Despite its kinship with the polar or brown bear, the Panda bear he enjoys neither meat nor fish. The only thing he likes to eat is bamboo. Lots of bamboo. At certain times of the year it can feed on the buds, much more nutritious. In others, on the other hand, he has no choice but to chew his leaves. And yet it always stays on top of protein and fat.
How can an animal that only eats plants be so Fat? And, above all, how can it be that it stays that way despite the fact that its only food is scarce at certain times of the year?
Both questions, but especially the last one, have been a mystery to scientists for years. However, a study that has just been published in Cell reports hand in hand with scientists Institute of Zoology of the Chinese Academy of Sciences give an answer about it. And it seems that the key is in the bacteria that live in your intestine. The gut microbiota to the rescue of those in need. As usual.
The little varied diet of the panda bear
Is calculated that a Giant panda bear (Ailuropoda melanoleuca) You can pass between 10 and 16 hours a day eating. This is because they generally only eat bamboo, and while it is very abundant in its habitat, it needs to eat a lot.
Specifically, eat some 20 kilos a day, which is almost 14% of the weight of an adult panda. And he eats so much for two reasons.
On the one hand, to be able to stock up on nutrients. About, 100 grams of bamboo shoot, the food of the panda bear in high season, they contain 0.30 grams of fat, 2.60 grams of protein, 5.2 grams of carbohydrates, and 2.2 grams of fiber. Therefore, with 20 kilos they would be ingesting 60 grams of fat, 520 grams of protein, just over a kilo of carbohydrates and 440 grams of fiber. But in reality that is not what they take advantage of. Here comes the second reason why they eat so much: the panda bear alone take advantage of 20% of the bamboo you eat.
This is because, apparently, they are still more prepared to digest meats, such as their cousins the brown and the polar. The reason why they do not do so is well studied. Some studies suggest that they do not taste meat well, others that it is due to an abnormal functioning of the reward systems. It is not clear, but the point is that they must eat a lot of bamboo to stock up on nutrients.
Above all, it is important that they maintain that layer of fat that keeps them safe from the cold and from the scratches that are made with the bamboo canes. And for that they need to eat a lot. But they can’t always eat as much as they’d like. From late spring to summer they can eat sprouts, with all the nutritional quality mentioned, yes. However, after this time they must settle for the leaves, much less nutritious. And yet they remain strong and with that fat layer that they need so much.
Bacteria to optimize bamboo
The authors of the just published study suspected that microbiota of the panda bear could be behind the optimization of the bamboo in the changes of seasons.
It would not be the first time, since changes have been observed at different times in the colonies of bacteria that live in the intestine of other animals. For example, as explained in a release, some species of monkeys they have a different composition in their microbiota between summer, when they feed on fresh leaves and fruits, and winter, when they have no choice but to eat the bark of trees. Changes have even been observed in the microbiota of some human forager tribes, for having to adapt to the foods that predominate at each time of the year.
To find out if the same thing happened with the panda bear, they collected faeces from these animals in spring-summer or autumn-winter and carried out a fecal transplant to a group of germ-free laboratory mice. Then, for three weeks, they fed the rodents only bamboo.
After this time, the mice that had received feces from spring-summer gained significantly more weight and they had a higher proportion of fat in their bodies, compared to those who received fall-winter feces. Despite having eaten exactly the same.
It only remained to know what was in that microbiota for such tangible changes to be generated. To do this, they proceeded to analyze the feces and found that in the spring-summer season, when they fed on shoots, it was richer in a bacterium called Clostridium butyricum. And with the metabolism of this bacterium, a substance called butyrate in which the key to everything seems to be, since it upregulates the expression of a circadian rhythm gene, called Per2, which increases the synthesis and storage of lipids. That is, when butyrate is generated, the reading of the genes that carry the instructions for storing the fat that reaches the body.
Thus, that greater contribution of fats that is achieved with the sprouts will be stored for when they arrive the skinny cows in autumn-winter.
So yes, it may have been easier for the panda bear to give up vegetarianism. But, in reality, his body is very well adapted to basing his diet on bamboo. They do their part by spending half their day eating and then gut bacteria they do the rest. A great team, for sure.