Sow Farrowing Nest Building and Behaviour

Nest building is one of the strongest behavioural drives in pre-farrowing sows. Denying this behaviour in conventional farrowing crates causes significant frustration and welfare compromise at a critical time.

Key Facts

Wild pigs walk up to several kilometres before farrowing to find suitable nest sites and gather nesting materials
Nest building begins 12-24 hours before farrowing and involves rooting, carrying, and arranging substrate
The motivation to nest build is driven by hormonal changes and is independent of available materials
Sows deprived of nesting material in farrowing crates perform vacuum nest-building behaviours on bare floors
Provision of straw, paper, or other nesting material significantly reduces pre-farrowing stress indicators
Sows provided with nesting material show reduced cortisol levels, reduced stereotypies, and better farrowing outcomes
Nesting reduces the farrowing duration, increases number of live-born piglets, and improves colostrum production
The EU has proposed banning farrowing crates in favour of loose farrowing systems that allow nesting behaviour

Welfare Considerations

The denial of nest building in conventional farrowing crates represents one of the most clear-cut examples of welfare compromise through housing design. The pre-farrowing period is highly motivated behaviourally and hormonally - sows are driven to nest build regardless of whether materials are available. The vacuum behaviour that results from complete deprivation (frantic rooting on concrete) is evidence of thwarted motivation causing chronic frustration. Providing even simple nesting material - loose straw, paper, or jute sacking - substantially reduces this distress at minimal cost. The broader move to loose farrowing systems that allow free movement represents an important structural improvement, though these systems require careful management to prevent piglet crushing.

What You Can Do

Support pork producers and retailers committed to providing nesting material to farrowing sows as a minimum standard
Advocate for the inclusion of nesting material provision in all farm welfare auditing schemes for pig production
Choose pork from producers using loose farrowing systems or at minimum providing nesting material in crates
Support research into loose farrowing system design that optimises both sow welfare and piglet survival
Engage with EU and UK regulatory processes on farrowing crate reform
Share information about the welfare significance of sow nesting behaviour with food industry contacts