Validation of proximity sensors to monitor social proximity in dairy cows: a pilot study

Social interactions of group-living farm animals can have important implications for animal welfare, health, and productivity. Understanding which factors can affect social behaviour is thus important to improve management strategies. We investigated the social structure of a group of 19 lactating dairy cows during a 14-day period through the use of proximity loggers. The proximity devices collected data on dyadic proximity of cows. The devices are non-invasive, weight 2.7 g, are powered by a lithium coin battery (3 g). The sensors have been attached to the cows by using custom collar-mounted cases, and were set to detect proximity events within a distance of 1–1.5 m. Colocation of animals at this distance indicated a close-contact situation, during which social in teractions between animals might occur. In addition, proximity sensors were placed in strategic locations of the barn (e.g., feeding trough, drinkers, cubicles) as fixed tags in order to evaluate the use of the space and resources by the cows. Video observations of the cows, their interactions and their location were used to assess the repeatability of the measurements produced by the sensors. At the time this paper was written, data analysis was still ongoing. Preliminary results indicate the proximity sensor technology used in this study has the potential to provide high resolution data that can be used to monitor the social behaviour and the location of dairy cattle. Further analysis is deserved to better evaluate the functioning of these type of proximity sensors within common dairy cow housing, especially in freestall barns.