The Use of Rumen Bolus Sensors to Measure Physiological Changes in Stressed Growing Holstein Steers

In the last decade, the wireless biosensor technologies for cattle have been widely spread over the world. The objective of this study was to evaluate the changes of physiological state in Holstein growing steers using the rumen bolus sensor. A total of thirty-two Holstein young steers (219.48 ± 16.61 kg, 7.25 ± 0.40 months of age) were used and the rumen bolus was orally administered to each steer before conducting this experiment. The rumen bolus used in this study (Smart alyac Ⓡ , Hankook Iot Corp, Gimcheon, Korea) can measure not only body temperature (BT) but also moving behavior which was expressed as indices (moving index, MI). All steers equipped with the bolus sensor were housed in pens (4 animals per pen) and the sensor data were collected for 29 days. During experimental period, the average MI for the day (day: 0700 –1900, night: 2000–0600) was significantly higher than that for the night (day: 111.10, night: 98.53, p < 0.0001), but the result of average BT was opposite (day: 39.04 ℃ , night: 39.62 ℃ , p < 0.0001). The average MI in animals having low average daily gain (ADG) was higher than those having high ADG (low ADG: 105.46, high ADG: 103.66, p < 0.0001) and average BT was the same (low ADG: 39.41 ℃ , high ADG: 39.33 ℃ , p < 0.0001). When the steers exposed to several stresses, the average MI was significantly lower than that in normal condition (normal: 117.40, stress: 109.88, p < 0.01). Stressed steers also showed increased BT compared to steers in normal condition (normal: 38.78 ℃ , stress: 39.50 ℃ , p < 0.0001). In conclusion, rumen bolus sensors, which generally used in cows to detect estrus, can be applied even to steers to detect the physiological changes rapidly in stressful environment.