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10 years of research on tail biting - where are the risks on Irish farms

10 years of research on tail biting - where are the risks on Irish farms

Laura Boyle, Roberta D’Alessio and Keelin O’Driscoll share some of their results form research in the area of tail biting over the past decade and identify the biggest risks for tail biting on Irish pig farms.

In a recent newsletter article, 10 years of research on tail biting - tail lesions in the slaughterhouse, we discussed how the biggest risk factor for tail biting in pigs is the presence of a tail, and Irish pigs are mostly tail docked to address this.

Nevertheless, it does not entirely eliminate the problem, especially if husbandry issues are unresolved, as confirmed by the data presented on slaughterhouse tail lesion prevalence and severity described in the previous article. In this article, we will share some preliminary data from the PigNoDock project, which gives us some insight into the risk factors for tail biting on Irish farms.

This work was carried out in collaboration with AHI, whereby we were given confidential access to the risk assessments for tail biting that were carried out on 27 Irish pig farms. Permission was granted by the farmer and their private veterinary practitioner (PVP) to analyse the data. From these reports, we were able to single out the main risks that the assessors (PVPs) identified.

The risk assessment tool

The AHI tail biting risk assessment tool is quick and easy to use. PVPs assess six pens per farm, spread across the production stages, and carry out a number of measurements, taking about 15 minute per pen. The first part of the assessment for each pen is to complete a section regarding pig housing and management. This includes measurement of pen length and width, estimation of the proportion of solid flooring, the sex of the pigs (male, female or mixed), the final weight achieved in the pen, tail length (docked, undocked or mixed length), whether pigs can all feed at the same time, the number of drinkers, and whether the assessor considered the vaccination schedule to be appropriate. Next, the assessor details the type (optimal, sub-optimal or marginal) and amount of environmental enrichment in the pen.

Following this, there is an assessment of physical and behavioural welfare indicators. The number of pigs in the pen are counted, and then the number affected by the following conditions: injured tails; injured or imperfect ears; flank lesions (circular); aggression lesions (straight); dirty flanks; and tucked tails, are identified. Finally, there is a five minute period of behaviour observation, focusing on the following behaviours: tail biting; ear biting; damaging biting of other parts of the body; investigation of fixture and fittings; investigation of enrichment material; and aggressive biting.

Using these data, the assessor considers whether or not there is an overall risk of tail biting occurring in the pen, and the level of risk (none, minor or major) associated with the following six broad categories: environmental enrichment; thermal comfort; pig health; competition; pen design; and feeding processes. These categories were selected because these areas are considered important for risk assessment by the European Commission.

Where was risk identified?

Across the 27 study farms, a total of 158 pens were included in the final study (finisher stage= 85 pens; weaner stage phase 1= 29 pens; weaner stage phase 2= 44 pen). The total number of pigs in the inspected pens came to 6,421, with on average about 40 pigs per pen. The PVPs considered overall that there was a risk of biting in 58% of pens. Nevertheless, for all the categories above, other than environmental enrichment, for most of the pens (76-87%), the level of risk assigned was minor. However, the level of risk assigned to environmental enrichment was considered ‘major’ in 87% of pens.

Figure 1 shows an overview of the results regarding pig management. When it came to enrichment, 12% of pens did not contain any form of enrichment, and as such this is an area that producers should focus on, as it is a legal requirement. As stated above, the assessors considered environmental enrichment to be a major risk factor for tail biting in 87% of the pens assessed. This is likely because even when it was provided, there were very few pens with ‘optimal’ enrichment (i.e. loose material). Providing optimal enrichment materials is complicated by the presence of fully slatted floors, which you can see in the figure was the case in 92% of pens inspected. In Moorepark, we also have fully slatted floors and so provide loose material in racks that hang from the side of the pen.

Another option to improve enrichment is to simply add more of what is there already – in 37% of the pens there was only one item. This could be planks of wood, or commercially available chew toys. Chains are considered minimally effective as enrichment for pigs, and there should always be something else provided in the pen as well, ideally items that are destructible for the pigs.

Positively, in 99% of pens, the assessor considered that the vaccination programme for the pigs was appropriate. Additionally, in 14% of the pens, the pigs could all feed at the same time, which significantly reduces tail biting risk. Likewise, 55% of the pens had two or more drinkers.

Although the pigs in the Moorepark unit cannot all feed simultaneously, we assessed double compared to single feeders, and found that the former significantly reduced aggression at the feeder, and improved FCE (Pig newsletter August 2022). Thus if you are upgrading feeders, it is worthwhile replacing them with ones that allow more pigs to feed simultaneously. Of further concern was that in 20% of pens, the pigs were overstocked, which is known to be a major stressor and trigger for tail biting. However, it must be noted that these inspections were carried out between 2020 and 2022, when the COVID pandemic resulted in an unavoidable backlog of pigs on many farms due to lack of capacity at the slaughterhouse.

Results regarding pig management in the pens assessed, explained in text.

Figure 1. Results regarding pig management in the pens assessed.


Tail biting is multifactorial which makes it unpredictable and difficult to control. The only way to manage it is to identify the risk factors on your farm, particularly if you are already docking tails. Use of a risk factor identification tool can help to identify where risks are on your farm. Moreover, when results from multiple farms are combined, they can give an overview of common industry issues that should be focused on, whether via advisory services, or in the form of financial schemes to support farm infrastructure and management improvements.

As part of this ongoing work, we developed a more detailed risk assessment tool in Moorepark which will provide more tailored advice to individual producers. We are currently recruiting farms to take part; it includes an on farm assessment, as well as inspection of tails in the slaughterhouse, and you will receive a personalised report. If you would like to take part, please get in touch with Roberta D’Alessio (RobertaMaria.DAlessio@teagasc.ie), or your Teagasc pig advisor. All data collected as part of the project will be anonymised and confidential.