Finding the Ideal Cow for Idaho Rangelands
Animal Science
Scott Jensen
Extension Educator
University of Idaho
MARSING
Abstract
A significant percentage of the beef cattle raised in the western United States spend at least a portion of each year on rangeland pastures. These rangeland pastures can be up to several thousand acres in size. Cattle distribution and utilization vary greatly across rangeland pastures. University of Idaho research suggests that “efficient” 2-yr-old lactating cows use rugged rangelands more sustainably than “inefficient” 2-yr-old lactating cows. Cows that were previously ranked as more efficient in a feedlot setting (using data from GrowSafeTM feeding units) climbed higher and spent more time out of the riparian areas at Rinker Rock Creek Ranch (RRCR) during the hot days of August. Further consideration of the differences observed in the spatial distribution of cattle grazing rugged rangelands during the heat of summer implied that there was a physiological link to the grazing behavior demonstrated by these divergent cattle. Specifically, cattle with greater appetite spend more time resting during the heat of the day at lower elevations possibly due to a larger gastrointestinal tract size. Are differences in observed grazing behavior for efficient vs inefficient cattle grazing rugged rangelands due to ‘nature’ or ‘nurture’? How important is the role of social learning? Research (Bailey et al., 2015) suggests that genetic markers may exist to classify “hill-climber” cows that better fit rugged rangeland environments. If differences in grazing behavior on rugged rangelands can be attributed mainly to genetic influences, then selection of replacement heifers could be aided by using genetic markers as those become available. To answer grazing behavior questions, a University of Idaho Extension research team installed grazing behavior collars on 35 cows + calves at RRCR during mid (May 18 to June 16, 2021) and late lactation (July 12 to August 25, 2021). First-year study data showed a need for software updates on the cow collars and promise of grazing behavioral differences between cow efficiency groups warranting further study.
Authors: K. Scott Jensen, Landon Sullivan, Jim Sprinkle
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K. Scott Jensen Extension Educator, University of Idaho, Idaho, 83639
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Landon Sullivan PhD Student, University of Idaho, Idaho, 83467
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Jim Sprinkle Extension Beef Cattle Specialist, University of Idaho, Idaho, 83467