OSU study: Cows in wolf attacks suffer PTSD-like symptoms - KLTV.com-Tyler, Longview, Jacksonville, Texas | ETX News

OSU study: Cows that witness wolf attacks suffer PTSD-like symptoms

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OSU researchers simulated a wolf encounter with German Shepherds to measure stress levels in beef cows. Photo: Reinaldo Cooke OSU researchers simulated a wolf encounter with German Shepherds to measure stress levels in beef cows. Photo: Reinaldo Cooke
Cows that had previously witnessed wolf attacks bunched together and showed high levels of stress during the experiment. Photo: Reinaldo Cooke Cows that had previously witnessed wolf attacks bunched together and showed high levels of stress during the experiment. Photo: Reinaldo Cooke
CORVALLIS, OR (KPTV) -

Cows that survive encounters with wolves may suffer from symptoms similar to post-traumatic stress disorder, according to a new Oregon State University study.

Researchers said they were told by ranchers that such cows are more aggressive, sickly and eat less. The memory of a wolf attack can also lead to decreased pregnancy rates and lighter calves for those animals that do give birth.

To measure the stress of a wolf attack on cows and estimate its lingering effects, researchers simulated a wolf encounter with 100 cows. Half of the cows had never seen a wolf, while the others had been part of a herd that was previously attacked on the range.

Cows were gathered in a pen scented with wolf urine while prerecorded wolf howls played over a stereo. Three trained German Shepherds, which closely resemble wolves, then walked outside the pen.

Researchers found that cortisol, a stress hormone, increased by 30 percent in cows that had previously been exposed to wolves. They bunched up in a corner, formed a protective circle and acted agitated.

Their body temperatures also increased rapidly, researchers said, another indicator of stress.

The cows previously unfamiliar with wolves were curious about the dogs and did not show signs of stress.

Multiple studies from Reinaldo Cooke, an animal scientist in OSU's College of Agricultural Sciences, and other researchers have established a link between cow stress and poor performance traits that can cost ranchers money.

"When wolves kill or injure livestock, ranchers can document the financial loss," Cooke said. "But wolf attacks also create bad memories in the herd and cause a stress response known to result in decreased pregnancy rates, lighter calves and a greater likelihood of getting sick. It's much like post-traumatic stress disorder - PTSD - for cows."

A 2010 OSU economic analysis estimated that wolves in northeastern Oregon could cost ranchers up to $261 per head of cattle, including $55 for weight loss and $67 for lower pregnancy rates, according to John Williams, an OSU extension agent in Wallowa County who conducted that study.

Cooke co-authored the most recent study with David Bohnert, an expert in ruminant nutrition at OSU's Eastern Oregon Agriculture Research Center in Burns.

The study was published in the Journal of Animal Science and funded by the Oregon Beef Council.

Both researchers called for further research into ways of successfully managing both wolves and livestock so they can co-exist.

More information: http://bit.ly/OSU_CowWolfStudy.

Copyright 2014 KPTV-KPDX Broadcasting Corporation. All rights reserved.

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