Bears are not pure carnivores

A new study adds to the growing body of evidence that bears are not carnivores.

The research findings suggest that bears are omnivores like humans – even when they are fed a protein-rich diet like carnivores in captivity.

«Bears are not carnivores in the strict sense like cats, which consume a protein-rich diet«, said the lead author of the study. «Zoos have long been advised to feed polar bears, brown bears, or sloth bears as though they were protein-rich carnivores. If you do that, you are slowly killing them».

The WSU Bear Center is the only research facility in the United States with a captive grizzly bear population. Professor Robbins, who founded the centre, has been studying bear nutrition for decades. In an earlier project, he and his students discovered that grizzly bears gain the most weight when fed a combination of proteins, fats, and carbohydrates.

For the latest study, the researchers examined the dietary preferences of captive giant pandas and sloth bears by conducting feeding studies. In human care, sloth bears die up to 20 years earlier, and there are few data on their nutritional needs. One theory holds that the bears are being fed too much protein, which leads to cancer and disease.

«The consumption of feed with unsuitable macronutrient profiles has been linked to increased energy expenditure, poor health, failure to reproduce, and premature death, the authors of the study write.

«We found that giant pandas are omnivores with low protein and high carbohydrate content, while sloths are omnivores with low protein and high fat content. The preference for a low-protein diet apparently developed early in the evolution of the primeval animals and may have been crucial to their worldwide distribution.«

When sloths were offered unlimited avocados, baked sweet potatoes, whey, and apples, they preferred almost exclusively the fat-rich avocados. This high-fat, low-carbohydrate diet resembles their wild diet of termites and ants as well as their eggs and larvae, according to the researchers.

The researchers also found that giant pandas prefer the carbohydrate-rich bamboo culms found in the woody stems over the more protein-rich leaves. The results of the study suggest that the bears know what they need to eat to maximize their health and fitness.

«There is certainly this long-held notion that people with doctoral degrees know far more than a sloth or a brown bear«, said Robbins. «All of these bears evolved about 50 million years ago, and when it comes to this aspect of their diet, they know more than we do. We are among the first willing to ask the bears: What do you want to eat? What makes you feel comfortable?«