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.
Behavioural
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:
4.4)
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:
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.
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).
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
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.
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.
• 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.
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.
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.
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.
• 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.
