Aggression between commercial pigs

Format of work:

Conference Presentation

Event presented at / Journal Name:

Seventh Annual Meeting of AWRN, Great North Museum, Newcastle

Speaker / Contact Author's Name:

Lucy Oldham

Speaker / Contact Author's E-mail Address:

  • Research aim:

    To understand whether pigs with an aggressive personality are immune to the emotional costs of fighting and fail to learn from past defeat.

  • Background:

    Commercial pigs are routinely mixed into new social groups on farm and often fight to establish new dominance relationships. Pigs vary in the aggressive behaviour they display, in terms of (a) individual threshold for aggression (aggressiveness), and (b) how they change their behaviour based on previous wins and losses.

  • Approach:

    The role of emotions and aggressive personality on a pig’s ability to learn (following an aggressive experience) were examined to see how these factors interact.

  • Key finding:

    Both unaggressive and highly aggressive pigs are able to learn from experience and adjust their aggressive behaviour depending on the outcome of previous fights. Unaggressive pigs did not appear to be more emotionally affected by aggression than highly aggressive pigs.

  • Industry or policy relevance:

    Aggressive pigs are not immune to the emotional costs of fighting. We should be concerned about the welfare of all pigs during conflict situations, including those that are the most motivated to fight. Interventions which reduce average aggressiveness should not cause pigs to avoid fighting simply because they are too afraid.

  • Route for practical application:

    Although a reduction in aggressiveness should improve the welfare of all pigs, this study does not provide a route to achieve this. Previous studies demonstrate that early social experience (e.g., allowing piglet litters to freely intermingle before weaning) can help pigs to establish new dominance relationships, with fewer injuries, in later life.

  • Confidence in findings and next steps towards realising impact:

    Published literature conclusively indicates that allowing piglets to intermingle before weaning reduces the risk of later injury when regrouped with unfamiliar pigs. Note: it is possible that studies which did not find this benefit were not published. Since pigs live in groups we are now using social network analysis to understand how aggressive personality in individuals affects the functioning of a whole group. This includes exploring how cognitive ability (e.g. learning, memory, decision making): (a) might help pigs avoid fights that they will lose, and (b) could be promoted via changes in management to help pigs navigate social interactions. This work is on-going.


BBSRC, SRUC, Scottish Government

Links to Open Access Publications or DOI:


Oldham, L. 2023. “Understanding the proximate causes of pig aggression: experience, emotions and everyone else” Seventh Annual Meeting of AWRN, Great North Museum, Newcastle. 18-19th January 2023.