Nest-building before farrowing is a powerful motivational drive in sows. Its frustration in barren farrowing systems causes significant stress, while its expression improves both sow and piglet welfare.
Nest-building deprivation in farrowing crate systems represents one of the clearest examples of motivated behaviour frustration in farm animal welfare. Sows in crates before farrowing paw vigorously at the concrete floor, attempt to gather non-existent material, and perform the complete nest-building sequence against the cage bars - the behavioural sequence is so strongly programmed it occurs even when substrate is entirely absent. This is not a minor inconvenience but a profound frustration of a biologically critical behaviour. Providing even a handful of straw reduces pre-farrowing stress hormones, improves maternal behaviour at birth, and contributes to better piglet welfare.