We’ve gotten comfortable with the idea that panda bears eat massive amounts of bamboo. Curiously, though, giant pandas cannot properly digest bamboo and are therefore forced to spend more than 14 hours daily consuming the plant.
Panda bears are actually poorly adapted for bamboo digestion.
A research team concluded that the black-and-white furry beasts are only capable of digesting a small portion of the total amounts of bamboo they ingest. In fact, only 17 percent of the plant is actually digested.
This nigh-horrible digestion rate traces back to the panda bear’s gut bacteria profile. Scientists showed that the beloved bears have too few bacteria in their stomach and intestines in order to properly digest the plants they ingest.
Bamboo, a fibrous plant, takes longer to break down and the specific bacteria types harboured in the panda bear’s digestive tract (mostly Shigella, Streptococcus and Escherichia) are better suited to help with meat digestion.
Approximately seven million years ago, ancient giant pandas began incorporating bamboo into their diets. However, they still remained carnivorous until 2 million years ago, when they became herbivores.
The research team’s investigations showed that despite millions of years of evolution, panda bears are still mostly carnivorous when it comes to their gut bacteria profiles. That’s precisely why the wondrous creature spends the majority of its waking time eating.
“The giant panda still retains a gastrointestinal tract typical of carnivores,” Zhihe Zhang, lead author said in a statement.
According to Mr. Zhang, panda bears have failed to do what other animals have succeeded: despite two million years of evolution, pandas haven’t developed a plant-eating-ready digestive system. As such, they cannot efficiently deconstruct the fibers in the plants they eat because they lack a plethora of digestive enzymes.
Gut Bacteria Particularities in Panda Bears
After analyzing the specifics of panda bear’s gut bacteria by carrying out genetic testing on fecal samples from 45 healthy pandas, the team moved on to panda cubs. They collected 112 samples in total, from adults, juveniles and cubs.
The pandas involved in the study (excepting the cubs, which were still breastfed) averaged approximately 22 pounds of bamboo and 1.7 pounds of steamed bread daily.
Despite these enormous quantities, the research team found high amounts of undigested plant fragments in the animals’ feces.
Specific bacteria responsible for plant digestion (such as Bacterioides and Ruminococcaceae) were absent in the collected samples. Variations were present, though, depending on season.
This unique digestive strategy may or may not work in the panda’s favor. The upside, though, is that this peculiar animal is capable of dealing with large volumes of food in short amounts of time.
Scientific literature is clear on the issue. Several studies have already proven that 92 percent of the cellulose and over 70 percent of the hemicellulose that panda bears ingest passes right through the animal’s digestive tract without being digested.
There are some variations between the diets and lifestyles of wild and captive pandas. However, the difference in diet did not translate into gut bacteria differences.
The scientists concluded that panda bears actually lie at a one-of-a-kind evolutionary dilemma. Because they lack the specific genes which carry the code for plant-digesting enzymes and because the panda bear’s gut microbial profiles haven’t adapted to this plant-based diet, the animal may be closer to extinction than previously believed.
There are currently fewer than 2,500 adult pandas left in the wild, so that giant pandas actually figure as endangered on the International Union for Conservation of Nature’s list. In captivity, there are approximately 300 pandas, although a steep decline has been reported by the IUCN in both wild and captive populations.
Whether the panda’s specific reproductive patterns reflect its digestive particularities remains to be seen. Female pandas are only capable of ovulating once every year. Moreover, there’s a very short fecundation window so that conception is a rare occurrence.
Scientists have postulated that this specific succession of ovulation, conception and implantation may be a result of the variation in nutrients found in bamboo plants.
Future research is necessary, the team explains, in order to gain more insight into this matter. Understanding how the gut microbiota influences the bear’s health and nutrition is one of the key targets of the team’s follow up work.
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