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Cognition studies with pigs: Livestock cognition and its implication for production¹

S. Held^*,2, M. Mendl^*, K. Laughlin^*,3 and R. W. Byrne

^* Centre for Behavioral Biology, Department of Clinical Veterinary Science, University of Bristol, Langford, Bristol BS40 5DU, U.K. and Scottish Primate Research Group, School of Psychology, University of St. Andrews, Fife, KY16 9AJ, U.K.

² Correspondence: phone: +44 117 9289571; fax: +44 117 9289582; E-mail: suzanne.held{at}bristol.ac.uk.

Abstract

The purpose of this paper is twofold. First, it discusses in general terms how animal production can be affected by the animals' cognitive abilities; second, it aims to introduce our work on pig cognition. We suggest that livestock cognition does not only affect production indirectly through its effects on livestock welfare, but also that cognition can have direct effects. Direct effects are evident when cognitive abilities limit feed intake, for example, or in the recognition of groupmates or offspring. We illustrate such direct effects with two case studies from pig production: voluntary feed intake after weaning and production losses associated with aggression in groups. Voluntary feed intake after weaning is affected by preweaning experiences, weaning age, and postweaning practices. Some studies suggest a link between early environment and cognitive development in piglets, as has previously been demonstrated in other species. We suggest this as a possible contributing factor to low feed intake immediately after weaning. The other case study centers on aggression in groups of pigs. Several studies indicate that some social assessment and recognition take place between individuals, allowing them to judge each other's aggressiveness and to avoid fighting once a dominance hierarchy has been established. However, the regrouping of previously familiar pigs can also lead to high aggression levels. This suggests that pigs may be able to form only short-term social memories, or that some aspects of their social memory are disrupted before regrouping. Our work shows that pigs have well-developed spatial memory abilities, which can be disrupted by common management procedures. If this were also the case for social memory, it could help explain increased aggression levels in previously familiar pigs after routine procedures. We also show that pigs are able to adjust their foraging behavior depending on the presence or absence of a subordinate, exploitable co-forager that knows where food is. This ability has potential implications for the way feed is best dispensed to pigs such that all group members can maximize their intake.

¹ The Biotechnology and Biological Sciences Research Council of Great Britain funded our work.

³ Present address: 1230B Anthony Hall, Dept. of Anim. Sci., Michigan State Univ., East Lansing, MI 48824.