DeHua Wang

Science China Life Sciences

Crossref

Low daily energy expenditure enables giant pandas to survive on bamboo

Springer - Publisher Connector

SCIENCE CHINA 
Life Sciences 
© The Author(s) 2015. This article is published with open access at link.springer.com life.scichina.com   link.springer.com 
                  
*Corresponding author (email:wangdh@ioz.ac.cn) 
• RESEARCH HIGHLIGHT • September 2015  Vol.58  No.9: 925–926 
 doi: 10.1007/s11427-015-4917-1 
Low daily energy expenditure enables giant pandas 
to survive on bamboo 
WANG DeHua* 
State Key Laboratory of Integrated Management of Pest Insects and Rodents, Institute of Zoology, Chinese Academy of Sciences, 
Beijing 100101, China 
Received August 9, 2015; accepted August 17, 2015; published online August 26, 2015 
 
Citation:  Wang DH. Low daily energy expenditure enables giant pandas to survive on bamboo. Sci China Life Sci, 2015, 58: 925–926, 
doi: 10.1007/s11427-015-4917-1 
 
 
 
Giant pandas (Ailuropoda melanoleuca) belong to the bear 
family (Urisidae) within the order Carnivora and specialize 
on a diet of bamboo, but still retain a typical carnivoran 
gastrointestinal tract. Consequently, they have a very low 
energy digestive efficiency (9.5%–34%) if fed only bamboo 
in captivity. The property of metabolic physiology of giant 
pandas is an interesting question. McNab [1] wrote in his 
new book Extreme Measures that “basal metabolic rate 
(BMR) of the giant panda, a semi-arboreal, bamboo-eating 
bear, has not been measured, but given its habits, it un-
doubtedly has a BMR that is appreciably less than expected 
from (body) mass. Its basal rate is possibly similar to, or 
less than, that found in the sloth bear (Melursus ursinus), 
which feeds heavily on termites and has a basal rate equal to 
80% (of expected). The sloth bear, and presumably the giant 
panda, differ in energetics from other bears such as omniv-
orous black (Ursus americanus) and brown bears (Ursus 
arctos), and strictly carnivorous polar bears”. Because of 
their special position in both conservation and culture, the 
physiology of giant pandas is no doubt of interest to many 
animal physiologists. Surprisingly there are no available 
data about their basal metabolism, although several papers 
stated their special digestive physiological function, such as 
the ability to digest fiber [2], but the role of gut microbiota 
is still unclear. It has been found that the gut microbiota of 
giant panda and red panda (Ailurus fulgens, also carnivo-
rous but eating bamboo), diverged rather than converged 
based on the same diet, and the bacterial taxa between giant 
and red pandas are different [3]. 
Scientists have long speculated that to survive on bam-
boo, which is such a low quality food, giant pandas should 
have a low rate of metabolism. It has been reported, by us-
ing remote radar technology to get heart rate, which is often 
closely related to oxygen consumption, that giant pandas 
might exhibit hypometabolism during sleep for energy con-
servation. Giant pandas have heart rates lower than captive 
black bears and brown bears during a time of seasonal leth-
argy after adjustment for body mass. According to calcu-
lated levels of metabolic depression, giant pandas lower 
metabolism on a daily basis to levels similar to those of 
black and brown bears during their seasonal lethargy [4]. 
McNab [5] has measured the basal rate of the red panda and 
found that their basal rate was equal to 49% of the value 
expected from mass, which undoubtedly reflects its bamboo 
diet and possibly its arboreal habits. He estimated the basal 
rate of giant pandas according to the equation for 62 car-
nivorans that the expected basal rate is 59% of the value 
expected from body mass for a giant panda with body mass 
of 120 kg.  
Recently in a collaboration between scientists from the 
Institute of Zoology and the Institute of Genetics and De-
velopmental Biology of the Chinese Academy of Sciences, 
and Beijing Zoo, new findings and advances on the ener-
getics and physiology of giant pandas were published in 
Science [6]. They applied the doubly-labelled water method 
to measure the daily energy expenditure (DEE) of five cap-
tive pandas and three wild pandas. Results showed that 
pandas have substantially lower DEE than almost all other 
926 Wang DH   Sci China Life Sci   September (2015) Vol.58 No.9 
mammals after correction for their body weight, which is 
38% of the predicted values of the mammals (45% for wild 
pandas). 
They tried to give the reasons to explain the low DEE 
from several aspects including anatomical, behavioural, 
physiological, and even genetical factors. Giant pandas can 
achieve this exceptionally low expenditure in part by re-
duced sizes of several vital organs and low physical activi-
ties. By using historical autopsy data they found that pandas 
have small vital organs such as brain, liver and kidneys 
which can make great contributions to BMR, for their body 
size. Their brains are 82% of the expected size, kidneys 
75% and livers 63% of the expected size. Minimizing the 
time spent in and intensity of physical activity can also con-
tribute to reducing DEE. They obtained the activity data for 
captive pandas by direct observation and by using global 
positioning system (GPS) and direct observations for wild 
pandas. In captivity, the pandas spent 33% of their time in 
physical activity, and in the wild 49% of their time was de-
voted to physical activity. For wild pandas, the mean 
movement speed was only 26.9 m per hour. Giant pandas 
maintain high body temperature and do not engage in torpor 
or hibernation. They proposed that pandas have a deep pel-
age able to trap their meagre body heat. Supporting this idea 
the lateral surface temperatures of pandas are significantly 
lower than those of zebras, dairy cattle and domestic dogs. 
Circulating levels of thyroid hormones thyroxine (T4) and 
triiodothyronine (T3) averaged 46.9% and 64% respectively 
of the levels expected for a eutherian mammal based on 
their body size. After comparing the panda genome with the 
genomes of five other carnivorans, as well as mouse and 
human, they found a unique variation in the dual oxidase 
two gene (DUOX2) in the panda which results in a prema-
ture stop protein and probably a truncated non-functional 
protein. DUOX2 encodes a transmembrane protein that cata-
lyzes the conversion of water to hydrogen peroxide, which is 
used in the final step of T4 to T3 synthesis. From their study 
and interpretation, we can see a suite of morphological, be-
havioral, physiological, and genetic adaptations, leading to 
the low energy expenditure, which likely enables giant 
pandas to survive on a bamboo diet. This is a nice integra-
tive research on animal conservation and zoology. 
Although scientists have studied extensively on the biol-
ogy, behavior and conservation of giant pandas, we still 
need more new information about their physiology, ecology 
and evolution. It has been shown in other species that BMR 
is positively related to DEE or sustainable maximum energy 
intake rate: the higher BMR, the higher DEE or sustainable 
energy intake. Therefore trying to measure the BMR is nec-
essary to fully understand the thermoregulatory physiology 
of giant pandas. It would be useful to establish the relation-
ship between thyroid hormones and BMR. One possibility  
would be a manipulation experiment such as adding thyroid 
hormones in the food or drink and see the changes in BMR, 
DEE or food intake, which would be helpful to clarify the 
roles of thyroid hormones. Further, it has been predicted 
that species with high BMR (mass-independent) probably 
showed more competitive and high population numbers. If 
this applied to giant pandas, is there a possibility that low 
BMR is one of the reasons to constrain population increase 
in wild pandas? We are also interested in the questions such 
as the population energy use of wild pandas and, as carni-
vores, what is their ecological role and how they interact 
with other species within the community. Size of organs 
contributes to the changes in body size. They suggested that 
small organ size is a reason to decrease DEE. Giant pandas 
live in mountain areas in nature, and the reproductive sea-
son is relatively cold. We can predict that small body size 
can increase thermal conductance (mass-specific). Low am-
bient temperature can increase the cost of living for giant 
pandas. Further, organ or tissue metabolic properties of mi-
tochondria (if there are opportunities to measure), such as 
mitochondria protein contents and cytochrome c oxidase 
activity, can provide a more comprehensive message. Fi-
nally, global warming can affect the growth of bamboo and 
consequently the life of cool giant pandas physiologically. 
More data are needed for understanding the effect of global 
warming on their physiological functions, behaviors, and 
geographic distribution. Many questions and mechanisms 
about giant panda physiology are still waiting for answers. 
New approaches of conservation physiology may help get 
new information, especially for wild pandas.  
Thanks to Professor Speakman John R, Institute of Genetics and Develop-
mental Biology of CAS, and Professor Wei Fuwen, Institute of Zoology, 
CAS, Professor McNab Brain K, Department of Zoology, University of 
Florida, and Drs. Zhang Xueying, Chi Qingsheng, and Xin Xing, and Xu 
Mengmeng, Institute of Zoology, CAS, for reading the draft and their help-
ful comments and suggestion.  
1 McNab BK. Extreme Measures: the Ecological Energetics of Birds 
and Mammals. Chicago: The University of Chicago Press, 2012 
2 Zhu LF, Wu Q, Dai JY, Zhang SN, Wei FW. Evidence of cellulose 
metabolism by the giant panda gut microbiome. Proc Natl Acad Sci 
USA, 2011, 108: 17714–17719 
3 Li Y, Guo W, Han SS, Kong FL, Wang CD, Li DS, Zhang HM, Yang 
MY, Xu HL, Zeng B, Zhao JC. The evolution of the gut microbiota 
in the giant and the red pandas. Sci Rep, 2015, 5: 10185 
4 Finley TG. Giant pandas balance energy budgets with metabolic de-
pression: insights from radar detection of heart rates. Doctor Disser-
tation. Little Rock: University of Arkansas at Little Rock, 2007 
5 McNab BK. Ecological factors influence energetics in the order Car-
nivora. Acta Zoologica Sin, 2005, 51: 535–545 
6 Nie YG, Speakman JR, Wu Q, Zhang CL, Hu YB, Xia MH, Yan L, 
Hambly C, Wang L, Wei W, Zhang JG, Wei FW. Exceptionally low 
daily energy expenditure in the bamboo-eating giant panda. Science, 
2015, 349: 171–174 
 
Open Access This article is distributed under the terms of the Creative Commons Attribution License which permits any use, distribution, and reproduction 
in any medium, provided the original author(s) and source are credited. 


file:///data/remote/core/dit/data/Springer-OA/pdf/27c/aHR0cDovL2xpbmsuc3ByaW5nZXIuY29tLzEwLjEwMDcvczExNDI3LTAxNS00OTE3LTEucGRm.pdf

Low daily energy expenditure enables giant pandas to survive on bamboo

Abstract

Similar works

Full text

Available Versions

Crossref

Springer - Publisher Connector

Springer - Publisher Connector