China looked at the gut microbiome of pandas by sequencing ribosomal RNA in the feces of 45 of these animals then compared this to those of other mammals such as horses, lions, bears and kangaroos.

The results revealed that there is little diversity in the microorganisms living in the gut of pandas and that there is none of the cellulose-degrading bacteria often seen in herbivorous animals. The researchers instead found that the gut of pandas were dominated by Streptococcus and Escherichia/Shigella typically seen in carnivores.

Study author Zhihe Zhang, from the Chengdu Research Base of Giant Panda Breeding in China, said that the animals' genomes do not have the genes for plant-digesting enzymes and this possibly increased the risk of the panda for extinction.

"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," said study co-author Xiaoyan Pang, from Shanghai Jiao Tong University.

The giant panda is one of the most threatened animals in the world. With only 1,826 pandas in the wild, the animal is considered endangered. Current efforts to protect the giant pandas include patrolling against illegal logging, poaching and encroachment; increasing the area of the animal's habit that is placed under legal protection; and continued research and monitoring.

A survey conducted by the Chinese government suggests that conservation efforts are working. The number of wild pandas grew by almost 17 percent over the last decade. In 2003, there were only 1,596 wild giant pandas.

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