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.


• 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.


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.

Tail biting causes acute phase response and inflammation in pig tails

Tail biting induces a strong acute phase response and tail-end inflammation in finishing pigs. By Heinonen M, Orro T, Kokkonen T, Munsterhjelm C, Peltoniemi O, Valros A., 2010. Vet J. 184:303-7.


The extent of inflammation associated with tail biting in finishing pigs was evaluated. Tail histopathology, carcass condemnation and the concentration of three acute phase proteins (APPs), C-reactive protein (CRP), serum amyloid-A (SAA) and haptoglobin (Hp), were examined in 12 tail-bitten and 13 control pigs. The median concentrations of APPs were higher (P<0.01) in bitten (CRP 617.5mg/L, range 80.5-969.9; SAA 128.0mg/L, 6.2-774.4; Hp 2.8g/L, 1.6-3.5) than in control pigs (CRP 65.7mg/L, 28.4-180.4; SAA 6.2mg/L, 6.2-21.4; Hp 1.2g/L, 0.9-1.5). There was a tendency for APP concentrations to rise with the histopathological score but the differences were only statistically significant between some of the scores. Five (42%) bitten cases and one (8%) control pig had partial carcass condemnations owing to abscesses (P=0.07). The results show that tail biting induces an inflammatory response in the tail end leading to an acute phase response and formation of carcass abscesses.

Simple enrichment block may improve pig welfare

Enrichment in the Sucker and Weaner Phase Altered the Performance of Pigs in Three Behavioural Tests. By Cameron Ralph, Michelle Hebart and Greg M. Croninm 2018. Animals 8: 74.


We tested the hypothesis that provision of enrichment in the form of enrichment blocks during the sucker and weaner phases would affect the behaviour of pigs. We measured the performance of pigs in an open field/novel object test, a maze test, an executive function test and the cortisol response of the pigs after exposure to an open field test. The provision of enrichment blocks altered the behaviour of the pigs in all three tests and these changes suggest an increased willingness to explore and possibly an increased ability to learn. The behavioural tests highlighted that young pigs have the capacity to learn complex tasks. Our findings support the notion that the benefits of enrichment cannot be evaluated by measuring the interactions the animal has with the enrichments in the home pen and it may simply be beneficial to live in a more complex environment. We have highlighted that the early rearing environment is important and that the management and husbandry at an early age can have long-term implications for pigs. The enrichment we used in this study was very simple, an enrichment block, and we provide evidence suggesting the provision of enrichment effected pig behavioural responses. Even the simplest of enrichments may have benefits for the welfare and development of young pigs and there is merit in developing enrichment devices that are suitable for use in pig production.

Toys and tail docking may reduce stress from mixing of pigs after weaning

Teeth clipping, tail docking and toy enrichment affect physiological indicators, behaviour and lesions of weaned pigs after re-location and mixing. By Fu, Lingling, Zhou, Bo, Li, Huizhi, Allan P. Schinckel, Liang, Tingting, Chu, Qingpo, Li, Yuan, Xu, Feilong, 2018. Livestock Science 212: 137-142.


• Re-location and mixing after weaning brought stress to weaned pigs.

• Toy enrichment decreased the stress of mixing after weaning.

• Pigs with intact teeth and tail got more lesions after mixing.

• Weaner pigs with intact teeth and tail should avoid to be mixed after weaning.

Abstract Re-location and mixing after weaning increase the risk of aggression in weaned pigs. To quantify the effects of tail docking, teeth clipping and toy enrichment on the growth performances, behaviour, lesions, and physiological indicators of weaned pigs after re-location and mixing, a total of 262 weaned pigs from four pig processing treatments were selected and regrouped to two enrichment treatments within each processing treatment. The experimental newborn piglets from 24 litters were treated tail docking and teeth clipping at 3 d of age and weaned at 24 d of age. At 30 d of age, pigs in each treatment were weighed, re-located to a nursery room and mixed into 2 pens. Eight rubber toys were installed in one of two pens in each group. The behaviour of weaned pigs was recorded and observed at 1, 2 and 3 d after mixing. At 3 and 6 d before mixing and 1, 3 and 6 d after mixing, lesions on the body and tail, body surface temperature (BST), respiration rate (RR) and salivary cortisol concentrations were determined. At 85 d of age, all experimental pigs were weighed again. Mortality rate, average daily gain (ADG), and feed efficiency of pigs were recorded. Pigs with clipped teeth performed less negative social behaviour (aggressive attacks/fight) (P < 0.05) and more positive social behaviour (non-aggressive social interactions) (P < 0.01) than pigs with intact teeth. Pigs with docked tails performed more positive social behaviour (P < 0.01) than pigs with intact tails. Toy enrichment decreased (P < 0.05) lesions on the ear and front body of pigs, and pigs with docked tail got fewer lesions on the tail (P < 0.01). Intact teeth increased (P < 0.01) RR, while toy enrichment decreased (P < 0.05) RR of pigs. Teeth clipping, tail docking and toys had no effects (P > 0.05) on ADG, body weight and mortality rate of pigs from 30 to 85 d of age. These results indicate that toy enrichment and pig processing treatments have positive effects on weaned pigs after re-location and mixing.

Providing enrichment to alleviate pain due to castration and tail docking in pigs

Evaluating environmental enrichment as a method to alleviate pain after castration and tail docking in pigs. By Brittany L. Backus, John J. McGlone, 2018. Applied Animal Behaviour Science 204: 37-42.


• Enrichment did not mitigate pain associated with management procedures.

• Enrichment had a positive effect on growth, activity and immunity.

• Enrichment improved pig welfare even if it did not mitigate piglet processing pain.

Abstract Castration and tail docking are common management practices performed on commercial swine farms in the US and around the world to reduce adverse behaviors and the occurrence of boar taint. However, these practices themselves are a welfare concern for the piglet because they cause acute pain. The provisions of environmental enrichment (EE) may reduce anxiety, protect from stressors, influence pain sensitivity, and improve the overall welfare of animals. Our objective was to determine if EE can reduce the physiological and behavioral stress response caused by castration and tail docking in piglets over time. Sows were randomly assigned to control farrowing stalls (CON; n = 9) or stalls enriched (ENRICH; n = 9) with newspaper, soil, ball and rope, so that EE was available to piglets upon birth. At 5 days old, ENRICH and CON piglets (n = 54 per treatment) were allocated to one of six piglet husbandry treatments; four boar piglets were randomly allocated to one of four treatments: 1) control handled (SHAM B), 2) tail docked (TAIL B), 3) castrated (CAST), or 4) castrated and tail docked (BOTH); and two gilt piglets were randomly allocated to one of two treatments: 5) control handled (SHAM G), or 6) tail docked (TAIL G). Live weight tended (P < 0.10) to be greater in all ENRICH pigs. Leukocytes and the neutrophil to lymphocyte ratio were decreased (P < 0.05) among ENRICH compared with CON piglets. ENRICH piglets were more active (P < 0.05) than CON piglets. Maintenance and play behaviors decreased (P < 0.05) 120 min after, but returned to baseline at 24 h. Cortisol was greater (P < 0.05) among CAST and BOTH piglets, but no differences were observed in cortisol concentrations between housing groups. Stress vocalizations were greater (P < 0.05) in CAST and BOTH compared with SHAM piglets, while all pig processing treatments displayed more (P < 0.05) pain behaviors than SHAM. The use of EE had no effect on reducing pain-induced stress of castration and tail docking. However, we found that pigs raised with EE were heavier and more active than pigs raised without enrichment. We also found that EE modulated the immune response in pigs. In conclusion, EE improved the overall welfare of pigs at an early age.

Risk factors for tail lesions in weaner pigs

Factors influencing the risk for tail lesions in weaner pigs (Sus scrofa). by Angelika Grümpel, Joachim Krieter, Christina Veit, Sabine Dippel, 2018. Livestock science 216: 219-226.


We identified five factors influencing the risk for tail lesions in weaner pigs.•

We can recommend regression tree analysis for describing tail lesion risk factors.•

Data interpretation should include information on correlations between variables.


Tail biting is a behavioural disorder in pigs which results in tail lesions. Many factors must be considered to reduce the risk for tail biting due to the multifactorial character of this behaviour. We developed a software-based tail biting management tool called “SchwIP” for analysing farm individual risk factors for tail biting in weaner pigs. SchwIP was applied on 25 conventional farms throughout Germany who kept weaner pigs in closed barns (median 1,800 weaning places). The farms were visited up to three times between August 2016 and November 2017 and a total of 368 pens were assessed. Data regarding enrichment, pen environment, feed, water, climate, health, farm management, transport and regrouping were analysed with regression tree analysis (RT) using pen level prevalence of tail lesions (%) as the outcome variable. There were five primary influencing factors for tail lesions: docking status, stocking density, daily weight gain, suckling piglet losses and number of litters mixed during weaning. The correlation between observed and predicted prevalence of tail lesions across all pens was 0.6. Most of the factors may represent combinations of influences on a farm which agree with the multifactorial nature of the problem. Even though weight gain may also be influenced by tail biting behaviour and thus be a parallel outcome, it could be used by farmers as an indicator for initiating closer examination and intervention. The use of RT for visualising complex risk factor analyses is recommendable, though their analytical suitability for clustered data should further be evaluated.

Early indicators of tail biting in pigs

Early indicators of tail biting outbreaks in pigs. By Maya Wedin, Emma M. Baxter, Mhairi Jack, Agnieszka Futro, Richard B. D’Eath.
Applied Animal Behaviour Science: 208: 7-12


Tail biting in pigs is unpredictable so early indicators could help farmers.•

Behaviour of tail biting vs no tail biting groups observed for 1 week pre-outbreak.•

Outbreak groups had fewer curly tails and more tucked tails.•

Activity pre-outbreak was no different in outbreak groups.•

Day and time of day had little or no effect on these findings.


Tail biting outbreaks in pig farming cause suffering through pain and stress, and producers lose revenue due to carcass condemnation. Reliable behavioural indications of when an outbreak is imminent would provide farmers with tools for mitigating the outbreak in advance. This study investigated changes in body and tail posture in the 7 days pre-outbreak.

Pigs in 15 groups with a mean (±s.d.) group size of 27.5 (±2.6; 427 in total) were raised from birth under intensive commercial conditions and with tails intact. Twice daily inspections were made, and a tail biting outbreak was identified (and treated) if 3 or more pigs had fresh tail injuries, or any pig was seen with a freshly bleeding tail or vigorously biting a tail. Video footage was recorded continuously to allow pre-outbreak behaviour recording of body posture (lying laterally, lying ventrally, sitting, standing) and tail posture (curled or uncurled (high, low, tucked)). Pigs were not individually marked, thus observations were made at pen level by group scan sampling 12 times per day on day -1, -3, -5 and -7 pre-outbreak. Each outbreak group was paired with a non-outbreak group of the same age and kept at the facility at the same time which served as a control. A total of 12 pairs were used. Outbreak pigs had fewer curled tails (P = 0.013) and more uncurled (P = 0.008) and tucked tails (P < 0.001) than control pigs overall, but particularly on day -1. Outbreak groups had more tucked tails compared to control on day -7 (P = 0.001). Tail posture did not vary over days, or with time of day. Body posture was not different between outbreak and control groups, and although it was affected by time of day, there was no interaction between outbreak vs. control condition and day, or time of day. Synchrony of behaviour between pigs (more pigs in the pen showing the same body posture) was not reduced in outbreak groups. In conclusion, this study supports other recent findings showing that an increase in tucked tails, and reduced curled tails is an advance indicator of a tail biting outbreak giving at least 7 days warning, and it does not matter what time of day tails are observed. Pig farmers could take note of tail posture changes to identify high risk pens. Considerable variability between pens, and in the timing and magnitude of change means that technology to automate tail posture detection will be of benefit.

Effect of straw on behaviour, lesions and pen hygiene in undocked pigs

Implication and impact of straw provision on behaviour, lesions and pen hygiene on commercial farms rearing undocked pigs. By Torun Wallgren, Anne Larsen, Nils Lundeheim, Rebecka Westin, Stefan Gunnarsson, 2018. Appl. Anim. Behav. Sci. In press.


Pigs that received more straw had more straw directed behaviour.•

Pigs that received more straw showed less pen directed behaviour.•

Increased straw ration decreased the amount of damaged tails in finishing pigs.•

Increased straw provision did not affect pen hygiene.


According to the European Union Council Directive 2008/120EC, measures to minimise the risk for tail biting shall be taken before practicing tail docking, e.g. provision of manipulable material. Still,>90% of the pigs within EU are tail docked. Thus, management routines for providing manipulable material in commercial pig production are needed. The aim of this study was to investigate how an increase from normal straw ration influence pig behaviour, occurrence of tail- and ear lesions and impact on pen hygiene.
The experiment was conducted on five Swedish commercial farms; one grower and four farrow-to-finish farms. One batch per farm was studied, following pigs throughout the grower or finishing pig period. Both age groups were examined in two of the farrow-to-finish farms and only finishers in the other two, studying three grower and four finisher batches in total. The pens in a batch were divided into Control (C) and Extra Straw (ES). Pens in C were provided with the farm normal daily straw ratio, while pigs in ES got a doubled C-ration. The pigs in eight focus pens per Treatment were scored for lesions on ears and tails every two weeks. In connection with lesion scoring, behaviour observation was conducted in active pigs during one hour (4 min scan sampling) in the focus pens. All pigs in the batch were examined for tail- and ear lesions during the first and last week of the experiment.
Both growers and finishers spent most of their active time manipulating straw. ES-pigs showed more straw-directed and less pen-directed behaviour in both age groups compared to C-pigs. Behaviour was also affected by farm and age revealing that the impact of an increased straw ration differed between farms and pig age. The increased straw ration did not affect the pen cleanliness, showing that it was practically feasible to increase the straw rations on all participating farms.
The prevalence of tail damages increased with age, and more severe damages was found in C compared to ES. Severe tail and ear lesions were found in ~0.6 and 0.07% of the growers and ~2.2 and 0.75% of the finishers, C- and ES pigs respectively. Approximately 50% of the finishing pigs had tail damages at the end of the study, but the majority of lesions were less than 5 mm long and might not have been detected without close clinical examination.

Optical flow to monitor tail biting outbreaks in pigs.

Utilization of optical flow to monitor development of tail biting outbreaks in pigs. By Y Li, H Zhang, L Johnston, M Dawkins, 2018. Journal of Animal Science 96: 519.


This study was conducted to evaluate activity changes in pigs associated with outbreaks of tail biting using an optical flow platform. Pigs (n=240, 24.9 ± 2.9 kg, 9-wk old) were housed in 8 pens of 30 pigs on slatted floors for 16 weeks. Four pens housed pigs with tails docked and the other 4 pens housed pigs with tails intact. Pigs were assessed for tail scores (0=no injury to 4=severe injury) once weekly. Behaviors of pigs were video-recorded twice weekly. One-hour video segments during morning, noon, and afternoon of each recording day were analyzed for optical flow using the OPTICFLOCK platform which measures movements of pigs in each pen. The same video segments were scanned at 5-min intervals to estimate time budget for standing/walking, lying, eating, drinking, and tail biting. Compared with docked pigs, intact pigs had higher tail scores (0.5 ± 0.29 vs. 0.1 ± 0.01; P < 0.001) and higher optical flow (8.2 vs. 6.9; SE=0.42; P < 0.05), suggesting more tail injuries and higher activity levels. Intact pigs spent less time lying (P < 0.001) and more time eating (P < 0.01) and tail biting (P < 0.01), and tended to spend more time standing/walking (P=0.08) than docked pigs, which support the optical flow data. During outbreaks of tail biting, intact pigs had higher optical flow during the first outbreak (14.59, SE=0.73; P < 0.05) compared to before (5.44) and after (10.54) the outbreak, suggesting activity changes during the development of tail biting outbreaks. Across tail docking treatments and observation days, pigs had lower optical flow at noon (6.9, SE=0.33; P < 0.001) compared to morning (7.8) and afternoon (7.9), suggesting that pigs were less active at noon which was supported by the behavioral time budgets. These results suggest that optical flow might be a promising tool for monitoring activity changes in pigs during the development of tail biting.