Given that Smithfield, as well as Elite Swine in Canada, have committed to phasing out gestation stalls, loose housing has become a hot topic. 

Before stalls, and even tethers, became popular in the late 1960s and early 1970s, the normal way to house gestation sows was in groups in pens, yards or dry lots. However, those were the days when a 100-sow unit was considered large.  The wheel has now turned full circle.

In the United Kingdom, stalls and tethers were made illegal as of Jan. 1, 1999. The rest of the European Union will partly ban stalls by 2013. Producers will be able to put sows in stalls for the first 30 days after breeding, to allow the fertilized egg to implant.

Management certainly is easier and less time-consuming with stalled sows versus those kept in groups. While pork producers put sows in stalls for obvious reasons, the public doesn’t understand that sows can be very aggressive animals.

Still, the data tend to show little performance difference between sows housed in groups and thosse in stalls. (See table.)

In the United Kingdom, gestating sows are kept in static/fixed groups or in dynamic groups. The big problem with dynamic groups is that sows get mixed in and taken out. This results in fighting, as animals have to re-establish a pecking order. Because the UK government’s ban keeps sows out of stalls immediately from weaning up until farrowing, sows are loose in groups at critical times — when the fertilized egg implants in the uterus (12 to 14 days after breeding). Mixing sows at this time can affect implantation.

Ideally, sows should be kept in the same group from weaning until just before farrowing, and then return to the same group. That is the static-group concept.

So, let’s take a look at some of the other group-housing systems.

Electronic Sow-feeder Systems: This system was adapted from dairy cow feeders. One ESF station can handle about 50 sows. Each sow has a transponder ear tag which activates the feeding station. A sow can eat dry or wet feed, and typically consumes its feed allowance in one visit. The system’s major advantage is that each sow is fed individually, according to her feed curve. Sows can be spray marked for pregnancy diagnosis, medication needs and other animal-care issues. A shedding facility can be incorporated  to house sows that are due to farrow.

Most of the other systems work on a flat-rate feeding system, which makes it vital that sows are grouped by size. Otherwise bullying is a problem, with some sows getting too fat and some too thin. 

Trickle-feed Systems: Here, sows are kept in small groups, and small metal dividers separate them while they eat. The daily feed allotments drop slowly — or trickle — into the trough at a rate so that the sow can consume the feed easily.

Free-access Stalls: With this system, each sow has access to a stall with a back gate that she can activate to leave whenever she wants; other sows cannot enter the stall once it’s occupied. Feeding occurs at a flat rate via an auger system, although you can provide extra feed by hand.

Spin-feeder System: A feed hopper is suspended above a group of sows. Feed pellets drop onto a spinning disc. The pellets are then dispersed over the pen floor. This system requires a solid floor.

Dump-box Feed System: This has been popular in the UK because of its low cost. The feed hoppers, or dump boxes, are suspended over the pen. A cone inside the box disperses pellets onto the floor at feeding time. Each dump box will feed six to eight sows. Again, a solid floor is needed. One problem with the system is that timid sows can get pushed out of the way and end up underfed.

Trough-fed Group System: Liquid feeding of byproducts such as whey and potatoes is common in Europe, as well as feeding ground meal and water. Sows are grouped in pens with a trough running through it. It’s critical that sows are sorted and sized to prevent bullying. 

Other lessons? There are floor-space recommendations in the UK; for gilts, it’s 1.64 square meters per animal, for sows, its 2.25 square meters. When sows or gilts are kept in groups of 40 or more, the unobstructed floor space can be reduced by 10 percent.

In pens with slatted floors, pen design and layout are important, such as the ratio of solid areas to slats.

Sow temperament is definitely important in group systems. Certain breeds and crosses are better suited to group housing.

Remember to involve your staff in the decision-making process. It doesn’t pay to put in an ESF system with state-of-the-art computerization if the workers who have to run it are technophobes. Having spare parts and technical back up is important, too.

Naturally, stockmanship and group housing go hand-in-hand. Stockpersons must handle sows daily in a gentle and quiet manner. This will let sows be more comfortable during things like pregnancy checking and giving injections. 

When the UK sow-stall ban became law eight years ago, many hog farmers were adamant that it would be unworkable to house gestation sows in groups. They were proved wrong. Adapting to group-sow housing is just another challenge that the U.S. pork industry will successfully overcome.

Loose-housed sows versus stall-housed sows

The data presented here suggest that sows kept in groups are not disadvantaged in terms of pigs born alive per litter, compared with sows housed in stalls. In fact, the opposite is true. Management will dictate the outcome, and that may take some time to adjust.






Number of sows (average)






Number of herds






Average pigs born alive (per litter)






Litters per sow per year (average)






Source: PICUKPig Management Yearbook