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.
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.
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
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.
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 https://www.mdpi.com/2076-2615/9/10/812
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 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.
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
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
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.
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The influence of time-unpredictable
and uncontrollable draught (forced cold air) on the behaviour of pigs
was observed in a climate-controlled pig house with two identical rooms
each with five pens. Two days after farrowing, pigs were matched
pairwise to correct for genetic, weight and sex differences, and weaned
at an average age of 35 days. From then on, the pigs in the experimental
room were submitted to draught in a time-unpredictable way. Days with
time-unpredictable draught were followed by days without draught.
studies started on Day 35 and ended on Day 75 of the experiment. The
total activity of the pigs was higher during draught (P<0.005).
Explorative behaviour was four times higher during draught periods than
during non-draught periods. Redirected explorative behaviour on
penmates, including earbiting, occurred more during draught periods (P<0.05). Agonistic behaviour increased strongly during draught periods (P<0.005); headknocks with biting as an excessive form of aggression occurred only during these periods.
Even in periods without draught, pigs in the experimental room had a sternum: recumbent lying ratio which was higher that that of pigs in the control room and lay in contact with penmates more than did pigs in the control room. Unpredictable and uncontrollable draught as a climatic stressor had enormous effects on the behaviour of pigs; redirected explorative behaviour on penmates and excessive aggression could be detrimental for health and the performance of pigs.
EC Directive 2001/93 requires that all pigs have access to proper investigation and manipulation materials. Intensively farmed pigs in Europe are frequently provided with a short/bare metal chain with or without an indestructible object attached to the chain. To date authorities are regarding this as proper enrichment. However, it has become increasingly clear that the chains do not provide proper enrichment, and that adding an indestructible object such as a ball, pipe or hard wood to the end of the chain may even reduce pig welfare. To test this hypothesis an expert survey was conducted. In total 36 international experts, mostly pig-welfare scientists, responded to the survey.
The experts only marginally agreed with the hypothesis (agreement
score 4.6 on average on a scale from 0-10). However, indestructible materials
generally received very low scores for welfare, indicating they did not provide
proper enrichment. Ranked from low to high average welfare score, the objects
were grouped in 5 significance levels:
Level 5 (totally insufficient): Chain hanging too high (for most
of the smallest pigs in the pen; average score 1.3 on a scale from 0 to 10
where 5.5 would be ‘acceptable’)
Level 4 (extremely insufficient): Short chain (3.1), Small
ball (2.8) and Big ball (average 2.5)
Level 3: (very insufficient) Pipe (3.5) and Bare chain (3.3)
Level 2-3 (very/rather insufficient): Hard wood (3.7)
Level 2 (rather insufficient): Chain on the floor (average:
Compared to the marginal enrichment provided before the EC Directive 2001/93 was implemented in 2007 (in the Netherlands generally a short/bare chain, scoring 3.1 and 3.3 respectively, i.e. Level 3-4), adding balls or pipe , as commonly done in The Netherlands and Germany, does not improve pig welfare. Hard wood, as practised esp. in the UK, is a most marginal improvement (only 0.4 higher on average than Bare chain). Chain on the floor scored a bit better (4.4), without being acceptable (set at 5.5). The ‘new’ Branched chains scored significantly better than all other indestructible materials and its welfare score (5.1 on average) was close to the pre-defined level of acceptability (5.5 on a scale from 0, worst, to 10, best). The welfare benefits of adding balls, pipes or hard wood to the metal chain were marginal, and well below what the experts considered acceptable enrichment. The branched-chains design, by contrast, appears to be the most viable alternative. It involves providing a longer chain, i.e. with the free end reaching to floor level, adding ‘branches’, i.e. several short chains ending at the nose height of the pigs, and providing more chains per pen (i.e. 1 branched chain per 5 pigs). Therefore, the implementation of current pig-enrichment legislation needs revision. Branched chains should be implemented widely (across the globe) and in the short term as a first step towards, and benchmark for, providing proper enrichment to intensively-farmed pigs.
See also the related publication and posts on this website:
Directive 2001/93 requires that all pigs have access to proper investigation
and manipulation materials. Intensively farmed pigs in Europe are frequently
provided with a short metal chain with or without an indestructible object
attached to the chain. To date authorities are regarding this as proper
enrichment, perhaps with (in)direct reference to the RICHPIG model as a
justification. However, it has become increasingly clear that the chains do not
provide proper enrichment, and that adding an indestructible object to the end
of the chain may even reduce rather than improve pig welfare. To test this
hypothesis an expert survey was conducted containing 26 more or less compound
questions. On a scale from 0 to 10 experts specified their level of agreement
with the hypothesis, the prevalence and welfare scores of nine indestructible enrichment
materials. In total 36 experts, mostly pig-welfare scientists, responded
(response rate: 39%). Indestructible objects are less prevalent in countries
that provide straw (like Sweden and the UK) and outside the EU (US). They are
more prevalent in the Netherlands, Belgium, France and Finland, while the
prevalence seems to be low in Spain. Balls, wood and pipes were provided most
frequently: hard wood especially in the UK (as specified in farm assurance); indestructible
balls and pipes in Germany and the Netherlands. The experts’ score for
agreement with the hypothesis was only 4.6 on average (scale 0-10; n=25). Enrichment
materials, ranked from high to low welfare score, were grouped in 5
significance levels as indicated by different superscripts based on Wilcoxon
signed rank tests: Branched chains (5.1a), Chain on the floor (4.4b),
Hard wood (3.7bc), Pipe (3.5c), Bare chain (3.3c),
Short chain (3.1d), Small ball (2.8d), Big ball (2.5d),
and Chain hanging too high (1.3e). Branched chains scored
significantly better than all other indestructible materials and its welfare
score (5.1 on average) was close to the pre-defined level of acceptability (5.5
on a scale from 0, worst, to 10, best). The welfare benefits of adding balls,
pipes or hard wood to the metal chain were marginal, and well below what the
experts considered acceptable enrichment. The branched-chains design, by
contrast, appears to be the most viable alternative. It involves providing a
longer chain, i.e. with the free end reaching to floor level, adding
‘branches’, i.e. several short chains ending at the nose height of the pigs,
and providing more chains per pen (i.e. 1 branched chain per 5 pigs). Branched
chains should be implemented widely and in the short term as a first step
towards, and benchmark for, providing proper enrichment to intensively-farmed pigs.
This post was published originally on the personal website of the first author (see here).