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Why is Nest-Building Behaviour So Important?

  • It is a highly motivated behavioural need
  • It affects maternal hormones and prepares the sow for farrowing
  • It can influence her maternal behaviour

Nest-building behaviour is a well researched and well documented behavioural pattern in pigs. It has been unaltered by domestication and no matter what environment a sow is kept in she will try to perform nest-building behaviour before giving birth to her piglets. It is considered a functional behaviour (i.e. it has a purpose).

In indoor systems the sow may not need to provide a protective nest for her piglets but she still wants to build one. Play the video showing nest-building behaviour of domestic sows in an outdoor farrowing environment and a conventional farrowing crate environment.

What Is The Purpose Of Nest-Building?

The act of building a nest prepares the sow for farrowing. The more active and satisfying the nest-building phase the more calm and relaxed the farrowing phase. A calm farrowing phase is vital to promote piglet survival. If the sow is calm she will lie with her udder exposed and allow the piglets safe access to drink colostrum.

What Does A Sow Need To Nest-Build?

The sow will start nest-building behaviour approximately 16-24h before farrowing. She performs very specific patterns of behaviour: increasing her restlessness and activity levels, carrying substrate to a preferred area (i.e. nest-site), digging and rooting that site to create a hollow and then manipulating and arranging the substrate. To do this behaviour she needs certain things from her environment:


  • to increase her activity levels and “seek” a separate nest-site
  • to turn-around and create the nest


  • to perform manipulation of nesting materials and get a sense of nest completion


  • to be able to withdraw from the herd and isolate herself
  • to give the nest-site a sense of protection

Suitable Flooring

  • to keep substrate in the nest

The farrowing crate does not and cannot satisfy the behavioural needs of the sow. Restriction and in particular not being able to turn around during this time is the largest welfare detriment for the sow. To read more about the research conducted on the welfare issues of farrowing crates please visit our Research pages.

Well designed free farrowing systems where the sow can be kept loose can satisfy many of the sow’s behavioural needs. However it is very important to remember the principal reason the farrowing crate was introduced – to protect piglets. To learn more visit Can We Keep Piglets Safe Without Crates.

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