Voters and government are increasingly placing restrictions on methods of pork production, including laws to reduce or eliminate the use of individual stalls for housing sows and gilts in the breeding herd.

The European Union plans to phase out individual sow stalls by 2013. Legislation in Florida, Arizona, Oregon and Colorado has banned or will ban gestation stalls in the coming years.

In November 2008, California voters approved Proposition 2, which restricts the use of sow gestation stalls; other states may follow.

Relatively little analysis has been done on the economic impacts of transitioning from stalls to pens. So in an effort to examine the economic costs of transitioning the breeding sector of the U.S. pork industry from gestation stall facilities to group housing, a comparative study was requested by the Joint Sow Housing Task Force of the National Pork Board and the National Pork Producers Council.

Are Pens Really Better?

A primary objective of voters, as well as some producers favoring these policies, is improved sow welfare. Regardless of economic considerations, it is not yet clear that the elimination of stalls achieves that objective.

A review of prior research on sow productivity and welfare suggests that the type of system does not necessarily determine sow welfare. For example, stalls allow for individual sow management and remove the potential for sow aggression and injury, but sows are incapable of full movement. Pens allow for greater mobility, but also allow sow aggression that can result in injury and also extreme variation in body condition between aggressive and submissive sows.

Prior research has also found no significant productivity differences between housing sows in stalls vs. pens. When asked in a survey if pen housing affected the level of productivity in a commercial setting, producers with both systems said they found no consistent differences. However, respondents indicated several key issues would affect group housing productivity:

1. Producers must learn to manage sow group dynamics.

2. Some stall use must be available after breeding for proper embryo implantation.

3. Base Assumptions for Economic Analysis

   Stalls are needed to isolate sows when they are injured, in poor condition or otherwise fall out of groups.

4. Feeding for management of body condition variation is critical.

5. Space allocation per sow relative to pen size is critical.

6. The potential for catastrophic productivity losses are greater with pens.

In summary, the surveyed producers suggested there are significant risks posed by transitioning the industry from stalls to pens in a short time frame due to variation in management and husbandry skills, which are more important to success with pen systems.

The following economic analysis is based on the economic impact of transitioning from existing gestation stall housing to group pen housing under a regulatory mandate.

Two major cost categories are analyzed:

1. The capital costs associated with investing in refurbished or new buildings and equipment, including the opportunity cost of refurbishing a building that has not reached the end of its useful life, and

2. The potential differences in sow and pig productivity during the transition.