Seasonal weather influences on yearling beef steer production in C3-dominated Northern Great Plains rangeland

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

Submitted to: Agriculture, Ecosystems and Environment
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/29/2013
Publication Date: 12/1/2013
Publication URL: http://handle.nal.usda.gov/10113/58163
Citation: Reeves, J.L., Derner, J.D., Sanderson, M.A., Hendrickson, J.R., Kronberg, S.L., Petersen, M.K., Vermeire, L.T. 2013. Seasonal weather influences on yearling beef steer production in C3-dominated Northern Great Plains rangeland. Agriculture, Ecosystems and Environment. 183:110-117.

Interpretive Summary: The effects of seasonal weather patterns on cattle production need to be better understood before decision support tools can be made to assist ranchers in setting stocking rates based on seasonal weather forecasts. In this study, we used yearling steer data from 1936-2005 collected at the Northern Great Plains Research Laboratory in Mandan, ND to determine the effects of spring (April – June) and summer (July – September) temperature and precipitation, as well as prior growing season (prior April – September) and prior fall/winter (prior October – March) precipitation on cattle production (kg/ha) under light and heavy cattle stocking rates. Kentucky bluegrass invaded the experimental pastures in the 1980’s, so we tested for weather effects both before and after the Kentucky bluegrass invasion. Heavy stocking made cattle production more sensitive to seasonal weather patterns whether Kentucky bluegrass was present or not. Before Kentucky bluegrass invaded, wet springs and winters increased cattle production under heavy stocking, while cool, wet springs and cool summers increased cattle production under light stocking. After Kentucky bluegrass invaded, cool, wet springs, wet winters, and wet prior growing seasons all increased beef production under heavy stocking. Under light stocking, wet winters and cool springs increased beef production. We analyzed the data here to make the results as usable for decision support tools as possible.

Technical Abstract: In the face of an increasingly variable climate, long-term cattle weight gain datasets are rare, yet invaluable, for determining site-specific influences of seasonal weather patterns on cattle production. Here, we present a long-term (1936 – 2005) yearling Hereford steer data set collected at the Northern Great Plains Research Laboratory (NPGRL) near Mandan, ND, USA. Data were analyzed using weighted AICc model averaging to examine the effects of spring (April – June) and summer (July – September) temperature and precipitation, as well as prior growing season (prior April – September) and prior fall/winter (prior October – March) precipitation on cattle production (kg/ha) under light (37.4 ±5.3 SD Animal Unit Days/ha [AUD] across all study years) and heavy (91.6 ± 22.2 SD AUD/ha) stocking rates. Because Kentucky bluegrass (Poa pratensis L.) invaded the grassland at NPGRL in the early 1980’s, we modeled cattle production separately for pre- (1936 – 1983) and post-invasion (1986 – 2005) years to determine if the plant community shift influenced sensitivity to seasonal weather patterns. Cattle production under heavy stocking was more sensitive to seasonal weather variability than under light stocking during both pre- and post-invasion years. Interestingly, the magnitude and robustness of coefficients changed between the pre- and post- invasion years, with seasonal weather patterns explaining more cattle production variation during the post-invasion years. Though cattle sensitivity to seasonal weather patterns differed between light and heavy stocking for both pre- and post-invasion years, invasion status did change cattle response to weather. For example, cattle production in Kentucky bluegrass invaded pastures was more heavily influenced by cool, wet springs and wet prior grazing seasons than was production in un-invaded pastures. For cattle stocked heavily in native pastures, wet winters more strongly increased cattle production than in invaded pastures.