Document type: scientific synthesis published in INRAE Animal Productions
Author: C. Clouard-Mésange
Preview (author's summary in English): The pig is a social species that lives within groups whose hierarchical structure is regulated by a set of agonistic interactions, such as aggression, as well as non-agonistic ones, such as snout contacts. This review aims to (i) provide an overview of current knowledge on the social behaviour of the domestic pig, (ii) describe the impact of farming practices on the expression of these behaviours, and (iii) propose research perspectives on social behaviour to improve animal welfare on farms. On pig farms, several husbandry conditions and practices, including social mixing, the formation of inadequate groups in terms of size or composition, or unsuitable infrastructures strongly affect the expression of social behaviours and relationships. Until recently, pig research on social behaviour has primarily focused on agonistic interactions. The role of these interactions in dominance relationships and in resource defence, as well as the impact of certain husbandry practices on these behaviours, are well-documented. In contrast, non-agonistic social behaviours have received little attention to date. Yet, their prevalence is significantly greater than that of agonistic behaviours, and they are believed to be involved in various biological processes, such as social recognition and communication, affiliation, and stress reduction. By favouring positive mental states, these behaviours could play a crucial role in maintaining animal welfare on pig farms. We need to better understand their functions and determinants. This knowledge should be incorporated in the design of new management practices in pig production systems.
