Autonomous on-animal sensors in sheep research: A systematic review

•An in-depth systematic review of the use of on-animal sensors in sheep research.•Sensors have been applied broadly with growing interest in their development.•Sensor capabilities continue to impact experimental design.•As technology improves, commercial applications are expected to increase. This systematic review explores the use of on-animal sensor technology in sheep research. A total of 71 peer-reviewed articles reporting on 82 independent experiments were reviewed, ranging in publication date from 1983 to 2017 and distributed across all populated continents. The findings demonstrate increasing numbers of published studies that validate the application of sensor technology to categorise and quantify sheep behaviour. The studies also used sheep sensors for environmental management, validation of data analysis methods and for health and welfare research. Whilst historically many applications of sensors in sheep research have been conducted over a short period with small numbers of experimental animals, this trend appears to be changing as technology develops and access improves. The literature suggests that many applications of sensors have already or are currently moving through a proof-of-concept stage, allowing future applications to focus on commercialisation of technology and potential integration with other technologies already in use (e.g. weather data).