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Pandas spend a lot of time eating due to their low efficiency in digesting cellulose from bamboo. Adding cellulase to their food, or feeding cellulase in between meals, could surely make the process more efficient. Why isn’t that done?

According to this study conducted in India, lactase supplements in humans have decreased indicators of lactose intolerance in lactose-intolerant individuals.

While this does not suggest a direct link with the main question, one may see how a similar cellulase supplement may allow captive pandas to better digest cellulose and thus, devote their time to other tasks.

Ref:

  • Baijal R, Tandon RK. Effect of lactase on symptoms and hydrogen breath levels in lactose intolerance: A crossover placebo-controlled study. JGH Open. 2020 Dec 1;5(1):143-148. doi: 10.1002/jgh3.12463. PMID: 33490624; PMCID: PMC7812489.
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    $\begingroup$ Do you know if adding lactase to milk works? If it doesn't, would that make you rethink the benefit of adding cellulase to a panda's diet? $\endgroup$
    – anongoodnurse
    Commented Aug 4 at 13:52
  • $\begingroup$ As I imagine nobody on this list is involved in feeding pandas, I think the use of “We” is unfortunate. I realize that it is a style of popular scientific writing, but I think the passive is preferable, even if it is more difficult for non-native speakers of English. I have done this for you. $\endgroup$
    – David
    Commented Aug 4 at 19:39
  • $\begingroup$ @anongoodnurse Lactase certainly seemed to help my children when very young - an almost overnight change in feces consistency, gas production etc. Part of the problem is that a lot of people conflate a dairy allergy (i.e. to what is presumably cow allergens of some sort) with lactose intolerance. The response in people who cut out dairy while breast feeding proves for many the response is not due to lactose because it won't make it out of the gut into the breast milk anyway and human milk naturally has more lactose than cow. $\endgroup$
    – bob1
    Commented Aug 4 at 22:19
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    $\begingroup$ @anongoodnurse Yeah, that's why I put "seemed" Could have been developmental stage - they are fine with milk now, level of intolerance, all sort of factors come into it. I wonder if pediatric studies have been done... off to PubMed I go... $\endgroup$
    – bob1
    Commented Aug 4 at 22:58
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    $\begingroup$ @anongoodnurse My guess is that stomach acid, similar to how bromelin works, deactivates lactase somehow. Then again, pandas don't have the same digestive system as humans (I would assume), so perhaps enzyme supplementation in pandas may work differently from humans. $\endgroup$
    – Critical Mass
    Commented Aug 5 at 1:32

1 Answer 1

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Most mammalian herbivores have digestive tracts that are highly specialized for digesting cellulose. For example, ruminants (including cattle) have a special stomach (rumen) that harbors microbes that can break down the cellulose in the cell walls of their food. This way, these herbivores can get a lot of energy out of the cell walls of the plants in their diet.

Giant pandas are different. They're evolved from weasel-like carnivorous animals, and therefore have digestive systems that resemble those of carnivorous mammals more than those of other herbivores. They don't have enough microbial activity in their guts to break down cellulose appreciably. Since they get very little energy from the cells walls of the plants in their diet, they instead get most of their nutrition from the cell contents of the plants. They have several adaptations1 that allow them to be able to get enough nutrition from just the cell contents:

  • They have very strong jaws and spend a lot of time chewing their food, which exposes the cell contents.
  • They eat a ridiculous amount of bamboo, so even though they can only digest a small portion of their food, they still get sufficient nutrition overall.
  • To be able to eat so much, bamboo has a very short residence time in their digestive system (~8 hours).

Because of these adaptations, giant pandas can get all the nutrition they need from bamboo without cellulase supplements.

And even if it were possible to reduce the time a captive panda spent eating bamboo, what would be the point? In captivity, there's not a whole lot else they have to do than eat.

And there might be risks involved with cellulase supplementation. It could result in large increase in the amount of glucose and oligosaccharides in the digestive tract and that the panda is absorbing, which we don't know the effects of. Running a study on that would be difficult (there aren't a whole lot of giant pandas around, and getting permission to manipulate individuals of endangered species is difficult), so without a compelling reason to pursue it, it hasn't happened.



1 Dierenfeld ES, Hintz HF, Robertson JB, Van Soest PJ, Oftedal OT. Utilization of bamboo by the giant panda. J Nutr. 1982 Apr;112(4):636-41. doi: 10.1093/jn/112.4.636. PMID: 6279804.

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  • $\begingroup$ Thank you for the response. In captivity, breeding will be encouraged in their spare time. In addition, going along the line of efficiency, perhaps it could be possible to allow pandas to survive while eating less bamboo than they currently do. I agree with the need for such studies, and hope that other more established scientists can ask similar questions as I have. $\endgroup$
    – Critical Mass
    Commented Aug 9 at 21:26
  • $\begingroup$ That being said, I would summarize your response as follows: herbivore mammals can digest cellulose well, pandas can't, they adjusted using XYZ adaptions, cellulase supplementation is ostensibly not needed and has not been tested yet. Are there reasons other than it being difficult to test upon pandas, that such cellulase supplementation has not been attempted? $\endgroup$
    – Critical Mass
    Commented Aug 9 at 22:57
  • $\begingroup$ ncbi.nlm.nih.gov/pmc/articles/PMC6184034 I have only skimmed through this article, but similar experiments as proposed have been done on chickens. The effect was positive, allowing higher nutrient absorption from relatively low nutritional value grains. One may see how a similar experiment on pandas can be done with ample scientific purpose, most notably to decrease panda consumption of bamboo so that their maintenance cost can be decreased and to allow panda survival even in a season of bamboo paucity. $\endgroup$
    – Critical Mass
    Commented Aug 9 at 23:03
  • $\begingroup$ @YoungJunLee Feed for industrial chicken farming is designed to maximize chicken growth with little regard for the health or wellbeing of the animals. Presumably, that's not what we want for giant pandas in captivity. Also, chickens aren't really adapted to eat a diet of mostly grain, which is what industrial farms feed them. Pandas are adapted to eat a diet of mostly bamboo. $\endgroup$
    – Eonema
    Commented Aug 10 at 1:08
  • $\begingroup$ @YoungJunLee It's also possible that the answer to your original question is that no one has thought of it. You'd have to ask someone actually involved with keeping giant pandas to get the exact reason. I just gave some reasons why it might not be necessary or safe based on what I know of nutrition and zoology. $\endgroup$
    – Eonema
    Commented Aug 10 at 1:13

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