According to an analysis headed by Charlie Robbins, a wildlife biologist at Washington State University, a high protein diet appears connected to renal illness and shorter lifespans for confined polar bears.
This relationship is also hypothesized in people.
Polar Bears May Suffer from High Protein Diets
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The article, published in Zoo Biology, carefully examined what polar bears have been fed in zoos and found that, contrary to what was discovered in the wild, large cats are typically provided a diet consisting of around two to three parts protein to one part fat.
According to Robbins, professor, and creator of WSU's Bear Center, zoos made certain assumptions in the past about the nutritional requirements of polar bears because their diet is nearly solely made of animals, as per ScienceDaily
However, unlike cats, they do not require and cannot handle heavy protein.
As carnivores, polar bears nearly exclusively consume seals.
However, recent studies have shown that the physiology and diet of polar bears, like those of other bears, are more similar to primates, such as humans.
Karyn Rode, a former doctoral student at the WSU Bear Center who is now with the US Geological Survey, performed earlier field experiments that demonstrated that polar bears preferentially eat a diet that is two parts fat to one part protein, keeping their protein levels within the low range of their needs.
In July 2021, Scientific Reports reported these findings.
Even though the researchers were aware that polar bears preferred their prey's blubber, Robbins said that it was the first time they were able to calculate how much fat polar bears were ingesting.
No one has been paying attention to the quantity of protein polar bears would need and had much fewer constraints on how much they might accept because the usual attitude when it comes to feeding polar bears has been that they are carnivores.
When given the choice between blocks of pure lard and blocks of meat with high protein content, captive bears preferred the same proportion of fat to protein as they typically eat in the wild.
The most frequent cause of death among captive polar bears of both sexes was kidney disease, according to a careful analysis of mortality data.
Bears with kidney disease passed away 10 years earlier than bears without the condition.
Cancer and liver disease were the two second-most frequent causes of death.
The team has collaborated with Mazuri® Exotic Animal Nutrition and its nutritionist Troy Tollefson, who received his doctorate while working at the WSU Bear Center, to create a dry kibble that has the same ratio of fat to protein as what a bear may naturally eat in the wild.
The scientists suggested that zoos use this meal or other substitutes that closely resemble the fat-to-protein ratio observed in the wild for captive polar bears, while closely observing the new regimen to determine whether it enhances the bears' health and longevity.
Ringed and bearded seals make up the bulk of polar bear diets.
They also consume hooded and harp seals, and they scavenge dead beluga whales, walruses, narwhals, and bowhead whales, depending on where they are, as per SeaWorld
Polar bears occasionally kill baby walruses and beluga whales.
Polar bears will consume almost any animal when other sources of food are scarce, including reindeer, small rodents, seabirds, waterfowl, fish, eggs, plants (including kelp), berries, and human waste.
An estimated 15-20% of a polar bear's body weight can be stored in its stomach. Typically, a polar bear only consumes this much food when it needs a lot of energy.
A bear can absorb 84% of the protein and 97% of the fat it consumes.
For polar bears to have enough energy to survive, they require 2 kg (4.4 lb) of fat on average each day.
A ringed seal weighing 55 kg (121 lb) could sustain a polar bear for up to eight days.
