PS6-12. Evaluation of Grazing Behavior and Performance of Beef Heifers under Different Shade Locations Relative to Water Access.

Abstract In the Texas High Plains grazing systems, natural shade is scarce and often lacking artificial shade, which may increase the risk of heat stress and alter grazing behavior in cattle. Understanding how shade availability and its placement relative to water sources influence animal behavior and performance is important for improving welfare and productivity in extensive rangeland systems. Therefore, this study evaluated the effects of shade placement on grazing behavior, activity patterns, and performance of beef heifers. In 2025, twenty Red Angus heifers (310 ± 80 kg) were stratified by weight and continuously grazed for 62 days on four native rangeland paddocks in Texas Tech Research Farm near New Deal, Texas. Each paddock was 2.6 Ha and stocked with five animals. All heifers were equipped with 701X xTpro® smart tags, which continuously recorded heart rate, step count, GPS position, and estimated activity (eating, resting, ruminating, walking, and unknown) using accelerometer-based algorithms. Four treatments were evaluated based on shade placement relative to water access: no shade (NS), adjacent shade (AS), intermediate shade (IS), and distant shade (DS). Shade structures consisted of 90% shade cloth and provided approximately 6.6 m² of projected shade (2.6 × 2.6 m). Body weight measurements and the collection of blood, urine, and fecal samples were conducted every three weeks to assess physiological and nutritional responses. Despite differences in shade availability and location, no significant treatment effects were observed for average daily gain (NS: 0.98 ± 0.13, AS: 0.99 ± 0.13, IS: 0.87 ± 0.13, and DS: 0.87 ± 0.13 kg; P = 0.986), step count (P = 0.31), or time spent ruminating (P = 0.45), eating (P = 0.53), resting (P = 0.25), and walking (P = 0.24). Numerically, heifers in the distant shade treatment spent more time eating (47.2 ± 10.6 min/d), whereas adjacent shade heifers exhibited greater time resting (122.2 ± 1.4 min/d) and ruminating (123.9 ± 3.4 min/d). Intermediate shade heifers had the highest step count (65.6 ± 8.2 steps/d), while no-shade heifers showed similar activity patterns across behaviors (eating: 39.2 ± 9.0, resting: 121.0 ± 3.6, ruminating: 122.3 ± 13.3 min/d; steps: 52.1 ± 16.7). However, these differences were not statistically significant. Under the conditions of this study, shade placement within small grazing paddocks (2.6 ha) did not influence grazing behavior or performance in beef heifers.