Cows Predated By Wolves Have Increased Stress Levels

Cows Predated By Wolves Have Increased Stress Levels

I’ve heard ranchers whose cattle pasture on land with wolves discuss the unseen expense of cattle being exposed to wolves — cows being more aggressive, decreased pregnancy rates and lighter calves. A recent Oregon State University study confirms those ranchers’ anecdotes.

The OSU researchers took wolf urine, recorded wolves howling and three trained dogs and watched two groups of cows as they played the howls and dogs walked near the pens. One group of cows had never interacted with wolves - the other a group had been experienced wolves predating their herd.

Researchers found that cortisol, a stress hormone, increased by 30 percent in cows that had previously been exposed to wolves. Yet the cows previously unfamiliar with wolves were curious about the dogs and did not show signs of stress.

OSU Animal Scientist Dr. Reinaldo Cooke shares that those cows that had been experienced wolves before had developed a memory of the predation event and so every time they are around wolves they are going to become stressed. He adds

Cooke: “All kind of stresses — it can be physiological physiological —it all boils down to cortisol — is the stress hormone — that directly impacts production, immune system, milk production, growth etc.. That is the main message of this study: the wolf issue is just not predation — not just wolves killing or hurting animals. It’s the constant stress animals go through having too many wolves around.”
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