The growing interest of animal welfare is prompted amongst other by understanding basic behavioural need of the animals. The aim of this study was to develop a system that automatically generates animal activity data. Therefore, a computer vision-based system for detecting sheep standing and lying behaviour was proposed. The system was composed of a multi-camera video recording system and a software module which can detect sheep standing/ lying behaviour by using the depth video stream and infrared video stream. Assessment of the detection results were carried out by comparison with the results by observation. The sensitivity of the system achieved for detecting sheep standing and lying was 96.4% and 94.16% respectively. The proposed system was able to compute sheep behaviour and the real-time detection can be achieved. The system can increase the convenience for animal behaviour studies and monitoring of animal welfare in the production environment.