Smithfield, the largest pork and hog buyer in the world and owner of hog processor Murphy-Brown LLC, has asked its independent suppliers to move pregnant sows from gestational crates to group houses to improve animal living conditions.

The company says it is encouraging independent suppliers to make the switch by 2022, and it will use a sliding scale of incentives to accelerate the timetable. Suppliers that commit to installing group houses will be able to renew their contracts with Smithfield after the conversions have been made.

The company says the change is not required, but contract renewals will be “much less likely” for suppliers that choose to maintain the crates. Smithfield has contracts with about 21,000 farms across 12 states, which supply roughly 40 percent of the company’s sows.

Gestational crates typically measure 6.6 ft. x 2.0 ft., with a slatted concrete floor to allow waste to be collected below. Crate proponents argue they prevent fights and food theft between sows.