The Barometer Online

Issue date: 3/2/09 Section: News

Media Credit: Cory Reed The OSU department of animal sciences hired Reinaldo Cooke last January to study the way stress impacts pregnancy rates of female beef cattle.

It turns out that the effects of stress may not be limited to college students. Last January, the OSU department of animal sciences hired Reinaldo Cooke, an assistant professor and beef cattle specialist based at OSU's Eastern Oregon Agricultural Research Center in Burns, to conduct further research on how stress can affect the pregnancy rates of female beef cattle and to expand the extension programs in place for cattle ranchers across Oregon.

Cooke, who is now OSU's second statewide extension beef specialist, intends to focus his research on enhancing the reproductive performance of beef cows and heifers by studying how low-stress handling by people affects the reproductive rates of female Hereford and Angus breeds.

"Calves see humans as predators, and if they are not used to being handled by people at an early age then they get extremely stressed and release a hormone called cortisol, which can be detrimental to their reproductive process," Cooke said. "Making them lose their fear of humans by the time they are weaned from their mothers (seven to eight months old) is a huge step in reducing their stress levels, and therefore will help them reach puberty at a younger age."

During his time at the University of Florida, Cooke (along with other researchers) tested this strategy on weanling heifers (female cows that have not had a calf yet) and found that acclimating the heifers to people at a young age reduced their stress and gave them higher pregnancy rates than those that had not been acclimated to humans.

"My goals are to understand the relationship between stress and reproduction," Cooke said. "It's an area that has not been investigated very well and I want to pursue it and do an in-depth study."

Along with researching the connection between stress and reproduction in beef cows and heifers, Cooke is also focused on expanding the public outreach side of the extension program. He plans to develop a statewide beef program for the Extension Service that would include educational workshops, an annual two-year report explaining OSU's latest beef research, an easily-accessible online database of articles, a field day where producers can visit the Burns research center and in-service training for extension agents.

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