125. Carryover Effects of Grazing Performance on Variability of Finishing Performance and System Profitability

Abstract Previous research (Beck et al., 2025) demonstrated that bovine respiratory disease incidence in the receiving phase of the stocker program has long-term implications on performance, carcass quality, and profitability. Building on this foundation, the objective of the current analysis was to examine variability in grazing performance by applying k-means clustering to early-season grazing (ES) ADG, and to evaluate the carryover impacts of these clusters on late season (LS) grazing performance, finishing performance, and profitability. This evaluation was conducted using stocker steers (n = 1,018) that grazed during the summers of 2020, 2021, 2022, and 2024 at the OSU Eastern Research Station, Klemme Range Research Station, and the USDA-ARS Southern Plains Experimental Range. Steers were finished in commercial scale pens at Buffalo Feeders in Buffalo, Oklahoma (Pratt Feeders Group, Pratt KS). Steers in each year were assigned to various supplementation treatments and weighed at the beginning, mid-point and end of the grazing season. Each supplementation treatment within site and year were assigned to a contemporary group for the analysis. Statistical analyses were conducted in SAS 9.4 (SAS Inst., Cary NC). Contemporary group effects were first adjusted using PROC GLM to obtain residuals for grazing ADG. K-means clustering was performed with PROC FASTCLUS to classify calves into performance groups based on ES grazing ADG. Associations between ES ADGclusters and subsequent LS season and finishing performance, and profitability were evaluated using PROC CORR (Spearman correlations) and PROC GLM, with differences in least squares means declared at P < 0.05. For the analysis of ES ADG clustering, ES ADG was positively correlated with late summer (r = 0.17; P < 0.01) and season-long (r = 0.82; P < 0.01) ADG. During finishing, ES ADG was positively correlated to ADG in early finishing phase (r = 0.11; P < 0.01) and negatively correlated to late finishing ADG (r = -0.11; P < 0.01) but not correlated with total finishing ADG (r = 0.01; P = 0.64). Steers with the least ES ADG (P < 0.01) in cluster 4 expressed compensatory gain in LS, but this did not result in improvement in ranking of season long grazing ADG. Early finishing ADG and hot carcass weights were the least for steers with the lowest ES ADG (cluster 4) and were greatest for steers with the greatest ES ADG (cluster 1). Days on feed were least (P < 0.01) for cluster 1 and greatest for cluster 4 with clusters 2 and 3 being intermediate. Steers with low ES ADG (cluster 4) were less profitable (P < 0.01) than steers in other clusters, indicating it would increase profitability to cull these steers at the end of the grazing season before finishing.