Gestation-sow welfare has been and will continue to be a hot topic for the foreseeable future. Certainly there’s no shortage of controversy over what constitutes improved sow welfare.

There are many different types of acceptable housing options for gestating sows, and management has always been the key to meeting the animal’s needs and well-being. Of course, the debate surrounds individual housing, or stalls, and group housing. Then there’s the hybrid, which combines features of both stalls and pens.

The American Veterinary Medical Association and the American Association of Swine Veterinarians have reviewed gestation-sow housing and have concluded that each type has advantages and disadvantages.

Individual housing minimizes animal aggression, injury and competition among sows.  It also allows for individual feeding, which makes it easier to monitor animal health and control the sow’s body condition. The drawbacks include restricted movement and natural foraging behavior. (For more information on sow stalls, go to

For group housing, advantages include freedom of movement and exercise as well as increased social interaction. Group-housing systems also tend to carry a more positive public perception.

However, sows are prone to aggression toward each other and can inflict serious injuries, such as vulva biting, on subordinate pen mates. Group-housing systems also require more intensive management and may require additional staff with higher skill sets, especially in systems equipped with electronic feeding stations.

Regardless of the system, what matters most is the individual care given to each pig. The National Pork Board outlines the following priorities:

• Minimize aggression and competition among sows.

• Protect sows from environmental extremes.

• Reduce sows’ exposure to hazards that result in injuries, pain or disease.

• Provide every animal with daily access to appropriate food and water.

• Monitor individual sow appetite, respiratory rate, urination and defecation, and reproductive status.

• Allow sows to express most normal patterns of behavior.

While you have choices in sow housing, the question remains which options provide the best alternatives? Ashley DeDecker, University of Illinois animal science department, conducted sow-housing studies to evaluate the impact of various components on sow well-being. The National Pork Board provided the funding and Janeen Salak-Johnson, associate professor, University of Illinois, supervised the studies.

In the United States, 60 percent to 70 percent of sows are housed in gestation stalls, DeDecker says. However, mounting pressure from animal activists is pushing to replace stalls with group-housing facilities.

 “It’s important that we develop welfare-friendly systems based on scientific assessment before implementation,” DeDecker says. “In searching for the system that offers improved animal welfare, we evaluated alternatives to individual stalls.”

The first study compared standard stalls, width-adjustable (flex) stalls and the free-access stalls/pens. The second study compared floor-space allowance in group pens as well as a control diet and a high-fiber supplemented diet. Both studies began with sows 30 days into gestation. Prior to that, the sows were kept in standard stalls.

The research assessed sow well-being by recording sow performance, productivity, physiology and behavior. Not surprisingly, each system was found to have distinct advantages and disadvantages.

The first study showed that sows housed in the free-access stalls/pens had more lesions, backfat and bodyweight and were less active compared to sows kept in flex stalls or standard stalls. “When sows housed in flex stalls were given 6 centimeters of additional space late in gestation, multiple immune traits were positively altered,” DeDecker says. “This indicates that simply providing sows more stall width can reduce stress.”

DeDecker points out that the flex stalls in the study had vertical bars instead of horizontal bars. “This design feature deprives a sow from performing its usual bar-chewing activity and influences alternative oral activity such as sham-chewing,” she notes.

“This study shows how motivated sows are to chew on bars, which should be considered when determining gate designs in housing systems.”

Sows kept in individual stalls had significantly more lesions than sows kept in flex stalls. This is attributed to the fact that sows in individual stalls had the opportunity to chew on the neighboring sow’s ears. Sows in the flex stalls did not have that opportunity.

The second study revealed that 10 sows housed in group pens with 1.7 square meters of space per animal and floor-fed a high-fiber diet had improved litter characteristics than those housed in pens allowing 2.3 square meters per sow and receiving high-fiber or control diets. It also showed that sows fed a high-fiber diet had higher bodyweight gain than sows fed a control diet.

DeDecker found that aggression was greatest among sows with a floor-space allowance of 2.3 square meters and fed a high-fiber diet, which greatly increases water consumption. This causes sows to fight for access to waterers as well as a spot in the feeding area.

“Based on these results, I would recommend that a producer who wants to implement a 10-sow, floor-fed, group-housing system feed a high-fiber diet that includes soy hulls and wheat middlings,” DeDecker says. “But the most important thing is placement and number of waterers; they must be located near the food source because sows are highly motivated to drink water because of the high-fiber diet.”

The question is not whether stalls or group housing is better, DeDecker says. Rather, producers need to determine which components within their existing systems can be adjusted or tweaked in order to improve animal well-being. “Whatever your system, use the biological and physical components to optimize sow health and well-being,” she says.

Environmental Enrichments Help
Providing environmental enrichment factors in group gestation facilities may improve animal well-being by engaging the sow’s natural interest or expression.

A USDA-supported study conducted by Monica Elmore, while at Purdue University, tested various environmental enrichment additions, including rubber mats, cotton rope and free access to straw and compost. The results confirmed that enrichment strategies have value in improving sow well-being.

“The study was on point-source enrichments, where materials such as straw or compost were placed in a trough in one corner of the group pen,” says Elmore, who’s now at the University of Illinois. “Sows were highly motivated for these items.”

The study also looked at the practicality of providing such enrichments. “When we provided straw, we placed a rubber mat under the trough to prevent material from falling through slats into the liquid manure system,” Elmore says.

When using compost, the source made a difference. Elmore discovered that sows preferred spent-mushroom compost over peat. “Sows ingest the materials with a rooting or foraging behavior,” Elmore says. “There is an advantage in well-being by keeping sows engaged with this natural behavior.”

Natural enrichments that can be refreshed daily, such as straw or compost, work better than toys which quickly become covered with manure. Sows quickly lost interest in toys and showed little motivation for cotton ropes provided for oral activity, she explains.

Because sows consume some of the material, researchers will examine the nutrition ramifications of compost or straw. “We don’t want these sows gaining too much weight,” Elmore says. “The compost is consumed very quickly while the straw seems to last longer.”

In group-housing systems, Elmore advises having more than one trough providing the

material to reduce sow aggression. “Producers using this strategy must watch closely that subordinate sows don’t get beat up while trying to access these enrichments. Social dynamics are very important.”

When rubber mats were provided there was no observed increase in sow aggression. Also, when provided, the sows preferred to rest on the mats, and there were also fewer lesions recorded. “The rubber mats may be an especially good enrichment in group systems,” Elmore notes.