Group sow housing, By Lee Johnston from the University of Minnesota

Quick facts

  • Regardless of the housing system, sow barn managers and caretakers should work to optimize their barn’s system.
  • Proper design of facilities is an important start, but does not guarantee a successful operation.
  • Effective stockmanship is crucial to making the facilities operate properly and ensuring sows are comfortable and productive.
Sows in a group housing system.

Pork producers are encouraged or mandated to stop using individual gestation stalls and start using group sow housing. Unlike stalled systems, there isn’t a standard, well-understood template for group housing systems. A lot of factors play a role in setting up a system that works best for your farm including:

  • Pen layout
  • Flooring type
  • Feeding system
  • Nutrition program
  • Grouping strategy
  • Timing of grouping
  • Pig flow
  • Husbandry skills
  • Genetics

As a result, it’s hard to accurately predict the success of any one group housing system. There are examples of good and bad transitions. Focus on these key features to increase your chances of success with group sow housing.

  • Floor space allocation for sows
  • Feeding plans to control changes in sow body condition
  • Plans for managing sows in dynamic groups, and knowing how to mix sows
  • Stockperson skills and ability to manage groups

Floor space allocation

It’s hard to establish an exact floor space allocation for sows to optimize reproductive performance and welfare. Space allocation depends on size or age of the sows, feeding system, group size and season.

The space occupied by a standard gestation stall and half of the aisle behind the stall is about 16 square feet. Most studies suggest this amount of space is inadequate for group-housed sows. In general, more space decreases aggression between sows and related injuries. It also increases farrowing rate (see Table 1).

Table 1. Effect of floor space allowance during gestation on litter size

Trait 15 sq. ft./ sow 24 sq. ft. / sow 35 sq. ft. / sow Stall
Total pigs/litter 12.4b 12.0b 14.2a 1.1b
Born live/litter 10.0 9.5 10.5 9.4
Weaned/litter 8.6 8.1 8.8 8.7

Increasing the floor space leads to an increase in building costs. Thus you won’t want to provide sows more space than they need. Increase floor space at least 10 to 20 percent when moving sows from individual stalls to groups. At a bare minimum, you must increase floor space from 16 square feet (stall size) to 18 to 19 square feet.

Group size

Group size affects proper floor space allocation. If group size is small (fewer than 10 sows), you should increase floor space allocation by 10 percent because there’s less total free space available in the pen. Free space is the area in a pen that a sow’s body doesn’t physically occupy.

If group size is large (more than 40 sows), you can reduce floor space allocations by 10 percent because there’s more free space.

Feeding to control changes in sow body condition

It can be hard to control sow body condition and weight gain among a group. Selecting a good feeding system is key.


Managing sows in dynamic groups

Effective competitive feeding systems require grouping sows uniform in age and body weight. Dynamic or static groups are two main approaches to keeping sows in a group housing system.


Stockperson skills

Stockperson skills is an important role on sow farms. These skills are slightly different for group housing than individual pens.


Stockpeople must employ an “animal-directed” approach to caring for group-housed sows. They need to understand what’s normal and what’s abnormal sow behavior. Stockpeople must then recognize the cause of abnormal behavior to properly correct it.

Knowing normal sow behavior can help stockpeople perform management tasks more efficiently, and with less stress on sows and workers. For example, recognizing when it works best to vaccinate sows in group housing. Stockpeople may notice after dropping feed, the sows focus on eating. Thus they pay little attention to the stock person or react to the injection.

Likewise, checking for sows in heat may be more efficient and effective when group-housed sows are usually resting and inactive. During this time, the sow in heat is more likely to be up and more active than her penmates, and she will stand out and be easier to identify.

Stockpeople must be open-minded about group housing and be willing to learn new skills or relearn old ones. Moving slowly, deliberately and quietly around sows increases the bond and trust between sows and their caretakers. This trust will make it easier to move sows and work around them.

Research shows trust can also improve reproductive performance of sows. When sows trust their caretakers, tasks like pregnancy diagnosis in pens can be fairly easy, because sows allow workers to approach with the ultrasound unit.

Sows have freedom to move in walking barns with pens. Thus the sows won’t always be in the same place each day as they are in stalled systems. This means workers must walk the barn in the same pattern each day but can start the pattern at a different spot each day. Doing this will allow them to see a given pen of sows at different times of the day. As a result this improves their chances of finding disadvantaged sows that need attention.

Evaluate sows for body condition, health, behavior and attitude.

Ensure the equipment (feeders, feeding stalls, gating, flooring, waterers, etc) in each pen is working properly and will not injure sows.

Monitor the air quality of the room or barn and the capacity of the manure storage system and adjust it as necessary.

Lee Johnston, Extension animal scientist and Yuzhi Li, associate professor of swine behavior and alternative production, College of Food, Agriculture and Natural Resource Sciences