• A switch-type sensor detected standing-to-be-mounted behavior in grazing beef cows. • Validation of sensor performance showed a 74% detection rate for mounting events. • The system detected at least one event in all estrus periods (100% estrus detection). • Most mounting events (91%) occurred outside routine visual observation periods. • Sensor-based monitoring improved identification of optimal timing for insemination. Estrus detection in grazing beef cattle is often difficult because animals are widely dispersed and opportunities for visual observation are limited under extensive pasture conditions. This study evaluated a switch-type sensor designed to detect standing-to-be-mounted (STBM) behavior for automated estrus detection in grazing beef cows. Sensor performance was first validated by comparison with video-recorded mounting behavior in a barn experiment involving 14 cows and 15 detected estrus periods. The sensor detected 20 ± 4.9 STBM events per estrus period, whereas video observation identified 27 ± 4.1 events, corresponding to a detection rate of 74.1%. Despite incomplete detection of individual mounting events, the sensor detected at least one event in all estrus periods, which corresponds to an estrus detection rate of 100%. The system was subsequently deployed in grazing beef cows, where 124 estrus periods were recorded. Most STBM events (91%) occurred outside routine visual observation periods. The conception rate was highest when artificial insemination was performed 13–24 h after the onset of STBM behavior. These results demonstrate that a switch-type mounting sensor can reliably identify estrus onset and support appropriate timing of artificial insemination in grazing beef cattle. Sensor-based monitoring systems combined with low-power communication networks may contribute to the implementation of precision livestock farming technologies in extensive grazing systems.
Nabenishi et al. (Wed,) studied this question.