Heart Rate (HR) Detection by Cattle Rumen Bolus

In livestock automation, a bolus sensor may be a useful tool to measure the physiological and behavioural characteristics of animals. Based on the 3D acceleration data measured by the cow's rumen bolus, the heart characteristics, namely the InterBeat Intervals (IBI) values and the derived Heart Rate (HR) frequency values were detected. The task is made more difficult by the fact that motion artifacts from other movements (walking, jumping, rumination) measured by the sensor typically have a larger amplitude than the signal generated by heart activity. The detection was carried out with a sampling frequency of 25Hz in the ±2G measurement range and the calculations were performed on a time series measured at 3s. During processing, the IBI values could be detected with an accuracy of ±50ms using data pre-filtering, Wavelet-Morlet transformation and Kalman filtering. The obtained results are suitable for implementing basic alarms (stress, illness, beginning of calving) in a Precision Livestock Farming (PLF) system.