The Humane Society of the United States said that an undercover worker at a farm owned by the world''s largest pork producer saw breeding pigs abused and crammed into small gestation crates, according to the Associated Press. The animal welfare organization released the results of a month-long undercover investigation at a Waverly, Va., factory farm owned by Murphy-Brown, a subsidiary of Smithfield Foods Inc. Murphy-Brown is Smithfield''s livestock production subsidiary and is the world''s largest producer of pigs for slaughter. The Humane Society called on Smithfield to renew its commitment to phasing out the crates. Photos and video from the investigation showed about 1,000 large female pigs crammed into metal crates that severely limited their ability to move. The pigs stay in the crates, also called sow stalls, during their four-month pregnancies. Afterward, they are moved for about three weeks to a crate large enough to nurse their piglets before being artificially inseminated and placed back into the gestation crates. Seven states have passed laws banning gestation crates, and the European Union is phasing out their use by 2013. However, the crates are legal in Virginia.