The Effect of Sows' and Piglets' Behaviour on Piglet Crushing Patterns in Two Different Farrowing Pen Systems

Simple Summary Farrowing crates-narrow cages where sows are kept during lactation-impede the sow in the expression of natural behaviours and, therefore, cause animal welfare concerns. However, piglet losses due to crushing by the sow are effectively reduced by farrowing crates. Hence, there is an urgent need to find a practical compromise between sows' and piglets' welfare. The aim of this study was to test two farrowing pens without fixation of the sow in comparison to pens with a farrowing crate. Piglet mortality, piglet crushing and sow and piglet behaviour in the first 72 h after birth were analysed. Piglet mortality was higher due to increased levels of piglet crushing in the free-farrowing pens. However, the majority of crushing occurred in the first three days after birth. The recorded active and resting behaviour of sows in the first 72 h after birth hardly highlighted differences between the three systems, i.e., sows in free-farrowing pens hardly used the offered possibilities for activity in the first 72 h after birth. In conclusion, our results suggest that a temporary fixation for a few days after birth could be sufficient to significantly reduce piglet crushing and could represent a practical solution for future farrowing systems. Pens with farrowing crate (FC) and two differently designed free-farrowing pens (LH-pens: 7.3 m(2), plastic flooring; GH-pens: 5 m(2), cast-iron and concrete flooring) were compared regarding piglet losses and postpartum sow behaviour (all treatments) and reasons for piglet crushing and postpartum litter behaviour (LH and GH). One-hundred-and-three crushing events were analysed in eight batches concerning sows' posture changes that crushed piglets and age of crushed piglets. Posture change frequency, amounts of single posture changes and total time spent in different body postures were evaluated for 41 sows (14 FC-sows, 13 LH-sows and 14 GH-sows) in six batches. Litter behaviour (location, active/inactive scoring, resting behaviour next to the sow) was analysed during sows' posture changes and piglet crushing. Piglet mortality was higher in LH (25.6%) and GH (19.9%) compared to FC (12.3%) due to higher levels of piglet crushing. Most crushing occurred during the three days postpartum in LH (92.7%) and GH (83.9%). However, crushing patterns differed between LH (rolling: 68.2%; sit-to-lie: 18.2%; stand-to-lie: 11.4%) and GH (rolling: 38.2%; sit-to-lie: 30.9%; stand-to-lie: 16.4%) and varying piglet behaviour may be the cause for this. The postpartum period was characterized by inactivity of the sow and behavioural differences were rarely seen between systems.