PULLMAN – Bears are neither cats nor dogs, and feeding them as they are probably shortens their lives.
A new study published in Scientific Reports on the diets of giant pandas and sloth bears adds more evidence that bears are omnivores like humans and need far less protein than they’re typically fed in zoos.
“Bears are not carnivores in the strict sense like a cat where they consume a high-protein diet,” said lead author Charles Robbins, professor of wildlife biology at Washington State University. “In zoos forever, whether it’s polar bears, brown bears or sloth bears, the recommendation has been to feed them as if they were protein-rich carnivores. When you do that , you kill them slowly.
In separate experiments, the researchers presented captive giant pandas and sloth bears at different US zoos with unlimited food of different types to see their preferences, then recorded the nutrient profiles of their choices.
In collaboration with researchers from Texas A&M University and the Memphis Zoo, feeding trials were conducted with a pair of giant pandas to measure their bamboo selection. They found that the giant pandas preferred the carbohydrate-rich bamboo culm found in the woody stems, to the more protein-rich leaves. At times, they consumed almost exclusively thatch – for example 98% of the time in March. The researchers also analyzed data from five Chinese zoos that had giant pandas that had successfully bred and returned to high-carb, low-protein diets.
In a series of feeding trials, six sloth bears from Cleveland, Little Rock and San Diego zoos were given ad libitum avocados, baked yams, whey and apples. They chose high-fat avocados almost exclusively, eating about 88% avocados to 12% yams — and ignoring all apples. This showed that sloth bears preferred a high-fat, low-carb diet, which may have a similar composition to their wild diet of termites and ants as well as their eggs and larvae.
It is also very different from the high carbohydrate diet they usually receive in captivity. Sloth bears, which are native to India, typically only live about 17 years in US zoos, nearly 20 years less than the maximum lifespan achievable in human care. Their most common cause of death is liver cancer.
The researchers found a similar pattern in previous studies of polar bears which showed that captive polar bears, which are normally fed a high-protein diet, would mimic the high-fat diet of wild polar bears if given any. the possibility. Polar bears in zoos typically die about 10 years earlier than they should, most often from kidney and liver disease. Both of these diseases can develop from long-term inflammation of these organs, potentially caused by many years of an unbalanced diet.
The current study, along with previous ones, also shows that when bears in captivity are given food options, they choose foods that mimic the diet of wild bears.
“There’s definitely this long-held idea that humans with PhDs know a lot more than a sloth bear or a brown bear,” Robbins said. “All of these bears started to evolve about 50 million years ago, and when it comes to this aspect of their diet, they know more than we do. We’re one of the first to want to ask the bears: what do you want to eat, what makes you feel good?
Robbins, the founder of the WSU Bear Center, the only research institution in the United States with a captive grizzly bear population, has studied bear nutrition for decades. He and his graduate students began investigating their unbalanced diet during a study in Alaska, watching grizzly bears eat salmon. At the time, researchers speculated that the notoriously voracious bears would gorge on salmon, sleep, get up and eat more salmon.
Instead, they saw the bears eat salmon, but then wander off and spend hours finding and eating small berries. Seeing this, Robbins’ lab began studying the diet of grizzly bears housed at the Bear Center and found that they gained the most weight when fed a combination of protein, fats and carbohydrates in a combination. of salmon and berries.
All eight types of bears, or ursids, had a carnivorous ancestor but have since evolved to eat a wide range of food, giving them the ability to spread to more areas without directly competing with resident carnivores.
“It opens up so many more food resources than just being a high-protein hetero carnivore,” Robbins said.