Preliminary results from a novel tail-mounted calving sensor in dairy cows

The objective of this study was to pilot-test a novel biosensor to predict the onset of stage two of calving in dairy cows. A monitor was developed containing an accelerometer and other gravitational measurement devices. It was attached to the upper side of the cow's tail approximately 6 cm below the anus. Three behavioural changes were monitored: (1) tail raise frequency and duration; (2) angle of tail raise; and (3) bouts of standing/ lying down. Measurement of these behaviours was taken every two seconds and the data transmitted to a receiver base. The device was tested on 20 dairy cows. The time of calving was established by 24 h staff supervision and CCTV. Of the 20 cows, 12 calvings were monitored, (six primiparae, six pluriparae); five unassisted, six easily assisted and one difficult. Prolonged elevation of the tail (> 30 - 45 degrees, > 20 seconds and four repetitions within 60 minutes), either alone or in combination with an abnormal standing pattern (within a 30 minutes period) were observed within four hours of each calving (unassisted calvings two - 3.3 h; assisted calvings 45 min - 3 h). Prolonged tail elevation combined with increased restlessness was indicative of imminent calving. The monitor was able to detect and record the pattern of calving behaviours and the algorithm was able to detect distinct onset of calving-specific behavioural change up to four hours before birth.