Influence of mild pain and/or sickness caused by lipopolysaccharide-induced clinical mastitis on the time budget, space use and social behaviour of dairy cows

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Cows suffering from mammary inflammation display 'individual-centred' pain and/or sickness behaviours; however, how they interact with their surroundings (physical environment, social context) is less documented. This study examined the effects of mild mammary pain and/or sickness on cows' daily activity patterns, spatial organisation, and social behaviours (dyadic interactions and social network metrics). Twenty-seven dairy cows were studied using a repeated-measures design over six observation days, comprising three 'non-challenge days' and three 'challenge days'. On each challenge day, a subset of cows received an intramammary infusion of 25 μg E. coli lipopolysaccharide (LPS) into a healthy udder quarter after morning milking, while the remaining cows served as CONTROL. Cows receiving LPS were either left untreated (LPS status, n = 14) or immediately treated with a non-steroidal anti-inflammatory drug (LPS+NSAID status, n = 13). Cows' behaviour was continuously video-recorded between morning and evening milkings across all 6 days, which allowed to collect data on location, activity, proximity to neighbours, and social interactions. Data were analysed using mixed effects models and social network analysis. The results showed significant effects of pain and/or sickness status on behaviour (location; activity) and social dynamics. First, compared to the CONTROL status, cows in the LPS status spent less time at the self-locking barrier and more time in cubicles. They spent longer durations of time standing still and perching and less time eating, engaged in fewer social interactions and maintained greater distances from their nearest neighbours. Social network analysis found that cows in LPS status reduced their level of social engagement (i.e. lower Strength) and of social connectivity (i.e. lower betweenness). Second, comparisons between the LPS+NSAID and CONTROL conditions revealed no significant differences, whereas comparisons between the LPS+NSAID and LPS conditions showed significant contrasts. Compared to cows in LPS status, those in LPS+NSAID status spent more time in self-locking barriers, less time in cubicles, more time eating, less time perching, and were involved in a higher number of social interactions and were closer to their first neighbour. Together, these results indicate that NSAID treatment alleviated most behavioural effects associated with pain and/or sickness. These findings highlight the potential value of behavioural indicators including activities, space use and social behaviour for improving mild pain and/or sickness detection in dairy cows. This study can be seen as a first step to identify relevant behaviours, which would be followed by the development or refinement of practical tools in on-field applications.

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