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Individual Wallows Reduce Heat Stress

21 February 2013

Sow mortality has been reduced and conception rates have increased since wallows were constructed on a farm in East Anglia with outdoor farrowing, BPEX reports in its Farm Case Study 35.

Farm facts

Location: East Anglia
Farm size and type: 600-sows; outdoor breeding; indoor finishing


The outdoor unit was having problems with sows becoming heat stressed during warm weather. Production was suffering as a result of heat stress, with weaning weights falling and up to three sows dying during the hottest spells. The sow deaths were occurring shortly before farrowing and at the end of the lactating period when their intake and metabolic rate is at its highest.

The System

  • Wallows are always available for sows to use
  • Sows spend more time with piglets in the arcs now wallows are available as they can cool down quickly and are then are happy to return to their litter
  • The wallows are filled via a pipeline which runs around the site
  • Each paddock has a valve off the pipeline so that the wallows can be filled on an individual basis, according to use
  • Arcs are turned north in the summer and south in the winter to optimise the environment within the arcs.


  • Through introducing wallows heat stress has been reduced
  • The overall welfare of the sows has been improved, which is reflected in improved productivity
  • Before the wallows were introduced, up to a 0.5kg reduction in weaning weights was noted each time there was a hot spell; with the wallows in place weaning weights have been maintained
  • Conception rates remain constant throughout the summer months
  • Before the wallows were in place the unit was losing up to three sows during the hottest periods, since introducing the wallows no sows have died from heat stress
  • These benefits have been observed over the last two summers
  • Sows are less inclined to play with their drinkers.
A wallow being replenished via an individual valve off of the main pipeline

Key to Success

  • The first hot spell that occurs each year is the critical one, that by having wallows in the farrowing paddocks has the biggest impact
  • The wallows are situated away from the drinkers so that there is no overlap or contamination
  • Valves allow wallows to be maintained on an individual basis
  • Do not allow wallows to become stagnant as this can lead to infections.

February 2013

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