AMES, Iowa (AP) – As the use of small crates to confine pregnant sows is phased out in large-scale pig operations, an Iowa State University swine expert says pork producers have some difficult and potentially costly decisions to make about how to handle pregnant sows.

Tyson Foods and Smithfield Foods, two leading pork producers, are moving away from using gestation crates, small enclosures which limit movement of pregnant sows.

Increasing pressure from retailers, consumers, and animal rights activists is forcing the change.

Iowa State University swine veterinarian James McKean says allowing multiple sows to share more spacious pens requires producers to retrofit existing facilities or build new ones, which could be expensive.

The European Union banned the use of gestation crates last year and other countries are considering similar polices.