PSXIV-6 Evaluating the relationship between residual feed intake and residual water intake in beef cattle across two locations.

Abstract Feed and water efficiency are critical for improving the sustainability of beef production. This study evaluates the stability and relationship of Residual Feed Intake (RFI) and Residual Water Intake (RWI) in beef steers raised under different nutritional environments at Wardensville (medium energy ration) and Morgantown (high energy ration) over three years (2022: n=37, 2023: n=40, 2024: n=41). Animals were classified into high, medium, and low efficiency groups for RFI and RWI using custom quantiles. Contingency analysis was conducted utilizing agreement test, Kappa to assess the association between RFI and RWI and test the hypothesis that beef steers maintain consistent RFI and RWI rankings across different environmental conditions. RFI rankings across locations showed weak and inconsistent agreement. In 2022 (Kappa = 0.03, p = 0.82) and 2023 (Kappa = -0.04, p = 0.73), no significant relationship was found. In 2024, the agreement improved slightly (Kappa = 0.23, p = 0.018. RWI rankings were similarly inconsistent. In 2022, weak agreement (Kappa = 0.27, p = 0.02) suggested slight stability, but agreement was minimal in 2023 (Kappa = 0.04, p = 0.73) and 2024 (Kappa = 0.12, p = 0.28), confirming no significant ranking shifts. The relationship between RFI and RWI rankings remained inconsistent across years and locations. In 2022, the agreement was weak at both sites (Wardensville: Kappa = -0.01, p = 0.45; Morgantown: Kappa = 0.07, p = 0.28), showing no major shifts. This pattern persisted in 2023 (Wardensville: Kappa = 0.08, p = 0.25; Morgantown: Kappa = -0.15, p = 0.09), indicating symmetrical ranking changes. By 2024, agreement remained low (Wardensville: Kappa = -0.06, p = 0.28; Morgantown: Kappa = 0.08, p = 0.23) suggesting no significant re-ranking. In conclusion, the slight agreement in RFI rankings indicates that environmental factors, especially diet, influence beef steer categorizations while the weak agreement between RFI and RWI rankings suggests feed efficiency does not strongly predict water efficiency in beef cattle.