88. Brahman Influence in Grazing Behavior and Water Use Patterns of Beef Cattle in South Texas.

Abstract

Precision livestock technologies provide new opportunities to quantify grazing behavior and spatial utilization of rangelands at high temporal and spatial resolution. Grazing behavior is also closely related to heat stress and adaptation, which is especially relevant in South Texas. The objective of this preliminary study was to evaluate the effect of Brahman (BR) genetic influence on grazing movement and water-use behavior of beef cattle monitored using GPS telemetry in a rotational grazing system. The study was conducted at the Texas A&M AgriLife Research Station in Beeville, TX. Crossbred beef cows (N = 39) were equipped with GPS collars for 85 days during summer 2025 while grazing improved grasslands across sequential paddocks. Cows were classified based on BR influence as low (0–15%, n = 10), mid (16–30%, n = 19), and high (>31%, n = 11). GPS data were processed in R using geospatial and data analysis packages. Pasture boundaries were defined using station shapefiles, and each GPS location was spatially assigned to its corresponding pasture. Water trough locations were georeferenced, and distances between animal positions and water sources were calculated for each observation. Daily behavioral metrics were derived, including number of GPS points, total distance traveled (km/d), mean speed (m/s), mean distance to water (m), time near water points (min/d), and number of water visits. Metrics were aggregated by animal and merged with animal-level information. We included the Brahman influence as the fixed effect, the age as random and the date as a repeated measure. Total daily distance traveled differed among BR groups (P < 0.001), with low BR cows traveling the greatest distances, followed by mid and high BR cows. A similar pattern was observed for movement speed (P = 0.002), where low BR cows showed the highest mean speed, followed by mid and high BR cows. Distance to water also differed (P < 0.001), with high BR cows maintaining the greatest distance from water, followed by low and mid BR cows. In contrast, time spent near water points was greater for mid and low BR cows compared to high BR cows (P < 0.001). Water visitation frequency followed a similar pattern (P < 0.001), with low and mid BR cows visiting water more frequently than high BR cows. Overall, BR genetic influence affected movement dynamics, spatial distribution, and water-use behavior. These preliminary results suggest that cattle with greater BR influence may be associated with reduced reliance on water proximity, potentially reflecting adaptation to heat stress. Integrating GPS telemetry with spatial analytics provides a powerful framework to quantify grazing behavior and support improved management in extensive beef systems.

For image description, please refer to the figure legend and surrounding text.