Category Archives: Pigs

Did European pig-welfare legislation reduce pig welfare? Perhaps not, but experts confirm that common indestructible materials are not proper enrichment for pigs at all, except perhaps for an enhanced novel branched-chains design.

Published as:
Marc B.M. Bracke and Paul Koene, 2019. Expert opinion on metal chains and other indestructible objects as proper enrichment for intensively-farmed pigs. PLOS ONE. Available at http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0212610.

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: 4.4)

Level 1 (almost sufficient): Branched chains (5.1)

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:

Chains as enrichment for pigs (Book chapter with 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

Original abstract of the PLOS ONE paper:

Marc B.M. Bracke and Paul Koene, 2019. Expert opinion on metal chains and other indestructible objects as proper enrichment for intensively-farmed pigs. PLOS ONE. Available at http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0212610.

Abstract

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 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.


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.
Two pigs playing simultaneously with a preferred anchor-type branched chain design.

This post was published originally on the personal website of the first author (see here).

Dealing with tail biting in pigs with intact tails

PigProgress – Early indicators for tail biting in pigs Should pigs in the EU keep the end of their tails, or should tails be docked in the 1st days of the pigs’ lives to reduce risk of tail biting? The subject is widely discussed which also underlines that there is no easy answer. However, there is work in progress and so are some very promising results, writes pig welfare expert Vivi Aarestrup Moustsen. Read more in Pig Progress

Providing enrichment materials enhances play in sows around regrouping

Provision Point-Source Materials Stimulates Play in Sows but Does Not Affect Aggression at Regrouping

By Emma Catharine Greenwood, William H. E. J. Van Wettere, Jessica Rayner, Paul E. Hughes and Kate J. Plush, 2019. Animals 2019, 9(1), 8;

Abstract

When sows are mixed into groups, hierarchies form and resulting aggression and stress can affect production and welfare. This study determined the effect of providing point-source materials on aggressive and play behaviors in gestating sows. Large white cross Landrace sows were mixed after insemination; six pens of 12 sows were housed in ‘standard’ pens, and six pens of 12 sows were housed in ‘enhanced’ pens. The ‘enhanced’ pens each contained two rubber mats, eight strands of 24 mm-thick sisal rope and two yellow plastic disks, suspended from the roof. The sows remained in these pens until pregnancy confirmation. Salivary cortisol concentration, injury counts, and sow behaviors were recorded the day before mixing (day 1), mixing (day 0) and post-mixing day 1, day 4, day 7 and day 20. At farrowing, reproductive outcomes were obtained. Play was observed (including locomotor and object play) in the ‘enhanced’ pen, and percentage of time spent playing was greater on d4 (1.48 ± 0.3 Square root transformed data (2.84% non-transformed adjusted mean)), d7 (1.43 ± 0.3 (2.97%)) and d20 (1.64 ± 0.3 (3.84%)), compared to d0 (0.56 ± 0.3 (0.70%)) and d1 (0.87 ± 0.3 (1.67%) (p < 0.05)). No play was observed in standard housing. Aggression, salivary free cortisol concentrations and injuries were unaffected (p > 0.05). The provision of materials had no impact on aggression, although their presence maintained sow interest and play behavior, suggesting a positive effect.

Tail posture as an indicator of tail biting in undocked pigs

Tail posture as an indicator of tail biting in undocked finishing pigs

By Torun Wallgren, Anne Larsen and Stefan Gunnarsson, 2019. Animals 210: 26-37. Special Issue Environmental Enrichment of Pigs.

Simple Summary

Tail biting is a large welfare problem in modern pig production, causing pain and reduced health and production. The identification of tail biting is important for minimising the risk of the escalation of the behaviour and its consequences. Tail posture (i.e., tail hanging or curled) has been suggested to depend on the presence of tail wounds and, therefore, has been suggested as an indicator of tail biting. This study investigated the relationship between tail position and tail damages at feeding, since that could be a feasible time for producers to detect tail posture. The experiment showed that 94% of the pigs had curly tails and that pigs with wounds were more likely to have hanging tails than pigs with nondamaged tails. By observing the tail position at feeding, we were able to identify pigs with tail wounds in 68% of cases simply by scoring pigs with hanging tails. To conclude, the scoring of pigs with hanging tails at feeding was found to be a useful tool for identifying tail damages, which may otherwise be difficult to detect by the caretaker.

Abstract

Tail posture (i.e., hanging or curled) has been suggested to be an indicator of tail biting, and hanging tails predisposed to damage. The aim of this study was to investigate if tail posture was feasible as a tail damage indicator in a commercial setting. The study was carried out on one batch of 459 undocked finishing pigs (30–120 kg in weight). Weekly scoring of tail posture was combined with the scoring of tail lesions. Tail posture was observed at feeding to facilitate the usage of the method in commercial settings. A curly tail was observed in 94% of the observations. Pigs with tails scored with “wound” were 4.15 (p < 0.0001) times more likely to have hanging tails, and pigs scored with “inflamed wounds” were 14.24 (p < 0.0001) times more likely to have hanging tails, compared to pigs with nondamaged tails. Tail posture correctly classified tails with “wound” or “inflamed wound” 67.5% of the time, with 55.2% sensitivity and 79.7% specificity, respectively. The method of observing the tail position at feeding seems useful as a complement to normal inspection for detecting tail biting before tail wounds are visible to the caretaker.

How to control injurious tail biting without tail docking of pigs

Injurious tail biting in pigs: How can it be controlled in existing systems without tail docking. By D’Eath RB, Arnott G, Turner SP, Jensen T, Lahrmann HP, Busch ME, Niemi JK, Lawrence AB, Sandøe P, 2014. Animal 8:1479-97.

Abstract Tail biting is a serious animal welfare and economic problem in pig production. Tail docking, which reduces but does not eliminate tail biting, remains widespread. However, in the EU tail docking may not be used routinely, and some ‘alternative’ forms of pig production and certain countries do not allow tail docking at all. Against this background, using a novel approach focusing on research where tail injuries were quantified, we review the measures that can be used to control tail biting in pigs without tail docking. Using this strict criterion, there was good evidence that manipulable substrates and feeder space affect damaging tail biting. Only epidemiological evidence was available for effects of temperature and season, and the effect of stocking density was unclear. Studies suggest that group size has little effect, and the effects of nutrition, disease and breed require further investigation. The review identifies a number of knowledge gaps and promising avenues for future research into prevention and mitigation. We illustrate the diversity of hypotheses concerning how different proposed risk factors might increase tail biting through their effect on each other or on the proposed underlying processes of tail biting. A quantitative comparison of the efficacy of different methods of provision of manipulable materials, and a review of current practices in countries and assurance schemes where tail docking is banned, both suggest that daily provision of small quantities of destructible, manipulable natural materials can be of considerable benefit. Further comparative research is needed into materials, such as ropes, which are compatible with slatted floors. Also, materials which double as fuel for anaerobic digesters could be utilised. As well as optimising housing and management to reduce risk, it is important to detect and treat tail biting as soon as it occurs. Early warning signs before the first bloody tails appear, such as pigs holding their tails tucked under, could in future be automatically detected using precision livestock farming methods enabling earlier reaction and prevention of tail damage. However, there is a lack of scientific studies on how best to respond to outbreaks: the effectiveness of, for example, removing biters and/or bitten pigs, increasing enrichment, or applying substances to tails should be investigated. Finally, some breeding companies are exploring options for reducing the genetic propensity to tail bite. If these various approaches to reduce tail biting are implemented we propose that the need for tail docking will be reduced.

Prenatal stress and enrichment affect piglet behaviour

Impact of prenatal stress and environmental enrichment prior to weaning on activity and social behaviour of piglets (Sus scrofa). By Sophie Brajon, Nadine Ringgenberg, Stephanie Torrey, Renée Bergeron, Nicolas Devillers, 2017. Applied Animal Behaviour Science 197: 15-23.

Highlights

• Prenatal stress (PNS) can have detrimental effects on piglets behaviour and welfare.

• Pre-weaning enrichment may compensate negative effects of PNS in piglets.

• PNS effects were delayed after weaning at d 27 as shown by an increased inactivity.

• Enrichment had positive effects but its removal at weaning affected behaviour.

• Pre-weaning enrichment did not compensate for the effects of PNS.

Abstract

Prenatal stress (PNS) can have detrimental effects on behaviour and welfare, such as decreased exploration. Whether housing enrichment before weaning compensate negative effect of PNS in commercial pigs is unknown. To address this question, 44 sows were assigned to either a mixing stress (T) or a control (C) treatment in mid-gestation. During lactation, half of the T and C sows were housed with their 12-piglets litter in straw enriched pens (E) while the others were housed in standard farrowing crates (S). At weaning, 6 piglets per litter were selected and moved to non-enriched standard pens. Lying down, exploration and social behaviour were recorded in the home-pen before weaning (d 6, d 12, d 20), on the day of weaning (d 21), and after weaning (d 22, d 27) using scan and one-zero samplings. Three piglets per litter were individually subjected to a social isolation test and a social confrontation test at d 17. Data were analysed by day using mixed models with PNS, housing enrichment and their interaction as fixed effects. We found no interaction between the treatments, suggesting the absence of a compensatory effect of enrichment on PNS. Pre-weaning enrichment promoted exploration (P< 0.004) and seemed to improve comfort, as piglets spent more time lying down (P< 0.02), but was associated with reduced locomotion and play fighting (P< 0.03) compared to no enrichment. After weaning, E piglets explored less (P< 0.01) and played less (locomotion and fighting play: P< 0.0003) than S piglets. They also performed more belly-nosing at d 27 (P =0.04). These results support the idea that the removal of enrichment at weaning negatively affects piglets. The E piglets exhibited higher emotional reactivity than S piglets (i.e. more high-pitched calls and escape attempts) during the social isolation test, but no clear effect was observed during the confrontation test. The effects of prenatal stress on behaviour were only apparent after weaning. On d 27, T piglets spent more time lying (P =0.02), and showed reduced exploration (P =0.004), locomotion play (P=0.03), fighting play (P=0.04) and mounting behaviour (P =0.002) than C piglets. In conclusion, both prenatal stress and pre-weaning enrichment affected piglet behaviour, but a compensatory effect of enrichment on the negative effects of prenatal stress could not be demonstrated.

Tail posture predicts tail biting outbreaks in pigs

Tail posture predicts tail biting outbreaks at pen level in weaner pigs. By Helle Pelant Lahrmann, Christian Fink Hansen, Rick D’Eath, Marie Erika Busch, Björn Forkman, 2018. Applied Animal Behaviour Science 200: 29-35.

Highlights

• Changes in tail posture can predict a tail biting outbreak at pen level.

• Percentage of hanging tails in pens close to an outbreak was almost doubled.

• A correlation between number of tail damages and lowered tails were identified.

• No changes in activity was identified prior to a tail biting outbreak.

Abstract

Detecting a tail biting outbreak early is essential to reduce the risk of pigs getting severe tail damage. A few previous studies suggest that tail posture and behavioural differences can predict an upcoming outbreak. The aim of the present study was therefore to investigate if differences in tail posture and behaviour could be detected at pen level between upcoming tail biting pens (T-pens) and control pens (C-pens). The study included 2301 undocked weaner pigs in 74 pens (mean 31.1 pigs/pen; SD 1.5). Tails were scored three times weekly (wound freshness, wound severity and tail length) between 07:00 h–14:00 h from weaning until a tail biting outbreak. An outbreak (day 0) occurred when at least four pigs had a tail damage, regardless of wound freshness. On average 7.6 (SD 4.3) pigs had a damaged tail (scratches + wound) in T-pens on day 0. Tail posture and behaviour (activity, eating, explorative, pen mate and tail directed behaviour) were recorded in T-pens and in matched C-pens using scan sampling every half hour between 0800–1100 h 1700–2000 h on day -3, -2 and -1 prior to the tail biting outbreak in T-pens. Further, to investigate if changes in tail posture could be a measure for use under commercial conditions, tail posture was recorded by direct observation from outside the pen. The live observations were carried out just before tail scoring on each observation day until the outbreak. The video results showed more hanging/tucked tails in T-pens than in C-pens on each recording day (P < 0.001). In T-pens more tails were hanging on day -1 (33.2%) than on day -2 (24.8%) and day -3 (23.1%). Further, the number of tail damaged pigs on day 0 was correlated with tail posture on day -1, with more tails hanging in pens with 6–8 and >8 tail damaged pigs than in pens with 4–5 tail damaged pigs (P < 0.001). Live observations of tail posture in T-pens also showed a higher prevalence of hanging tails on day 0 (30.0%; P < 0.05) than on day -3/-2 (17.2%), -5/-4 (15.4%) and -7/-6 (13.0%). No differences in any of the recorded behaviours were observed between T-pens and C-pens. In conclusion, lowered tails seem to be a promising and practical measure to detect damaging tail biting behaviour on pen level even when using live observations. However, there were no changes in activity, eating, exploration or tail-directed behaviours prior to a tail biting outbreak.

3D cameras can detect lowered tail posture before an outbreak of tail biting in pigs

Automatic early warning of tail biting in pigs: 3D cameras can detect lowered tail posture before an outbreak. By Richard B. D’Eath, Mhairi Jack, Agnieszka Futro, Darren Talbot, Qiming Zhu, David Barclay, Emma M. Baxter. 2018. PlosOne.

Abstract

Tail biting is a major welfare and economic problem for indoor pig producers worldwide. Low tail posture is an early warning sign which could reduce tail biting unpredictability. Taking a precision livestock farming approach, we used Time-of-flight 3D cameras, processing data with machine vision algorithms, to automate the measurement of pig tail posture. Validation of the 3D algorithm found an accuracy of 73.9% at detecting low vs. not low tails (Sensitivity 88.4%, Specificity 66.8%). Twenty-three groups of 29 pigs per group were reared with intact (not docked) tails under typical commercial conditions over 8 batches. 15 groups had tail biting outbreaks, following which enrichment was added to pens and biters and/or victims were removed and treated. 3D data from outbreak groups showed the proportion of low tail detections increased pre-outbreak and declined post-outbreak. Pre-outbreak, the increase in low tails occurred at an increasing rate over time, and the proportion of low tails was higher one week pre-outbreak (-1) than 2 weeks pre-outbreak (-2). Within each batch, an outbreak and a non-outbreak control group were identified. Outbreak groups had more 3D low tail detections in weeks -1, +1 and +2 than their matched controls. Comparing 3D tail posture and tail injury scoring data, a greater proportion of low tails was associated with more injured pigs. Low tails might indicate more than just tail biting as tail posture varied between groups and over time and the proportion of low tails increased when pigs were moved to a new pen. Our findings demonstrate the potential for a 3D machine vision system to automate tail posture detection and provide early warning of tail biting on farm.

Wood is a potentially suitable enrichment material for pigs

Use of different wood types as environmental enrichment to manage tail biting in docked pigs in a commercial fully-slatted system. By Jen-Yun Chou, Rick B. D’Eath, Dale A. Sandercock, Natalie Waran, Amy Haigh, Keelin O’Driscoll. 2018. Livestock Science 213: 19-27.

Highlights

• Spruce was consumed more quickly than other wood types.

• Pigs interacted with spruce more frequently than other wood types.

• No time effect was found on wood use.

• Replacement rate rather than cost may be a practical concern.

Abstract

Provision of adequate environmental enrichment on pig farms is a legal requirement under current EU legislation and also alleviates the risk of tail biting. Wood is an organic alternative where loose bedding, which has been identified as the optimal enrichment, is not possible on fully-slatted floors since it may disrupt the slurry system. The study compared four different wood types (beech (Fagus sylvatica), larch (Larix decidua), spruce (Picea sitchensis), and Scots pine (Pinus sylvestris L.)) as enrichment, taking into account the qualities of the wood, economic considerations, and effectiveness at reducing damaging behaviours and lesions. A total of 800 tail docked finisher pigs on an Irish commercial farm were used. Eight pens were provided with each wood type (25 pigs/pen), and the study was conducted over 2 replicates in time. In each pen a single wooden post was presented to the pigs in a metal dispenser with two lateral chains during the finisher period (12–22 weeks of age). The rate of wear, moisture content, and hardness of the wood along with lesion scorings and behavioural observation on pigs were monitored. Spruce was consumed more quickly than other wood types in terms of weight loss and reduction in length (P < 0.001), resulting in a greater cost per pig. Pigs were observed interacting with the spruce more frequently than the other wood types (P < 0.05). Pigs also interacted with the wood more often than the chains in spruce allocated pens (P < 0.001). Overall the interaction with wood posts did not decline significantly across time. However, there was no difference in the frequency of harmful behaviours (tail/ear/flank-biting) observed between wood types, and also no difference in the effectiveness of the different types of wood in reducing tail or ear damage. There was a positive correlation between ear lesion and tear-staining scores (rp= 0.286, P < 0.01), and between tail lesion and tail posture scores (rp= 0.206, P < 0.05). Wood types did not affect visceral condemnation obtained in the slaughterhouse. Wood is a potentially suitable enrichment material, yet the wood species could influence its attractiveness to pigs.

Enrichment may be joyful and reduce stress in young pigs

Pre-weaning environmental enrichment increases piglets’ object play behaviour on a large scale commercial pig farm. By Chung-Hsuan Yang, Heng-Lun Ko, Laura C. Salazar, Lourdes Llonch, Xavier Manteca, Irene Camerlink, Pol Llonch, 2018. Applied Animal Behaviour Science 202: 7-12 Environmental enrichment is a legal requirement for European pig farms. The suitability of enrichment materials for neonatal pigs is understudied and has not been tested in commercial settings. This study investigates the effect of hanging objects and substrate as two enrichment strategies pre-weaning, and compares the effect of these enrichment objects on play behaviour, aggression, growth and stress coping ability during lactation until 10 days after weaning. Farrowing crates were equipped with either six hanging objects (OB), a substrate box with wood bark (SUB), or nothing (control; CON). The behaviour of over 600 piglets (∼210 piglets/treatment) was recorded weekly by instantaneous scan sampling (10 s/piglet, repeated 6 times per day for 6 days). Aggression was monitored through skin lesions on focal piglets on 1 day before weaning and 1 and 2 days after weaning. Piglets were weighed individually every week. Stress coping ability was assessed through salivary cortisol from a sample of six piglets per litter on 1 day before (baseline), and on days 1 and 2 after weaning. Both enrichment groups showed more object play during lactation as compared to the control group (P < 0.001). The amount of object play increased linearly with age (P < 0.001). Enrichment did not affect social play or locomotor play during lactation. Enrichment did not influence the amount of skin lesions before weaning, but heavier piglets had more skin lesions (P < 0.01). The enrichment strategies had no influence on weight gain at any stage. The baseline of the salivary cortisol concentration was similar amongst the treatment groups; however, the cortisol concentration of the object group and control group was significantly higher at one day after weaning than at baseline (P < 0.001) whereas the substrate group showed no significant increase. In conclusion, providing either hanging objects or substrate alone could encourage neonatal piglets to express more object play behaviour. Compared to the hanging objects, providing substrate in the commercial neonatal environment demonstrated to decrease piglets’ stress at weaning, and therefore increase animal welfare.