High protein diet may harm polar bears

A high-protein diet appears to be linked to kidney disease and shorter lifespans for polar bears in captivity, a relationship that is also suspected in humans, according to a review led by U.S. State University wildlife biologist of Washington, Charlie Robbins.

The article, published in zoo biologytakes a closer look at what zoos have fed polar bears and reveals that they were mostly fed a diet intended for big cats, containing around 2-3 parts protein to 1 part fat, a reversal of what observed in nature.

“Zoos have made some assumptions in the past about the nutritional requirements of polar bears because their diet is almost exclusively animal,” said Robbins, professor and founder of the WSU Bear Center. “But unlike cats, they don’t need and can’t tolerate high protein.”

Polar bears feed almost exclusively on seals and are classified as carnivores. But recent research has shown that polar bears, like other bears, have nutrition and physiology more akin to primates, including humans.

Earlier field studies led by Karyn Rode, a former WSU Bear Center graduate student now with the US Geological Survey, showed that wild polar bears preferentially consume a diet consisting of 2 parts fat to 1 part protein, which that keeps your protein levels within the low range of your requirements. These findings were published in scientific reports in July 2021.

“Although we knew that polar bears selected for fat from their prey, this was the first time we were able to quantify how much fat they actually consumed,” Robbins said. “When it comes to feeding polar bears, the general mindset has been that they are carnivores. No one has really paid attention to how much protein they might need, much less the limitations on how much they might tolerate.”

In the current article, the researchers propose that both polar bears and their closest relative, the grizzly bearrequire relatively low levels of protein similar to the requirements of humans, primates and other omnivorous species.

When the captive bears were offered blocks of pure lard and blocks of high-protein meat, they preferentially chose the same ratio of fat to protein that they would normally consume in the wild.

A careful examination of death records for captive polar bears of both sexes clearly showed that the most common cause of death was the kidney. illness. Bears that die with kidney disease die 10 years sooner than bears without kidney disease kidney illness. Liver disease and cancer were the second most common causes of death.

Of more than 600 wild bears examined, the team found no evidence of liver or nephropathy.

“A list of early deaths between the sexes that is limited to two major organs raised several red flags for us,” said Robbins, who has researched the nutrition of brown and polar bears for more than 35 years.

The team has worked with Mazuri Exotic Animal Nutrition and its nutritionist, Troy Tollefson, who also earned his Ph.D. while working at the WSU Bear Center, to develop a dry kibble that contains the equivalent ratio of fat to protein that they would naturally consume in the nature. .

The authors propose that zoos adopt this food or other alternatives that mimic fat.protein proportion found in the wild for captivity polar bearswhile carefully monitoring the new regimen to see if it improves the bears’ health and longevity.

WSU research was used in the development of the feed, but none of the WSU scientists have any commercial interest in the company or its products.