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Considerations for Free Farrowing Systems

Most lactation sows in North America are typically housed in some form of crate system. First introduced in the 1960's farrowing crates offered many advantages to producers: reduced sow fighting, lower piglet mortality, better pen hygiene, improved worker safety and higher performance. However, in moving to crates, studies have shown that sows now spend significantly more time standing inactive. This inactivity can lead to joint problems, muscular weakness in the legs and eventually impaired mobility. In addition, crated sows are unable to demonstrate normal behaviours such as nest building or rooting. This deprivation can lead to a number of disorders including chronic stress, depression and frustration, aggression, and abnormal and stereotypic behaviours.

Due to welfare concerns, in many European Union countries, crates systems are no longer permitted or are being phased out. In Canada, the certified organic and "humane" production systems also do not allow the use of crates and lactation sows must be housed in free farrowing systems or pens. However, there are two major issues for producers moving to these systems; increased pre-weaning mortality, due to crushing, and significantly higher labour requirements.

A recent Austrian study compared three types of free farrowing systems with regard to behaviour, health, performance and labour requirements. The trial was conducted from June 2005 to December 2006 in an Austrian commercial sow unit. The 600 sow herd was batch farrowed in a four-week cycle and piglets were weaned at 3 weeks of age. Three types of free farrowing systems were investigated:

• Free System #1 (FS1, n=20): 7.6 m², lying area with concrete floor, separate dunging area with slatted floor; anti-crushing bars, provision of a minimum of straw.
• Free System #2 (FS2, n=23): 4.9 m², rectangular, slatted floor, no provision of straw, anti-crushing bars and bars to direct lying behaviour of sows.
• Free System #3 (FS3, n=24): 4.2 m², trapezoid, slatted floor, no provision of straw, anti-crushing bars.

The behaviour of sows and litters was observed indirectly by means of a digital video recording system. Researchers examined sows' general activity (walking, standing, sitting, lying), time spent lying down and standing up, use of creep area and situations in context to crushing of piglets. In addition, labour requirements and production data (piglets born, piglets weaned per litter, weaning weight, pre-weaning mortality) were evaluated for each system.

The researchers found that in all three systems, the activity of sows was highest during the last 24 hours before farrowing, indicating nest building behaviour. Sows in Farrowing System #1 (FS1) were more active during the farrowing and lactation period compared to sows in the other two systems. In all three systems, changes in sow lying posture was the most dangerous activity for piglets and the centre of the lying area was the most critical zone. The majority of dangerous situations to piglets (60 to 80 %) were observed during farrowing and within 24 hours post farrowing. In Farrowing System #1 (FS1) fewer changes of lying postures were observed during the 24 hours before farrowing. No matter what type of flooring within the free farrowing system, slipping when standing up and lying down was frequent (35-45 % incidence) and did not differ between systems.

No statistical differences between the three free farrowing systems were found in the number of piglets weaned per litter (FS1: 8.87; FS2: 9.05; FS3: 9.29), in piglet loss (FS1: 23.12%; FS2: 20.96%; FS3: 19.09%) and in proportion of piglet loss due to crushing (FS1: 49.1%; FS2: 52.1%; FS3: 53.0%). The pen related labour requirements ranged from 41.9 (FS3) to 63.1 (FS1) minutes per sow over the lactation period.

Based on their study the researchers made the following recommendations to assist producers and direct future research efforts:

• Pre-weaning piglet mortality in the free farrowing systems investigated was high due to a high risk for piglet crushing. In order to minimize the crushing of piglets, the pen layout has to be optimized in terms of size, arrangement and micro climate of the lying and creep areas.
• Care at farrowing has to be adapted to free farrowing conditions. Restlessness and stress of sows must be avoided. Frequent interventions during and after birth provoke posture changes of sows increasing the risk for piglet crushing.
• The activity of sows prior to farrowing indicates nest building behaviour. An adequate amount of straw should be provided in this period.
• From an animal health and welfare point of view, fully slatted free farrowing pens with less than 5.0 m² and no provision of straw are not different than traditional crate systems.

Source:

Baumgartner, J. 2008. Welfare and economic aspects of non-crate farrowing systems. Internal report. Housing of farrowing and lactating sows in non-crate systems. Aarhus University, Copenhagen, Denmark. pp 37-38.