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Success with Group Housing for Sows

26 September 2014

At the 2014 London Swine Conference, Jennifer Brown of the Prairie Swine Centre and Laurie Connor of the University of Manitoba explained the differences in sow management between group and stall housing, and how to prepare for and make the most out of managing sows in groups.

London Swine Conference 2014


Managing sows in group housing requires different skills and activities compared to stall housing. This can pose new challenges to barn staff, but it can also provide rewards such as improved handling in sows, a better understanding of the animals and their individual differences and a more rewarding work environment.

Producers who implement group housing are generally positive about the switch.

Both the University of Manitoba and Prairie Swine Centre research herds have made this transition, and have found that barn staff prefer working with sows in groups.

This workshop focuses on differences in management between group and stall housing, and how to prepare for and make the most out of managing sows in groups.

Frequently Asked Questions

For those who have always worked with sows in stalls, it is hard to imagine working with sows in loose housing. Questions frequently raised by barn staff include:

  • Will the workload change (and will I still have a job)?
  • How much will my daily routine change?
  • Is it safe working in group pens?
  • What can be done to reduce aggression at mixing?
  • Do sows really need this extra space?
  • How will I find sows and treat them when needed?

It is important to know that although some new skills may be required to manage groups of sows, the overall workload with groups is very similar. If the barn undergoes renovation, production will be disrupted during the transition phase as sows are moved or herd size is temporarily reduced, but once construction is finished and staff have the opportunity to adjust and retrain, staffing requirements will be very similar.

Comparing feeding systems

Unlike stall housing, group housing comes in many different shapes and sizes. It is important to understand the long term consequences of each system in order to make good choices based on staff capabilities, barn layout and herd size. Feed competition between sows is an important consideration. Electronic sow feeder (ESF) and free-access stall systems are known as ‘non-competitive’ feeding systems.

They are designed to provide individual feeding to sows and limit competition for feed by isolating the sows at feeding time, so that all sows have access to feed and cannot be displaced by other sows. Short stalls, open stalls and floor feeding are known as ‘competitive’ feeding systems. Feed is provided in open troughs or directly onto the floor, and all sows will compete for access to this resource. Dominant sows in these systems can often get more than their share of feed: subordinates may be driven off and not receive their due share.

Different approaches are used to manage competitive and non-competitive systems in terms of group size and daily checks. In competitive systems, sows are typically managed in smaller groups, typically from less than 10 up to 30 animals. In free-access stall pens, group size generally ranges from 30 to 60 animals, and ESF pens can be managed with large groups, ranging from 60 sows to over 300 sows in dynamic ESF systems.

In competitive systems, sows of similar size and body condition should be selected when gestation groups are formed. Having sows of similar size in the group helps to ensure that all sows will be successful when competing for access to feed. Also, feed can be provided in ways that reduce competition, making it more difficult for one sow to dominate a large share of feed. Despite this, some ‘dropout’ sows will occur, animals should be observed regularly at feeding time, and any sows not actively feeding or losing condition must be identified and removed promptly to another pen to ensure the health of the sow and subsequent litter.

In non-competitive systems, a wide mix of sow parities can be accommodated, however, even in these systems the smaller and subordinate sows can be at a disadvantage. In ESF systems, this can result in younger sows accessing the feeding stall later in the daily feeding cycle, and lying in less preferred areas of the pen (Strawford et al., 2008); in free-access stalls, younger animals have been found to spend more time in feeding stalls and less time in the open loafing area (Riocha-Lang et al., 2013), but this generally does not affect body condition or productivity.

Managing the transition to group housing can be the most challenging time. Sows that have spent their previous gestations in stalls may be more aggressive when first mixed.

Once sows or gilts become accustomed to being in groups, they learn to become more tolerant and show less aggression, especially after repeated mixings. Thus the first mixing can be the most stressful, and some animals may not adapt well and should be housed separately or culled.

The transition to ESF systems also requires training sows on how to access the feeding system. Once established, only the incoming gilts need to be trained. Training of gilts should be done before breeding in order to minimize impact on production, and is sometimes done at the gilt development site. However, as noted when making the transition all sows must be trained, and this will require extra care and attention. A separate ESF training pen is helpful in teaching sows how to access the feeder. More cautious sows can be fearful around the entry gate and may need some encouragement from a handler, for example by tying the entry gate partially open or placing feed at the entry, in order to learn how to access the feeder. Other group systems generally do not require sow training.

Aggression between sows

When sows are mixed together, there is usually some fighting among sows. Sows typically fight in pairs, with two sows lining up sideways with head to head or head to hindquarters, thrusting and biting vigorously. Fighting does not occur because sows are ‘inherently aggressive’, but can be better understood by examining the social structure of sows in the wild. In the wild, pig groups are made up of several closely related females, with each group having a home territory that it will drive other groups of pigs away from. When we mix two groups of pigs they respond in the same way, trying to drive off the strangers. This understanding is helpful when implementing changes to reduce and minimise sow aggression.

Many things can be done to reduce aggression and injury at mixing. These can include changes to the pen environment, changes to development of gilts (experience), and genetic selection for reduced aggression. Some ‘tricks’ to reduce aggression and injury at mixing include: extra pen space, adding partitions/hiding areas, improved flooring to reduce leg and foot injuries, providing extra feed at mixing, use enrichment, e.g. straw, as a distraction. Changes to gilt development to reduce aggression include management in large groups (Samarakone and Gonyou, 2009), and multiple mixings.

Multiparous stall housed sows put into group pens will typically show more aggression at mixing, as they have had little experience with ‘fitting into the group’. For this reason, older sows often have more difficulty adjusting to group housing. Aggression can also occur at feeding time, especially in competitive feeding systems. In general, by 48 hours after mixing overt aggression (fighting) drops off significantly, and sows show more subtle behaviours when interacting, with subordinate animals avoiding dominant individuals by turning or moving away. This is one reason why adequate space is needed in group housing; it allows subordinate sows to move through the pen without confronting/ getting in the way of dominant individuals.

Even in established groups, however, aggression can still occur at feeding time, especially in competitive feeding systems. When mixing different groups of sows, it is advisable to add at least 20% new sows to the group. This rule of thumb ensures that new sows added enter with a familiar sub group, and the aggression of resident sows is directed at multiple sows.

Dominant sows are typically the larger, more mature individuals. For gilts and small sows, it can therefore be more stressful to be grouped with larger sows. Studies have shown that sub-grouping sows, based on their age and size can help to reduce problems due to aggression, and is especially helpful for younger sows (Brown, unpublished data).

It is common to group first parity sows separately so they experience less stress and can be monitored more closely during gestation. Recent studies in Denmark (Ulrich Hansen, personal communication) have focused on the subject of gilt social development. The Danish studies found that gilts which experienced multiple mixings over time had better social skills; interacting better with other sows and showing reduced aggression.

Worker safely is another important consideration when mixing sows. Fighting sows can be extremely dangerous- the animals remain focused on fighting but they can easily injure a human handler. If sows are fighting, handlers should never intervene. It is better to wait a few minutes and see if it has resolved. Fights will normally finish within minutes, and by 48 hours after mixing there should be minimal fighting. However, in some cases sows may be persistently aggressive. These ‘bully sows’ can stress and injure other sows, so if fighting persists these sows should be found and removed from the group, and housed separately. Be sure that fighting has subsided before approaching the sow and removing her to a separate area using a panel or handling board.

Sow handling

Whether managing sows in stalls or groups, having good handling skills is an important asset. However, working with sows in groups will involve more daily interaction, so having attentive, calm and skilled handlers becomes more important, as it will encourage sows to respond calmly and to be more responsive during handling. It is common to find that handling becomes easier when sows are group housed. This can be the result of more daily handling and also improved fitness in sows.

These benefits are seen especially when moving sows to farrowing. Whether using stalls or groups it is helpful when moving sows into farrowing crates that feed be distributed beforehand, so that sows are rewarded immediately on entering the crate. If this practice is repeated, sows will learn to anticipate it, and will return more willingly in subsequent cycles.

Stockmanship and daily observation of the sows is also essential to identify sows which are ‘off’ and may require attention. Because sows in groups can move freely within the pen, it is important to be aware of their normal daily activities and recognize changes in behaviour or location in the pen that indicate a problem.

Routine management practices such as giving injections and pregnancy checking can be done while sows remain in the group. With good handling, sows do not move away from people fearfully and when people are not associated with feeding, such as with ESFs, a stockperson can often enter the pen without arousing resting sows. However, if sows are skittish and/or handlers are not confident around them, sows should be moved to a confined area for treatment. In free-access stall pens, this can be easily accomplished using the feeding stalls. For other systems, sows can be moved to nearby stalls, if necessary, for health treatments.

The human factor

Stockpeople often find more enjoyment and job satisfaction when working with sows in groups. They have opportunities for positive interaction with animals, and to observe individual differences. Watching sow behaviour in a group pen can provide more information to evaluate sow health and well-being. Lying, feeding, pen investigating and social behaviours can be readily observed and provide valuable knowledge.

Adopting new technology can be a challenge, but in most cases this is a bonus, creating greater diversity of work and added interest. Technologies such as ESF also provide tools to improve the housing system and animal monitoring and management. Although this requires staff with technical abilities, this is less of a drawback now that computer literacy is more common than in the past. Such requirements may also contribute to recruitment of new young staff.


Managing sows in groups will hold new challenges for many of our current barn staff.

Group housing requires a different set of skills and involves different daily activities compared to stall housing. This can pose difficulty, especially during the transition, but it can also provide rewards such as improved ease of handling in sows and a better understanding of the animals and their individual differences.

The use of computer equipment as in ESF systems can also be a positive addition, and can result in increased staff engagement and better employee retention.

Producers who implement group housing are generally positive about the switch.

As discussed, success in group housing relies in a significant way upon a good understanding of sows’ social behaviour.

Management of groups – including controlling sow feed intake, minimising stress and reducing inter-sow aggression – can be optimised based on this understanding, giving equivalent or better production levels compared to stall-housed sows, and providing equivalent or better working conditions for barn staff.


Manitoba Pork Council, 2013. ‘Smart Pig Handling’ video produced in collaboration with DNL Farms, Ltd.

Rioja-Lang, F.C., Hayne, S.M. and Gonyou, H.W., 2013. The effect of pen design on free space utilization of sows group housed in gestation pens equipped with free-access stalls. Appl. Anim. Behav. Sci. 148:93-98.

Samarakone, T.S. and Gonyou, H.W., 2009. Pigs alter their social strategy in response to social group size. Appl. Anim. Behav. Sci. 121:8-15.

Strawford, M.L., Li, Y.Z. and Gonyou, H.W., 2008. The effect of management strategies and parity on the behaviour and physiology of gestating sows housed in an electronic sow feeding system. Can. J. Anim. Sci. 88:559-567.

Ulrich Hansen, E. Danish Pig Research Centre. Personal communication.


Brown J. and L. Connor. 2014. Success with group housing. Proceedings of the London Swine Conference. London, Ontario, Canada. 26 to 27 March 2014. p29-33.

Further Reading

You can view other papers presented at the 2014 London Swine conference by clicking here.

September 2014

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