PS4-23. Associations Between GPS-derived Grazing Behavior and Feed and Water Efficiency in Grazing Beef Heifers.

Abstract Understanding how grazing behavior relates to efficiency traits may improve management and selection strategies in grazing beef production systems. This study evaluated associations between GPS-derived grazing behavior, movement patterns, and efficiency traits in beef heifers. Seventy-one heifers were monitored at the JW Ruby Research, Education, and Outreach Center, Reedsville, West Virginia for a testing period of 57 days (18th July- 12th September 2025) using GPS collars to quantify grazing time and daily movement distance. Behavioral metrics were evaluated in relation to residual feed intake (RFI), residual water intake (RWI), dry matter intake (DMI), and average daily gain (ADG). Greater grazing time was associated with lower RFI (R² = 0.064, p = 0.033), indicating reduced residual feed intake among animals that spent a greater proportion of time grazing. Grazing time was also negatively associated with RWI (R² = 0.214, p < 0.001). Greater mean daily distance traveled was associated with lower RFI (R² = 0.068, p = 0.028), while grazing time was positively associated with ADG (R² = 0.157, p = 0.001). Efficiency group comparisons further indicated behavioral differences, with efficient animals grazing longer than inefficient animals (31.7% vs. 29.5% of the day; p = 0.022). These findings indicate that grazing behavior is associated with variation in both feed and water efficiency in grazing cattle. GPS-based behavioral monitoring may provide additional insight into efficiency variation in pasture-based production systems.