Category Archives: Straw

Can enrichment help reduce tail docking?

In several episodes, leading welfare researchers explain the results they obtained within the international framework ‘FareWellDock’. This project investigates how to steer away from tail docking. Swedish and Danish researchers took a look at straw – does its use reduce the occurrence of tail biting?

Read more in Pig Progress.

From the article:
Tail docking is completely banned in Sweden, Finland and Switzerland.

Science suggests that lack of proper manipulable material is one of several major risk factors for tail biting.

A moderate amount of straw (150 g/pig/day) reduced the risk of injurious tail biting by more than two-fold, while docking seemed to be more effective as it reduced the risk by more than four-fold.

A combination of straw and increased space (1.2 m2 per pig) reduced the risk (of first occurrence) in undocked pigs to the same level as found in docked pigs kept under high stocking density (0.72 m2 per pig) without straw.

To provide a suitable outlet for exploratory behaviour under production conditions, materials have to be varied and complex, and are most effective when easily destroyed by chewing, or if they are edible.

Increasing the amount of straw from 10 to up to 400g/pig/day had multiple positive effects by progressively reducing the occurrence of tail injuries and stomach ulcers, increasing growth rate, increasing straw-directed behaviour, and reducing redirected behaviours towards other pigs.

Left-over straw may be a promising candidate method to screen for appropriate level of straw allocation.

Tail biting app (advisory tool)

The Tail Biting “WebHAT” (Web based Husbandry Advisory Tool) is a website designed to be an interactive resource providing information about the key risks for tail biting in pigs and practical suggestions to help reduce these risks on-farm.

Taking information from evidence-based sources and scientific literature, this WebHAT identifies a number of risks associated with tail biting (a key pig behaviour), and can be used to generate a report of prioritised, key tail-biting risks found on a farm and obtain suggestions to address the specific risks identified

You can access the WebHAT tool here.

Tail biting pigs

Weighing tail biting against tail docking

Weighing tail biting against tail docking

Tail docking is an undesirable mutilation of pigs. Currently virtually all young piglets are docked in conventional farming so as to prevent tail biting later in life. However, throughout Europe efforts are made to reduce tail docking. Often farmers provide additional enrichment to try and prevent tail biting. Nevertheless, stopping the practice of tail docking may, and frequently does, lead to elevated levels of tail biting, resulting in tail wounds. In relation to this farmers and policy makers would like to know what levels of tail biting would be equivalent to tail docking in terms of pig welfare, i.e. how much tail biting can be allowed before deciding it would be better to continue tail docking. But this poses the problem how to weigh the (lack of) welfare involved in tail biting of a grower or finishing pig against the pain of tail docking of young piglets. Is this possible? And if so, how?


We recently had a brainstorm session on this subject. This is an outline of what we came up with, including a very tentative personal estimate (by MB).

In my personal view when (in the end up to) about 12% of undocked pigs were tail bitten that would be roughly equivalent in welfare to the docking of all piglets. The uncertainty margin, however,  is high, at least ranging from 5-25%. The reasoning underlying my estimate is as follows.


Firstly, piglets are normally docked using hot iron cautery. This is quite painful as it involves applying both heat and rather blunt trauma. The heat kills bacteria and thus may reduce the chance of subsequent infection of the tail wound. Tail biting at a later age, by contrast, is caused by even more (and multiple) blunt trauma (due to biting). It also has a substantially higher likelihood of infection. In addition, there is e.g. fear in the tail bitten pig due to being chased by a biter. Based on this I would say that pain (and stress directly related to tail biting) may roughly be about ten times as high in intensity and about ten times as long in duration, compared to tail docking. This would imply that 1 tail-bitten pig is off-set by about 100 docked piglets as regards the intensity and duration of the pain involved.


However, animal welfare encompasses more than just pain. An important additional factor is the level of stress which is not directly related to tail biting activity.

Firstly, there may be stress related to the treatment of tail biting, e.g. when biters and/or victims are taken out of the pen (resulting in social isolation and/or fighting). This stressor, however, is partly offset by the enhanced enrichment normally provided to pigs experiencing an outbreak of tail biting (though not all pigs are equally affected by the ‘costs’ and ‘benefits’). Note that there is another, more macabre, offset involving ‘happiness’ too, and that is the excitement experienced by the (sometimes fanatic) biter pigs when a tail-biting outbreak has started. Note also, that this biter ‘welfare’ is at the same time an indicator of the level of (background) stress experienced by pigs leading to this abnormal behaviour in the first place.

A much more important source of stress that must be taken into account, therefore, is related to the general housing conditions to which the pigs are exposed prior to a tail biting outbreak. Tail biting is an unnatural behaviour that is triggered by (some kind of) stress. Pig farmers are aware of this and will try and prevent tail biting by generally improving the housing conditions when they (start to) raise pigs with intact (undocked) tails. Thus the expected level of stress to which the pigs are exposed is likely to be higher in the case of routine tail docking. When farmers stop tail docking they normally provide much better enrichment (rooting material & space). Farmers raising pigs with intact tails will also take other measures to reduce stress, e.g. provide better climatic conditions, better feed and better health care. These stress-reducing measures don’t just apply to the biters or the victims of tail biting. They apply to all pigs in the pen. Furthermore, they don’t just apply during an outbreak of tail biting, but they apply throughout the pigs’ lives. Hence, the reduced stress levels are a major factor reducing the off-set between docking and tail biting based exclusively on pain (and pain-related fear). I would estimate that the improved living conditions may reduce the off-set by at least a factor 10. This would mean that taking into account both pain and stress, 100(%) docked pigs (kept with minimal care and in a more barren environment) could be roughly equivalent to similarly-sized group of pigs with intact tails under enriched conditions and in which 10% of the pigs has been tail bitten.

Tail biting in docked pigs

However, we know that tail biting does not only occur in undocked pigs. It is also seen in docked pigs. Roughly 2% of docked pigs are tail bitten. It seems safe to assume that the level of pain from being tail bitten is roughly comparable in docked pigs and in undocked pigs (though docked tails may be more sensitive and thus less likely to get bitten). Taking this into account would imply that 100 docked pigs of which 2% also experiences tail biting later in life would be having a level of (poor) welfare comparable to 100 undocked pigs of which 12% gets tail bitten. This is about 6 times as much tail biting as the 2% base-line set under conventional docking conditions.

Much uncertainty

It must be emphasised again, however, that this level of 12% tail biting is a very rough estimate. So, a wide safety-margin applies, e.g. 5-25%. This may depend in particular on the quality of enrichment and the extra care provided under non-docking conditions.

Please note, that this post is the result of a brainstorm session only and presents a personal view. It illustrates how systematic reasoning (using principles of semantic modelling) can be used to start to answer this rather important welfare question. I have provided a very rough estimate. For a more accurate assessment more detailed studies would certainly be required, both in terms of more carefully including what is already known and in terms of accumulating more empirical knowledge about what is not known yet. At present the assessment is still very speculative, and meant to illustrate primarily how to in principle deal with the question of what level of tail biting is equivalent to a practice of routine tail docking.

‘Weighing’ a pig ‘manually’

Postscript: Excluded aspects and some feedback from readers

Note that, in my estimate I neglected several (minor) aspects.

Firstly, I neglected the fact that for tail docking piglets must be picked up. This results in stress, both in the mother sow and in the piglets. From an evolutionary perspective the procedure of catching piglets may be equivalent to experiencing capture by a predator. This would mean that the given estimate would be a moderate underestimation. However, tail docking may be performed in combination with other treatments such as iron injection and castration. If so, the additional stress from handling may be relatively minor. Note, however, that castration applies only to males and may be banned in the near future, and iron injection may be given orally as a kind of ingestible compost, or as has recently been shown, may not be necessary at all. Hence, combining such treatments with tail docking has a reducing likelihood.

Secondly, I assumed that teeth cutting will not be practiced to treat an outbreak of tail biting, neither in the docked pigs, nor in the undocked pigs. Or, more precisely, at least I assumed teeth cutting is not practiced in substantially different numbers of pig. Such teeth cutting is painful and illegal, so it could be considered appropriate to ignore the practice. However, if it were practiced more in undocked pigs (which are likely to experience higher levels of tail biting), then it would have a substantial impact on the level of equivalence, pushing the percentage back down again substantially.

A third point to note is that I did not include in the estimate other ethical considerations or our (anthropomorphic) emotional responses. An example of the latter may be related to the amount of blood seen in the pen, the farmer’s level of stress (unpredictability) associated to this, and the potentially adverse economic consequences associated with tail biting. An example of other ethical considerations is the fact that tail docking may be considered to be an infringement of the animals’ integrity or intrinsic value. In such a rights-based moral view tail docking may be considered ethically wrong, regardless of the level of tail biting when tail docking is stopped. Such aspects were excluded because these are aspects not directly related to animal welfare. They are more related to our human perception of ethics and/or human welfare, rather than animal welfare.

Finally, it is most important to emphasise that I have considered steady-state conditions, but realize that all practices are subject to optimisation. The practice of tail docking has already been optimised for over a period of at least 50 year. By contrast, the practice of raising pigs with intact tails still more or less has to enter the phase of optimisation in commercial practice. This implies that substantially higher levels of tail biting may be regarded as acceptable, provided this is only temporary and provided it leads to substantially lower levels of tail biting later on. In other words, it requires that farmers will persist in raising pigs with intact tails and have a chance to learn to deal with it over a certain transition period, both in terms of prevention and treatment of tail-biting outbreaks.

Feedback reader 1:

Regarding the painfulness of tail biting vs tail docking, I find it impossible to guess the relation – especially as tail biting comes in so many forms.

I absolutely agree that a weighing like this is necessary, but I also think it is a bit dangerous to throw out estimates that are not really based on any evidence (or at least you do not present any?), such as the 100 times worse pain experienced by bitten pigs than docked pigs. Also, tail biting is very heterogeneous, from just a small, one-time bite, to a chronic situation, where the entire tail is lost, so the way you estimate the pain simplifies the matter greatly.

As to the expected level of actual tail biting when docking is stopped: I estimate a two-fold increase in tail biting if no docking is performed. Perhaps somewhere between 2- and 4-fold, based on e.g. slaughterhouse data. There may be a 4-fold increase when the housing situation is not improved otherwise – which you also take into account in your text – when applying a non-docking policy the farmer would normally also improve housing conditions, thus reducing the risk further. I certainly agree that when a farm stops docking, they will probably have a higher incidence of tail biting initially, but on the long-term (as is shown e.g. in Finland where tail docking is totally forbidden, and the tail-biting incidence, based on abattoir data is around 2%), a 10 or 12% incidence is certainly higher than I would expect.

Feedback reader 2:

Having read your blog I think you need to factor in adaptive, compensatory pain modulation into your model.

It is sometimes too easy to fail to take into account post-injury peripheral and central modulation of pain signalling that occur as part of the normal healing process and only focus on the ‘pro-pain’ component.

I also don’t see how you can substantiate this claim?

‘Based on this I would say that the pain of tail biting may be about ten times as high and about ten times as long, compared to tail docking. This would imply that 1 tail-bitten pig is off-set by about 100 docked piglets as regards the intensity and duration of the pain involved’.

While I think it might be possible to attribute weighting to some risk factors within systems, I don’t think it can be applied to pain experienced by an individual (or even at group level as you are suggesting) because there are so many factors that contribute to an individual’s experience of pain? I don’t think you can quantify the painfulness of tail biting and tail docking.

Also when thinking about stress you might want to define what you mean by that in relation to chronicity?

Short-term compensatory responses to stress are in my view positive for the animal; however beyond that when there is a failure of compensation and ultimately homeostatic decompensation then they are undoubtedly negative.

I guess I’m suggesting that any weighting approach might need to accommodate (or factor in) changes over time (i.e. dynamic weighting?)

I hope you find my comments helpful?


As to substantiation, again, it’s my suggestion for a start of an argument to answer this in my view fairly important question. My answer is based on my personal experience as a vet and scientist, and on reasons indicated in the blog. It is certainly in need of further study, examination and assessment. I fully acknowledge the considerable level of uncertainty as well as the risk associated with trying to answer the question. At the same time, however, I would also argue that there is a considerable risk in refusing to try to answer the question, as this leaves the issue to stakeholders.

Feedback reader 3:

Joining the discussion rather late, but basically I agree with the points others have made. I think it quite reasonable to conceptually set out the trade-offs which would determine the level of tail biting above which tail docking could be ethically justified, but putting numbers on some of these things is rather difficult.

For risk of tail biting in docked and undocked pigs we have a growing number of published sources and comparative national data.

For experimental comparisons we have old data suggesting increases of 30-60% in pigs in unbedded systems.

More recently we have studies suggesting somewhat lower results if straw is given.

So this part is perhaps simple, but depends on your assumptions about which husbandry systems will pertain across Europe.

For the welfare detriment of tail docking and tail biting, data indicate that both have long lasting effects on pain processing pathways, but the implications of this for pain perception for the individual are uncertain.

For tail docking, the data I have seen are still contradictory on whether cautery is more or less painful than simple section (some suggest the cautery destroys the nerves whilst others suggest greater pain). There is also the possibility of tail docking with anaesthesia/analgesia as a route of adoption.

For tail biting, the short term pain will certainly depend on the severity and, even more, on the prevalence of infection. The data on this are currently lacking to my knowledge.

The welfare impairment of keeping in conditions which give rise to tail biting is clearly the greatest of all in magnitude (severity x duration x no of animals) but I don’t think we have any way of comparing the welfare severity of ‘behavioural frustration’ against that of injury/pain. I would be concerned about taking arbitrary figures in the absence of any logical basis.

So, I guess my suggestion would be to explore the framework for this decision, but be very wary about pretending we can quantify it.

I also think the issue not addressed in your blog is the time course of any transition to cessation of tail docking and how to manage this. What proportion of farmers would have the awareness, capital and staff training to implement the changes necessary to their existing housing if obliged to cease tail docking (some older, fully slatted and large group housing systems will pose much bigger challenges and possibly require replacement of buildings), and how long would it take across Europe to reach the ‘acceptable’ situation of relatively low differential in tail-biting prevalence between docked and intact tails, rather than the ‘unacceptable’ differential shown for “one off” change in tail-docking experiments (stopping docking without further improvement of the environmental conditions). I think it important to highlight that your analysis relates to a ‘steady state’ situation and the importance of how any transition is managed and the welfare implications which this will have.


Note that I have not been comparing docking versus non-docking in a mono-factorial way. I compared docking in a more barren environment versus not docking in a more enriched environment supplemented with special attention by the farmer, as that is what will normally happen in practice. I have now emphasised this more clearly in the text.

I largely agree that we currently largely lack the data needed to quantify more precisely. However, I also believe that in principle it is possible to do so, and that the estimate/assessment can be more or less verified empirically (as the body of knowledge accumulates and modelling principles are improved). Personally, I am inclined to try and quantify despite considerable uncertainty, because it provides a better starting point for further discussion. In addition, such preliminary but more science-based estimates are much needed to complement the inevitably politically-loaded figures and personal assessments presented by farmer-representatives and NGO’s arguing either (rather exclusively) against or in favour of ending tail docking as a routine practice to prevent tail biting.

An important point I’ve been trying to make is that pain is not the only relevant aspect of welfare involved in tail docking and tail biting, and that the levels of enrichment and care should also be taken into account. I don’t think it is even possible to honestly say it is not possible to ‘add’ these aspects, since proper political decision making (in all kinds of areas, not just tail biting) simply does and has to, whether it is considered scientifically possible or not. And if so, I would argue it is most reasonable to try and provide the best possible scientific support, while being as honest as possible e.g. about uncertainty margins and the relevance of incorporating more information. I also think the estimate provides broad support to ‘farewell-dock’ initiatives such as those in Finland, Sweden, Denmark, the Netherlands, the UK and Germany.

Just a nice picture of what a pig’s tail should look like

What do you see?

Please have a look at this pig’s tail. You may note that contrary to most EU pigs, this Finnish pig has a curly tail. In addition, please note that this pig does not only has a curly tail. Its tail also has a hairy plume. That is what a pig’s tail should look like: It is the pig’s welfare thermometer.

Curly tail as sign of melting pig-welfare iceberg

The FareWellDock project has accumulated scientific information directed at reducing the need for tail docking in Europe. In this way it has contributed to ending the progressive melting of the pig-welfare iceberg. But sometimes, a picture says more than a thousand words, for the pig’s tail is an iceberg indicator for pig welfare.

Culty pig tail with brush

Curly pig tail (© Mari Heinonen).

Survey on straw use and tail biting on Swedish pig farms

Wallgren, T. R. Westin and S. Gunnarsson, 2016.  A survey of straw use and tail biting in Swedish pig farms rearing undocked pigs. Acta Veterinaria Scandinavica 58:84.


Background: Tail biting is a common problem in intensive pig farming, affecting both welfare and production. Although routine tail docking is banned within the EU, it remains a common practice to prevent tail biting. Straw as environmental enrichment has been proposed as an alternative to tail docking, but its effectiveness against tail biting and function in manure handling systems have to be considered. The aim of the study was to survey how pigs with intact tails are raised and how tail biting is handled in Sweden, where tail docking is banned through national legislation. The study emphasises straw usage and its association with tail biting pigs and problems in the manure handling system. The expectation is that this information could be conveyed to the rest of the EU to reduce the need for tail docking.

Results: In a telephone survey of randomly selected Swedish pig farmers (46 nursery and 43 finishing pig units) with at least 50 sows or 300 finishing places, it was found that straw was used by 98% of the farmers. The median daily straw ration provided was 29 g/pig for nursery and 50 g/pig for finishing pigs in systems with partly slatted flooring. The reported prevalence of tail biting was 1.6% at slaughter. The majority of farmers reported that they never had manure handling problems caused by straw (56% of nursery units and 81% of finishing pig units). A proportion of farmers (37%) also provided with additional material apart from straw on some occasions, which may have affected tail biting prevalence and manure handling problems.

Conclusions: Swedish farmers rear undocked pigs without large problems with tail biting. Straw is the main manipulable material used, and additional manipulable material is used to various extents. The low incidence of straw obstructing the manure handling systems implies that it is indeed possible to use straw in partly slatted flooring systems, reducing the need for tail docking. The impact of using additional manipulable material is unknown and requires more investigation to separate the impact of such material from the impact of straw.

Straw survey in Sweden (3 conference abstracts)

A survey of straw use and tail biting in Swedish undocked pig farms
ICPD 2016, 20-23 June 2016, Wageningen (oral presentation)
T. Wallgren, R. Westin, S. Gunnarsson
Swedish University of Agricultural Sciences, Department of Animal Environment and Health, Skara, Sweden


Tail biting is a common problem in todays’ pig production, affecting production and welfare. As tail biting behaviour is more prominent in systems with no or limited access manipulable material, it has been considered related to exploratory behaviours. Tail docking, commonly used as tail biting prevention, is a painful procedure that can decrease pig welfare does not eliminate the tail biting behaviour. Although tail docking is not accepted as a routine procedure according to the EU Directive 2008/120/EC it is still a common practise within the EU, which is why other measures to reduce tail biting behaviour are needed. In Sweden, tail docking is banned and tail biting must be reduced otherwise. Furthermore, Swedish legislation banned fully slatted floors and demands pigs to have access to manipulable material. In order to investigate the prevalence of tail biting in Sweden and the relationship with provision of straw, we performed a telephone survey in nursery (n=46) and finishing pig (n=43) farms. Farmers were interviewed regarding straw usage (e.g. daily ratios) and tail biting (e.g. frequency). All participating farmers gave access to manipulable material and 98% used straw. The median straw ration reported by farmers was 29g/pig/day (min: 8g, max: 85g) in nursery and 50g/pig/day (9g, 225g) in finishing farms when excluding deep litter systems. Farmers reported having observed tail bitten pigs, at any time, in 50% of nursery and 88% of finishing pig farms. Of these, tail bitten pigs were reported to be found ≤2 times/year (78%), 3-6 times/year(17%) or monthly (4%) in nursery and ≤2 times/year (21%), 3-6 times/year (37%), monthly (34%) or weekly (8%) in finishing farms. Finishing farmers reported on average 1.6% tail bitten pigs/batch (0.1-6.5%), which is in line with abattoir data. Spearman rank correlation was used for statistical analysis. Increased straw ration was correlated with decreased reported tail biting frequency in finishing farms (r=-0.39, P=0.03, n=31), and a tendency for this was found in nursery farms (r=-0.33, P=0.08, n=29) when deep litter systems were included. In finishing farms, excluding deep litter systems, an increased tail biting frequency observed by farmers was correlated to the percentage of tail bitten pigs (r=0.64, P=<0.001, n=33), indicating that an increased frequency of tail biting reported may be associated with more pens affected at outbreaks. Even though provided straw rations were quite small (i.e. 30-50 g/pig/day), this amount of straw may provide pigs with enough occupation to limit tail biting outbreaks. We conclude that tail biting can be kept at a low level (ca 2%) in partly slatted flooring systems, without tail docking, by supplying straw.

Raising undocked pigs: straw, tail biting and management
ISAE 201612-15 July 2016 (poster presentation, see below)
Torun Wallgren, Rebecka Westin and Stefan Gunnarsson
Swedish University of Agricultural Sciences, Department of Animal Environment and Health, Skara, Sweden


Tail biting in pigs is common in pig production and has been suggested correlated to several behaviours. It is associated with reduced welfare and production losses. A common practice to reduce tail biting within EU is tail docking where part of the tail is removed; a painful procedure that does not eliminate the behaviour. According to the EU Directive 2008/120/EC routine tail docking is banned and other measures to reduce tail biting must replace docking. An alternative is to improve the pig environment by using straw and thus decrease development of tail biting. Straw usage has been difficult to implement since it is argued that straw provision is incompatible with fully slatted floors. In Sweden, tail docking and fully slatted floors are completely banned through national legislation. Furthermore, it is a legal requirement that pigs should have access to manipulable material. The implementation of straw usage in Swedish farms was investigated in a telephone survey to study straw usage and farmers’ opinion on straw impact on tail biting and farm management. A total of 46 nursery and 43 finishing farmers were interviewed, all reporting providing pigs with enrichment material, most commonly straw (98%). Median straw rations provided in systems with partly slatted floor was 29 g/pig/day (8-85 g) in nursery and 50 g (9-225 g) in finishing farms. Straw was the only manipulable material in 50% of nursery and 65% of finishing farms while remaining farms used additional material, most commonly wood shavings (65%). ‘Toys’, e.g. balls and ropes, were used by 13% of nursery and 16% of finishing farmers as a supplement to other manipulable material. Of these, 62% only provided these ‘toys’ occasionally, e.g. at re-grouping or when tail biting had been observed. Problems in the manure handling systems caused by straw had occurred in 32% of the farms, of these 25% had problems at yearly and 7% monthly, or more seldom (58%). Tail biting had been observed in the production at least once by 50% of nursery and 88% of finishing farmers, an average of 1.6% finishing pigs were reported tail bitten per batch (0.1-6.5). Tail biting was observed ≤twice/year (78%) 3-6 times/yr (17%) and monthly (4%) by nursey and ≤2 times/yr (21%), 3-6 times/yr (37%), monthly (34%) and weekly (8%) by finishing farmers. The provided amounts of straw seem to be sufficient to keep tail biting at a low level in undocked pig herds (<2%/batch). The low incidence of straw obstruction in manure handling systems reported also implies that straw usage at this rate 30-50 g/pig/day) is manageable in pig production systems.

Production of undocked pigs, a survey of farmers’ experiences
EAAP Annual Meeting, 29 August – 2 September 2016, Belfast (oral presentation)
T. Wallgren, R. Westin, S. Gunnarsson
Swedish University of Agricultural Sciences, Department of Animal Environment and Health, Skara, Sweden


Tail biting is a common cause for reduced welfare and production rates within commercial pig production and is more prominent in barren environments. Using enrichment as straw has been shown to reduce tail biting behavior and thus reduce need for tail docking. Implementation of straw in practice has however partly default since it is argued that straw will cause obstruction in the manure handling systems. Sweden has a long tradition of rearing undocked pigs with access to straw due to national legislation banning docking and fully slatted floors while demanding access to manipulable material for pigs. We surveyed 60 randomly selected Swedish nursery and finishing pig farmers’ usage of straw and their opinions on straw impact on tail biting and manure handling management. All farmers provided manipulable material, 98% straw. In 50% of nursery and 35% of finishing farms the straw was complemented with material such as wood shavings. Straw rations were 29g/pig/day (8-85g) in nursery and 50g (9-225g) in finishing farms. Straw was commonly chopped (76%) to a mean length of 6 cm (1-10) in nursery and 8 cm (1-20) in finishing farms. Straw causing problems in the manure handling system occurred in 32% of the farms who experienced this yearly (25%) or monthly (7%). Most common causes were straw making the slurry sluggish, stacked in pivot or blocking slats. The low incidences of problems indicate current systems are able to cope with presented straw rations. Tail biting had been seen at least one time ever in 50% of nursery and 88% of finishing farms. Frequency of observed tail biting was ≤twice/year (78%) 3-6 times/yr (17%) and monthly (4%) by nursey and ≤ 2 times/yr (21%), 3-6 times/yr (37%), monthly (34%) and weekly (8%) by finishing farmers. An average of 1.6 (0.1-6.5) finishing pigs were reported tail bitten each batch. In partly slatted flooring systems a correlation was found between increased tail biting frequency and percentage of reported tail bitten pigs (r=0.64, P= <0.0001, n=38) (Spearman Rank correlation). The limited tail biting problems indicate that straw usage at this level is enough to prevent major tail biting outbreaks in undocked pigs.

Poster straw survey Sweden

Online Training Improves Understanding of Pig Welfare Legislation

A recent research paper has reported a positive effect of an online training tool on participants’ understanding of taildocking and enrichment legislation, as well as risk factors for tail biting. The training tool was aimed at official inspectors and others involved in enforcement of legislative requirements on pig farms. The research was a collaboration of 15 researchers from 9 EU countries, led by the University of Bristol, UK. The online training tool is free to use and is available in 7 different languages: English, French, German, Polish, Italian, Spanish and Dutch. It can be accessed here:

Click this link to access the EUWelNet Training Tool on pig enrichment and tail docking.

Hothersall, B., Whistance, L., Zedlacher, H., Algers, B., Andersson, E., Bracke, M., Courboulay, V., Ferrari, P., Leeb, C., Mullan, S., Nowicki, J., Meunier-Salaun, M-C., Schwarz, T., Stadig, L. & Main, D. 2016 Standardising the assessment of environmental enrichment and tail-docking legal requirements for finishing pigs in Europe. Animal Welfare 25:499-509.


An online training package providing a concise synthesis of the scientific data underpinning EU legislation on enrichment and taildocking of pigs was produced in seven languages, with the aim of improving consistency of professional judgements regarding legislation compliance on farms. In total, 158 participants who were official inspectors, certification scheme assessors and advisors from 16 EU countries completed an initial test and an online training package. Control group participants completed a second identical test before, and Training group participants after, viewing the training. In Section 1 of the test participants rated the importance of modifying environmental enrichment defined in nine scenarios from 1 (not important) to 10 (very important). Training significantly increased participants’ overall perception of the need for change. Participants then rated nine risk factors for tail-biting from 1 (no risk) to 10 (high risk). After training scores were better correlated with risk rankings already described by scientists. Scenarios relating to tail-docking and management were then described. Training significantly increased the proportion of respondents correctly identifying that a farm without tail lesions should stop tail-docking. Finally, participants rated the  importance of modifying enrichment in three further scenarios. Training increased ratings in all three. The pattern of results indicated that participants’ roles influenced scores but overall the training improved: i) recognition of enrichments that, by virtue of their type or use by pigs, may be insufficient to achieve legislation compliance; ii) knowledge on risk factors for tail-biting; and iii) recognition of when routine tail-docking was occurring.

EUWelNet Training Tool enrichment and tail docking

Note that the training tool is being used in Poland to train animal science students, farm assurance in the UK has shown recent interest in using the tool, and the Austrian pig health service is compiling a brochure based on EUWelNet on tail biting/enrichment material.

Proper enrichment for intensively-farmed pigs – From review to preview

Bracke, M.B.M. 2016. Enrichment materials for intensively-farmed pigs – From review to preview (Conference abstract & presentation, ICPD 2016). In: Kemp, B. et al., 2016. 16th International Conference on Production Diseases in Farm Animals. June 20-23, 2016. Wageningen, NL. p. 179.


Tail biting is a well-known production disease in intensively-farmed pigs raising concern for animal welfare, e.g. related to the practice of routine tail docking. To reduce tail biting pigs are provided with enrichment materials. EU legislation requires that pigs have permanent access to a sufficient quantity of material to enable proper investigation and manipulation activities. In order to meet this directive many pigs are provided with a metal chain with or without a rather indestructible object attached to the chain. The European commission recently revised current guidelines as to what constitutes adequate enrichment, apparently moving into the direction of the status-quo in welfare schemes. Building on extensive previous work at Wageningen UR Livestock Research, especially on the modelling of pig enrichment (the so-called RICHPIG model) a review is presented of our current state of knowledge. In addition, an outline is given as to how so-called AMI-sensors, measuring Animal-Material Interactions (AMI) (semi-)automatically, can be used to assess the pig’s need for enrichment, also in relation to aspects associated with health status, such as feed restriction, biting wounds and streptococcus infection. It is suggested that the use of chains with or without rather indestructible materials such as pipes, balls or (hard)wood is generally inadequate to enrich the pens of intensively-farmed pigs. An evolutionary mechanism appears to be underlying the causation of multifactorial welfare problems in general, the issues of enrichment, tail biting and tail docking in pigs in particular. In this respect ongoing selection for increased resource efficiency has been exerting a profound impact on livestock production. Various routes are explored as to how persistent welfare problems may be resolved, including a method that has been called Intelligent Natural Design (IND).

Branched chain
Two organic pigs interacting simultaneously with a branched chain in the snow. Despite access to a straw bed for rooting, even organic pigs may interact with such chains for long periods of time, esp. directed towards the floor. In fact they will root the chain on the floor more than twice as much as playing with it in a horizontal position. In intensive pig production chains are often (too) short, and when a hockey-type ball or ‘sustainable’ plastic pipe is attached to the end of such a chain the pigs’ interest, and their welfare, is often even reduced further. By contrast, to improve the chain further 7mm stainless-steel anchor chains may be recommended for growing pigs over the cheaper c-chain shown here, as anchor chains have heavier and more rounded shackles.

See also an older previous presentation on tail biting.

Bracke, M.B.M, Wolthuis, M., Zonderland, J. J., Kluivers, M., 2011. TAILS TO TELL – Tail docking, tail biting and enrichment for pigs – Experiences from the Netherlands. Herning, DK, May 25-26, 2011.

Improving Welfare, Health and Productivity in Pigs by Optimizing Adaptation

Improving Welfare, Health and Productivity in Pigs by Optimizing Adaptation
By J.E. Bolhuis and B. Kemp, 2016. Journal of Animal Science (conference paper, March 14-16, 2016, Des Moines, USA).


Welfare problems in pigs often arise from an imbalance between the challenges they are exposed to and their adaptive capacity. A major challenge for pigs is the weaning transition. Weaning often results in reduced growth, intestinal problems and damaging behaviors. The natural behavior of pigs and their adaptive strategies can inspire us to reduce weaning-related problems. We found that early ingestion of feed can be stimulated by facilitating information transfer from sow to piglet, both through flavor learning in utero and social learning. This early feeding, in turn, seems vital for a good post-weaning performance. Also enrichment substrates that stimulate early sampling of feed positively affect piglet performance around weaning. We are developing a multi-litter group housing system for lactating sows and their piglets in which both opportunities for sow-piglet information transfer and enrichment substrates are provided. Piglets raised in this system and kept in large groups post-weaning show improved performance until at least 9 weeks of age. Measures that facilitate the weaning transition in pigs typically also reduce the occurrence of damaging behaviors directed at pen mates, such as tail biting and ear biting. These behaviors both reflect and generate welfare problems, and are influenced by multiple factors. Apart from the impact of early life conditions, we studied the contribution of (genetic) characteristics of pigs and of their environment to the tendency of displaying damaging behaviors. Tail biting seems associated with fearfulness, serotonin metabolism and with (genetic and phenotypic) production characteristics. Excessive levels of damaging behaviors lead to reduced growth in the victims, and we therefore investigated the impact of a novel breeding strategy, targeting indirect genetic effects on growth. Pigs with high indirect genetic effects on growth inflicted less tail damage and showed less ear biting. They also seemed less fearful and showed lower leukocyte, lymphocyte and haptoglobin levels. Enrichment with straw bedding had similar beneficial effects additive to those of the new genetic strategy. On most farms it is, however, not feasible to provide pigs with straw, and we therefore studied the effectiveness of a simple enrichment material – a burlap sack – and found a twofold reduction in damaging behaviours and a five-fold reduction in the proportion of animals with a tail wound. In conclusion, – small and large – changes in genetic background, early life conditions and quality of the environment that contribute to the adaptive capacity of pigs, and reduce their stress load, can be used to improve pig welfare and performance in concert.

Impact of straw on gastric ulceration in pigs

Impact of the amount of straw provided to pigs kept in intensive production conditions on the occurrence and severity of gastric ulceration at slaughter.
Herskin MS, Jensen HE, Jespersen A, Forkman B, Jensen MB, Canibe N, Pedersen LJ. 2016. Res Vet Sci. 104: 200-6.


This study examined effects of the amount of straw offered on occurrence and severity of gastric lesions in pigs kept in pens (18 pigs, 0.7m(2)/pig) with partly slatted flooring and 10, 500 or 1000g straw/pig/day from 30kg live weight. The pigs had ad libitum access to dry feed. Forty-five pigs were used, three from each of 15 pens. After euthanisia, the dimension of the non-glandular region of the stomach was measured. Lesions were characterized and scored. Irrespective of straw provided, 67% of the pigs showed signs of gastric pathology. Pigs provided with 500 or 1000g straw were pooled as ‘permanent access’. The proportion of pigs with ulcerations was reduced by permanent access to straw (7 vs. 33%; P<0.05), suggesting that permanent access to straw may improve animal health, and be considered as one possible strategy to limit gastric ulceration in pigs.

500gr straw/pig/day
500gr straw/pig/day
10gr straw/pig/day
10gr straw/pig/day