Now our research has found that they can cope with this low-quality diet because they have an extremely slow metabolic rate. The report states: “These reduced organ sizes likely contribute to their low energy demands”. As for the mean value derived from the investigation of wild pandas, the researchers found that the animals expended 6.2 megajoules per day, which can be translated to approximately 45 percent of the expected number for these animals. There are many, and justified, hurdles to jump to do scientific work on animals in general, but they are even higher when it comes to pandas. However, we are slowly starting to fill in these gaps. Pandas have the shortest gestation period among all bears – only 2-3 months in comparison with six months for others. The giant bears are more like giant reptiles, the study found. For example, in spring when pandas’ mating season takes place they eat young wood bamboo shoots rich on nitrogen and phosphorous. That implies as many as 15 hours of spent eating. So they have to eat lots of it, perhaps as much as 10-20kgs per day.
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“It is my long-time dream to accomplish this fascinating study to understand how low the giant panda metabolism would be, and why the giant pandas can survive on their specialized and low quality bamboo diet”. The leader of the study was scientist Fuwen Wei who measured how much energy pandas consumed. The researchers examined three wild pandas from the Foping Nature Reserve in Shaanxi province, and five specimens living in captivity in the Beijing Zoo.
One big problem with having such a low metabolic rate is keeping warm. Corrected for their body weight of about 92kg (203lbs), it is substantially lower than nearly all other mammals.
The paper was published in the journal Science. The researchers believe that pandas’ small size of internal organs such as liver, brain and kidneys has the same function. They also determined their laziness comes from poor thyroid hormone development.
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Their thyroid hormone levels “are only a fraction of the mammalian norm – comparable to a hibernating black bear’s hormone levels”, added the study, which identified a gene variation in pandas that matches one seen in humans with underactive thyroids. The giant pandas’ energy measurements “are among the lowest, relative to body mass, ever made” for mammals not in torpor, which is sort of like suspended animation, the authors write.
