万万想不到：竹子并非大熊猫最理想食物？！

The mystery of why giant pandas are forced to spend 14 hours a day eating foods has finally been solved - they can only digest around 17 per cent of the bamboo they swallow.

大熊猫不得不一天14个小时都在进食的谜题近日终于被解开了。它们只能消化大概17%吞食下去的竹子。

Researchers found their gut bacteria are not the type for efficiently breaking down bamboo. In fact they are built to eat meat. The giant panda actually harbours a carnivore-like gut, according to the research published in the journal mBio.

研究人员发现大熊猫体内的那种肠道细菌不能有效降解竹子。实际上它们却能消化肉食。据《mBio》期刊报导的研究称，大熊猫其实拥有与肉食者类似的肠道。

Pandas are one of the most endangered species on Earth, with only 1,600 animals left in the wild.

大熊猫是地球上最濒危的物种之一，野生大熊猫只剩下1600只。

The study's 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 specialised digestive systems to efficiently deconstruct fibrous plant matter, the giant panda still retains a gastrointestinal tract typical of carnivores.

这个研究的第一作者、中国成都大熊猫繁育基地的主任张志和说：“其他植食性动物已经进化成功，构造上有着专门的消化系统能有效地分解植物纤维，然而大熊猫和这些动物不同，它们仍保留着肉食性动物的消化道。

"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."

“大熊猫自身的基因组里还没有植物消化酶的基因。这些综合情况也许会加剧它们灭绝的危机。

Study co-author Doctor Xiaoyan Pang, 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."

这项研究的共同作者、上海交通大学生命科学与技术学院的副教授庞小燕博士指出：“这一研究结果出人意料，而且十分有趣。因为这表明大熊猫的肠道细菌也许没能很好地适应大熊猫特殊的饮食，并让大熊猫陷入进化的困境。

The researchers said that giant pandas evolved from bears that ate both plants and meat, and started eating bamboo exclusively about two million years ago.

研究人员们称，大熊猫从杂食性熊进化而来，并在大约两百万年前开始专吃竹子。

The animals spend up to 14 hours daily consuming up to 12.5 kilos (27.5 pounds) of bamboo leaves and stems, but can digest only about 17 per cent of it; their faeces is mainly composed of undigested bamboo fragments.

大熊猫每天花上14个小时消耗多达12.5公斤(27.5磅)的竹叶和竹竿，但是只能消化大概17%。它们的粪便大多由未消化的竹子残渣组成。

The researchers had been intrigued by how the animals digest bamboo fibre and extractnutrients from it.

研究人员对大熊猫怎么消化竹子纤维，从中获取营养物质很感兴趣。

The researchers found that despite their diet, the giant pandas, together with nine captive and seven wild individuals investigated previously, showed extremely low gut microbiota diversity and an overall structure that diverged from non-panda plant-eaters but was similar to carnivorous and omnivorous bears.

他们发现尽管它们的饮食如此，这些大熊猫，包括之前被研究的9只圈养大熊猫和7只野生个体，都表现出极低的肠道细菌多样性。而且它们肠道菌整体的结构不同于其他植食性动物，反而和肉食性和杂食性的熊类似。