Nature guiding how we nurture: Using the behavioral ecology of the domestic sow to advance welfare legislation

Abstract

During the twentieth century, pork production transitioned from small extensive farms to large intensive systems, leading to widespread confinement of commercial sows. This global intensification of pig production generated substantial welfare concerns, including questions about the expression of maternal behaviors. Ethologists often use the behavioral repertoire of wild animals to understand the ecological and welfare needs of their domestic counterparts. Thus, we hypothesized that the welfare of today’s commercial sow will depend, at least in part, on 1) evidence that the domestic sow maintains the motivation to perform those behaviors intrinsic to the wild sow, and 2) evidence that suppression of these behaviors results in measurable indicators of negative welfare. We compiled evidence from the literature to investigate the maternal behavioral repertoire of the wild sow during each stage of her reproductive cycle and the domestic sow’s enduring motivation to perform these behaviors. Our findings detail the survival of the wild sow’s maternal behavioral repertoire within the modern-day domesticate and the negative welfare outcomes associated with inhibition of these behaviors under most commercial conditions. Using this ethological framework, we examined California’s Proposition 12 to identify opportunities to advance welfare through housing legislation informed by a sow’s behavioral ecology. Collectively, this work substantiates the use of wild sow behavior as a comparative framework to assess the welfare outcomes of commercial sow housing and highlights the critical role that animal behavior science should play in shaping evidence-based policy.