The impact of lying down support on the lying down behaviour and piglet trapping in temporarily crated lactating sows

The housing of lactating sows remains a persistent animal welfare concern. Temporary crating may offer a compromise that supports the welfare of both sows and piglets in the farrowing pen. This study examined whether sows used lying-down supports (e.g. slope wall) before and after crate opening, and whether such use reduces the risk of piglet crushing. Nineteen healthy sows without any leg problems were housed in temporary farrowing crates from 5 days before farrowing until 3 days postpartum (pp), when crates were opened on the morning of day 4. The pen design included a slope wall angled at 18°, while the other wall, door, and nest barriers could also serve as supports. Sow and piglet behaviours were video-recorded for 24 h at three time points: 24 h before crate opening, 24 h after crate opening, and on day 25 pp. Analysed behaviours included the number and duration of lying-down events, use of supports, sow positions, and piglet positions in the pen and creep area. Continuous variables were analysed using linear mixed models accounting for repeated measures, and binomially distributed variables were evaluated using generalised linear mixed models. Following crate opening, sows significantly reduced their use of all supports compared with both the preopening period and day 25 pp, with nearly 34% of events occurring in the middle of the pen. Use of the slope wall declined significantly immediately after crate opening and decreased further by day 25. Lying-down events lasted longer when supports were used. Trapping events were rare (16 out of 1 539 lying-down events), with fatal crushing occurring in only four cases. These findings indicate that lying-down supports are not essential for preventing piglet crushing once the crate is removed; however, it is important to note that this applies only to healthy sows without mobility problems. Overall, releasing sows from close confinement does not appear to compromise piglet safety and may allow for more natural and maternal behaviours.