Pig Farrowing Nest-Building: A Fundamental Welfare Need in Farm Systems

Nest-building is one of the most strongly motivated behaviours in sows approaching farrowing. Denying this need in farrowing crates causes significant frustration and stress.

Key Facts

Wild boar and feral sows spend 12-24 hours building a nest before farrowing, gathering and arranging vegetation in a specific sequence of behaviours
Nest-building motivation in sows is hormonally driven — it peaks sharply 24-48 hours before farrowing and cannot be redirected to other activities
Sows in farrowing crates display vacuum nest-building behaviour — rooting at bare floors and pawing futilely — a clear indicator of frustrated motivation
Providing straw to sows 24-48 hours before farrowing significantly reduces vocalisation, heart rate, and cortisol compared to sows given no nesting material
EU legislation requires enrichment for sows pre-farrowing but does not mandate nesting material of sufficient quantity for functional nest construction
Research by Sandra Edwards and colleagues at Newcastle University demonstrated that straw provision before farrowing improved piglet survival as well as sow welfare
The farrowing crate prevents sow movement entirely — the combination of physical restriction and frustrated nest-building motivation creates severe welfare compromise

Welfare Considerations

The farrowing crate is one of the most welfare-compromising confinement systems in modern agriculture. Designed to reduce piglet crushing by an immobilised sow, it achieves this at the cost of complete freedom of movement and the ability to perform the highly motivated nest-building sequence that is hormonally primed and behaviourally imperative. A sow in a farrowing crate who cannot build a nest does not simply stop wanting to — she continues displaying the behaviour in a vacuum, rooting at concrete and showing the physiological markers of acute frustration. Free farrowing pens with adequate straw allow nest-building and are associated with better sow welfare and comparable piglet survival when managed well. They represent the direction of welfare travel for the pig industry.

What You Can Do

Choose pork from free-farrowing systems or certified higher-welfare schemes that prohibit farrowing crate confinement
Advocate for regulatory reform prohibiting farrowing crates — several European countries have implemented or planned phase-outs
Support Compassion in World Farming campaigns for farrowing crate abolition and free-farrowing system adoption
Engage with supermarkets and food service companies on their supplier requirements for sow welfare at farrowing
Donate to research programmes developing free-farrowing systems that maintain piglet survival while improving sow welfare
Raise awareness that farrowing crate confinement is not a welfare-neutral management tool — it causes significant suffering to highly motivated sows
Promote the welfare science of nesting motivation to agricultural students and farmers — understanding the evidence changes practice