Seasonal weather influences on yearling beef steer production in C3-dominated Northern Great Plains rangeland.
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 dataset 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 [AUD]/ha 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 1980s, 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 P. pratensis 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.