Does initial body size influence weight gain of stocker steers in western Great Plains rangeland?

Authors: Derner, Justin; Augustine, David; IRISARRI, J. GONZALO - University Of Wyoming; RITTEN, JOHN - Colorado State University; RAYNOR, EDWARD - Colorado State University

Submitted to: Rangeland Ecology and Management
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/18/2025
Publication Date: N/A
Citation: N/A

Interpretive Summary: What a yearling steer weighs at the start of a grazing season may influence weight gains during this period, and if so, subsequently influence marketing decisions at the end of the grazing season. We evaluated weight gains from the summer grazing season (mid-May to October) of >2000 yearling steers over ten years (2014-2023) in semiarid, shortgrass prairie with moderate stocking of these steers. Entry weights of the steers over the range evaluated here, from 500 to 814 pounds, did not affect grazing season gains of these steers. Steers, on average, gained nearly 300 pounds over the four-and-a-half months of summer grazing and this value can be used for planning purposes by ranchers for marketing/economic aspects and placement into confined feeding operations for the finishing phase. Low amounts of spring precipitation substantially impact summer weight gains of yearling steers through low forage availability and high amounts of spring precipitation reduce forage quality to also constrain weight gains. Stocker producers can use this information along with available decision tools and seasonal forecasts to reduce risk and enhance opportunities for economic returns.

Technical Abstract: For stocker (i.e., yearling) operations, entry weights at start of the summer grazing season (mid-May) in the semiarid, shortgrass steppe have important economic implications for managerial decision-making as producers need to understand how various entry weights impact final (early October) marketing weights, dates, and therefore prices received. In aggregate, this information also impacts subsequent feedlot finishing options related to timing of harvest. However, the influence of entry weight on stocker steer performance during the summer grazing (mid-May to early October) remains unclear. We used ten years (2014-2023) of weight gains from 2,162 stocker steers that had entry weights ranging from 222.7 kg to 370.0 kg to assess if grazing season performance under traditional, season-long grazing management with moderate stocking rate was influenced by entry weights, spring (April through June) precipitation, pasture productivity (low vs. high), and their interactions. Knowledge that summer weight gains in the semiarid, shortgrass steppe are not affected by entry weights, at least within the range studied here, provides stocker operations with a benchmark value of 135 kg steer-1 gain across years that can be used for strategic planning purposes for end of grazing season weights of stockers for loan/credit aspects, marketing, and placement into confined feeding operations for the finishing phase. Understanding that amount of spring precipitation can impact summer weight gains of yearling steers through low forage availability when spring precipitation is limited, and through low forage quality when substantial aboveground plant productivity occurs due to abundant spring precipitation provides stocker operators with key knowledge for effectively using available decision tools and seasonal forecasts.