Dr. Nigel Cook and Kelly Lund, and partners at Alberta Agriculture and Food , have recently completed a comparative study on the economic and welfare implications of housing gestating sows in conventional stalls and in three different group housing situations. One study compared gestation stalls (GS) and free access stalls (FA) and the second looked at FA stalls with an electronic sow feeder (EFS) and open access stall system with a two tiered space(2T).

They say that difficulty in comparing conventional housing with alternative group housing systems is the lack of consistent welfare standards. Each system has benefits and costs associated with it.

“The difficulty with comparing housing systems is trying to balance the lack of social contact in stalls with the risks of aggression seen in group housing, and comparing the injuries pigs receive from group housing with injuries pigs received in stall housing,” says Adrienne Herron, livestock welfare specialist with Alberta Agriculture and Food, Red Deer.

In this study, sows housed in gestation stalls received fewer injuries when compared to sows in free-access stalls. However, group housed sows received mostly minor injuries such as superficial skin scratches - deemed a consequence of allowing sows to have freedom of movement and social interaction. Most of the injuries and fights occurred shortly after mixing sows.

When comparing types of group housing systems in this study the ESF poses potential technical challenges to producers as well as significant costs to install or retro-fit barns. In terms of welfare, the sows in the ESF system experienced more aggressive encounters and received more minor injuries than any other housing system.

“It is possible that the levels of aggression seen in ESF would be reduced with more ESF stations and with the presence of straw bedding,” says Herron. “The aggression seen in ESF was likely due to competition for access to the feed source.”

The sows housed in free-access stalls avoided the competition for food resources, but the stall size and difficulties with gate mechanisms made this housing option challenging. Producers considering the FA or 2T systems also need to consider the increased labour challenges that are posed by systems that feed to the lowest weight sow.

“The open system with two tiered space provided by a mezzanine appears to be the best option for increasing common space while avoiding increased aggression and costs/problems of equipment,” says Herron. “Retro fitting barns with gestation stalls would be easily accomplished by removing the back of the conventional gestation stall and installing the mezzanine to increase available space. The difficulty with increasing floor space is the temptation by producers to further increase stocking densities which negates the benefit of increased space.”

It is likely that most decisions will be sue to consumer pressures and meat suppliers, rather than science as society's concern over animal welfare is likely to increase in the future, says Herron.

“Welfare-friendly housing systems are likely to become the standard in Canada if public interest remains high. However, the potential benefit of group housing systems is difficult to quantify as market trends towards ‘welfare-friendly’ foods remains unclear,” she adds.

Alberta Agriculture and Food and the Prairie Swine Research Centre plan to carry out more investigations.