Livestock Management RANCHING


Studies Show Cow Temperament Affects Reproduction


Regardless of breed composition, calmer cattle are more productive cattle


By Heather Smith Thomas


Dr. David Bohnert


F


LIGHTY OR AGGRESSIVE CATTLE ARE MORE DIFFICULT (AND dangerous) to handle and have several other disadvantages. Studies during the past decade


have shown that “wild” cattle don’t gain as well in the feedlot, have a higher incidence of “dark cutters” and are less likely to allow feedlot cowboys to determine when they are sick. More recent research showed that temperament also


affects reproduction rates. Cows with bad dispositions have lower conception and calving rates. Studies in Florida a few years ago showed that


Brahman-cross cattle with excitable temperaments had lower pregnancy rates than their calmer herdmates. This study was expanded a couple years ago at Or-


egon State University to look at the effect of tempera- ment on reproductive performance in Angus-Hereford cross cows. Dr. Reinaldo Cooke and Dr. David Bohnert were 2


of the researchers involved in this study. “The work on these projects started when we hired


Dr. Reinaldo Cooke to be our beef Extension special- ist,” says Bohnert. “He came from Florida, where he got his Ph.D. One of the fi rst projects he did in Florida looked at temperament. Most of that work was with Bos indicus infl uenced cattle — predominantly Brah- man crosses.” By contrast, the Northwest has mostly British breeds,


a few continental breeds used mainly as terminal sires, and only a few Brangus, Santa Gertrudis and other Brahman-derived cattle.


60 The Cattleman November 2013


Bos taurus temperament “After seeing the results with Bos indicus cattle,


we decided to try some studies on Bos taurus cattle,” Bohnert says. “At the experiment station here at Burns we have about 300 Angus-Hereford black baldy cows. Our station at Union has about 250 Angus. At Burns we use some AI [artifi cial insemination] for breeding but mainly use a lot of bulls. The cattle at Union are all bred AI, with just a clean-up bull. This gave us dif- ferent production environments to compare.” “With AI, all the cows are being handled and stress


could be a large factor. So we did a temperament study looking at the effects on reproduction in these 2 dif- ferent breeding environments. “What we saw was that it didn’t really matter wheth-


er it was a bull breeding situation or AI. We still saw an advantage (in higher pregnancy rates) with the cows that had moderate to calm temperament. Those that were more aggressive or fl ighty didn’t get pregnant as readily, even under natural conditions,” he says. “We think hormones are partially involved in this


difference. This includes cortisol, a stress hormone. Some of the data has shown elevated cortisol in the animals that have poor temperament (more aggressive or fl ighty and excitable). These are the high-headed, tail-in-the-air cattle that tend to run away from people and jump over fences. They have higher cortisol lev- els and we are confi dent that this is partially what’s involved when we look at the different reproductive hormone cascades.”


thecattlemanmagazine.com


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