Michigan switches to pen gestation; Ohio is next

Hog operations in Michigan faced an April 1, 2020, deadline for switching from individual stalls to pens for sow gestation. The state legislature passed the mandate requiring group housing for gestating sows in late 2009.

Michigan joins several states already phasing out gestation stalls for pregnant sows. These include Florida, Arizona, California, Oregon, Colorado, Maine and Rhode Island.

Ohio is the next state to discontinue crated gestation. The state’s hog operations must make the change to pen gestation by 2025.

Some hog producers have already switched to group sow housing without a mandate. Smithfield Foods began the process in 2007 and, in 2018, announced all pregnant sows on company-owned farms are housed in pens. Contract growers are asked to convert to pen gestation by 2023.

Law requirements

Michigan’s mandate allows sows to be in stalls until verified pregnant, according to James Kober, DVM, with Four Star Veterinary Service, Holland, Michigan. This allows producers to individually crate sows during breeding and early pregnancy during implantation.

The law does not include space requirements for the pens. It also doesn’t include a method to check producers for compliance. Instead, if a complaint is lodged about a producer, the state will investigate to determine compliance.

Many of the state’s pork producers have already switched to pens, Kober says. The pens vary from a small number of sows (5-6) to large numbers (300-350). Most of the pens are created in the space where gestation crates were removed, but some new construction also took place.

Feeding methods for sows in pens range from electronic sow feeders to individual feed stalls to feed simply dropped on the floor.

Lessons learned

The biggest difficulty with pen gestation is sow aggression. “While there are no space regulations in the law, there are guidelines for square footage for pen gestation from the Extension service,” Kober said.

Some genetics appear to experience more leg and feet issues from fighting than other genetics. Kober expects these problems to be worked out in a couple of generations.

Tips from veterinarians

To read more about improving pen gestation, visit “Tips to improve pen gestation for sows” from Four Star Veterinary Service veterinarians.

Tips to improve pen gestation for sows

Many pork producers successfully manage sows in group gestation pens after completing breeding and pregnancy checks in crates. Veterinarians with Four Star Veterinary Service (FSVS) offer management suggestions to help maximize sow productivity in pen gestation.

“Most of our clients are converting to pen gestation,” reported Randy Jones, DVM, FSVS, Kinston, North Carolina. “Some of our better performing farms are pen gestation. After all, we managed sows in pens before we put them in crates.”

Pen size

“Give the sows plenty of space,” stated James Kober, DVM, FSVS, Holland, Michigan. “There are no space regulations in the Michigan law, but there are guidelines available that suggest 18 to 20 square feet per sow. If you get under 18 square feet, sows will start experiencing pregnancy problems.”

If crates are remodeled into pen gestation, utilize the walkway behind the crates for pen space to maximize space per sow. The extra room helps deter fighting.

Reduce fighting

When sows are first mixed, they fight. Kober suggests mixing sows late in the evening, feeding them and then turning off the lights.

“Some producers will mix sows every week and have a dynamic group,” he added. “The sows will fight some, but if the pens are big enough, they can move away.”

Feed and water

Adequate feed and water are vital for sow productivity, especially in pen situations, according to Jones. Boss sows will “hog” the feeders and waterers if not enough are available.

Jones recommends feeding all sows at once in some type of feed stall. The design and size of the feed stall varies among manufacturers and producers. But the important thing is offering some protection for sows while they eat.

“Another aggression point is not enough waterers,” reported Cary Sexton, DVM, FSVS, Kinston, North Carolina. “I’ve had some farms put in additional waterers because of [sow fighting].”

The waterers should be installed on different side panels of the pen to prevent sows from congregating and fighting.

Treat immediately

“I always tell clients if you think there’s anything wrong with a sow, pull her out now and treat her right away,” said JoAnna Kane, DVM, FSVS, Holland, Michigan.

“If you think you can come back later to do it, all the sows will be lying down and you won’t be able to find her.”

Sows needing treatment or time to recover from an injury are moved to individual hospital stalls.


Sows bred for gestation crates may experience leg and feet issues when housed in pens. Genetics will need to address those issues. For Sexton who works with many herds already in pen gestation, that has already occurred.

“Genetics have changed to a much hardier animal,” Sexton said. “The animal I started practicing with early in my career would not handle the competitive nature of today’s group-housing environment.”