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275
© 2014 Universities Federation for Animal Welfare
The Old School, Brewhouse Hill, Wheathampstead,
Hertfordshire AL4 8AN, UK
www.ufaw.org.uk
Animal Welfare 2014, 23: 275-285
ISSN 0962-7286
doi: 10.7120/09627286.23.3.275
Docking the value of pigmeat? Prevalence and financial implications of
welfare lesions in Irish slaughter pigs
S Harley†, LA Boyle‡, NE O’Connell§, SJ More#, DL Teixeira*‡and A Hanlon#
†School of Veterinary Science, University of Liverpool, Neston, Cheshire CH64 7TE, UK
‡Animal & Grassland Research & Innovation Centre, Teagasc Moorepark, Fermoy, Co Cork, Republic of Ireland
§Institute for Global Food Security, Northern Ireland Technology Centre, Queens University Belfast, Malone Road, Belfast BT9 5HN, UK
#UCD School of Veterinary Medicine, University College Dublin, Belfield, Dublin 4, Republic of Ireland
* Contact for correspondence and requests for reprints: dayane.teixeira@teagasc.ie
Abstract
Expansion of the meat inspection process to incorporate animal-based welfare measurements could contribute towards significant
improvements in pig (Sus scrofa domesticus) welfare and farm profitability. This study aimed to determine the prevalence of different
welfare-related lesions on the carcase and their relationship with carcase condemnations (CC) and carcase weight (CW). The financial
implications of losses associated with CC and CW reductions related to the welfare lesions were also estimated. Data on tail lesions,
loin bruising and bursitis, CW and condemnation/trimming outcome (and associated weights) were collected for 3,537 slaughter pigs
(mean [±SEM] carcase weight: 79.2 [± 8.82]kg). Overall, 72.5% of pigs had detectable tail lesions, whilst 16.0and 44.0% were
affected by severe loin bruising and hind limb bursitis, respectively. There were 2.5% of study carcases condemned and a further 3.3%
were trimmed. The primary cause of CC was abscessation. While tail lesion severity did not increase the risk of abscessation, it was
significantly associated with CC. Male pigs had a higher risk of tail lesions and of CC. The financial loss to producers associated with
CC and trimmings was estimated at €1.10 per study pig. CW was reduced by up to 12kg in cases of severe tail lesions. However,
even mild lesions were associated with a significant reduction in CW of 1.2kg. The value of the loss in potential CW associated with
tail lesions was €0.59 per study pig. Combined with losses attributable to CC and trimmings this represented a loss of 43% of the profit
margin per pig, at the time of the study, attributable to tail biting. These findings illustrate the magnitude of the impact of tail biting
on pig welfare and on profitability of the pig industry. They also emphasise the potential contribution that the inclusion of welfare param-
eters at meat inspection could make to pig producers in informing herd health and welfare management plans.
Keywords:animal welfare, carcase, economics, meat inspection, pig, tail biting
Introduction
It is widely accepted that the most valid approach to animal
welfare assessment is to focus on the animal rather than its
environment (Keeling & Veissier 2005; Smulders et al 2006;
Main et al 2007). Consequently, assurance schemes increas-
ingly measure ‘welfare outcomes’ such as the prevalence of
skin lesions in pigs (Sus scrofa domesticus) (Velarde &
Geers 2007). Abattoir meat inspection involves examination
of each carcase and, hence, presents an ideal opportunity to
measure animal-based welfare outcomes (Harley et al
2012a). The extensive use of meat inspection data in
epidemiological studies over a number of decades corrobo-
rates this (Cleveland-Nielsen et al 2004; Mullan et al 2011;
Swaby & Gregory 2012). Additionally, meat inspection is a
cost effective means of collecting data over long time-
periods as it is a continuous practice which is already in
place (Huey 1996; Cleveland-Nielsen et al 2004). For this
reason, and also for biosecurity reasons, it has advantages
over welfare inspections of pigs at farm level.
Tail biting is a major welfare problem in modern pig
farming systems. In spite of a ban on routine tail docking,
many pigs are still tail docked in EU countries (eg Harley
et al 2012b) in an attempt to control tail biting. There have
been extensive investigations into the epidemiology and
consequences of tail biting (Wallgren & Lindahl 1996;
Moinard et al 2003; Sinisalo et al 2012). Its reported asso-
ciation with carcase disease lesions, decreased carcase
weights and condemnations at slaughter means that it has
adverse economic implications for producers (Huey 1996;
Valros et al 2004; Kritas & Morrison 2007; Heinonen et al
2010). Furthermore, tail wounds are an important welfare
outcome measure (EFSA Panel on Animal Health and
Welfare 2007) as lesions seen at slaughter can generally be
attributed to practices at farm level. Indeed, a recent
technical report to EFSA on the future development of
animal-based measures for assessing the welfare of pigs
recommended that tail length and injury status be monitored
in slaughter pigs (Spoolder et al 2011).
Universities Federation for Animal Welfare Science in the Service of Animal Welfare
276 Harley et al
During an earlier study of over 36,000 slaughter pigs by
Harley et al (2012b), several other lesions potentially related
to pig welfare were readily observed. These included loin
bruising and hind limb bursitis. Anecdotal evidence from
pigmeat processors in the Republic of Ireland (where entire
male pigs are produced) suggests that the prevalence of loin
bruising is increasing. This lesion necessitates carcase
trimming at the processing stage and therefore results in
downgrading of the value of the loins. This contributes to
financial losses for the processor which have not been quan-
tified. Both the localisation of the bruising to the loin region
and its diffuse nature suggests that mounting behaviour plays
a part in its aetiology. Mounting is performed as part of the
sexual behavioural repertoire of entire male pigs (Conte et al
2010). When a male pig mounts another, its sternum applies
significant pressure to the loin area of the pig being mounted
(L Boyle, personal observation 2012). This may cause injury,
and usually elicits vocalisations and escape behaviour by the
mounted pig, which are suggestive of poor welfare
(Faucitano 2001; Rydhmer et al 2006).
Bursitis is a lesion found on the metatarsal region of the hind
limbs of pigs (Gillman et al 2008). Bursae are naturally
occurring fluid-filled sacs that decrease friction at points
where muscles and tendons glide over bones (McFarland et al
2000). Bursitis is a pathological response to trauma, the preva-
lence and severity of which is influenced by the degree of
pressure exerted on the limbs by commercial pig flooring
systems (Smith 1993; Lyons et al 1995; Mouttotou et al
1998). It is therefore representative of sub-optimal environ-
mental conditions on farms (Gillman et al 2008; Kilbride et al
2008). Bursitis has implications for animal welfare, not least
due to its associations with lameness, which can infringe all of
the five freedoms (Heinonen et al 2013).
Harley et al (2012b) conducted investigations in Irish and
Northern Irish abattoirs and provided herd-level data on the
prevalence of tail biting and of carcase condemnation.
Studies in Northern Ireland and other parts of Europe
(Tuovinen et al 1994; Huey 1996; Hunter et al 1999; Valros
et al 2004; Martínez et al 2007) also explored tail biting in
this way. However, the potential link between tail lesion
severity and carcase weight does not appear to have been
investigated previously. Similarly, the prevalence of other
welfare outcomes in slaughter pigs (such as loin bruising
and bursitis), and their effects on economically important
parameters, such as carcase condemnations and carcase
weight, have not been investigated. Consequently, the aims
of this study were: i) to determine the prevalence of loin
bruising and severe hind-limb bursitis; ii) to assess pig-level
associations between these welfare-related lesions (and tail
lesions) and carcase condemnation, carcase trimming and
carcase weights; and iii) to estimate the financial losses
associated with the parameters measured. It was postulated
that such information might strengthen the case for devel-
oping meat inspection as an animal welfare surveillance
tool in the Republic of Ireland which could, in turn,
contribute not only to improvements in pig productivity,
health and welfare, but also to the profitability of pig
production at producer and processor level.
Materials and methods
Data collection
Data collection was carried out by four people over seven
days during April 2012. The study took place in a single
abattoir with a weekly throughput of approximately
10,500 pigs (circa 20% of total pigs slaughtered per week in
the Republic of Ireland during April 2012) (Irish Central
Statistics Office 2012). Data collection began at 0900h and
continued until the end of the working day at approximately
1800h. The appropriate sample size for the study was
generated using data from the literature (Valros et al 2004)
and AusVet Epitools software (AusVet Animal Health
Services 2009). To account for the effect of clustering at
herd level, the sample size was expanded by 15% (Dohoo
et al 2003), to 3,492 study pigs. The sampling interval of
every third pig on the slaughterline was determined by
dividing the study population size (in this case weekly
abattoir throughput) by the required sample size (Dohoo
et al 2003; EFSA 2011).
Data were collected at three points on the slaughter line: i)
between dehairing and evisceration; ii) at post mortem meat
inspection; and iii) at the weighing scales. An identification
tag was suspended from one hind foot of each study pig at
the first data collection point, enabling identification of
study pigs at the later stages. Pig gender and herd identifica-
tion code were also recorded at this stage. The latter measure
enabled estimation of batch size, which is correlated with
herd size (Harley et al 2012b). Tail and loin lesion scoring
also occurred at the first data collection point and was
conducted by the same person throughout. Tails were scored
on a 0–4 scale (Figure 1). As it was already established that
over 99% of Irish pigs are tail docked (Harley et al 2012b),
tail length was not recorded in this study. Loin bruising was
recorded on a three-point scale (Figure 2).
The reason and anatomical locations of carcase condemnations
and trimmings were recorded by the second data collector at
the point of meat inspection, on the basis of the decision of the
acting Department of Agriculture, Food and the Marine
(DAFM) Temporary Veterinary Inspector(s) (TVI) on the line
(see Table 1). Hind-limb bursitis (see Figure 3) was recorded as
severe or absent/mild by the same person at this point. Partial
condemnations (ie, removal of a limb/head on public health
grounds and trimmings (ie, removal of a superficial
lesion — tail abscess, bursitis, skin wound) from the study pigs
were weighed by a third person. It was not possible to weigh
carcases that were entirely condemned.
There were three TVI teams, each of three people, working
separate shifts to the following schedule each day: shift 1,
0700–1030h; shift 2, 1050–1420h; and shift 3, 1450–1750h.
For the majority of shifts, the TVI teams included the same indi-
viduals, however there were some substitutions during the study.
At the third data collection point, a fourth person
recorded the line ‘kill number’ of each study carcase and
removed the identification tag from the leg of study
carcases before they entered the chill rooms. Using this
© 2014 Universities Federation for Animal Welfare
Welfare lesions in slaughter pigs 277
approach, it was possible to subsequently capture the
carcase weight and grade of each study pig. The carcase
weight of a pig correspond ed to th e cold weight
following bleeding and removal of the internal organs
(including genitalia), tongue, bristles, hooves and flare
fat (Irish Central Statistics Office 2012).
Data analysis
Descriptive statistics were calculated using Microsoft®
Excel® for Windows. Tail-biting scores were re-organised
into four categories: no lesion (score = 0); any tail lesion
(score ≥ 1); moderate lesions (score ≥ 2); and severe lesions
(score ≥ 3). Carcase condemnations, trimmings and absces-
Animal Welfare 2014, 23: 275-285
doi: 10.7120/09627286.23.3.275
Figure 1
Tail-lesion scoring system (Scores 0–4, left to right).
Figure 2
Loin-bruising scoring system (Scores 0–2, left to right).
Figure 3
Hind-limb bursitis (absent/mild and severe, left to right).
278 Harley et al
sation were classified as present (score = 1) or absent
(score = 0). Loin bruising was recorded on a three-point
scale which was collapsed to either severe (score of 2) or
none/mild (scores of 0+1).
The relationship between gender of the pigs and welfare
lesions (tail lesions, loin bruising and hind-limb bursitis)
were analysed using generalised estimated equations in
PROC GENMOD of SAS (SAS Institute Inc 1988).
Gender was considered as the dependent variable.
Univariable models were built separately to assess the
influence of each predictor variable on the dependent
variables. Tail lesions, loin bruising and hind-limb bursitis
were included as categorical variables.
The relationship between welfare indicators (tail lesions,
loin bruising and hind-limb bursitis) and the total number of
carcase condemnations (partial + entire), carcases
condemned for abscessation and carcases trimmed were also
analysed using generalised estimated equations in PROC
GENMOD of SAS (SAS Institute Inc 1988). Total carcase
condemnations, carcases condemned for abscessation and
carcases trimmed were considered as the dependent
variables. Firstly, univariable models were built to separately
assess the influence of each predictor variable on the
dependent variables. Predictor variables with P< 0.20
(Dohoo et al 2003) were used to build multivariate models.
TVI shift and gender were forced into the models to assess
their influence on the outcome variables. The tail-lesion
scores were also included as a categorical variable in the
model for carcases condemned for abscessation. Tail-lesion
scores and hind-limb bursitis scores were included in the
model for total number of carcase condemnations. Finally,
tail-lesion and loin-bruising scores were included as categor-
ical variables in the model for carcases trimmed. Backward
selection was used to eliminate predictor variables until only
those with P< 0.05 remained in the model.
Carcase weight was tested for normality before analysis
using the Shapiro-Wilk test and examination of the normal
plot. One hundred and ninety-four carcases were excluded
from the analysis of the relationship between the severity of
welfare lesions and carcase weight as their weight was
reduced because of being partially/entirely condemned
and/or trimmed. The relationship between welfare lesions
and carcase weight was assessed using mixed model
equations in PROC MIXED (SAS Inst Inc, Cary, NC, USA).
Tail-lesion score, loin bruising and hind-limb bursitis were
included as fixed effects and carcase weight as a random
effect. Statistical differences were reported when P< 0.05.
Results are reported as least square means (± SEM).
The direct financial losses resulting from carcase condemna-
tion and trimming at the point of meat inspection were calcu-
lated by multiplying recorded weights of condemned and
trimmed material by the average Irish pig meat price at the
time of writing up the study (€1.70 per kg) (Cleary 2012),
using Microsoft® Excel® for Windows v 2000. In the
absence of weights of carcases that were entirely condemned,
the average weight for such carcases based on recordings
made at Northern Irish abattoirs as per Harley et al (2012b)
was used. It was not possible to weigh or calculate the losses
associated with fat/muscle trimming beyond the point of meat
inspection and thus the impact of loin bruising on trimming
during processing could not be evaluated.
In the economic analysis, the potential impact of tail-lesion
severity on final carcase weight considered the carcase
weight for each score ≥ 2 relative to carcases with tail-lesion
scores of 0 or 1 (ie, unaffected carcases). Carcases that were
partially condemned or trimmed were not included in this
analysis as they would automatically have been lighter irre-
spective of their tail-lesion score.
Results
Descriptive results
A total of 3,537 pigs were observed during the study. In the
absence of a full dataset for 115 of the pigs, the final study
population was 3,422 pigs. A general description of the
study population is shown in Table 2. Of the final study
population, 85 carcases were condemned. The majority
were partial condemnations, of which the hindquarters were
the most commonly affected anatomical region.
Abscessation alone accounted for almost 70% of total
condemnations. Carcase trimming occurred more
frequently than condemnation; cumulatively 5.7% of the
study population was either trimmed or condemned.
Tail lesions (score ≥ 1) were observed in 72.5% of the study
pigs (Table 2), with 2.5% affected by severe tail lesions (ie,
© 2014 Universities Federation for Animal Welfare
Table 1 Definition of disease lesions and carcase condemnations* as per Straw et al (2006) and Ellerbroek et al (2011)
detected at meat inspection.
Anatomy affected Disease Appearance/description
Entire carcase* Various Systemic disease
Partial carcase* Localised disease/injury
Hindquarter* Localised disease/injury affecting one or both hind limbs
Forequarter* Localised disease/injury affecting one or both forelimbs
Abscess Abscessation Single or multiple focal, spherical, encapsulated purulent lesions
Other infectious Septicaemia, septic peritonitis/endocarditis/arthritis Localised or systemic caused by an infectious agent
Trimmings Various Small, superficial disease/injury lesion/external abscess
Welfare lesions in slaughter pigs 279
Animal Welfare 2014, 23: 275-285
doi: 10.7120/09627286.23.3.275
Table 2 General description of the study population, including the prevalence of carcase condemnations and trimmings,
tail and loin lesions, hind-limb bursitis and carcases condemned for abscessation.
†Four carcases were both trimmed and condemned.
Total % study population
Farms 49 –
Batches 74 –
Pigs Male 1,777 51.9
Female 1,645 48.1
Total 3,422 100.0
Condemnations Total 85 2.5
Entire carcase 14 0.4
Partial carcase 71 2.1
Partial condemnations Hindquarters 48 1.4
Forequarters 10 0.3
Head 8 0.2
Other 5 0.1
Causes Abscessation 58 1.7
Other 27 0.8
Trimmings 113 3.3
Trimmings and condemnations†194 5.7
Welfare lesions
Tail lesions None Male 401 22.6
Female 540 32.9
Total 941 27.5
Score ≥ 1 Male 1,376 40.2
Female 1,105 32.3
Total 2,481 72.5
Score ≥ 2 Male 533 15.6
Female 371 10.8
Total 904 26.4
Score ≥ 3 Male 67 1.9
Female 20 0.6
Total 87 2.5
Loin bruising None/mild Male 1,493 43.6
Female 1,380 40.4
Total 2,873 84.0
Severe Male 284 8.3
Female 265 7.7
Total 549 16.0
Hind-limb bursitis None/mild Male 984 28.7
Female 934 27.3
Total 1,918 56.0
Severe Male 793 23.2
Female 711 20.8
Total 1,504 44.0
Carcase condemned for abscessation
Tail lesions None 23 0.7
Score ≥ 1 62 1.8
Score ≥ 2 33 1.0
Score ≥ 3 13 0.4
280 Harley et al
score ≥ 3). Males were more frequently affected by tail
lesions than females, a trend which became exaggerated
with increasing tail-lesion severity (Score 1: OR = 1.55;
95% CI 1.314–1.819; P < 0.001; Score 2: OR = 1.78; 95%
CI 1.479–2.160; P < 0.001; Score ≥ 3: OR = 4.51; 95% CI
2.693–7.556; P< 0.001). Severe loin bruising affected
16.0% of pigs and severe hind-limb bursitis was detected in
almost half the study population. Male gender was not a risk
factor for severe loin bruising (OR = 0.99; 95%
CI 0.825–0.189; P> 0.05) or severe hind-limb bursitis
(OR = 1.06; 95% CI 0.924–1.212; P> 0.05).
Factors affecting carcase condemnations and trimmings
Hind-limb bursitis, tail-lesion score and gender were signif-
icantly associated with carcase condemnation (P≤ 0.05;
Table 3). Tail lesions with a score ≥ 3 and male gender
increased the risk of condemnations, whilst bursitis was a
protective factor. TVI shift and loin bruising were not
significantly associated with carcase condemnations. Tail
lesions with a score ≥ 3 and TVI were significantly
associated with carcase trimming (P≤ 0.05).
Factors affecting carcase weight
There was a significant negative effect of tail-lesion
severity score on carcase weight (P≤ 0.05) such that there
was an average reduction in weight of 1.19, 3.27 and
12.0 kg associated with tail lesions scored 2, 3 and 4,
respectively, relative to tails scored 0 or 1 (Table 4). In
contrast, there was no effect of loin bruising or hind-limb
bursitis on carcase weights (P> 0.05).
Economic analysis
The pigmeat losses associated with the 85 carcase condemna-
tions in the study population amounted to over 1,800 kg and had
a value of more than €3,200. This equated to €0.94 per study pig
and increased to €1.10 per study pig when costs associated with
approximately 330 kg of trimmings were included (Table 5).
© 2014 Universities Federation for Animal Welfare
Table 3 Final generalised estimating equation (GEE) model of risk factors associated with carcase condemnation
(includes entire and partial condemnations), carcases condemned for abscessation and carcases trimmed. The variables
gender and Temporary Veterinary Inspector (TVI) shift were forced into the final model.
* Significantly different from reference category; P≤ 0.05.
OR = Odds ratios.
CI = 95% confidence interval.
NI = Not included in the model.
Explanatory variables Carcase condemnation Carcase condemned for abscessation Carcase trimmed
OR CI OR CI OR CI
Tail lesion score 0
1 0.66 0.380–1.159 1.22 0.347–4.308 0.86 0.503–1.456
2 0.85 0.461–1.572 1.74 0.417–7.262 1.26 0.702–2.246
≥ 3 5.07* 2.428–10.581 0.78 0.167–3.656 25.84* 13.83–48.29
Gender Female (0)
Male (1) 2.55* 1.547–4.200 0.26 0.067–1.003 0.70 0.463–1.059
TVI shift 1
2 0.97 0.546–1.704 0.27 0.064–1.136 1.09 0.665–1.794
3 0.89 0.480–1.650 0.44 0.092–2.144 0.52* 0.286–0.961
Hind-limb bursitis None/mild
Severe 0.59* 0.373–0.950 NI NI NI NI
Loin bruising None/mild
Severe NI NI NI NI 0.67 0.438–1.023
Table 4 Mean (± SEM) carcase weight (kg) of pigs (not
condemned and/or trimmed) in each of the tail lesion,
loin lesion and hind-limb bursitis score categories.
abc Carcase weights differ significantly (P≤ 0.05).
Welfare-related lesions Carcase weight
Tail lesion score
≤ 1 80.02 (± 0.18)a
2 78.83 (± 0.31)b
3 76.75 (± 1.45)b
4 68.02 (± 2.28)c
Loin bruising
None/mild 79.63 (± 0.17)
Severe 79.53 (± 0.36)
Hind-limb bursitis
None/mild 79.46 (± 0.20)
Severe 79.79 (± 0.23)
Welfare lesions in slaughter pigs 281
The total estimated reduction in carcase weight in the study
population when tail lesions were scored greater than 1 was
1.182 kg (Table 5). This equated to a loss of €0.59 per pig
in the final study population. There was an estimated loss of
€1.69 per study pig when the value of pigmeat lost as a
result of carcase condemnation/trimming and reduced
carcase weights were combined.
Discussion
Data recording at abattoir meat inspection is a valuable
way of monitoring the prevalence of a number of health
and welfare conditions that affect food-producing animals.
This study found a high prevalence of tail biting, loin
bruising and hind-limb bursitis, as well as a high frequency
of carcase condemnations within the study population. In
association with these findings, considerable financial
losses were identified which were primarily associated
with lesions caused by tail biting. These findings highlight
the potential value of enhanced data capture and feedback
at abattoir meat inspection.
In this study, 72.5% of inspected pigs had detectable tail
lesions. This figure is higher than the mean prevalence of
detectable tail lesions found by Harley et al (2012b) for
over 36,000 pigs. However, the abattoir involved in the
current study was also included in the study by Harley et al
(2012b), and the current figure corresponds well with the
previous figure for detectable tail lesions in slaughter pigs
of 76% in that abattoir under the same scoring system.
Harley et al (2012b) discussed some of the potential
reasons why the prevalence of detectable tail lesions in the
pigs supplied to this particular abattoir was so high
compared to the national average. However, even the
national average figure for pigs affected by detectable tail
lesions demonstrates that tail biting is a widespread behav-
ioural problem, and that the widely practised control
method of docking (Harley et al 2012a) is ineffective.
The observed prevalence of tail lesions in this study is much
higher than reported for other countries where comparable
studies were conducted (Finland: Valros et al [2004] and
Sweden: Keeling et al [2012]). This may reflect differences
in animal welfare policy (eg, tail docking is totally banned
in Finland) and farm management. For example, straw is
widely used in pig production in Sweden and this is likely
to have had a significant positive impact on tail biting
(EFSA Panel on Animal Health and Welfare 2007).
Nevertheless, the lesion-scoring systems and lesion
threshold criteria used also differed greatly between the
studies, and this will have influenced the findings on tail
lesions (Keeling et al 2012). Furthermore, the location
where the tails were inspected differed between the three
studies. In both the current study and the study by Valros
et al (2004), pigs were inspected after scalding whereas they
were inspected after exsanguination in the study by Keeling
et al (2012). Based on our observations, minor lesions
(scores 1 and 2 in this study) are not detectable unless the
pigs are scalded and dehaired. Keeling et al (2012) cite
concerns about mechanical damage to the tails during the
scalding process as a reason for choosing their scoring
location. However, the fact that gender differences
prevailed even between the milder scores in the study by
Animal Welfare 2014, 23: 275-285
doi: 10.7120/09627286.23.3.275
Table 5 Weight (kg) of carcase condemnations and trimmings, the average reduction in carcase weight associated
with tail-lesion score and their associated financial cost (€).
†Using the average weight of entirely condemned carcases recorded by Harley et al (2012b).
‡Using average Irish value for pig meat over the study period (€1.70 per kg).
§Four carcases were both trimmed and condemned.
Prevalence (number of pigs affected) Weight (kg) Cost (€)‡(Total) Cost (€)‡(Per study pig)
Carcase condemnations
Entire 14 977.62†1,661.95 0.48
Partial 71 911.53 1,549.60 0.45
Total 85 1,889.15 3,211.55 0.94
Carcase trimmings
Total 113 329.84 560.73 0.16
Cumulative carcase condemnations and trimmings§
Total 194 2,218.99 3,772.28 1.10
Potential loss associated with final carcase weight
Score 2 (less 1.19 kg) 774 921.06 1,565.80 0.46
Score 3 (less 3.27 kg) 32 104.64 177.89 0.05
Score 4 (less 12 kg) 13 156.00 265.20 0.08
Total 1,181.70 2,008.89 0.59
Cumulative carcase condemnations, trimmings and loss in carcase weight
Total 3,400.69 5,781.17 1.69
282 Harley et al
Harley et al (2012b) suggests that the aetiology of such
damage is animal-based and not mechanical.
Tail-biting lesions provide not only a point of entry for
infection (Heinonen et al 2010), but three separate routes for its
dissemination around the body (venous, lymphatic and
cerebro-spinal drainage) (Huey 1996). Hence, there is a close
association between tail lesions and abscessation (Huey 1996;
Valros et al 2004; Heinonen et al 2010). However, in spite of
the high prevalence of tail damage in the current study, no
significant association between tail lesions and condemnation
due to abscessation was detected. This may possibly reflect the
smaller sample size and subsequent inadequate statistical
power of the current study relative to those mentioned above.
However, there was a significant association between the
severity of tail lesions and carcase condemnations, and
abscesses were the primary cause of condemnations.
The findings of the current study support observations by
Harley et al (2012b) that, similar to castrates (Hunter et al
1999; Valros et al 2004), entire male pigs are more
frequently and severely affected by lesions caused by tail
biting than females. The reason behind gender differences in
propensity to be (severely) bitten has yet to be established
(Schrøder-Petersen & Simonsen 2001; Taylor et al 2010).
However, our findings extend those of Harley et al (2012b)
by showing that male carcases are also more likely to be
condemned than female carcases. Even though there was no
association between gender and condemnation for abscessa-
tion, it is probable that the greater likelihood of males having
internal infections arising from tail lesions was responsible
for the increased risk of condemnation. These findings need
to be confirmed with larger numbers of animals.
We can conclude from the above that tail biting is a major
cause of financial loss to producers arising from carcase
condemnation. However, severe tail lesions are also positively
associated with carcase trimming which represents another
source of financial loss not only to the producer because of the
reduction in carcase weight but also to the processor because
of the associated labour. The direct losses to producers from
carcase condemnations and trimmings recorded in this study
were valued at €1.10 per pig slaughtered.
Another source of financial loss associated with tail biting
arises from the reduction in animal performance (Sinisalo
et al 2012) which, in this study, was reflected in the lower
weights of carcases affected by tail lesions. It is likely that
inflammatory processes associated with infection arising
from the tail lesions (Valros et al 2004) interfered with
growth performance, but the effect of stress on the victim of
tail biting cannot be discounted (Schrøder-Petersen &
Simonsen 2001). It could be argued that lighter/smaller pigs
are more susceptible to being bitten, however, there is little
scientific evidence to support this. In fact there is evidence
that smaller pigs (or ‘runts’) are more likely to be tail biters
(Van de Weerd et al 2005).
The most severe tail lesions were associated with carcases
which were, on average, 12 kg lighter than unaffected
carcases (ie, carcases with a tail score of 0 or 1). However,
even carcases with tail-lesion scores of two (which could be
considered to be relatively ‘mild’ lesions) were associated
with a 1.2 kg reduction in weight relative to unaffected
carcases. Such lesions likely arise from tail
manipulation/chewing (rather than biting) which can occur
at chronically high levels in intensive pig production systems
(Schrøder-Petersen & Simonsen 2001). It is possible that this
can occur even in the absence of severe/acute outbreaks of
tail biting, ie those leading to cannibalism. Producers are
often unaware that tail manipulation is being performed
because of the absence of blood and of overt behavioural
reactions of the recipient. In spite of this, tail manipulation is
likely a stressor, with implications for animal performance
and therefore for profitability at farm level. Information on
these minor/moderate tail lesions might lead producers to
improve the types/quantities of environmental enrichment
provided to pigs as this could reduce levels of tail manipula-
tion (Taylor et al 2010) or to make other management
changes, eg reduce stocking densities, improve ventilation
etc. Such changes would not only lead to improvements in
pig welfare but could also improve farm finances. Minor,
and sometimes moderate, lesions are not visible on the live
animal. Therefore, the only way in which producers can be
provided with information on such lesions, to inform their
herd health and welfare management plans, is if they are
recorded on the carcase at meat inspection.
As producers are paid on a per kg basis, a reduction in
carcase weight represents a serious financial loss to
producers. The lost potential carcase weight associated with
tail lesions was equivalent to 1,181.70 kg or €0.59 per pig
slaughtered. When combined with losses arising from
carcase condemnation (€1.10 per pig), the resulting figure
of €1.69 represents almost 43% of the current profit margin
(estimated at €0.05 kg or circa €3.95 per 79 kg carcase) for
Irish pig producers. In the context of increased production
costs in a number of EU countries since 2010 (BPEX 2012),
such losses represent a serious threat to the viability of pig
farms. In an industry with such tight margins, financial
implications such as these may act as a significant driver for
addressing the problem of tail biting by improving pig
husbandry and welfare.
This study is the first to report on the prevalence of loin
bruising as a welfare outcome at slaughter. Severe bruising
was detected in 16.0% of study carcases, confirming
anecdotal reports from processors in the Republic of Ireland
that loin bruising is prevalent in slaughter pigs. It was
beyond the scope of this study to determine the aetiology of
loin bruises but the absence of a gender effect on this lesion
could reflect the fact that most pigs are kept in mixed sex
groups on Irish farms and entire male pigs in mixed sex
groups mount other males as frequently as they mount
females (Conte et al 2010). Severe loin bruising also incurs
costs to processors (L Boyle, personal communications with
pigmeat processors 2012). This is because affected cuts are
downgraded, diminishing the retail value by over 50%, and
the removal/trimming of damaged tissue incurs labour and
disposal costs. Such trimming occurs at the processing stage
and was not included in the trimming measured in this study
© 2014 Universities Federation for Animal Welfare
Welfare lesions in slaughter pigs 283
(which took place on the slaughter line). Hence, the specific
financial impact of such welfare lesions is unknown.
Trimming of bruised loins often removes the rind upon
which slapmarks or kill numbers are stamped, preventing
identification of producers with batches showing a high
prevalence of loin bruising. However, scoring of loin
bruising at meat inspection provides a solution to this
problem because the identification of the producer can be
recorded simultaneously. If the financial impact of loin
bruising is established, processors may consider introducing
penalties for carcases with bruised loins in the future. Hence,
a better understanding of the aetiology of such lesions will
be required in order to be able to advise pig producers on
ways to reduce these lesions in their slaughter pigs.
Though it is difficult to quantify its implications for produc-
tivity and profit, hind-limb bursitis is a valuable indicator of
flooring quality (Gillman et al 2008). Hind-limb bursitis
was identified in 44% of pigs in this study, in contrast to a
lower prevalence observed in finishing pigs in the UK
(Kilbride et al 2009). This may reflect the fact that straw-
based systems are more commonly employed in the UK
than in the Republic of Ireland. The current study provides
further evidence that concrete slatted flooring (which is the
predominant flooring used in intensive systems of pig
production in the Republic of Ireland) has adverse effects on
limb health. There is a strong relationship between bursitis
and lameness (Kilbride et al 2009), but it is not known
whether bursitis causes lameness or is simply a conse-
quence of lameness, mediated perhaps by prolonged lying
in lame animals (Bonde et al 2004). However, the relation-
ship between bursitis and lameness suggests that it is a good
measure of on-farm welfare, and this is supported by the
fact that it is included in the Welfare Quality® protocol
(Welfare Quality® 2009). Lameness in pigs is associated
with large industry losses arising from decreased produc-
tivity and rejection of breeding animals (Kilbride et al
2009), so bursitis potentially merits inclusion for measure-
ment at meat inspection as an animal welfare surveillance
measure. The finding that hind-limb bursitis was a protec-
tive factor for the risk of condemnation was unexpected and
is difficult to explain.
It is worth noting that abattoir meat inspection has limita-
tions as a tool for animal welfare surveillance. Severely
affected animals may die or be culled during production,
whilst detection and recording of lesions that resolve pre-
slaughter is similarly impossible. Consequently, the preva-
lence of welfare lesions recorded at meat inspection is likely
to underestimate that on-farm (Marques et al 2012).
Conversely, lesions occurring during transport or lairage, eg
limb fractures and fresh tail lesions, may cause an overesti-
mation of the prevalence at production level.
Despite the above limitations and as illustrated in this
study, the health and welfare status of food-producing
animals can be assessed and recorded during abattoir meat
inspection (Alban et al 2011; Swaby & Gregory 2012).
Denmark and The Netherlands are examples of countries
which routinely record such information and use it to
target problem areas at production level (Willeberg et al
1984; Stärk 1996; Nielsen 2011). Indeed, producers
provided with such information have lower incidences of
disease and welfare problems on their farms (Sanchez-
Vazquez et al 2011). However, despite the potential value
of this information, many countries still have no recording
and feedback system in place (Harley et al 2012b).
Animal welfare implications
This paper outlines the high prevalence of three welfare
lesions detected at slaughter, and their association with
carcase condemnations, trimmings and carcase weight.
Additionally, it calculates the financial losses incurred by
pig producers as a result of carcase condemnations,
trimmings and reduced carcase weights primarily associated
with lesions caused by tail biting. Importantly, the paper
also illustrates that the behaviour of tail manipulation, as
opposed to tail biting, is highly prevalent on farms, and, for
the first time, that the resulting minor to moderate lesions
are also associated with significant reductions in carcase
weight. This paper also illustrates that there are significant
advantages associated with monitoring the incidence and
severity of a number of animal diseases and welfare
outcomes during the process of abattoir meat inspection.
Expansion of the meat inspection process to incorporate
such lesions has the potential to be highly valuable for
producers and the pig industry as a whole.
Acknowledgements
The authors acknowledge the financial support provided by
the Wellcome Trust Intercalation Funding Award for Sarah
Harley and the Irish Government’s National Development
Plan 2007–2013 for Dayane Teixeira (Department of
Agriculture, Food and the Marine’s Competitive Research
Programme – RSF 11/S/107). We thank the abattoir manager
and staff for their co-operation and Dr Paul Whyte and Tracy
Clegg of UCD for their advice. Great thanks to staff of the
Teagasc Pig Development Department (PDD) (Tómas Ryan
and Tara Fitzgerald) and to students on work placement at the
PDD (Walter Walsh, Maria Garza Valles, Denis O’Grady and
Carles Collibeltran) for their help with data collection.
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