Editing Giant panda (section)

===Diet===
[[File:Giant Pandas having a snack.jpg|thumb|Pandas eating bamboo]]
[[File:Pandas playing 640x480.ogv|thumb|Pandas eating, standing, and playing]]
Despite its [[taxonomy (biology)|taxonomic]] classification as a [[carnivora]]n, the giant panda's [[diet (nutrition)|diet]] is primarily [[herbivory|herbivorous]], with approximately 99% of its diet consisting of bamboo.<ref name="Britannica Earth">{{cite book|title=Earth's Changing Environment |series=Learn & Explore |publisher=Encyclopædia Britannica, Inc |year=2010 |isbn=978-1-61535-339-2 |page=[https://archive.org/details/earthschangingen0000comp/page/49 49] |url=https://archive.org/details/earthschangingen0000comp |url-access=registration}}</ref> However, the giant panda still has the digestive system of a carnivore, as well as carnivore-specific genes,<ref name=nature08696>{{Cite journal |last1=Li |first1=R. |last2=Fan |first2=W. |last3=Tian |first3=G. |last4=Zhu |first4=H. |last5=He |first5=L. |last6=Cai |first6=J. |last7=Huang |first7=Q. |last8=Cai |first8=Q. |last9=Li |first9=B. |last10=Bai |first10=Y. |last11=Zhang |first11=Z. |last12=Zhang |first12=Y. |last13= Wang |first13=W. |last14=Li |first14=J. |last15=Wei |first15=F. |last16=Li |first16 =H. |last17=Jian |first17=M. |last18=Li |first18=J. |last19=Zhang |first19=Z. |last20=Nielsen |first20=R. |last21=Li |first21=D. |last22=Gu |first22=W. |last23=Yang |first23 =Z. |last24=Xuan |first24=Z. |last25=Ryder |first25=O. A. |last26=Leung |first26=F. C. C. |last27=Zhou |last29=Sun |first29=X. |last30=Fu |first30=Y. |last28=Cao |first28 =J. |display-authors=1 |title=The sequence and de novo assembly of the giant panda genome |journal=Nature |volume=463 |issue=21 |pages=311–317 |year=2010 |pmid=20010809 |pmc=3951497 |doi=10.1038/nature08696 |doi-access=free |bibcode=2010Natur.463..311L}}</ref> and thus derives little energy and little protein from the consumption of bamboo. The ability to break down cellulose and [[lignin]] is very weak, and their main source of nutrients comes from starch and [[hemicellulose]]s. The most important part of their bamboo diet is the shoots, that are rich in starch and have up to 32% protein content. Accordingly, pandas have evolved a higher capability to digest starches than strict carnivores.<ref>{{cite journal |year=2018 |doi=10.1038/s41396-018-0051-y |title=Age-associated microbiome shows the giant panda lives on hemicelluloses, not on cellulose |last1=Zhang |first1=W. |last2=Liu |first2=W. |last3=Hou |first3=R. |last4=Zhang |first4=L. |last5=Schmitz-Esser |first5=S. |last6=Sun |first6=H. |last7=Xie |first7=J. |last8=Zhang |first8=Y. |last9=Wang |first9=C. |last10=Li |first10=L. |last11=Yue |first11=B. |last12=Huang |first12=H. |last13=Wang |first13=H. |last14=Shen |first14=F. |last15=Zhang |first15=Z. |journal=The ISME Journal |volume=12 |issue=5 |pages=1319–1328 |pmid=29391488 |pmc=5931968|bibcode=2018ISMEJ..12.1319Z}}</ref> Raw bamboo is toxic, containing cyanide compounds. Pandas' body tissues are less able than herbivores to detoxify cyanide, but their gut [[microbiome]]s are significantly enriched in putative genes coding for enzymes related to cyanide degradation, suggesting that they have cyanide-digesting gut microbes.<ref>{{cite journal |last1=Zhu |first1=L. |last2=Yang |first2=Z. |last3=Yao |first3=Ran |last4=Xu |first4=L. |last5=Chen |first5=H. |last6=Gu |first6=X. |last7=Wu |first7=T. |last8=Yang |first8=X. |title=Potential mechanism of detoxification of cyanide compounds by gut microbiomes of bamboo-eating Pandas |journal=mSphere |volume=3 |issue=3 |date=2018 |pmid=29898983 |pmc=6001608 |doi=10.1128/mSphere.00229-18}}</ref> It has been estimated that an adult panda absorbs {{cvt|54.8|–|66.1|mg}} of [[cyanide]] a day through its diet. To prevent poisoning, they have evolved anti-toxic mechanisms to protect themselves. About 80% of the cyanide is metabolized to less toxic thiocyanate and discharged in urine, while the remaining 20% is detoxified by other minor pathways.<ref>{{cite journal |doi=10.1038/srep34700 |title=Dietary resources shape the adaptive changes of cyanide detoxification function in giant panda (''Ailuropoda melanoleuca'') |year=2016 |last1=Huang |first1=H. |last2=Yie |first2=S. |last3=Liu |first3=Y. |last4=Wang |first4=C. |last5=Cai |first5=Z. |last6=Zhang |first6=W. |last7=Lan |first7=J. |last8=Huang |first8=X. |last9=Luo |first9=L. |last10=Cai |first10=Ka. |last11=Hou |first11=R. |last12=Zhang |first12=Z. |journal=Scientific Reports |volume=6 |page=34700 |pmid=27703267 |pmc=5050549 |bibcode=2016NatSR...634700H}}</ref> 

During the shoot season (April{{endash}}August), pandas store a large amount of food in preparation for the months succeeding this seasonal period, in which pandas live off a diet of bamboo leaves.<ref>{{Cite journal |last1=Huang |first1=Guangping |last2=Wang |first2=Le |last3=Li |first3=Jian |last4=Hou |first4=Rong |last5=Wang |first5=Meng |last6=Wang |first6=Zhilin |last7=Qu |first7=Qingyue |last8=Zhou |first8=Wenliang |last9=Nie |first9=Yonggang |last10=Hu |first10=Yibo |last11=Ma |first11=Yingjie |last12=Yan |first12=Li |last13=Wei |first13=Hong |last14=Wei |first14=Fuwen |date=January 2022 |title=Seasonal shift of the gut microbiome synchronizes host peripheral circadian rhythm for physiological adaptation to a low-fat diet in the giant panda |journal=Cell Reports |volume=38 |issue=3 |pages=110203 |doi=10.1016/j.celrep.2021.110203 |pmid=35045306 |issn=2211-1247|doi-access=free }}</ref> The giant panda is a highly specialised animal with unique adaptations, and has lived in bamboo forests for millions of years.<ref name=si>{{cite web |title=Giant Panda Facts |url=http://nationalzoo.si.edu/animals/giantpandas/pandafacts/default.cfm |publisher=National Zoological Park |access-date=8 June 2012 |archive-date=23 June 2012 |url-status=live |archive-url=https://web.archive.org/web/20120623163015/http://nationalzoo.si.edu/Animals/GiantPandas/PandaFacts/default.cfm}}</ref>
The average giant panda eats as much as {{cvt|9|to|14|kg}} of bamboo shoots a day to compensate for the limited energy content of its diet. Ingestion of such a large quantity of material is possible and necessary because of the rapid passage of large amounts of indigestible plant material through the short, straight digestive tract.<ref name=":0">{{Cite journal |last1=Zeng |first1=Ying |last2=Han |first2=Han |last3=Gong |first3=Yihua |last4=Qubi |first4=Shibu |last5=Chen |first5=Minghua |last6=Qiu |first6=Lan |last7=Huang |first7=Youyou |last8=Zhou |first8=Hong |last9=Wei |first9=Wei |date=2023-04-01 |title=Feeding habits and foraging patch selection strategy of the giant panda in the Meigu Dafengding National Nature Reserve, Sichuan Province, China |url=https://doi.org/10.1007/s11356-023-25769-0 |journal=Environmental Science and Pollution Research |language=en |volume=30 |issue=17 |pages=49125–49135 |doi=10.1007/s11356-023-25769-0 |pmid=36773257 |bibcode=2023ESPR...3049125Z |issn=1614-7499|url-access=subscription }}</ref><ref>{{cite journal |last1=Finley |first1=T. G.|last2=Sikes |first2=Robert S.|last3=Parsons |first3=Jennifer L. |last4=Rude |first4=Brian J. |last5=Bissell |first5=Heidi A. |last6=Ouellette |first6=John R. |title=Energy digestibility of giant pandas on bamboo-only and on supplemented diet |journal=Zoo Biology |date=2011 |volume=30 |issue=2 |pages=121–133 |doi=10.1002/zoo.20340 |pmid=20814990}}</ref> It is also noted, however, that such rapid passage of digesta limits the potential of microbial digestion in the gastrointestinal tract,<ref name=":0" /> limiting alternative forms of digestion. Given this voluminous diet, the giant panda defecates up to 40 times a day.<ref>{{Cite journal |last1=Jin |first1=Lei |last2=Huang |first2=Yan |last3=Yang |first3=Shengzhi |last4=Wu |first4=Daifu |last5=Li |first5=Caiwu |last6=Deng |first6=Wenwen |last7=Zhao |first7=Ke |last8=He |first8=Yongguo |last9=Li |first9=Bei |last10=Zhang |first10=Guiquan |last11=Xiong |first11=Yaowu |last12=Wei |first12=Rongping |last13=Li |first13=Guo |last14=Wu |first14=Hongning |last15=Zhang |first15=Hemin |date=2021-05-20 |title=Diet, habitat environment and lifestyle conversion affect the gut microbiomes of giant pandas |url=https://www.sciencedirect.com/science/article/pii/S0048969721003831 |journal=Science of the Total Environment |volume=770 |pages=145316 |doi=10.1016/j.scitotenv.2021.145316 |pmid=33517011 |bibcode=2021ScTEn.77045316J |issn=0048-9697|url-access=subscription }}</ref> The limited energy input imposed on it by its diet has affected the panda's behavior. The giant panda tends to limit its social interactions and avoids steeply sloping terrain to limit its energy expenditures.<ref name=Johnson>{{Cite news|last1=Ciochon |first1=R. L. |author-link=Russell Ciochon |last2=Eaves-Johnson |first2=K. L. |date=2007 |title=Bamboozled! The Curious Natural History of the Giant Panda Family |url=http://scitizen.com/screens/blogPage/viewBlog/sw_viewBlog.php?idTheme=27&idContribution=855 |archive-url=https://web.archive.org/web/20070721092645/http://www.scitizen.com/screens/blogPage/viewBlog/sw_viewBlog.php?idTheme=27&idContribution=855 |archive-date=21 July 2007 |access-date=22 July 2008 |periodical=Scitizen}}</ref>

Two of the panda's most distinctive features, its large size and round face, are [[adaptation]]s to its bamboo diet. Anthropologist [[Russell Ciochon]] observed: "[much] like the vegetarian gorilla, the low body surface area to body volume [of the giant panda] is indicative of a lower metabolic rate. This lower metabolic rate and a more sedentary lifestyle allows the giant panda to subsist on nutrient poor resources such as bamboo."<ref name = Johnson/> The giant panda's round face is the result of powerful jaw muscles, which attach from the top of the head to the jaw.<ref name = Johnson/> Large molars crush and grind fibrous plant material.<ref name="ng.2494">{{cite journal |vauthors=Zhao S, Zheng P, Dong S, Zhan X, Wu Q, Guo X, Hu Y, He W, Zhang S, Fan W, Zhu L, Li D, Zhang X, Chen Q, Zhang H, Zhang Z, Jin X, Zhang J, Yang H, Wang J, Wang J, Wei F |date=January 2013 |title=Whole-genome sequencing of giant pandas provides insights into demographic history and local adaptation |journal=Nature Genetics |volume=45 |issue=1 |pages=67–71 |doi=10.1038/ng.2494 |pmid=23242367 |s2cid=1261505}}</ref>

[[File:Giant Panda Eating.jpg|thumb|A panda feeding on bamboo]]
The morphological characteristics of extinct relatives of the giant panda suggest that while the ancient giant panda was omnivorous 7 million years ago (mya), it only became herbivorous some 2–2.4 mya with the emergence of ''[[Ailuropoda microta|A. microta]]''.<ref name="ng.2494"/><ref name="ReferenceB">{{cite journal |last1=Jin |first1=C. |last2=Ciochon |first2=R. L. |last3=Dong |first3=W. |last4=Hunt Jr |first4=R. M. |last5=Liu |first5=J. |last6=Jaeger |first6=M. |last7=Zhu |first7=Q. |title=The first skull of the earliest giant panda |journal=Proceedings of the National Academy of Sciences of the United States of America |date=2007 |volume=104 |issue=26 |pages=10932–10937 |pmid=17578912 |doi=10.1073/pnas.0704198104 |pmc=1904166 |bibcode=2007PNAS..10410932J |doi-access=free}}</ref> Genome sequencing of the giant panda suggests that the dietary switch could have initiated from the loss of the sole [[umami]] taste receptor, encoded by the genes [[TAS1R1]] and [[TAS1R3]] (also known as T1R1 and T1R3), resulting from two [[frameshift mutation]]s within the T1R1 exons.<ref name=nature08696/> Umami taste corresponds to high levels of [[glutamate]] as found in meat and may have thus altered the food choice of the giant panda.<ref name="pone.0022602">{{cite journal |last1=Jin |first1=K. |last2=Xue |first2=C. |last3=Wu |first3=X. |last4=Qian |first4=J. |last5=Zhu |first5=Y. |last6=Yang |first6=Z. |last7=Yonezawa |first7=T. |last8=Crabbe |first8=M. J. C. |last9=Cao |first9=Y. |last10=Hasegawa |first10=M. |last11=Zhong |first11=Y. |last12=Zheng |first12=Y. |title=Why does the giant panda eat bamboo? A comparative analysis of appetite-reward-related genes among mammals|journal=PLOS ONE |date=2011 |volume=6 |issue=7 |page=22602 |bibcode=2011PLoSO...622602J |doi=10.1371/journal.pone.0022602 |pmid=21818345 |pmc=3144909 |doi-access=free}}</ref> Although the pseudogenisation (conversion into a [[pseudogene]]) of the umami taste receptor in ''Ailuropoda'' coincides with the dietary switch to herbivory, it is likely a result of, and not the reason for, the dietary change.<ref name="ng.2494"/><ref name=nature08696/><ref name="pone.0022602"/> The mutation time for the T1R1 gene in the giant panda is estimated to 4.2 mya<ref name="ng.2494"/> while fossil evidence indicates bamboo consumption in the giant panda species at least 7 mya,<ref name="ReferenceB"/> signifying that although complete herbivory occurred around 2 mya, the dietary switch was initiated prior to T1R1 loss-of-function.<ref name=chinaflora/>

Pandas eat any of 25 bamboo species in the wild, with the most common including ''[[Fargesia dracocephala]]''<ref name=chinaflora>{{Cite book |last1=Li| first1=D.-Z. |last2=Guo |first2=Z. |last3=Stapleton |first3=C. |contribution=Fargesia dracocephala |year=2007| title=Flora of China |editor-last=Wu |editor-first=Z. Y. |editor2=Raven, P.H. |editor3=Hong, D.Y. |volume=22 |page=93 |place=Beijing |publisher=Science Press; St. Louis: Missouri Botanical Garden Press |contribution-url=http://www.efloras.org/florataxon.aspx?flora_id=2&taxon_id=200025413| access-date=7 November 2007 |archive-date=9 January 2012 |archive-url=https://web.archive.org/web/20120109002236/http://efloras.org/florataxon.aspx?flora_id=2&taxon_id=200025413|url-status=live}}</ref> and ''[[Fargesia rufa]]''.<ref name=chinaflora2>{{Cite book |last1=Li| first1=D.-Z. |last2=Guo |first2=Z. |last3=Stapleton |first3=C. |contribution=Fargesia rufa |year=2007|title=Flora of China|editor-last=Wu |editor-first=Z. Y. |editor2=Raven, P.H. |editor3=Hong, D.Y. |volume=22 |page=81|place=Beijing |publisher=Science Press; St. Louis: Missouri Botanical Garden Press |contribution-url=http://www.efloras.org/florataxon.aspx?flora_id=2&taxon_id=200025444| access-date =7 November 2007| archive-date =10 November 2016| archive-url =https://web.archive.org/web/20161110092337/http://www.efloras.org/florataxon.aspx?flora_id=2&taxon_id=200025444| url-status =live}}</ref> Only a few bamboo species are widespread at the high altitudes pandas now inhabit. Bamboo leaves contain the highest protein levels; stems have less.<ref>{{cite web |url=http://lrrd.cipav.org.co/lrrd4/2/dolberg.htm|title=Progress in the utilization of urea-ammonia treated crop residues: biological and socio-economic aspects of animal production and application of the technology on small farms |last=Dolberg |first=F. |date=1992 |publisher=University of Arhus|access-date=10 August 2010|archive-date=7 July 2011|archive-url=https://web.archive.org/web/20110707053325/http://lrrd.cipav.org.co/lrrd4/2/dolberg.htm|url-status=live}}</ref> Because of the synchronous flowering, death, and regeneration of all bamboo within a species, the giant panda must have at least two different species available in its range to avoid starvation. While primarily herbivorous, the giant panda still retains decidedly ursine teeth and will eat meat, fish, and eggs when available. In captivity, zoos typically maintain the giant panda's bamboo diet, though some will provide specially formulated biscuits or other dietary supplements.<ref>{{harvnb|Lumpkin|Seidensticker|2007|pp=63–64}} (page numbers as per the 2002 edition)</ref>

Pandas will travel between different habitats if they need to, so they can get the nutrients that they need and to balance their diet for reproduction.<ref>{{Cite journal |last1=Ma |first1=Ying-Jie |last2=Wang |first2=Meng |last3=Hu |first3=Xiao-Yu |last4=Gu |first4=Xiao-Dong |last5=Li |first5=Yu-Mei |last6=Wei |first6=Fu-Wen |last7=Nie |first7=Yong-Gang |date=2023 |title=Identifying priority protection areas of key food resources of the giant panda |url=https://www.zoores.ac.cn/en/article/doi/10.24272/j.issn.2095-8137.2022.526.pdf |journal=Zoological Research |language=en |volume=44 |issue=5 |pages=860–866 |doi=10.24272/j.issn.2095-8137.2022.526 |issn=2095-8137 |pmc=10559099 |pmid=37537140}}</ref>