Making It Work: Housing Gestating Sows in Group Pens

The current social trend in sow housing is away from gestation stalls. This change has lead to Ontario pork producers examining management skills to facilitate the change from gestation crates to group housing. Listed below are a number of practices which have been shown to reduce aggressive sow behavior when housed in group pens. The following suggestions are listed in order from the least to the greatest difficulty (based on labor and cost) to implement.

Wean sows into breeding crates
It is imperative that your facility have enough breeding crates to hold the required number of sows for the time they will be crated. Crates prevent the injuries associated with sow activities during estrous. Many producers hold sows in crates until after 28 day pregnancy confirmation. Others have success when sows are mixed after 7 days in the crates or immediately after breeding. Implantation typically occurs 12-14 days past breeding, so it may be best to group sows before or after this time.

Add extra feed to the floor of the pen before sows enter
This is a distraction device. Some people, where possible, add a bag of shavings to the floor. Sows become engrossed in eating or exploring their environment, and tend to fight less. It also helps to feed up to one and a half times the normal daily feed rations for two to three days after a group is mixed.

Add a boar to the pen
The boar's role of "leader" keeps aggressive encounters between sows to a minimum. It takes a boar of a stable temperament, neither too aggressive (attacker) nor too passive (attacked), to perform this role well.

Mixing times
Try mixing at the end of the day then turn out the lights. This action, plus extra feed, leads to sows that are full in a dark, quiet environment.

Sow size in groups
Try for as uniform a sow size as possible. Very large or very small animals in a group can lead to overly dominant or overly submissive behavior. Small sows or gilts can often be overly aggressive.

Group size (20 or more)
Larger sized groups reduce aggressive encounters. It is easier for a pursued sow to hide in a large group. It appears that if sow numbers are over 20, the animals give up on establishing a hierarchy. Smaller groups of 10 or less tend to establish strict hierarchies.

Partition walls
Walls can be of cement or of hanging rubber mats, or of sections of pen dividers removed between adjacent pens. This gives sows a place to escape to when pursued and some choice as to a pen location they may choose to congregate in.

Spread out the feed
Most aggressive encounters occur during feeding. Spreading the feed over the floor reduces sow encounters. The addition of an inverted Y or a cone distribution to the feed drop can do this reasonably well.

Multiple feedings
On once a day feedings, anxiety prior to feeding causes sows to hoard feed and increases fighting. Feeding from three to eight times per day results in calmer sows at feeding.

Suggested innovation
Much of this work is still in the development stages and it is suggested that one well laid out mixing pen be used for the week after sows are taken out of the breeding crates. At the end of this week they can then be moved into traditional and possibly less than ideal loose housing systems.

If anyone wishes to contact the author of this paper, Kathy Zurbrigg, she is available at or 519-846-3418.

Kathy Zurbrigg, OMAFRA - Pork News & Views, April 2008

Atlantic Swine Research Partnership Newsletter, May 29, 2008