3. Gestation group housing of sows

Abstract

Group housing of gestating sows is currently replacing individual housing systems around the world. Modern group housing systems allow performance in groups to be equal to that in individual housing systems. A crucial element in the success of a housing system is the way in which it deals with social (aggressive) interactions of the animals: sows will fight to ascertain their position in the group, or to get access to resources. This is normal sow behaviour, but management, feeder design and pen layout can help to avoid potential negative consequences such as injury, reduction in welfare and loss of production. Applied research has identified several elements of successful management of group housing systems. It appears that mixing unfamiliar animals during weeks 2-4 of pregnancy should be avoided. Sows should have sufficient space to be able to avoid each other or to flee from aggression, particularly shortly after unfamiliar animals are introduced. The size of the group seems less relevant, but it is advisable to house first and second parity sows separate from older parity sows. Presence of a (vasectomised) boar in the group may help to reduce aggression among the sows. Finally, gilts can be taught to deal with social interactions in an adequate way, or can be familiarised with the group they are about to enter. Both approaches will reduce the impact of social interactions at introduction into the group. The design and type of feeder have a great impact on aggression over access to food. Sequential and consecutive feeding systems are used and can both be effective. Important elements are the level of protection from other sows during feeding, and the degree to which dominant sows can steal food from subordinates. Feeding level can also affect aggression: restricted feeding promotes activity level and social interactions near the feeder. Finally, the layout of the pen should allow for separate feeding, sleeping and defecating areas. In addition, climate control to avoid overheating and presence of a comfortable lying area will support normal resting behaviour, and promote sow health and welfare. Several types of group housing systems exist, one of the main distinctive features being the way in which the food is offered to the sow. The choice of system depends on what the farmer finds most important: economic aspects, animal health and welfare, level of control and labour requirement are all elements which may differ between systems. With the right management, each system can be the basis of a successful way to keep gestating sows in groups. Keywords : sow, group housing, animal welfare, aggression, sow productivity, sow housing system