Tess Faulkner, from South West Ontario Veterinary Services, Chains For Enrichment: Are There Better Alternatives?


The European Union has taken a regulatory approach aimed at reducing the risk of damaging behaviours such as tail, ear and flank biting. Those vices are not only painful when they occur but can lead to chronic painful tissue damage and infections. The infections that occur as a consequences of biting can result in costly carcass condemnations. Current EU legislation requires that all pigs must have access to material that allows for investigation and manipulation. These Irish researchers wanted to determine associations between biting behaviours performed by finisher pigs, the related body lesions and the use of different types of enrichment materials.

This study involved the observation of six randomly selected pens of finisher pigs for 10 minutes each on 31 commercial pig farms in Ireland. All pigs were counted and the number of pigs affected by tail, ear and flank lesions was recorded. During the last 5 minutes of observation, all occurrences of tail, ear and flank biting  were recorded. The type and number of enrichment objects was recorded. Chains were the most common enrichment material (41.4% of farms), followed by plastic (37.9%) and wood (20.7%). It is important to note that there is no negative control group because a negative control would not be allowed under current legislation. The study design had some limitations because enrichment materials were not randomly assigned within farms.

The researchers made the following observations.

  • biting behaviour was more frequent with chains compared to plastic or wood.
  • flank directed behaviour was more frequent with chains compared to plastic devices.
  • lesions that were a result of biting tended to be higher on farms where chains were provided compared to wooden enrichment devices and most of this effect was by a difference in the prevalence of mild tail lesions.

Take Home Messages:

  • This research agrees with the results of previous studies that demonstrated that pigs will spend more time investigating and chewing on enrichment materials that are softer and more easily manipulated.
  • This research does not say that chains are of no use as an environmental enrichment but confirms that there are probably more effective alternatives such as rope, straw, plastic,  wood or rubber.

Submitted by Tess Faulkner MSC

Ref:   van Staaveren N, Hanlon A, Boyle LA.   Damaging Behaviour and Associated Lesions in Relation to Types of Enrichment for Finisher Pigs on Commercial Farms.  Animals (Basel). 2019 Sep 12;9(9). pii: E677. doi: 10.3390/ani9090677.


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