The farrowing period — when sows give birth and nurse piglets — is one of the most welfare-critical stages in pig production, with the type of system having profound impacts on both sow and piglet welfare.
The farrowing crate prevents sow crushing at the cost of completely eliminating maternal behaviour. A sow in a farrowing crate cannot build a nest — a behaviour she is strongly motivated to perform in the 12-24 hours before birth — nor turn to interact with piglets or choose her lying position. The frustration of nest-building motivation in sows is measured in repeated stereotypic rooting at the floor. Modified free-farrowing systems demonstrate that good piglet survival rates are achievable without continuous confinement, through temporary voluntary entry during the peak crushing risk period combined with nest materials and appropriate space.