Temperature and precipitation affect steer weight gains differentially by stocking rate in northern mixed-grass prairie

Authors: Reeves, Justin; Derner, Justin; Sanderson, Matt; Petersen, Mark; Vermeire, Lance; Hendrickson, John; Kronberg, Scott

Submitted to: Rangeland Ecology and Management
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/26/2013
Publication Date: 7/2/2013
Citation: Reeves, J.L., Derner, J.D., Sanderson, M.A., Peterson, M.L., Vermeire, L.T., Hendrickson, J.R., Kronberg, S.L. 2013. Temperature and precipitation affect steer weight gains differentially by stocking rate in northern mixed-grass prairie. Rangeland Ecology and Management. 66(4):438-444.

Interpretive Summary: Seasonal weather conditions may impact beef production on rangelands, but very few experiments have studied this. The effects of seasonal temperature and precipitation on beef production need to be better understood to help ranchers select stocking rates that will be most profitable based on weather conditions. We used three decades (1982 – 2011) of yearling steer weight gain data from the High Plains Grasslands Research Station near Cheyenne, WY to study how spring (April – June) and summer (July – September) temperature and precipitation impact beef production. Precipitation from the prior year was also studied. Three stocking rates (light, moderate, and heavy) were used during each of the study years, and effects of temperature and precipitation on beef production were compared between these stocking rates. We found that heavy stocking rates were more sensitive to seasonal weather variation. Cool, wet springs and warm, wet summers were best for beef production at moderate and heavy stocking rates. The light stocking rate was not impacted by seasonal weather differences. When poor weather conditions are forecasted for spring or summer, ranchers can lighten their stocking rate to reduce economic risks. Our results will be used in decision support tools to help ranchers decide stocking rates based on expected spring and summer weather conditions. These seasonal forecasts can easily be gathered from the National Oceanic and Atmospheric Administration (NOAA) up to a year in advance. Our results will help ranchers to decide stocking rates well before the grazing season.

Technical Abstract: Cattle weight gain responses to climate variability are difficult to predict for rangelands, as few long-term (>20 yr) studies have been conducted. However, an increased understanding of temperature and precipitation influences on cattle weight gains is needed to optimize stocking rates and reduce enterprise risk associated with climatic variability. Yearling steer weight gains collected from Northern Mixed-grass Prairie at the USDA-ARS High Plains Grasslands Research Station at light, moderate, and heavy stocking rates for 30 years (1982 – 2011) were used to examine the effects of spring (April – June) and summer (July – September) temperature and precipitation, as well as prior year precipitation, on beef production. At heavier stocking rates, steer weight gains were more sensitive to climate variations. A novel finding was that temperature (relatively cool springs and warm summers) had a large predictive role on beef production. Beef production on Northern Mixed-grass Prairie was highest during years with cool, wet springs and warm, wet summers, corresponding with optimum growth conditions for this mixed C3-C4 plant community. The novelty and utility of these findings may increase the efficacy of stocking rate decision support tools. The parsimonious model structure presented here includes three-month seasonal clusters that are forecasted and freely available from the U.S. National Oceanic and Atmospheric Administration up to a year in advance. These seasonal weather forecasts can provide ranchers with an increased predictive capacity to adjust stocking rates to climate variability, thereby reducing enterprise risk, well in advance of the grazing season.