Effects of journey duration and temperature during pre-slaughter transport on behaviour of cull sows in lairage.

ABSTRACT

This observational field study investigated the effects of journey duration, temperature, and waiting duration before unloading on the behaviour of 562 cull sows during lairage from 23 commercial loads. Each load consisted of sows originating from more than one herd, thus experiencing variable pre-slaughter transport and management. In lairage, sows were mixed in groups of 25, involving animals from all journey durations (min-max 0.8-8.4 h) and video monitored for 60 min. At first most sows were in upright position (approximately 80-90%), decreasing to 30-40% after 30 min. After 60 min, 42% of the sows had initiated aggression (min-max 0-43 events/sow), 28% had been subjected to aggressive behaviour (min-max 0-14 events/sow), and 36% s were observed drinking (min-max 0-16 events/sow). Several significant interactions were found between journey duration, the average temperature in the vehicle and lairage pen (averages 4.3-26.2 °C) and waiting duration before unloading (min-max 3-25 min). For example, after short journeys, sows exposed to higher temperature carried out more aggressive behaviour, while a higher temperature after long journeys was associated with more lying and less drinking. This suggests that the sows prioritised lying behaviour over drinking and establishing a dominance hierarchy. We discuss how the results may be interpreted as behavioural signs of fatigue, but further studies, for example involving quantification of physiological and motivational indicators, are needed to clarify this. Irrespectively, the present findings suggest that a stay in a lairage pen, as part of the pre-slaughter logistic chain, involves challenges for the welfare of the cull sows.