Technical Report: Development and validation of continuous monitoring system for calves based on commercially available sensor for humans

In the last decade, development of continuous sensor based monitoring systems for farm animals (Precision Livestock Farming (PLF)) has markedly increased with the aim to automate and improve disease detection. In calves, multiple technologies exist, but most detect only a single parameter, and none are available for continuous heart rate and electrocardiogram (ECG). The objective of this paper was to develop and validate a sensor system, derived from a commercially available sensor for humans, for heart (ECG, heart rate), movement (inertial measurement unit with nine degrees of freedom (IMU9)) and temperature data. Data is sent over Bluetooth Low Energy (BLE) to a gateway equipped with a built-in camera for monitoring individual calves. The gateway transmits the data using the Message Queuing Telemetry Transport (MQTT) protocol to a server for long term storage. The data can also be shown on a real-time dashboard. Results indicate a very high correlation for heart rate compared with a widely used veterinary sensor (Pearson correlation coefficient (r) = 0.98), and a high level of accuracy for the movement data for lying versus standing detection (94.3 %). However, a lower correlation between sensor temperature and rectal temperature measurements was observed (r = 0.56). In conclusion, the adapted Movesense system exhibits the capability to accurately measure heart rate and detect the position (lying - standing) of calves but was insufficient as such for temperature monitoring. This sensor system has potential not only for disease detection, but equally for continuous, non-invasive heart rate monitoring, which can be used as an indicator (besides others) for animal welfare.