Something about bull's urine puts cow moose in the mood

Posted: Monday, October 16, 2000

STERLING (AP) -- Mattie the cow moose sniffed two sponges placed in front of her long, bulbous nose at the moose research center here.

The first sponge brought no response -- not even a quivering nostril. But when Mattie got a whiff of sponge No. 2, she went practically berserk. She pawed the ground. She stuck her pink tongue through the chain link fence for a lick.

And then she drove her whole head into the fence, like a cat grinding its face against an owner's leg.

That sponge was soaked with the urine of a bull moose in rut. The other had a cocktail of some bull urine components.

Wildlife managers want to know which compounds are responsible and what role they play in the moose mating ritual.

Mattie and some other cows at the state-run Kenai Moose Research Center north of Sterling were part of a recent study to identify moose pheromones, chemicals that trigger physiological and behavioral changes.

The study is led by University of Alaska Fairbanks graduate student Chris Whittle, who hopes to unlock the key ingredient or ingredients in bull urine that stimulate the cows.

All over Alaska, moose are gathering to mate now. Bulls are urinating by the gallon in large holes and wallowing in the pungent, nearly lung-searing substance. Cows are responding.

To figure out why, Whittle spent two weeks at the Moose Research Center in late September testing her latest hypothesis.

The center has four giant pens, each containing a square mile of rolling woodlands and small lakes. The unique facility was created in the late 1960s to study how changing vegetation affected moose, and vice versa.

It has since become a proving ground of sorts. Researchers there perfected a chow now fed to moose in zoos nationwide. They proved that a diet of hay alone can be fatal to moose.

About 30 moose live here, either born within its welded-wire fences or brought in as orphans. They are not exactly wild, but they are not tame either.

The urine was collected a couple of years ago by a patient technician with a long-handled pan. The collection is kept in a deep freeze.

Whittle believes something in that urine acts as a primer, actually triggering estrus in cows. She's not sure what.

State wildlife biologists say her research could help them figure out whether hunting regulations are working as intended. Should hunters bag fewer bulls? Can they hunt more? Or is the ratio of bulls to cows about right?

Only mature bulls produce the aromatic urine. And they do most of the breeding. Wildlife managers want to make sure there are enough older bulls to impregnate the available cows.

If a bull misses a cow in estrus, he gets a second chance a month later. But, according to Kris Hundertmark, senior scientist at the center, that means the calf will be born later the next spring, giving it less time to gain strength for its punishing first winter.

Biologists think dwindling daylight is what brings moose together in the fall. Once the animals have gathered, Whittle believes, it's the whiff of rut urine that brings cows into estrus.

''It is a theory in moose, but it is known to occur in swine and red deer,'' Hundertmark said.

Whittle was the first to study the chemical components of moose urine, during a six-month internship at Monell Chemical Senses Center in Philadelphia.

Using a mass spectrometer and gas chromatography, she identified 38 compounds that might be the key.

''It's great to apply chemistry to a living system, to see how it works,'' she said.

Whittle is trying to solve the riddle of moose pheromones by process of elimination. She blended the two dominant components of bull urine, an alcohol and a phenol, into a ''cocktail'' and placed a sponge soaked in the mixture beneath the cows' rubbery snouts.

It had no effect.

Only the second sponge, doused with full-strength bull urine, drove Mattie and the others wild.

''Unfortunately, it's not working out as I had planned,'' she said. ''These two compounds in combination are not the pheromone.''

Her next step will be to develop a different cocktail and try it out on the cows next summer. She wouldn't divulge the compounds she has tested or those she is waiting to try. She wants to be the one who unlocks the mystery.

''I started this, and I want to finish it,'' she said.


(Distributed by The Associated Press)

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