Research on Group-Housing for Sows

Sow housing is a controversy issue in the swine industry. The conventional confinement housing system for sows, such as gestation stalls and farrowing crates have been used in the western countries for more than 30 years. Despite the advantages of confinement sow housing systems, concern over sow welfare due to restriction of movement has resulted in gestation stalls being banned in the European Union and several states in the U.S. In addition, the largest pork producers in the U.S. and Canada, some chain restaurants and grocery stores have announced to phase out gestation stalls in favor of group housing systems. However, group-housing systems for gestating sows present challenges of controlling individual feed intake and fighting at mixing. To control individual feed intake, several feeding systems, such as electronic sow feeders, free access stalls, and trickle feeding systems have been developed for group-housed gestating sows. Each feeding system has advantages and disadvantages in terms of controlling individual feed intake, efficient use of floor space, and facility investment. Regardless of the type of feeding facility chosen, all group-housing systems subject sows to aggression at mixing, which compromises the welfare and performance of sows. Management strategies to minimize aggression among sows include nutritional, social, and physical interventions. Scientists at the University of Minnesota investigated whether these management strategies, such as supplementation of dietary tryptophan, mixing after pregnancy confirmation, sorting by parity, and providing hiding spaces could reduce aggression among sows. The data showed that some management strategies reduced aggression-associated injuries and improved farrowing rates, suggesting that the welfare and performance of group-housed gestating sows can be safeguarded by proper management strategies and housing facilities.