Sow welfare in the farrowing crate and alternatives

The farrowing crate 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. Although alternative farrowing systems exist, a major barrier to the uptake of these systems is that they must deliver acceptable levels of piglet mortality. Research efforts have led to successful development of loose farrowing systems delivering high performance and high welfare. The key to success has been recognising that allowing the display of species-typical behaviours contributes to the biological fitness of the animal, which encompasses important economic performance parameters including number of offspring produced, viability of offspring and maternal rearing ability. Further welfare challenges have developed as sows have been subject to genetic selection pressure for leanness and prolificacy. A more balanced equation where the cost of maternal investment (for instance shoulder lesions, loss of body condition, lower residual reproductive output and thus shorter longevity) is balanced against the increase in the number of piglets born and weaned, is needed as a basis for breeding programs. Therefore system design optimisation must be accompanied by optimisation of both human inputs (i.e., through augmentation of management) and animal inputs (i.e., through appropriate genetic selection strategies).