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Docking the value of pigmeat? Prevalence and financial implications of welfare lesions in Irish slaughter pigs

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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.
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© 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 condemnations194 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 14 977.621,661.95 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 Qualit 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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... Based on several studies, Valros and Heinonen [18] reported that tail docking reduced the occurrence of severe lesions by half. In 2015, a study in Ireland where 99% of the pigs were docked still showed a 72.5% prevalence of tail damage along with a 2.5% incidence for severe lesions alone [19]. Two other Irish studies also showed that the frequency for severe tail lesions could be as high as 3.1% in docked animals [20], indicating that docking itself does not eliminate tail biting. ...
... When questioned, pig producers acknowledged the potential of developing and applying meat inspection data as an animal health and welfare diagnostic tool [22]. However, abattoir data for tail biting are not very accurate and tend to underestimate tail damage [19,21]. A Danish study that included 111 herds showed that tail lesions, evaluated by clinical examination of animals on the farm, were actually double the number detected by meat inspection at the abattoir [23]. ...
... In all production systems, ribs were the most condemned area, followed by head, anterior third, rabada, hock, posterior third, shoulder and ham. Similar results were previously found by [2,19]. In this study, condemnations of ribs were related to pleurisy, where the adherence of the pleura made it impossible to detach it from the ribs. ...
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Tail biting has been recognised as an intractable problem in pig production. This study aims to evaluate tail lesion occurrence in slaughtered pigs and explore the relationship between carcass condemnations and tail lesion considering different production systems and tail lengths and to evaluate the importance of creating a detailed tail score classification that includes scarred lesions. Data on a total of 9189 pigs from 73 batches with different tail lengths (undocked; docked mid-length; fully docked) and from distinct production systems (conventional; conventional antibiotic-free and organic) were collected at a Spanish abattoir. Batches with higher tail lesion scores presented a significantly higher chance of total condemnation and total condemnation due to pyaemia, being even more associated with scarring score. The within-batches probability for local condemnations and local condemnation due to abscesses increased significantly with higher scarring scores. Regarding tail length, docked at mid-length and undocked carcasses presented significantly higher odds to be condemned due to abscess. Organic farms showed a higher probability of total condemnations. This research highlights the importance of tail lesions on carcass condemnations that may also be influenced by docking and type of production. Results suggest that scarring score should be included in the tail surveillance program.
... Stressful events on the farm and during transport and pre-slaughter conditions have deleterious effects on the final product [2], causing abnormal enzymatic changes in postmortem muscle-to-meat transformation and determining bruises and lesions that can penalize the quality of the carcass and cuts [1][2][3]. Blemishes and severe damages on the carcass skin are an economical problem for the pig production chain, as skin lesions can lead to downgrading of carcass and cuts [4,5], increased costs to remove the lesioned parts [4][5][6], and discarding of bruised hams from the Protected Designation of Origin (PDO) circuit [7,8]. Italy contributes to about one-third of the European meat product heritage [9], and the majority of the heavy pigs reared for PDO production are located in Northern Italy, in particular in the Po Valley. ...
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... The prevalence of bursitis (at least one limb affected) has been reported in different studies to be very high: 41.2% on farm recorded on the four limbs [28]; 44% at abattoir recorded on the hind legs [29]. Older pigs have been reported to be at higher risk to develop this lesion because their greater body weight exerts additional pressure on the limbs and they spend a greater proportion of time lying [30], so we expected higher bursitis prevalence at slaughter in Italian heavy pigs. ...
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... The aggressive interactions between pigs occur to determine the order of dominance (Turner et al., 2006). However, high level of aggression influence productivity of animals and decrease the economic efficiency of the enterprise (Harley et al., 2014;Haigh & O'Driscoll, 2019). The aggressive social interaction indicates that the environment does not meet the behavioural needs of pigs. ...
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In industrial complexes, the environment for fattening pigs has limited space and often does not respect natural behaviour of pigs. The implementation of EU legislation in Ukraine requires from farmers to use enrichment materials that improve the welfare of pigs. This article shows possible solution for big industrial challenge – creating of comfortable conditions for pigs, which meet their ethological needs. The experiment was performed on 180 pigs. From 77 days of age, all experimental animals were divided into three groups (on the principle of analogues) of 60 heads in each. As criteria of aggressive social behaviour the fights and biting were chosen. It was found that at the first period of fattening in pigs of the control group (no enrichment materials) 24 cases of biting were registered, in animals with straw blocks (experimental group II) – 6, with plastic bottles filled with grain (experimental group III) – 4 cases. At the second period of fattening, the situation regarding intragroup aggression was identical to the first one, which was reflected by the level of the cortisol in the blood serum. Among pigs that had free access to enrichment materials, a significant increase in their live weight by 2.4–5.8%, and in average daily gain by 1.4–27.6% compared with animals in the control group was registered. This study aims to prove that the use of enrichment materials for fattening pigs helps to identify their natural behaviour in industrial complexes, avoids social aggression, increases productivity and improves their welfare.
... This multifactorial nature creates difficulties when attempting to accurately predict TB and record TB prevalence on commercial farms (11). Tail lesion estimates have been recorded at abattoirs between 13-72% (12)(13)(14), demonstrating the varying prevalence of TB on commercial farms. ...
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... Farm and abattoir based studies frequently report that male pigs are more likely to be the recipients of tail-biting (i.e., to have tail lesions) than female pigs irrespective of whether they are castrated (5,23,25) or entire (24,64,(92)(93)(94). However, Sinisalo et al. (22) found no difference between the sexes. ...
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Damaging behaviors (DB) such as tail and ear biting are prevalent in pig production and reduce welfare and performance. Anecdotal reports suggest that health challenges increase the risk of tail-biting. The prevalence of tail damage and health problems show high correlations across batches within and between farms. There are many common risk factors for tail-biting and health problems, notably respiratory, enteric and locomotory diseases. These include suboptimal thermal climate, hygiene, stocking density and feed quality. The prevalence of tail damage and health problems also show high correlations across batches within and between farms. However, limited evidence supports two likely causal mechanisms for a direct link between DB and health problems. The first is that generalized poor health (e.g., enzootic pneumonia) on farm poses an increased risk of pigs performing DB. Recent studies indicate a possible causal link between an experimental inflammation and an increase in DB, and suggest a link between cytokines and tail-biting. The negative effects of poor health on the ingestion and processing of nutrients means that immune-stimulated pigs may develop specific nutrient deficiencies, increasing DB. The second causal mechanism involves tail-biting causing poor health. Indirectly, pathogens enter the body via the tail lesion and once infected, systemic spread of infection may occur. This occurs mainly via the venous route targeting the lungs, and to a lesser extent via cerebrospinal fluid and the lymphatic system. In carcasses with tail lesions, there is an increase in lung lesions, abscessation, arthritis and osteomyelitis. There is also evidence for the direct spread of pathogens between biters and victims. In summary, the literature supports the association between poor health and DB, particularly tail-biting. However, there is insufficient evidence to confirm causality in either direction. Nevertheless, the limited evidence is compelling enough to suggest that improvements to management and housing to enhance pig health will reduce DB. In the same way, improvements to housing and management designed to address DB, are likely to result in benefits to pig health. While most of the available literature relates to tail-biting, we suggest that similar mechanisms are responsible for links between health and other DB.
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Slaughterhouse workers are strategic capital for the meat industry in terms of operational and animal welfare issues; however, information about the attitudes of workers toward the human-animal relationship is limited. The main aim of our study was to identify the profiles of workers based on their attitudes toward pigs, occupational satisfaction, sociodemographics, and animal handling. The survey included 171 workers in 12 Colombian pig slaughterhouses. A factor analysis and a hierarchical cluster analysis identified four segments or worker profiles. The first comprised workers who relate to animals and their work in a mechanical way, the second comprised professional workers who are emotionally close to animals, the third comprised those committed to animals and their work, and the fourth comprised workers who are apathetic toward animals and work activity. The human-animal relationship at the slaughterhouse level is multifaceted, but is influenced by dependent on work satisfaction and sympathy toward the animals.
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The welfare status of an animal is dependent on its ability to cope and exist in harmony with its environment, such that good physical and psychological health is maintained. Improving animal welfare is an increasingly important aspect of livestock production systems due, in a large extent, to increased consumer concerns about animal production practices. Animal welfare is an integrated part of quality assurance programmes for sustainable animal production, considering that welfare, health, management, economy, consumer acceptance and environmental impact are interdependent. The major welfare concerns in the livestock industry in recent years relate to the rearing and management of dairy calves, the welfare of the dairy cow, effect of husbandry management procedures on the welfare of beef cattle, rearing of sows in gestation and farrowing crates, and the broiler (meat) chicken sector. The paper will focus on scientific research underpinning these welfare concerns, with a particular focus on research conducted on the island of Ireland.
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The present study assessed the association of tail-biting lesions in finishing pigs with weight gain, occurrence of locomotion or respiratory disorders and abscesses during finishing period, and carcass condemnation at slaughter. The study was carried out on 4 different farms. For each animal with a tail biting lesion, two control pigs were selected. The total number of animals in the study was 312, with 104 of them being tail-bitten. Tail lesions were classified according to the degree of severity into four scores: score 0 -normal tail withou lesion; score 1-3 - increasing lesion severity, and score 4 - healed lesions. Overall, the occurrence of severe tail lesions (score 3) varied from 55 to 73% of tail-bitten pigs among farms. On all farms, healing of tail lesions was observed in 95% to 100% of the animals at the evaluation performed within 41-43 days after the commencement of the study. In two out of the four evaluated farms, pigs with score of 3 showed lower weight gain (P
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Despite extensive utilisation in epidemiological investigations of animal health, to date there has been little consideration of the value of abattoir meat inspection as a pig welfare surveillance tool. This study measured the prevalence of tail-docking, tail biting, carcase condemnations and associated financial losses of the latter (Northern Ireland only) in 36,963 pigs slaughtered in six abattoirs from the Republic of Ireland and Northern Ireland in July and August 2010. Over 99 per cent of inspected pigs had been tail-docked, while 58.1 per cent and 1.03 per cent had detectable and severe tail lesions, respectively. Producer losses resulting from carcase condemnation were estimated to be €0.37 per pig slaughtered. Enhanced capture and utilisation of meat inspection data for use in animal welfare surveillance schemes has the potential to drive improvements in production efficiency and animal welfare. However, significant differences were detected in the prevalence of carcase condemnation conditions between abattoirs and judiciaries (Republic and Northern Ireland). This reflects variation in the criteria and methods of data capture used in meat inspection in different abattoirs. Thus, the meat inspection process needs to be standardised and reformed before it can be reliably utilised in large-scale pig welfare surveillance schemes.
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The aim of this paper is to review existing literature concerning the impact of lameness and claw lesions on welfare, health and production of sows. When using the five freedoms, a common method to conceptualize animal welfare, to assess the impact of lameness, it appears that lameness as a single disease, may affect all of the freedoms. There is a wide variability with respect to the impact of claw lesions on welfare of sows, because only a proportion of animals are affected. Lameness affects welfare due to physically reduced locomotion ability, pain or general discomfort and sickness behavior. Cross-sectional studies show that the within-herd prevalence of sow lameness is quite high and may range from 8.8% to 16.9%. There are several reasons for lameness and claw lesions and they are very difficult to be identified during herd-level clinical examinations. Therefore, many researchers have studied the sows post-mortem and quite often found more than one lesion likely to cause lameness. Not all lesions are associated with lameness, but the location and severity of the lesions are important factors. Lameness can also affect the general health of the sow and predispose to loss of body condition, shoulder lesions and urogenital infections. Longevity of lame sows is decreased when compared with that of healthy-legged animals. Acutely and severely lame sows are removed immediately from the herd, and chronic, less severe lameness can affect the performance of sows and thus indirectly lead to culling. However, only few articles report about production or fertility figures of lame vs non-lame sows, except for ample data on longevity. In conclusion, lameness of sows is an important welfare and health problem and may also severely affect the profitability of sow herds.
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Aggressive and sexual behaviour in entire males and females were studied on 408 pigs. The sum of aggressive interactions in the pen during routine feeding (ALP) was lowest in single-sex pens with females. ALP was higher at 132 than at 155 days. High ALP correlated with high average growth rate. Aggressive interactions in a competition test (IA) increased after slaughter of the three fastest-growing pigs in a pen (at 155 days), although the slaughtered pigs had initiated the most IA earlier (at 132 days). Entire male pigs displayed more sexual behaviour (mounting) than females. In 15% of entire males and 6% of females there were health problems specifically involving lameness or injured legs or feet. Five entire males and one female were euthanized in response to lameness or leg fracture. The rearing of entire male pigs may cause welfare problems, given their higher levels of aggression and sexual behaviour.
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Productivity, behaviour and injury was compared in four housing treatments for pigs within one building: deep-straw, Straw-Flow®, bare-concrete and slats. Three replicates of four uniform lots of entire male pigs (15 per treatment) were studied. The pigs were grown from 27 to 90 kg liveweight. They were offered food and water ad libitum. Due to significantly greater food intake, the pigs from the pooled treatments with straw grew significantly faster than pigs from the pooled treatments without straw. There were no significant differences in food-to-gain ratio. Pigs with straw spent a large proportion of their time manipulating it. Pigs without straw were less active and spent more time manipulating the pen hardware and other pigs. Pigs with straw played more than those without straw. Pigs in the pooled treatments with straw had significantly lower injury scores. Adventitious bursitis of the hock was significantly reduced by keeping pigs on deep-straw and significantly increased by keeping pigs on slats. The welfare of pigs with straw appeared better than those without straw. There were few significant differences between the two straw treatments or between the two treatments without straw.
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Tail biting is an important animal welfare problem that is known to negatively affect production performance. We studied how tail biting influences the production performance in fattening pigs. Production performance was measured as the average daily gain (ADG), gross feed conversion ratio (FCR), red meat percentage (Meat%). Pigs' genetic merit, gender and breed were taken into account in the analysis. In addition, differences between breeds and genders in the prevalence of tail biting were studied. The data were collected from a farm and they included individual records for 3190 pigs. Altogether, 11.4% pigs were identified as victims. Between boars, females and barrows there were not significant differences in the risk for being a tail biting victim. Yorkshire (Y) pigs were identified as victims more often than Landrace (L) pigs, 13.8% and 10.0%, respectively (p=0.001). Non-victims had a greater ADG than victims (33.4g/d difference in observed means but 10.8g/d difference when adjusted to genetic merit). These values correspond to 1 to 3% reduction in ADG. By contrast, no significant differences between victims' and non-victims' FCR and Meat% were found. The results highlight the need to take into account genetics, breed and other factors affecting production performance when estimating the effects of a health disorder.
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Tail biting is an abnormal behaviour of pigs that is thought to have a multi-factorial origin. It is considered an unpredictable event on farms and is hard to reproduce experimentally. Therefore, a novel approach involving a case control study was used to investigate risk factors for tail biting on commercial units in England. Ninety-two pig farms across England were visited over a period of 11 months. At each visit, the owner or the manager of the unit was interviewed and the unit inspected. Data were recorded on standard forms. Farms were categorised into those that had tail biting in at least one pig in the past 6 months and those that had not. Univariate and logistic regression analyses yielded the following main results. Adding straw in the creep area once or more per day decreased the risk of tail biting 10-fold. Keeping grower pigs on partially or fully slatted floors versus solid floor increased risks of tail biting (odds ratio (OR)=3.2). Using a feeding system with five or more grower pigs per feed space increased risks of tail biting (OR=2.7). A stocking density during the growing phase of 110kg/m2 or greater increased risks of tail biting (OR=2.7). Farms that belonged to a holding of five or more pig units had an increased risk of tail biting (OR=3.5). As the number of pens per stockman increased by one, the risk of tail biting increased 1.06-fold. Tail biting was also associated with the following disease and production information: as the P2 back-fat value increased by 1mm, the risk of tail biting decreased by 1.5-fold; post-weaning mortality above 2.5% was associated with a 3.9-fold increase in the risk of tail biting; presence of respiratory diseases was associated with a 1.6-fold increase in the risk of tail biting. Tail docking was associated with a three-fold increase in the risk of tail biting. This study has identified and quantified some management practices on commercial farms that can be changed to decrease the risk of tail biting in growing and finishing pigs.