The careful monitoring of cows helps minimise pain and distress during calving; moreover, knowing the exact time of birth is important to ensure timely assistance and the adequate ingestion of colostrum by the calf. However, direct visual observation is time-consuming, and the continuous presence of an observer during stage two of calving can disturb cows. Video cameras or accelerometers recording the behaviour of cows can be integrated in systems using image analysis or locomotive activity to alert the farmer as to when calving is imminent. However, alerting systems require the input of benchmark information about behaviours and changes in behaviours that can be predictive of the time of calving. Eight cows in a calving barn were continuously video-monitored. The recordings of the 24 h before delivery were analysed by instantaneous time sampling to identify the behaviours associated with an imminent birth. The same were collected in an ethogram including lying, standing, walking, turning the head towards the abdomen, eating, ruminating, drinking, sniffing the ground, allogrooming, self-grooming, and posture-changing. In our conditions, the only behaviour that was significantly influenced by the distance to delivery was posture-changing (p < 0.0001). Two h before the delivery, the proportion of posture changes was different from all of the hourly proportions measured from −24 to −3 h relative to delivery (p < 0.005), resulting in 3.6 times the average of the previous 22 h relative to delivery. An increase of posture changes may be an indicator of calving approaching, but further studies are needed to input benchmark values in alerting systems.
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