Yearling steers grazing on an experimental research pasture of the ARS Rangeland Resources Research Unit. Photo by David Augustine. For decades, Agricultural Research Service scientists in the northern plains have kept meticulous records on cattle weight gains during the growing season. Although their main focus was on trends in livestock and forage production, they also tracked weather conditions as part of their studies.
A few years ago, ARS rangeland management specialist Justin Derner assembled a scientific team from three ARS locations in Wyoming, North Dakota, and Montana to study the influence of seasonal weather patterns on cattle production. The team wanted to determine whether past trends could help cattle producers improve management strategies for dealing with future production challenges that might arise from increased seasonal weather variability.
“It’s impossible to answer long-term questions about cattle production using short-term data,” says ecologist Justin Reeves, who works in the ARS Rangeland Resources Research Unit in Cheyenne, Wyoming, and headed up the analyses. “We need a lot of years and a lot of variation in seasonal weather patterns to accurately determine the effect on cattle production.”
The first step was to transfer all the historical written records into electronic databases, a task that took around 2 years. Then, Reeves, Derner, and a team of ARS colleagues began searching for patterns in the long-term data.
In one of their studies, the team determined the effects of seasonal weather variables on cow-calf production in Cheyenne. The cattle production data they used was taken from records kept from 1975 to 2012 on both Herefords and Red Angus crossbred cattle. The crosses generally outweighed the Herefords and on average produced more beef every year, so the breed groups were studied separately.
The weather variables included spring and summer temperatures, spring and summer precipitation, prior winter precipitation, and prior growing season precipitation. An important factor in the research design was using weather variables that would be easily available to ranchers as forecasts. These same weather variables were used in all the studies, which provided consistency and allowed for results to be compared from location to location.
The scientists found that over the study period, up to two-thirds of the variation in Hereford cattle production could be explained by seasonal weather variations. In addition, Hereford cow-calf pairs were potentially more sensitive to seasonal weather variability than the crossbred animals were. For example, under moderate stocking rates, Hereford cow, calf, and pair beef production increased after wet winters and/or wet springs.