In modern pig production up to 50 % of the sows are slaughtered each year. So far, only few studies have focused on how sows are handled and moved within slaughterhouses. We examined effects of group size on the behaviour of sows and the ease of moving them from the entrance of a slaughterhouse and towards the lairage pens. The study included 30 truck loads of cull sows (and a few breeding boars, as they were transported to slaughter together with the sows; 1917 sows and 55 boars). The sows were transported between 4.2–7.5 hours in fully air-suspended two-deck trucks, approved for transport of sows. Half of the loads were moved from the trucks as full loads (32−95 sows per load), the other half split into smaller groups of 5–6 sows. The behaviour of sows and handlers was observed directly, while they were entering the slaughterhouse and walked along a downward sloping concrete aisle measuring 1.1 m (width) and 13.2 m (length) ramp, approaching a 90° corner on the way to the lairage pens. Differences in the behaviour of the handlers between the two treatments were minor, but moving sows in smaller groups did, contrarily to our expectations, prolong the duration of the procedure, probably due to the sorting into smaller groups onboard of the truck. The results confirmed that passing a corner may constitute an obstacle for the ease of moving sows, especially when they were moved as full loads, as a higher proportion of these sows stopped or blocked the aisle near the corner, than the sows moved in smaller groups. In addition, a higher proportion of the sows moved as full loads turned 180° against the direction of intended movement. In conclusion, modulation of the group size of sows upon arrival at a slaughterhouse affected their behaviour and the ease of movement. Further studies are needed to examine cost-benefit of low group size when moving sows in terms of animal welfare, human well-being and logistics.
|Publication Title||Applied Animal Behaviour Science|
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