Category Archives: Uncategorized

Tail biting and straw usage in Swedish farms

To rear pigs with intact tails

Did you know that over 90% of pigs are tail docked in the EU? During the pig’s first week of life, the tail is docked and its length reduced. The reason for this is that pigs later in life can start biting each other on the tail, which affects both their health and production. A shorter tail reduces the risk of tail biting, but is also associated with both acute and long-term pain while not solving the underlying problem.

Read more on how to rear pigs with intact tails.

See the brochure ‘Tail biting and straw usage in Swedish farms‘ .

Review: Early life predisposing factors for biting in pigs

Prunier, A., X. Averos, I. Dimitrov, S. A. Edwards, E. Hillmann, M. Holinger, V. Ilieski, R. Leming, C. Tallet, S. P. Turner, M. Zupan and I. Camerlink, 2019. Review: Early life predisposing factors for biting in pigs. Animal.

The pig industry faces many animal welfare issues. Among these, biting behaviour has a high incidence. It is indicative of an existing problem in biters and is a source of physical damage and psychological stress for the victims. We categorize this behaviour into aggressive and non-aggressive biting, the latter often being directed towards the tail. This review focusses specifically on predisposing factors in early life, comprising the prenatal and postnatal periods up to weaning, for the expression of aggressive and non-aggressive biting later in life. The influence of personality and coping style has been examined in a few studies. It varies according to these studies and, thus, further evaluation is needed. Regarding the effect of environmental factors, the number of scientific papers is low (less than five papers for most factors). No clear influence of prenatal factors has been identified to date. Aggressive biting is reduced by undernutrition, cross-fostering and socialization before weaning. Non-aggressive biting is increased by undernutrition, social stress due to competition and cross-fostering. These latter three factors are highly dependent on litter size at birth. The use of familiar odours may contribute to reducing biting when pigs are moved from one environment to another by alleviating the level of stress associated with novelty. Even though the current environment in which pigs are expressing biting behaviours is of major importance, the pre-weaning environment should be optimized to reduce the likelihood of this problem.

Evidence of Pain, Stress, and Fear of Humans During Tail Docking and the Next Four Weeks in Piglets (Sus scrofa domesticus)

Céline Tallet, Marine Rakotomahandry, Sabine Herlemont and Armelle Prunier, 2019. Evidence of Pain, Stress, and Fear of Humans During Tail Docking and the Next Four Weeks in Piglets (Sus scrofa domesticus). Front. Vet. Sci., 11 December 2019|


Tail docking is widely performed in pig farms to prevent tail biting. We investigated the consequences of this practice on behavioral indicators of pain and stress, and on the human-piglet relationship during lactation. Within 19 litters, piglets (1–3 days of age) were submitted on day 0 (D0) to docking with a cautery iron (D), sham-docking (S), or no docking (U). Piglets from the D and S groups were observed during the procedure (body movements and vocalizations) and just after, in isolation, during 20 s for body, tail and ear postures as well as ear movements. Piglets from the three treatments were observed in their home pen after docking on D0 and D3 afternoon for body posture, tail posture and movements. Piglets from the D and U groups were observed on D6, D12, D19, and D26 in their home pen for oral behavior, body, and tail posture. Tail damage and tear staining were scored on D5, D11, D18, and D25. A 5-min motionless human test was performed on D14. During the procedure, D piglets screamed more and with a higher intensity (P < 0.05) than S piglets (n = 48–50). Just after docking, D piglets held their ears in a posture perpendicular to the head-tail axis and changed their ear posture more often (P < 0.05). Between D6 and D26, D piglets kept their tail immobile (P < 0.001) and in a horizontal position (P < 0.01) more often than U piglets (n = 45–47). Between D11 and D25, U piglets had higher scores for tail damage and damage freshness than D piglets (0.09 < P < 0.02) whereas tear-stain score was similar. In the human test, D piglets interacted later with an unfamiliar human than U piglets (P = 0.01, n = 18/group). Present data indicate signs of acute pain and stress in piglets due to docking during the procedure itself and adverse consequences throughout lactation thereafter, including on their relationship with humans. On the other hand, the presence of tail lesions shows that undocked piglets are subject to more tail biting, even before weaning

Physiology, Behaviour, Productivity and Meat Quality of Pigs Raised in a Hot Climate

Physiology, Behaviour, Productivity and Meat Quality of Pigs Raised in a Hot Climate.

Emma Fàbrega, Míriam Marcet-Rius, Roger Vidal, Damián Escribano, José Joaquín Cerón, Xavier Manteca, Antonio Velardem, 2019. Animals 9; doi:10.3390/ani9050235.

Abstract: Some positive effects regarding the use of enrichment material on the stimulation of pig exploration and a reduction in redirected behaviour was reported. This study aims to evaluate the effects of four enrichment materials on the behaviour, physiology/health, performance and carcass and meat quality in pigs kept in Spanish production conditions. Ninety-six male pigs (six pigs/pen) ranging from 70 to 170 days old were used. Chains were used for the control group (CH), and wooden logs (W), straw in a rack (S) or paper (P) were also used. The pigs were subjected to two pre-slaughter treatments: 0 or 12 hours of fasting. Their behaviour was observed for 12 weeks using scan and focal sampling. Samples of the Neutrophil: Lymphocyte (N:L) ratio and lactate were obtained from the pigs at 66 and 170 days old. Saliva samples for Chromogranin-A (CgA) were obtained at 67, 128, 164 and 170 days old. The weight, skin lesions and feed intake of the pigs were recorded. S triggered more exploratory behaviour than W and CH (P < 0.001). Skin lesions and redirected behaviour were lower for pigs with S (P < 0.01 and P < 0.05, respectively). The pigs offered S presented lower CgA after no fasting than pigs with P or CH (P = 0.055). Lactate was higher in pigs with W and CH treatments, regardless of fasting (P < 0.05). The N:L ratio increased over time (P < 0.05). No other significant effects were found. Overall, straw in a rack was the enrichment material that enhanced pig inherent behaviour.

Evidence for a link between tail biting and central monoamine metabolism in pigs (Sus scrofa domestica)

Valros A, Palander P, Heinonen M, Munsterhjelm C, Brunberg E, Keeling L, Piepponen, P, 2015. Evidence for a link between tail biting and central monoamine metabolism in pigs (Sus scrofa domestica). Physiol Behav.143:151-7. doi: 10.1016/j.physbeh.2015.02.049.
Tail biting in pigs is a major welfare problem within the swine industry. Even though there is plenty of information on housing and management-related risk factors, the biological bases of this behavioral problem are poorly understood. The aim of this study was to investigate a possible link between tail biting, based on behavioral recordings of pigs during an ongoing outbreak, and certain neurotransmitters in different brain regions of these pigs. We used a total of 33 pigs at a farm with a long-standing problem of tail biting. Three equally big behavioral phenotypic groups, balanced for gender and age were selected, the data thus consisting of 11 trios of pigs. Two of the pigs in each trio originated from the same pen: one tail biter (TB) and one tail biting victim (V). A control (C) pig was selected from a pen without significant tail biting in the same farm room. We found an effect of tail biting behavioral phenotype on the metabolism of serotonin and dopamine, with a tendency for a higher 5-HIAA level in the prefrontal cortex (PFC) of TB compared to the other groups, while V pigs showed changes in both serotonin and dopamine metabolism in the striatum (ST) and limbic cortex (LC). Trp:BCAA and Trp:LNAA correlated positively with serotonin and 5-HIAA in the PFC, but only in TB pigs. Furthermore, in both ST and LC, several of the neurotransmitters and their metabolites correlated positively with the frequency of bites received by the pig. This is the first study indicating a link between brain neurotransmission and tail biting behavior in pigs with TB pigs showing a tendency for increased PFC serotonin metabolism and V pigs showing several changes in central dopamine and serotonin metabolism in their ST and LC, possibly due to the acute stress caused by being bitten. Copyright © 2015. Published by Elsevier Inc.

Rearing Pigs with Intact Tails—Experiences and Practical Solutions in Sweden

Wallgren, T., Lundeheim, N., Wallenbeck, A, Westin, R. and Gunnarsson, S. 2019. Rearing pigs with intact tails- experiences and practical solutions in Sweden. Animals 2019, 9, 812; doi:10.3390/ani9100812


Tail biting is a common issue within commercial pig production. It is mainly an indicator of inadequate housing environment and results in reduced health welfare and production. To reduce the impact of tail biting, pigs are commonly tail docked, without pain relief, within the first week of life. EU Council Directive 2008/120/EC prohibits routine tail docking, but the practice is still widely used in many Member States. Sweden has banned tail docking since 1988 and all pigs have intact tails, yet tail biting is a minor problem. This paper summarises and synthesises experimental findings and practical expertise in production of undocked pigs in Sweden and describes solutions to facilitate a transition to producing pigs with intact tails within intensive pig production in the EU. Swedish pig housing conditions and management differ in many aspects from those in other EU Member States. Swedish experiences show that lower stocking density, provision of sufficient feeding space, no fully slatted flooring, strict maximum levels for noxious gases and regular provision of litter material are crucial for success when rearing pigs with intact tails. To prevent tail biting and to eliminate the need for tail docking, we strongly recommend that EU legislation should more clearly match the biological needs of pigs, as is done in Swedish legislation.

Tail docking in pigs is an amputation causing sustained transcriptomic expression changes in the spinal cord indicative of inflammation and neuropathic pain

Transcriptomics Analysis of Porcine Caudal Dorsal Root Ganglia in Tail Amputated Pigs Shows Long-Term Effects on Many Pain-Associated Genes
By Dale A. Sandercock, Mark W. Barnett, Jennifer E. Coe, Alison C. Downing,
Ajit J. Nirmal, Pierpaolo Di Giminiani, Sandra A. Edwards and Tom C. Freeman.  Frontiers in Veterinary Science, September 2019 | Volume 6 | Article 314.


Tail amputation by tail docking or as an extreme consequence of tail biting in commercial pig production potentially has serious implications for animal welfare. Tail amputation causes peripheral nerve injury that might be associated with lasting chronic pain. The aim of this study was to investigate the short- and long-term effects of tail amputation in pigs on caudal DRG gene expression at different stages of development, particularly in relation to genes associated with nociception and pain. Microarrays were used to analyse whole DRG transcriptomes from tail amputated and sham-treated pigs 1, 8, and 16 weeks following tail treatment at either 3 or 63 days of age (8 pigs/treatment/age/time after treatment; n = 96). Tail amputation induced marked changes in gene expression (up and down) compared to sham-treated intact controls for all treatment ages and time points after tail treatment. Sustained changes in gene expression in tail amputated pigs were still evident 4 months after tail injury. Gene correlation network analysis revealed two co-expression clusters associated with amputation: Cluster A (759 down-regulated) and Cluster B (273 up-regulated) genes. Gene ontology (GO) enrichment analysis identified 124 genes in Cluster A and 61 genes in Cluster B associated with both “inflammatory pain” and “neuropathic pain.” In Cluster A, gene family members of ion channels e.g., voltage-gated potassium channels (VGPC) and receptors e.g., GABA receptors, were significantly down-regulated compared to shams, both of which are linked to increased peripheral nerve excitability after axotomy. Up-regulated gene families in Cluster B were linked to transcriptional regulation, inflammation, tissue remodeling, and regulatory neuropeptide activity. These findings, demonstrate that tail amputation causes sustained transcriptomic expression changes in caudal DRG cells involved in inflammatory and neuropathic pain pathways.

PhD live stream: A tale of tails – prevention of tail biting in pigs by early detection and straw management. Torun Wallgren. Friday 20-9-2019, 09.15u, Sweden

Dissertation: Friday 20 September 2019, 09.15 in Audhumbla, VHC, SLU Ultuna

Torun Wallgren defends her thesis “A tale of tails – prevention of tail biting in pigs by early detection and straw management”. View the live stream / recording

Torun Wallgren: A tale of tails – Prevention of tail biting by early detection and straw management

Opponent /external evaluator: Professor Nicole Kemper, Institute for Animal Hygiene, University of Veterinary Medicine Hannover, Germany

Examination board:

Professor Andrew Michael Janczak, Norwegian University of Life Sciences (NMBU), Oslo, Norway

Agr. Dr. Anne-Charlotte Olsson, Inst för Biosystem och Teknologi, SLU Alnarp

Professor Lotta Rydhmer, Professor, Inst för Husdjursgenetik (HGEN), SLU Ultuna

Professor Linda Keeling, Institutionen för husdjurens miljö och hälsa (HMH), SLU Ultuna (reserv).


Docent Stefan Gunnarsson, HMH, SLU Skara

Assisting supervisors:

Nils Lundeheim, Professor, HGEN, SLU Ultuna

Rebecka Westin, VMD, HMH, SLU Skara


Pigs in their natural environment spend the majority of their time exploring their surroundings through rooting, sniffing and chewing to find food and resting places. Rooting under commercial conditions is often fully dependent on the provision of rooting material. Lack of rooting opportunity may redirect the exploratory behaviour and cause tail biting, an abnormal behaviour that causes acute, long- and short-term pain. Tail biting is a common issue in modern pig production, reducing health, profitability and animal welfare. To fulfil pigs’ explorative needs, the Council Directive 2008/120/EC states that pigs should have permanent access to a sufficient amount of material, such as straw, to enable proper investigation and manipulation activities.

However, instead of improving pig environment to reduce tail biting, >90% of pigs in the EU are tail docked despite the prohibition of routine docking. Docked pigs have a less attractive and more sensitive tail tip and are less willing to allow biting. Docking aims at reducing the symptoms of tail biting rather than eliminating the cause. One argument for not increasing exploration through e.g. straw provision is fear of poor hygiene.

The overall aim of this thesis was to investigate the effect of straw on tail lesions, behaviour and hygiene (Studies I and II) as well as investigating tail position as a method for early detection of tail biting (Study III) in commercial production. Study I showed that 99% of Swedish farmers provide their pigs with straw (mediangrowers: 29 gram/pig/day; medianfinishers: 50 gram/pig/day). The amount of tail biting recorded at the abattoir was on average 1.7%. Study II showed that an increased straw ration decreased presence of tail wounds and initiated more straw-directed behaviour. Straw had little effect on hygiene. Study III showed that tail posture (hanging or curled) at feeding correctly classified 78% of the pigs with tail wounds. Less severe tail damage, e.g. swelling or bite marks, did not affect the tail posture.

The main conclusions are that increased straw reduces tail damage as well as pen-directed behaviours. Instead, straw increases straw-directed behaviours, while not affecting pig and pen hygiene negatively. Hence, it should be possible to rear pigs with intact tails without the use of tail docking in the EU.

Please check your video and audio settings before the meeting starts – Feel free to use our Test call service for this purpose.

Participants will join using one of the following ways:

  • SLU-systems (Locations)will be connected automatically to the meeting.
  • Skype for Businessthrough the link on the right (then click the camera icon and Start My Video).
  • Web Browserusing the link on the right.
  • Video conferencing systemsusing the video address (SIP/H323)
  • Or by IPfollowed by the Access code, end with # or £

Note that you cannot join the meeting before the scheduled start time.


Conference Details


Use app:


Skype for Business


Use web browser:




Video address:


Join by IP:

Access code:





SLU Ultuna Audhumbla

P Skara Lunchrummet






Call-in number:

+46 (18) 278780


Access code:




Test call service


Use app:


Skype for Business / Lync


Use web browser:




Video address:


Chains as enrichment for pigs (Book chapter with supplement)

Chains as proper enrichment for pigs (incl. supplement) (Book chapter in Advances in Pig Welfare, M Spinka (Editor), Elsevier).

Rearing pigs in barren conditions reduces their welfare. Enrichment of pig pens is needed to allow the performance of species-specific natural behaviour like rooting. A metal chain provides rather limited enrichment, but when presented in an optimized way, may substantially improve the welfare of conventionally reared pigs in a most feasible way. The short metal chain can be optimize into the branched chain design. This is a long anchor-chain type chain reaching til floor level, with 2 or 3 shorter chain branches at nose height, and 1 such a branched chain being provided for every 5 pigs in the pen.

The underlying ideas are described in this book chapter:

Bracke MBM. Chains as proper enrichment for pigs (incl. supplement). In: Spinka M, editor. Advances in Pig Welfare: Elsevier (2017). The chapter (without supplement) can also be downloaded here.


This chapter primarily compiles work in which the author (Marc Bracke) has been involved with providing science-based decision support on the question of what is proper enrichment material for intensively-farmed pigs as required by EC Directive 2001/93/EC. Proper manipulable material should primarily provide occupation (i.e. reduce boredom), and preferably reduce tail biting.

The RICHPIG model was built expressing enrichment value as a score on a scale from 0 to 10. Metal objects like short metal chains had the lowest score. Subsequently, the Dutch government banned the use of metal chains, and most Dutch pig farmers attached a hard plastic ball or pipe to the prevalent, short metal chain. Unfortunately, our on-farm observations repeatedly suggested that this ‘enrichment’ may have reduced pig welfare, rather than improving it as intended by the Directive.

So-called AMI (animal-material interaction) sensors can be used to (semi-)automatically record object manipulation by attaching a motion sensor to hanging objects. Exploratory data are presented to, directly and indirectly, record enrichment value. AMI-sensors may provide objective, flexible and feasible registration tools of enrichment value, but their application is still rather demanding.

That the enrichment value of short metal chains can be improved upon, e.g. by providing branched chains. Essentially, this entails making chains longer, preferably reaching until the floor, and making them more readily available in a pig pen. To facilitate the process towards proper enrichment the principle of intelligent natural design (IND) is proposed. IND entails organising a repeated selection process of the (currently) best-available enrichment material so as to gradually reduce pig boredom and enhance the opportunities for the rearing of pigs with intact tails. IND should start with basically all pig farmers implementing promising enrichment like the branched-chain design on their farms as soon as possible, followed by conducting small-scale on-farm experiments to compare and improve enrichment through sharing of available knowledge. Suggestions are given as to how and why this novel approach can be implemented to solve persistent animal-welfare problems like providing proper enrichment for intensively-farmed pigs.

Related posts:

Chains as enrichment for pigs (Book chapter with supplement)
Ketting als hokverrijking voor varkens (incl. link naar het supplement)
Pig animation – Improved, branched chain design as proper enrichment for pigs
Branched chains as enrichment for pigs (technical description, pictures and video)
Proper enrichment for intensively-farmed pigs – From review to preview
A collection of pictures of other enrichment materials for pigs can be found here: Prize contest (Prijsvraag) 2011.
Do pigs play with chains? Science versus society

The video below shows the value of a branched chain provided in the outdoor run of organic pigs. This prototype branched was called ‘enriched chain’ because it was having various branches and reaching till the floor. The prototype was not yet made of stainless steel anchor chain links, but of relatively large c-chain links (2.5 cm wide, 5.5 cm long). It also shows that pigs show signs of frustration when trying to manipulate the hockey-type ball hanging on a short chain.

AMI-sensors, Farewelldock and the future of pig farming

This is a brief note on the use of AMI-sensors and the future of pig farming from the NL partner (MB) in the FareWellDock project.

The future of pig farming

The world is rapidly changing it seems, in major respects. A major energy transition is taking place reducing the dependence on fossil fuels. Agriculture must become more circular to reduce its impact on global warming. Another major transition that is taking place is the increasing role of information technology. Smart farming may soon become reality.  At the same time farm-animal welfare is an increasingly-recognised societal concern.  Since I have been working as an scientist on the interface between information-technology and pig welfare for some time now, I thought it could be interesting to share some thoughts on what the future of pig farming might look like.

AMI sensors

My most recent work related to smart farming, at least to some extent, was on AMI sensors of pig enrichment. AMI stands for animal material interactions. AMI sensors can take various shapes and forms. In some way or other AMI sensors record the amount of interaction pigs have with enrichment materials for pigs. Mostly this concerns hanging toys like chains and ropes with or without suspended materials like pieces of wood. So far the use of AMI sensors is (mainly) restricted to applications for scientific purposes, e.g. to measure the value of (different aspects of) enrichment materials (directly or indirectly), the effect of tail-biting ointments, and abnormal and/or sickness behaviour. Using AMI sensors it was possible to acquire new knowledge about enrichment. For example it was confirmed more objectively that destructibility is important for pigs. And we found that repellents may have some effect in reducing tail biting, and that pigs in tail biting pens seem to be more eager to interact with enrichment than pigs in control pens. (You can find my publication list of AMI sensors and abstracts here.) However, AMI sensors are not ready to be implemented for on-farm use, as their application generates difficulties partly because pig pens constitute a rather challenging environment for electronics but also in relation to how to properly interpret what is being recorded.

Decision support system

In 1996 I started my PhD research. I examined ways in which information technology could be used to assess animal welfare. I developed a methodology, called semantic modelling of animal welfare to derive welfare scores based on scientific knowledge. I implemented these principles to assess the welfare state of pregnant sows by developing a decision support system to assess sow welfare (the SOWEL model). A lesson regarding the future of pig farming from my PhD research may be that farmers shouldn’t be expecting that information technology and smart farming is going to make their life a lot simpler. The implementation of smart farming won’t be comparable to farmers buying a sat nav device for their farms, allowing them to forget all about road maps.

AMI sensors are not like sat nav

Tail biting and FareWellDock

As the name suggests the FareWellDock project was an international research project aimed to reduce routine tail docking of pigs in the EU. EU legislation has banned tail docking for many years now and it is most likely that future pig farming will require raising pigs with intact tails without much tail biting. This is going to be a major challenge for conventional pig farming. Countries like Denmark, the UK, Germany and the Netherlands are in various stages on the road towards this goal. Some countries like Finland and Sweden may even be said to have arrived at their final destination in this respect. Even in these countries, however, there is a continuing need to reduce tail biting and improve pig enrichment, a major risk factor for tail biting.

From my work on tail biting two major suggestions regarding the future can be made. One recommendation extends the previous one, that farming isn’t going to be simple. Tail biting is a multifactorial problem, i.e. many stressors related to enrichment, climate, feed and social conditions, may contribute to it. Underlying most of these risk factors, however, are decisions made by the farmer him/herself. In line with this I have previously suggested that perhaps the pig farmer may well be the most important risk factor for tail biting. Farmers do not always appreciate this.

The other suggestion concerns the conventional view that scientists should first solve a problem before farmers should implement it. This may have worked well with problems in the past, but it may not work for the remaining, more persistent problems like improving enrichment and raising pigs with intact tails. It is more likely that pig farmers will have to take the initiative and perhaps even start to do some collaborative ‘research’ themselves (for more details on this idea, which I have labelled ‘intelligent natural design’ see Bracke, 2010, Bracke et al., 2011, Bracke, 2016 and esp. Bracke, In press (forthcoming in june 2017)).