Pen-Scale Heat-Risk Mapping in an Open-Sided Beef Cattle Barn Using Long-Range Wireless Multi-Point Monitoring

Barn-level monitoring may mask local heat-risk exposure in open-sided beef cattle barns. This study evaluated a long-range wireless multi-point monitoring framework for pen-scale heat-risk mapping in a commercial open-sided double-row barn during the hot season. Environmental data were continuously collected from representative front, middle, and rear pens, and the temperature–humidity index (THI) was matched with respiration rate, per-head daily water intake, and descriptive body-weight records. The data completeness of the main analytical nodes was 99.75–99.88%. Mixed-effects models showed that the middle and rear pens had higher daily and daytime THI intensity than the front pen (p < 0.001), whereas the daytime duration of THI ≥ 78 was similar among pens. The rear–front THI difference was amplified during 10:00–16:00 (β = 1.19, p = 0.006). Respiration rate increased by 1.25 breaths min−1 for each one-unit increase in THI (95% CI: 0.92–1.57, p < 0.001). Per-head daily water intake was more strongly associated with daily mean THI than with daily maximum THI. These findings indicate that pen-scale monitoring can identify local thermal heterogeneity and provide a data basis for targeted environmental assessment in open-sided beef cattle barns.