A Successful System for Housing Pregnant Sows in Groups

In August 1997, an Alternative Swine Systems Task Force (ASSTF) was created at the University of Minnesota. State legislation had been introduced to fund research on technologies to deal with noxious odors from the state's industrial-style pig farms. Family farm advocates reasoned that if any tax dollars were to be spent on odor research, it was only right that some of them should be devoted to demonstrating pig rearing systems that were already environmentally friendly. Led by Minnesota's Land Stewardship Project, they convinced the legislature to appropriate funds to study better systems, among them the Swedish deep-bedded group housing systems for swine (see Fall 1994 AWI Quarterly). The ASSTF was created to see that the legislative directives were carried out. Marlene Halverson, AWI's farm animal economic advisor, who first advocated the Swedish deep-bedded systems in the US for welfare reasons, serves on the task force as one of its original members. After several years of planning, examples of the Swedish systems of deep-bedded group housing for gestating sows and for lactating sows and their litters are operating at the University's West Central Research and Outreach Center (WCROC) at Morris, Minnesota. (The group housing system for sows and their litters will be discussed in a forthcoming Quarterly.)

In 2001, a hoop structure was built to house the Swedish system for gestating sows. Preferred by farmers, this housing system is based on the sow's biology and natural social behaviors and has been used in Sweden for nearly three decades. Along one length of the structure is a row of individual feeding stalls, one for each sow in the group, that the sows can enter at will. The stalls can be locked behind the sows while they are eating, allowing sows to be fed individually, eliminating competition for feed, and ensuring that each sow gets a full ration. This feeding method satisfies normal sow preferences to eat simultaneously as a social group. Behind the feeding stalls is a deep-straw bedded lying and activity area with nearly 30 square feet of space for each sow. New straw is added daily, providing natural material for occupation and munching between meals. Sows are kept in stable groups. New sows are only introduced to an existing group in stable subgroups of six or more new sows, never singly. This permits sows to form and maintain normal avoidance relationships that minimize fighting and promote peaceful group relations. These accommodations to the sows' natural behaviors demonstrate the Swedish farmers' philosophy of "fitting the system to the animal, rather than the animal to the system."

Before leaving for a new post in Australia this May, Dr. Rebecca Morrison, the University's former sustainable swine scientist reported "we have been overwhelmed by the success of this alternative housing system for gestating sows...and we have received many positive comments from the stock people working with the sows." Swedish farmers' experiences raising pregnant sows in groups in this system as well as the results at WCROC demonstrate that group housing of pregnant sows is successful when the natural behavior and biology of sows are both understood and accommodated in the design.