Sow welfare in farrowing systems

Most sows worldwide farrow while restrained in a farrowing crate. This poses a welfare dilemma. The restriction of sow movement interferes with the performance of species-specific behaviours such as nest-building, orientation, exploration, and communication with the piglets and leads to increased physiological stress. However, allowing the sow more freedom to perform motivated behaviours often results in increased crushing of piglets and hence a piglet welfare problem. Research efforts have led to successful development of loose farrowing systems delivering high performance and high welfare. Key to success is allowing species-typical behaviours that contribute to biological fitness, which encompasses important performance parameters such as number of offspring produced, offspring viability, and maternal rearing ability. Performance and welfare can improve by optimising system design (e.g. housing), human inputs (e.g. management), and animal inputs (e.g. genetic selection strategies). Continuing genetic selection pressure for sow leanness and prolificacy has, however, significant impacts on their welfare. A more balanced equation, where the cost of maternal investment is balanced against the increase in the number of piglets born and weaned, is needed as a basis for breeding programs.