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Non-traditional livestock

by Wyoming Livestock Roundup

UW researches progesterone management in reindeer bulls

While most animal science related research conducted at the University of Wyoming (UW) is focused around the state’s traditional species of livestock, a small team of UW personnel is currently studying a less familiar animal in order to understand the feasibility of managing male reproductive behavior with progesterone. 

In collaboration with University of Alaska-Fairbanks Director of Agriculture and Forestry Experiment Station Dr. Milan Shipka and University of Nebraska-Lincoln Reproductive Physiologist Dr. Andrea Cupp, UW Professor of Reproductive Biology Dr. Brenda Alexander, UW Professor Emeritus Dr. Gary Moss and UW Undergraduate Student Robert Ziegler have been hard at work studying the effects of utilizing progesterone as a management tool in farmed reindeer at the University of Alaska Fairbanks.

Research objectives

“This research was initiated by Dr. Milan Shipka in Alaska where reindeer are farmed,” explains Alexander. “I am currently in a western regional research project with Dr. Shipka.” 

Alexander further explains the objective of this particular research project is to determine how the treatment of bucks with a progesterone agonist influenced sperm production and neural activity in areas of the brain known to be important for the expression of reproductive behavior in males.

“The overall goal of our research is to find a way to safely manage reindeer bucks during the rut, because bucks become very dangerous to their handlers during the rutting period,” she says. “Many producers in Alaska have been using progesterone agonists to alter behavior for years, but how that influences fertility and changes behavior has not been determined.” 

She continues, “The importance of this research for Wyoming and other western states is how it will have potential application to the management of beef and dairy bulls. Certainly handling bulls is challenging and there is interest in a way to decrease their aggressive behavior while conserving reproductive potential.” 

Data collection process

As far as the data collection process, Alexander says she had a lot of fun.

“Robert Ziegler, Gary Moss and I had the opportunity to go to Fairbanks, Alaska to collect tissue from the reindeer herd managed by the University of Alaska Fairbanks,” Alexander says. “Dr. Shipka had treated the reindeer bucks with medroxyprogesterone acetate, a progesterone agonist, two weeks prior to the onset of rut. Tissue was then collected early- to mid-breeding season.” 

Currently, the team is completing their analysis, according to Alexander.

“We are interested in how this treatment influenced serum concentrations of testosterone and how it may influence sperm production and testes architecture,” she says. 

Research findings 

Alexander notes the most interesting results they have found in their study so far has to do with fear.

“I think the most interesting thing we found is treatment seems to allow the bucks to remain fearful, which weirdly protects handlers. When the bucks lose their fear of people, they are dangerous,” she says.

“In treated bucks, reproductive signaling within the brain appears intact following medroxyprogesterone acetate treatment. Increased neural activity within the central amygdala, an area of the brain that integrates sensory signals and is known to be important for fear signaling, may partially account for an increased fear of herdsmen in treated bucks, therefore reducing aggressive behavior during the rut,” she adds. 

Alexander notes her and her colleagues will continue working to finish the testosterone data and study the influence of progesterone on fertility. 

“I would really like to apply this work to beef and/or dairy bulls to determine if it could be applied to different species,” she states. 

Hannah Bugas is the assistant editor for the Wyoming Livestock Roundup. Send comments on this article to

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