Deadly diet of hay can bring down a moose

Ornamental trees and human food can hinder digestion in moose

Posted: Friday, December 26, 2003

FAIRBANKS - Wolves, bears, hunters and motor vehicles aren't the only moose killers in Alaska.

A bale of hay can bring down a moose just as effectively as a pack of wolves or a Suburban.

"Last year we had a call about a dead moose on Chena Hot Springs Road, and I went out there to check it out and that moose had about 200 pounds of hay in its gut," said wildlife biologist Tom Seaton at the Alaska Department of Fish and Game here.

"It was all in little, mouth-size balls, like someone had stuffed it in there by the fistful. That moose starved to death with 200 pounds of hay in its gut."

While hay may be for horses, it is not for moose. Neither are chokecherry, crab apple, mountain ash and other ornamental trees people grow in their yards. But every year moose end up eating them, sometimes with deadly results.

Moose have tremendous appetites and will eat just about any plant material that will fit down their throats. But they can't process everything they eat, said Perry Barboza, an associate professor at the University of Alaska Fairbanks who specializes in wildlife physiology and nutrition. Moose can't digest hay as cows and horses can.

"The question of what a good diet is for a moose and what characterizes that diet chemically has always been a big debate and is still open for questions," Barboza said.

Two months ago, biologists euthanized an emaciated cow moose from a residential subdivision here only to discover the moose had a stomach full of chokecherry pits and ornamental flowers.

A necropsy showed that the moose had excessive tooth wear, was loaded with parasites, had a scarred and inflamed intestine and was severely deficient in copper - conditions that the biologists said could have resulted from a long-term diet of ornamental trees, plants and human food.

Residents said the moose, which was about 12 years old and accompanied by a healthy calf, had lived in the area for at least 10 years and was a regular visitor in yards and gardens.

The copper deficiency caused part of the moose's intestine to swell up and stop functioning, which basically killed the moose, said Fish and Game veterinarian Kimberlee Beckman.

That's one of the reasons it's illegal to feed moose and other wildlife, biologists said. While people may think they are helping hungry animals get through the winter, they could really be causing them to starve to death by providing them foods that hinder, or even prevent, digestion.

"People put human values on moose," Seaton said. "They see them standing out in the cold and think there's nothing for them to eat when in fact they're adapted to the cold, and there are good things for them to eat out there."

Moose have two diets. In the summer, they eat soft vegetation such as leaves and sedges they pull from the bottom of ponds, as well as twigs from birch, willow and aspen trees. In the winter, their diet consists almost exclusively of wood.

"If they're basically consuming wood chips and you throw in something like an apple that's totally different, you could end up with an explosive fermentation or something that produces a bunch of gas and trauma that might not be a problem in the spring when they're used to eating more of that kind of stuff," Barboza said.

When a moose - or any ruminant - eats something, it is deposited in the rumen and reticulum, a kind of internal septic tank where food is broken down by a host of bacteria and protozoa.

Scientists suspect the composition of bacteria in a moose's rumen fluctuates with its diet. Once the food is broken down, it is transformed into fatty acids that are absorbed through the rumen and that provide the moose with most of its energy.

Any undigested fragments are passed to the omasum, where water is removed, and then on to the abomasum, the moose's true stomach. If food particles are too big to reach the omasum, they remain in the rumen, giving the moose the impression its stomach is full. When that happens, the moose stops eating while it tries to break down the food in its rumen.

"If they're not digesting correctly, things just sit there and don't get broken down," Beckman said.

Moose gorge themselves until the rumen and reticulum are full and then find a place to lie down and digest by ruminating, which involves regurgitating what they've eaten and chewing it again to make it more digestible.

Moose possess built-in defense mechanisms, such as chemicals in their saliva, to deal with toxins in many of the plants they eat, said Terry Bowyer, wildlife professor and moose researcher at the Institute of Arctic Biology.

The chemicals will either neutralize the toxins or warn the moose not to eat them. Bowyer, who has studied moose for about 20 years, suspects the sick moose that was put down by biologists two months ago was in poor condition because of tooth wear.

Biologists said the moose's teeth looked like those of a 15-year-old moose instead of a 12-year-old.

Moose in Fairbanks can live to be 17 if their teeth hold out.

"That's a kiss of death for ruminants," Bowyer said. "Once they wear out their teeth, they can't process food."

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