Farrowing pen size and maternal behaviour

Summary

Growing litter sizes with lower birth weights lead to more vulnerable newborn organic piglets. Combined with the free movement of the sow around parturition the risk of piglet mortality increases. A larger farrowing pen with more opportunities to perform nest building and maternal behaviour is a potential way for better care for the piglets. In this project we compared farrowing pens of 8 and 24 m² in order to improve natural behaviour (welfare) and survival of newborn piglets (welfare and economy).
Behaviour and performance of 60 sows and litters was studied on a commercial organic pig farm during 1.5 years. Video footage was recorded from 24 h before birth of the first piglet until 72 h after birth of the last piglet. Activity and postural changes of the sows, piglets and position of the nest were scored by scan sampling. Performance data was recorded by the pig farmer on a score sheet per sow.
As expected the sows showed and increased activity during the 12 h pre farrowing, but without any difference between the two pen sizes (see figure). However a qualitative assessment showed more sows with nest building behaviour (collecting straw) in the large pens. Risky body movements of the sow are a risk factor for piglet mortality (crushing). These postural changes did not differ between the two treatments. The piglet mortality was 7% lower in the larger pens (20 vs 13%; p=0.04), resulting in 10.1 vs 11.1 weaned piglets.
Figure. Proportion of activity per treatment per period around farrowing (no differences between treatments; differences between periods indicated by different superscripts)