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SID 5
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
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Research Project Final Report
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SID 5 (Rev. 3/06)
Project identification
AW0135
Impact of floor types on the health and welfare of pigs
Contractor
organisation(s)
University of Warwick
Coventry
CV4 7AL
54. Total Defra project costs
(agreed fixed price)
5. Project:
Page 1 of 20
£
495,000
start date ................
01 April 2003
end date .................
31 December 2006
6. It is Defra’s intention to publish this form.
Please confirm your agreement to do so. ................................................................................... YES
NO
(a) When preparing SID 5s contractors should bear in mind that Defra intends that they be made public. They
should be written in a clear and concise manner and represent a full account of the research project
which someone not closely associated with the project can follow.
Defra recognises that in a small minority of cases there may be information, such as intellectual property
or commercially confidential data, used in or generated by the research project, which should not be
disclosed. In these cases, such information should be detailed in a separate annex (not to be published)
so that the SID 5 can be placed in the public domain. Where it is impossible to complete the Final Report
without including references to any sensitive or confidential data, the information should be included and
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Executive Summary
7.
The executive summary must not exceed 2 sides in total of A4 and should be understandable to the
intelligent non-scientist. It should cover the main objectives, methods and findings of the research, together
with any other significant events and options for new work.
A total of 103 pig farms, 21 outdoor and 82 indoor, were visited between August 2003 and July
2004. At each visit the farmer was interviewed and one litter of preweaning pigs of 1, 2, 3 and 4
weeks of age were randomly selected and the sow, piglets and pen examined. A pen of pigs was
randomly selected from each of those aged 6, 8, 10, 12, 14, 18 and 22 weeks and up to ten pigs
per age group and their pen were examined. Data were also collected from one pen of up to ten
maiden gilts, pregnant gilts and dry sows. Finally one boar per farm was randomly selected and
examined Data were obtained on herd size and breed lines. With the farmer’s permission a
postal questionnaire was sent to the farm veterinarian to collect data on the health status of the
herd including the diseases present on the farm.
There were 92.4% commercial, 3.3% multiplier and 4.3% nucleus farms. The median herd size
on outdoor farms was 600 (IQR 355-800) and on indoor farms was 290 (IQR 202-390). A total of
11,923 pigs and their environment were examined.
The majority of farms (91.2%) had more than one type of flooring; 96.4% of farms had some
solid pens, 76.2% had some part slatted pens, 65.5% had some fully slatted pens and 20.4% of
farmers reared some stages outdoors. Concrete slats were more prevalent in older age groups,
whereas metal and plastic floors were more prevalent in preweaning and weaning pens. Bedding
was present in 50% of preweaner, 37% of weaner, 57% of grower, 49% of finisher and 92% of
adult accommodation. Straw was used in 87% and woodshavings were used in 11% of bedded
pens.
In this cross sectional study there were associations between floor and bedding type and foot
and limb lesions. The general associations were that soil and straw surfaces were very
protective of lesions associated with hard or abrasive floors but were linked with erosion of the
toe. In indoor housed pigs abrasive surfaces e.g. concrete were associated with sole and skin
erosions in young pigs and hard floors (concrete and slats) were associated with thickening of
skin (calluses) and formation of adventitious bursae (bursitis and capped hock) in older pigs and
adults. In post weaning pigs, a layer of deep bedding reduced the prevalence of capped hocks
and the prevalence of bursitis increased as floors went from solid with deep bedding throughout
to fully slatted with no bedding. Overall, weaner to adult pigs had a lower prevalence of foot and
limb lesions when on solid concrete floors and bedding whilst baby pigs had a higher prevalence
of sole erosions and skin abrasions on such floors. Lactating sows did have different lesion
SID 5 (Rev. 3/06)
Page 2 of 20
prevalences to dry sows, suggesting some change in risk as they moved between
accommodation types. Skin abrasions and body sores were only seen in lactating sows and
sows that could only lie on one side, were large for their crate or of poor body condition had
more skin abrasions than sows that could lie to the left or right, fitted in their crate or were of
good body condition.
When considering injuries between pigs, tail biting was associated with an absence of straw,
while vulva biting and skin lesions over the body were associated with large group sizes and
these were correlated with large yards with solid floors and straw bedding.
The most prevalent foot lesions in growers and adults were sole erosion, toe erosion, and
heel/sole flaps. The importance of these lesions is unclear, but initial studies indicate that they
could be high and, with the evidence of foot lameness in other farm species this warrants further
study.
An abnormal gait was recorded in approximately 20% of pigs. An increased prevalence of
abnormal gait was associated with slatted floors and solid floors with sparse bedding compared
with solid floors with deep bedding in all areas. The prevalence of abnormal gait was higher in
finishers with bursitis, capped hock or calluses, in sows with capped hock and calluses and in
boars with capped hock or high body condition score. Although the feet of pigs that were
locomotion scored were not examined, we hypothesise, given the associations with floor type
that poor gait may be linked to foot abnormalities.
Lesions on pigs that originated from different floors types were pathologically identical; indicating
that different floor types did not produce different lesions with the same gross clinical
presentation.
In preweaning pigs, skin abrasions were mainly superficial uninfected wounds. The pathologist
We speculate that skin abrasions were likely to be associated with pain but would cause little
discomfort to the piglet once healing had begun. In contrast, external foot lesions were
associated with more internal infection and dissolution of the pedal bone. The pathologist
speculated that since space was restricted in the foot, swelling would be painful. In addition, an
infected pedal bone is unlikely to heal.
In post weaning pigs bursitis and capped hock lesions were solid or fluid-filled; this was not
associated with clinical size. The pathologist’s speculation was that pain may be present at the
time of development and the lesions may persist as a protective barrier.
In this study, there was no association between observed or veterinary reported disease and
indoor or outdoor farms or pen flooring.
The council directives 2001/88/EC specifies slat and slot dimensions for concrete slatted floors
for pigs of all ages from preweaning up to adult sows. Overall in the 1,227 pens from the 93
randomly selected farms examined for this study 13% had concrete slats. However, only 0.5%
(2/338) of preweaning piglets and 1.5% (3/195) of weaner pigs were housed on concrete slats.
Concrete slats were used in 32% (136/423) of the growing and finishing pig pens. Only 5%
(7/129) of the slats were within dimensions specified by the 2001/88/EC directive. The void was
too wide in 92% (118/129) of the pens and the slat was too narrow in 25% (32/129) of the pens.
Concrete slats were used in 8% (21/271) of the sow and gilt pens. In 67% (14/21) of these pens
the dimensions of the concrete slats were outside of the directive. The void was too wide in 43%
(9/21) of pens and the slat was too narrow in 24% (5/21).
The pig farms visited were a compliant sample of farms. They were representative of the spatial
distribution of pig farms and of herd size. We do not know if they were representative of floor
types of health and welfare of pigs.
The small number of pens that are within the dimensions specified by the directive meant that
there was not sufficient power for complex statistical analysis. When considering these data the
difficulty in gaining accurate measurements of void and slat widths should be taken into account.
SID 5 (Rev. 3/06)
Page 3 of 20
Wear on the edge of the slat may increase the void width or build up of dirt may reduce the width
of the void by several millimetres.
Floor materials, presence of voids and bedding and floor quality do impact on the health and
welfare of pigs of all ages. The impact varied by the outcome of interest and was not significant
for all outcomes.
This is the first study to examine outdoor farmed pigs. Overall, outdoor systems with soil and
deep bedding were associated with lower prevalences of foot and limb lesions in all ages. There
was no one indoor floor surface that was ‘best’ for pig foot and limb injuries and even in the
same environment the age of pig led to differing disease effects e.g. in preweaning piglets vs
lactating sows.
Project Report to Defra
8.
As a guide this report should be no longer than 20 sides of A4. This report is to provide Defra with
details of the outputs of the research project for internal purposes; to meet the terms of the contract; and
to allow Defra to publish details of the outputs to meet Environmental Information Regulation or
Freedom of Information obligations. This short report to Defra does not preclude contractors from also
seeking to publish a full, formal scientific report/paper in an appropriate scientific or other
journal/publication. Indeed, Defra actively encourages such publications as part of the contract terms.
The report to Defra should include:
 the scientific objectives as set out in the contract;
 the extent to which the objectives set out in the contract have been met;
 details of methods used and the results obtained, including statistical analysis (if appropriate);
 a discussion of the results and their reliability;
 the main implications of the findings;
 possible future work; and
 any action resulting from the research (e.g. IP, Knowledge Transfer).
Below the objectives are listed and explained. All objectives were met in the project
Objective 1. Enrolment of units
A total of 549 breeder-finisher pig farms with >100 breeding sows in England and Wales were randomly
selected from the National Pig Association (NPA) database. In 2003 this contained 85% of all pig farms
in England and Wales and nearly all pig farms with more than 100 breeding sows. The farmers were
contacted and invited to participate in this study and in a study investigating PMWS (Woodbine et al., in
press). A total of 100 farmers from England and one farmer from Wales agreed to take part in the study
(18% compliance). From these, seven farms were used to pilot test data collection methods and 94
farms were used in the main analysis. A further nine farms were non-randomly selected for participation
(five from Scotland, recruited by Quality Meat Scotland and four in England recruited via their
veterinarian) and were included in the study, giving a total of 103 farms, 21 outdoor and 82 indoor. Only
the randomly selected farms in England were included in calculations of prevalence and population
attributable percentages (n=93). As far as it was possible to ascertain these farms were representative
of the population of English farms spatially and by ratio of indoor:outdoor and will be referred to as
‘random’ farms in the remainder of the report. It was not possible to estimate whether they were
representative of all pig farms for other aspects such as floor type or health and welfare standards. The
additional convenience selected farms were included in the risk factor analysis (n=103).
Objective 2. Preparation for farm visits
Between 26/08/03 and 23/09/03 visits were made to seven farms to pilot test scoring systems (Tables
1 and 2) and questionnaires.
Objective 3. Visits to farms
On each farm one litter of preweaning pigs of 1, 2, 3 and 4 weeks of age were randomly selected and
the sow, piglets and pen examined. A pen of pigs was randomly selected from each of those aged 6, 8,
SID 5 (Rev. 3/06)
Page 4 of 20
10, 12, 14, 18 and 22 weeks and up to ten pigs per age group were examined. Data were also
collected from one pen of up to ten maiden gilts, pregnant gilts and dry sows. Finally one boar per farm
was randomly selected and examined. Recordings were made on the number of pigs per pen and their
health and cleanliness. One of eight observers recorded data on pigs and one of eleven observers
collected data on the condition and construction of the pen (Table 2).
An interview was conducted with each farmer at the time of the farm visit. Data were obtained on herd
size and breed lines. With the farmer’s permission a postal questionnaire was sent to the veterinarian
to collect data on the health status of the herd including the diseases present on the farm.
The veterinarians for 96 of the 103 farms visited returned the questionnaire (93.2%). All but one farmer
completed the management interview.
Objective 4. Data management and checking
Data were entered into Microsoft Access 2003 databases. The data were checked for errors and
outliers and obviously incorrect codes were re-checked against the raw data. Calculations were made
from the dimensions recorded in the pens such as space allowance per pig and percentage void in the
slatted area.
Descriptive results
There were 92.4% commercial, 3.3% multiplier and 4.3% nucleus farms. The median herd size on
outdoor farms was 600 (IQR 355-800) and on indoor farms was 290 (IQR 202-390). A total of 11,923
pigs were examined (Table 3). The three most common breed crosses used on farms were Large
White x Landrace (41 farms), Large White x Landrace x Duroc (26 farms) and Large White x Landrace
x Pietrain (10 farms).
Table 1 Health and welfare observations
Limb lesions – recorded in all ages of pigs
Bursitis; fluid filled sacs in the subcutaneous tissue
0 = no lesion
Capped hock; bursa swelling on the point of the hock joint on the hind limb
1 = <25%
Skin abrasion; loss of the outer epidermis of the cranial surface
2 = 25-50%
Callus; thickening and hardening of the skin
3 = >50% of the size of the
Hairless patch; hair is missing but no damage on the skin is apparent
limb joint
Swollen joint; swelling of the digital or carpal joint
Foot lesions - recorded in preweaning, 6, 8, 14 weeks, maiden gilts and sows
Toe/sole/heel erosion; loss of horny tissue
0 = no lesion
Heel flaps; peeling of the superficial layer
1 = just identifiable lesion
Heel corrugation; corrugated and flaky appearance
2 = clearly identifiable lesion
Sole/heel bruising; congestion and bruising of the solar corium presenting
but where structural damage
Overgrown hooves; long hooves with elongated toes and a concave sole
is minimal
Unequal claw size; visible inequality in size between the medial and lateral claw
3 = obvious lesion resulting in
Wall crack (False sand crack); a crack on the axial or abaxial surface of the wall, severe structural damage and
which varies from a fine crack to a wide fissure with necrotic edges
possible discomfort
Wall bruise; dark red pigmentation on the horn of the wall
Wall penetration; loss of part of the hard horn of the wall
White line lesions; black line in laminae separating the wall from the sole
Wall separation; penetration of the white line by debris with a visible gap
Behaviour and locomotion
Initial response to human
0 = Bright alert and responsive pigs rise immediately and approach inquisitively
presence
1 = Bright but less responsive, may remain down, or dog sitting, before
Recorded in finisher pigs,
eventually rising
gilts, boars, dry and lactating
2 = May be dull, only rises when strongly motivated
sows
3 = Dull and unresponsive, not willing to rise
Standing posture
0 = stands squarely on all four legs
Recorded in finisher pigs,
1 = Uneven posture
gilts, boars, dry and lactating
2 = Will not bear weight on affected limb
sows
3 = Affected limb elevated off floor
4 = Will not stand unaided
SID 5 (Rev. 3/06)
Page 5 of 20
Gait
Recorded in finisher pigs,
gilts, boars and dry sows
Body lesions
Tail biting
Recorded in post weaning
pigs
Old; scars which have healed
with no blood or scabs
evident
New; fresh open or healing
wounds
Body sores
Recorded in lactating sows
Scored on the shoulders,
back bone, hip bones and at
base of tail
Old; scars which have healed
with no blood or scabs
evident
New; fresh open or healing
wounds
Scratch marks
Recorded in all ages
Surface skin damage, mostly
scratches from fighting on the
head and neck, shoulders,
trunk and hindquarters
Vulva damage
Recorded in gilts and sows
Old; scars which have healed
with no blood or scabs
evident
New; fresh open or healing
wounds
Body condition score
Recorded in gilts, sows and
boars
0.5 intervals using the MLC
scoring system
Group observations
Coughs and sneezes
Frequency during observation
period recorded in all age
groups
Manipulation of the
environment
Number of pigs observed
during observation period in
sows only
SID 5 (Rev. 3/06)
0 = Even strides. Caudal body sways slightly while walking. Pig is able to
accelerate and change direction rapidly
1 = Abnormal stride length, movements no longer fluent. Pig still able to
accelerate and change direction
2 = Lameness detected. Swagger of caudal body while walking. No hindrance in
pig’s agility
3 = Minimum weight-bearing on affected limb. Will still trot and gallop
4 = Pig may not place affected limb on the floor while moving
5 = Does not move
0 = no signs of biting
1 = signs of biting but full length of tail intact
2 = <50% of tail length lost
3 = >50% of tail length lost
0 = no body sores
1 = area of redness/soreness where the surface of the skin is not broken or a
small area of broken skin (<2cm)
2 = moderate area of broken skin (2-4cm)
3 = large area of broken skin (>4cm)
0 = no scratch marks
1 = <5 scratch marks
2 = 5-10 scratch marks
3 = >10 scratch mark
0 = no vulva damage
1 = damage is identifiable but the vulva is not misshapen
2 = clear damage is evident and vulva is misshapen
3 = the majority of the vulva is misshapen and parts of the vulva may be missing
1 = Sow is visually thin with hips and backbone very prominent and no fat cover
over hips and backbone.
2 = The hipbones and backbone are easily felt without any pressure on the palm
of the hands
3 = It takes firm pressure with the palm to feel the hip bones and backbone
4 = It is impossible to feel the bones at all, even with pressure on the palm of the
hand.
5 = The sow is carrying so much fat that it is impossible to feel the hip bones and
backbone even by pushing down with a single finger
Occasional = cough/sneeze approx. every 5-10min
Regular = cough/sneeze approx. every 2-3 min
Continuous = cough/sneeze approx. every min
0= no pigs manipulating environment
1 = <25% of the pigs manipulate the environment
2 = 25-50% of the pigs manipulate the environment
3 = >50% of the pigs manipulate the environment
Page 6 of 20
Size uniformity
Recorded in weaners and
growers
Even = pigs are predominantly of one size
Variation = there is some variation with 1-2 smaller or larger pigs but the
majority are of one size
Uneven = pigs are of uneven sizes and a predominant group of one size is not
apparent
Cleanliness
Recorded in all age groups
0 = None of the skin is covered with dirt
1 = <25% of the skin area is covered with dirt
2 = 25-50% of the skin area is covered with dirt
3 = >50% of the skin area is covered with dirt
Diarrhoea
Recorded in all age groups
Eye and nose discharge
Recorded in all age groups
Presence / absence
Presence / absence
Table 2 Summary of pen observations
Pen design
Dimensions; dunging area, lying area, creep area, total area
Internal divisions within the pen; number of divisions, width of doorways created
Steps in the pen; number, location, height
Pen floor
Floor type; solid, part slatted or fully slatted, Floor material; soil, concrete, metal or plastic
Slats
Void dimensions; area, width and length (if more than one void size in the pen largest used)
Percentage void in the slatted area, Shape of void; rectangle, diamond or oval
Slat descriptions; curved or flat profile, textured or smooth surface, sharp or smooth edged
Condition of floor; lying area, dunging area, front of feeder, front of drinker
Wetness, Fresh dung, Dry slurry, Wet slurry, Food, Sharpe edges, Damage, Wear, Slip and skid marks
Bedding
Bedding material; straw or wood shavings, Depth of bedding; deep or sparse
Condition of bedding; cleanliness and dryness, Location of bedding; lying area or dunging area
Feeder/drinker
Type of feeder; floor, hopper, trough, drop, bowl, ESF,Automatic or manual
Feeder/drinker dimensions and number, Type of drinker; bite, nipple, bowl, trough
Toys
Type and number of toys present
Table 3 Number of pigs and pens in sample including data from non random farms
Approximate age range No. of pigs No. of pens
Group of pigs
Preweaning pigs
3-28 days
3203
339
Weaner
6-8 weeks
1984
200
Grower
10-14 weeks
2763
277
Finisher
18-22 weeks
1638
169
Maiden gilts
6 months +
687
87
Pregnant gilts
7 months +
534
74
Dry sows
12 months +
679
85
Lactating sows
12 months +
339
339
Boars
6 months +
96
96
Total
11 923
1 666
The number of piglets per litter ranged from 3-16 with a mean of 9.7. The median number and IQ range
of pigs per pen varied by age; with 40 (20-70.3) in weaners, 30 (19-59.8) in growers, 18 (13-31.8) in
finishers, 9 (6-13) in gilts and 12 (6-40) in dry sows. The median group sizes (and inter-quartile range)
were similar by indoor floor types with a median of 20 – 22 pigs in solid concrete, part slatted fully
slatted floored pens. Group sizes were approximately double in outdoor pens.
SID 5 (Rev. 3/06)
Page 7 of 20
90
80
% of age group
70
60
50
Preweaning
Weaner
Grower
Finisher
Adult
40
30
20
10
0
Soil
Solid concrete
Part slatted
Fully slatted
Floor type
Figure 1 Floor types used by each age group
Pen details
The majority of farms (91.2%) had more than one type of flooring; 96.4% of farms had some solid pens,
76.2% had some part slatted pens, 65.5% had some fully slatted pens and 20.4% of farmers reared
some stages outdoors (Figure 1). Concrete slats were more prevalent in older age groups, whereas
metal and plastic floors were more prevalent in preweaning and weaning pens (Figure 2). Bedding was
present in 50% of preweaner, 37% of weaner, 57% of grower, 49% of finisher and 92% of adult
accommodation. Straw was used in 87% and woodshavings were used in 11% of bedded pens.
100
Preweaning
Weaning
Grower
Finisher
Adult
90
80
70
%
60
50
40
30
20
10
0
Concrete slats
Plastic slats
Metal slats
Metal and plastic
Floor type
Figure 2 Slat materials used for each age group
A total of 36.0% of 628 pens contained toys, the most popular of which were chains (56%), balls (11%),
pipes (10%) and plastic containers (6%). Other toys included tyres, salt licks, wooden planks and
barrels. Toys were used fairly evenly throughout weaner (33%), grower (37%) and finisher (38%)
accommodation. There was no bedding or toy present in 50% of part slatted and 33% of fully slatted
pens
A total of 91% of farmers mixed their pigs at weaning, 26% of these pigs were not mixed again, 19%
were mixed once more and 25% twice or more. In sows housed in small groups 30% (of 46 farmers)
did not mix the groups between weaning and farrowing, 50% mixed them once and 18% mixed sows
twice or more. The median space allowance per pig was greater then the EU directive for all ages, but
a proportion of pigs of each age group were estimated to be overstocked using a conversion of age for
weight.
SID 5 (Rev. 3/06)
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Objective 5. Data analysis
Pigs without clinical signs of a lesion were not affected histologically but there was no difference in the
severity of the histopathology by size of external lesion for bursitis, sole erosions and sole bruising (see
objective 6). Therefore the clinical lesion was coded as present or absent in the analyses of outcomes
from Table 1. In contrast score 1 lesions were pathologically different to scores 2 and 3 for capped
hock and data were analysed with score 1 coded as normal or abnormal.
A pig was classed as affected with a lesion when at least one of that lesion was observed. Multilevel
binomial logistic regression models were used to identify factors associated with lesion prevalence with
litters / pens clustered within farms. For all models the outcome was the proportion of affected pigs
from the sample examined in that pen / litter. Floor type and bedding use were combined to create a
single variable that allowed all pens to be included in one model. All models were adjusted for age of
pigs and observer.
The models took the form: Yij = β0 + ∑βnXij + γnXj + v0j + u0ij
Where B0 = intercept, β1-n = coefficients for Xij Xij = variables varying between pens, γ1-n = coefficients for Xj, Xj = variables
varying between farms, v0j = residual error between farms, u0ij = residual error between pens, j = farms and i = pens.
The population attributable percentages were calculated as
%AFp = [RD * p(E+) / p(D+)]*100
Where %AFp is the population attributable percentage, RD is the prevalence of a lesion in the exposed group minus the
prevalence of a lesions in the baseline category group, p(E+) is the proportion of pigs on each floor type and p(D+) is the
proportion of pigs with a lesion on each floor type.
Results
All results presented are adjusted OR (odds ratios) with all variables measured in Table 2 tested in the
models. OR presented are significant at p≤0.05 with 95% CI not including 1; these are not presented
because of space limitations. An OR>1 = an increased association and <1 a decreased association.
Preweaning piglets
A total of 338 litters; 288 indoor and 50 outdoor were examined. All outdoor lactating sows and piglets
were housed in huts set on soil with deep straw bedding. In the litters housed indoors 12% were on
solid concrete floors with bedding, 20% on part slatted floors with bedding on all areas of solid
concrete, 18% on part slatted floors with bedding in some areas, 35% on part slatted pens with no
bedding and 15% on fully slatted floors without bedding. Overall 78% of indoor housed piglets had at
least one foot or limb injury compared with 9% of piglets housed outdoors. The prevalence of skin
abrasions, sole bruising and sole erosion was 50%, 75% and 17% respectively in indoor piglets
compared with 5%, 1% and 5% in outdoor piglets respectively; 5% of indoor piglets and no outdoor
piglets had swollen joints.
The prevalence of sole bruising and skin abrasions decreased with each week of age from 1-4 weeks.
In indoor housed piglets there was an increased prevalence of sole bruising associated with part
slatted (OR 3.0) and fully slatted floors (OR 3.0) and an increased prevalence of sole erosion on part
solid floors where some (OR 2.9) or all (OR 2.4) areas of solid concrete were exposed compared with
piglets housed on solid concrete floors with bedding. In piglets less than 1 week of age, there was a
reduced prevalence of skin abrasions associated with fully slatted (OR 0.2) and part slatted floored
pens without bedding (OR 0.3) and a higher prevalence of skin abrasions in pigs on rough floor
surfaces in the sow lying area, where the piglets lay to feed (OR 3.5)
Lactating sows
Limb Injuries
Overall 98% of indoor and 69% of outdoor housed sows had at least one limb lesion. The prevalence of
bursitis, capped hock (score 2-3 only), calluses (score 2-3 only) and skin abrasions was 38%, 67%,
33% and 19% respectively. The prevalence of all of these lesions was significantly lower in outdoor
sows. No skin abrasions were observed on outdoor sows.
In sows housed indoors the prevalence of bursitis increased (OR 1.5) with each week of lactation with
the prevalence of calluses following a similar but non significant trend. Conversely, the prevalence of
SID 5 (Rev. 3/06)
Page 9 of 20
skin abrasions decreased significantly with week of lactation (OR 0.5). The dry sow accommodation
floor type prior to farrowing was not significantly associated with the prevalence of any of the limb
lesions observed in the farrowing house. The prevalence of bursitis decreased (OR 0.3) and the
prevalence of capped hock increased (OR 2.1) with increasing body condition score.
There was an increase in prevalence of capped hocks in sows housed on part slatted floors with no
bedding (OR 4.2) and fully slatted floors (OR 5.4) and an increase in prevalence of calluses in sows
housed on part slatted floors with bedding (OR 5.0), without bedding (OR 5.4) and on fully slatted floors
(OR 11.0) and an increase in prevalence of skin abrasions in sows on fully slatted floors (OR 10.8) all
compared with sows housed on solid floors with bedding.
There was an increase in prevalence of skin abrasions in sows that were only able to lie on one side
(OR 4.6), and in sows in crates with a moveable bottom bar (OR 3.8). There was a reduced prevalence
of skin abrasions in sows with 5-10cm (OR 0.2) and >10cm (OR 0.3) from the spine to the top of the
crate when standing compared with sows that had less than 5cm between their spine and the top of the
crate.
Body Injuries
There were body injuries on 35% of lactating sows. These were old injuries in 17% and new injuries in
20% of sows. Injures were located on the shoulder (19%) hip (9%), tail (4%) and back (11%). There
was a reduced prevalence of injury in outdoor housed sows compared with indoor (OR 0.3). There was
no association between floor type, crate size or sows behaviour in the farrowing accommodation and
the prevalence of old body injuries.
There was no association between the week of lactation and prevalence of new body injuries but there
were fewer new body injuries with increasing body condition score (OR 0.5). There was a higher
prevalence of body injury in sows on fully slatted floors (OR 5.4) compared with sows on solid concrete
floors with bedding. There was a trend for a lower prevalence of new body injuries in sows with 1020cm between their tail and the back of the crate and a significantly lower prevalence associated with
sows with more than 20cm (OR 0.2) compared with a reference category of sows with <10cm between
the sows tail and the back of the crate.
Foot lesions
Data were collected on the hind left foot of 229 indoor housed sows; it was not possible to collect data
on the feet of outdoor housed sows because the sows were unrestrained. The overall prevalence of
foot lesions was 76.9%. Lesions were most prevalent on the volar surface of the foot. Abnormal hoof
growth and all lesions on the hoof wall or the wall/volar junction occurred at a prevalence of 10% or
less. The three most prevalent lesions were sole erosion, toe erosion and heel flaps.
There was no significant association between the week of lactation and the prevalence of sole erosion,
toe erosion or heel flaps. Sows on slatted floors had a higher prevalence of sole erosion (OR 6.2)
compared with those on solid floors with bedding. There was an increased prevalence of sole erosion
in sows kept on a worn, rough lying area (OR 2.9) while those on the slats with sharp edges in the lying
area had a higher prevalence of toe erosion (OR 5.3). Sows that had came from dry sow
accommodation with slatted floors had a higher prevalence of heel flaps (OR 4.6) and a reduced
prevalence of toe erosions (OR 0.2) compared with those kept on solid concrete floors.
Post weaning pigs
6250 post-weaning pigs from 646 pens on 103 farms were examined. Of these, 21 farms reared at
least some stages of pigs outdoors. There were 58 pens (9%) with a soil floor, 249 (39%) with a solid
floor, 162 (25%) that were part slatted and 175 (27%) that were fully slatted; 283 (44%) pens had
bedding.
Limb Lesions
The prevalence of lesions was bursitis (41%), capped hock (17%) and calluses (47%). The prevalence
of capped hock (OR 1.2) and bursitis (OR 1.1) increased with each week of age, with a prevalence of
37% for capped hock and 59% for bursitis at 22 weeks. There was no significant association between
the prevalence of skin calluses and age.
SID 5 (Rev. 3/06)
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There was an increase in the prevalence of bursitis in pigs housed on solid concrete floors with deep
bedding (OR 4.6), sparse bedding in part (OR 3.7) or sparse in all areas (OR 9.0), part slatted (OR 8.0)
and fully slatted floors (OR 18.7) compared with pigs housed on soil floors. There was an increase in
the prevalence of skin calluses in pigs on solid concrete floors with deep bedding (OR 3.6), sparse
bedding in parts (OR 3.6) or sparse throughout (OR 7.6), part slatted (OR 14.5) and fully slatted floors
(OR 14.7) compared with soil floors. For both bursitis and skin calluses there was no significant
difference in the prevalence in pigs kept on solid floors where the bedding was deep either in part or all
the pen.
There was an increase in the prevalence of capped hocks in pigs housed on solid concrete floors
where bedding was sparse in part (OR 3.2) or all of the pen (OR 3.1) and part slatted (OR 3.7) and fully
slatted floors (OR 3.8) compared with pigs kept on soil floors. There was no significant difference
between soil floors and deeply bedded solid floors (OR 1.9).
Among pigs housed on slats those kept on metal floors had a higher prevalence of bursitis (OR 1.7)
and a lower prevalence of capped hock (OR 0.4) when compared with pigs on concrete. Concrete slats
had a smaller void:slat ratio compared with plastic slats and metal slats
Foot Lesions
Foot lesions were observed on the left hind foot of 39% of 2454 pigs. The most prevalent lesions were
toe erosions (11%), sole erosions (10%), heel/sole flaps (8%) and sole bruising (7%); 11.0% of pigs
had more than one lesion.
There was a decrease in the prevalence of sole bruising and sole erosion and an increase in the
prevalence of heel/sole flaps and toe erosion in 8 and 14 week old pigs compared with a baseline of 6
week old pigs.
There was an increase in the prevalence of sole bruising, sole erosion and heel/sole flaps on all floor
types compared with soil floors. There was an increase in the prevalence of toe erosion on soil floors
compared with all other floor types except deeply bedded solid concrete pens.
Concrete slats were characterised by large void widths and lengths, but also a large slat surface area.
Plastic slats were characterised by a small void area and flat slat profile and about 40% void in the
slatted area. Sole bruising, sole erosions and heel/sole flaps were more prevalent in pigs on slatted
floors with properties of plastic slats, whereas the lowest prevalence of toe erosion was seen on slatted
floors with properties of concrete slats.
The most tightly stocked quintile of pigs (stratified by age) was associated with a greater prevalence of
sole bruising compared with all other more loosely stocked pens.
Locomotion
An abnormal gait was recorded in 19% of 1638 finishing pigs. There was a higher prevalence of
abnormal gait in pigs on sparsely bedded concrete floors (OR 6.2), part slatted floors (OR 5.9) and fully
slatted floors (OR 9.5) compared with a baseline of solid concrete floors with deep bedding. Factors
associated with poor walking conditions (a wet floor and dry slurry in the dunging area) were
associated with a greater prevalence of abnormal gait. As the severity of bursitis, capped hock and
calluses increased, the prevalence of abnormal gait increased.
Dry sows and gilts
Limb Lesions
A total of 3640 dry sows, pregnant and maiden gilts were examined from 246 indoor pens and 34
outdoor paddocks. Indoors, 8% of pens had slatted floors, this included some part and some fully
slatted floors, 7% had sparse bedding in the lying area only, 10% had deep bedding in the lying area
only, 19% had sparse bedding all over the pen, 31% had bedding all over the pen that was sparse in
some areas and deep in others and 22% had deep bedding all over the pen.
The prevalence of bursitis in 2132 sows and gilts from 93 random farms was 31% and the prevalence
of skin calluses was 44%. The prevalence of capped hock was 13% when pigs with score 2 and above
were classified as affected. Multiparous sows had a higher prevalence of capped hock (OR 2.5) and
SID 5 (Rev. 3/06)
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calluses (OR 1.8) but not bursitis compared with maiden gilts. However there was no difference in the
prevalence of bursitis, capped hock and calluses between maiden and pregnant gilts. Indoor housed
sows and gilts had a higher prevalence of bursitis (OR 3.3), capped hock (OR 3.2) and calluses (OR
14.1) compared with outdoor housed sows and gilts.
There was an increased prevalence of bursitis on sows in pens with slats (OR 2.0) and pens with
bedding all over the pen where the bedding was sparse in some (OR 1.9) or all (OR 1.8) areas when
compared with sows in pens with solid concrete floors with deep bedding all over the pen. There was
an increased prevalence of calluses in pigs in pens with slatted floors (OR 4.7) and floors where the
bedding was sparse in the lying area (OR 3.5) in the dunging area (OR 2.1) or all over the pen (OR
2.2), There was no association between floor type and the prevalence of capped hock in dry sows and
gilts. There was no association between the sow body condition score and the prevalence of bursitis in
dry sows and gilts.
Gait
Multiparous sows had a higher prevalence of abnormal gait compared with maiden gilts (OR 1.6) but
there was no difference between pregnant and maiden gilts. An increased prevalence in abnormal gait
was associated with slatted floors (OR 4.4) and sparse bedding all over the pen (OR 2.1) compared
with solid floors with deep bedding in all areas. There was an increased prevalence of capped hock
score 2 or 3 (OR 1.8) and calluses (OR 1.5) associated with an abnormal gait.
Foot Lesions
The hind left foot of 1174 dry sows and 446 maiden gilts was examined. The overall prevalence of foot
lesions was 71% in dry sows, and 37% in maiden gilts. The prevalence of 11 types of lesion was
recorded, a large number of these occurred with a low prevalence. The most prevalent lesions were
sole erosion, toe erosion, and heel flaps. These three lesions were investigated in more detail
There was no association between the floor type and the prevalence of foot lesions. This may occur
because the maiden gilts are likely to have recently changed accommodation and may not have been
housed in the current pen long.
There was a reduced prevalence of any foot lesion (OR 0.6) in outdoor dry sows (60%) compared with
indoor (74%). There were fewer volar lesions in outdoor housed sows compared with indoor (OR 0.5);
when the most prevalent lesions types were investigated individually there was a reduced prevalence
of sole (OR 0.3) and toe erosion (OR 0.3) in outdoor housed sows but an increased prevalence of heel
flaps (OR 2.2). There was an increased prevalence of one or both claws overgrown (OR 1.2) and sole
erosion (OR 6.7) with increasing parity.
There was an increased prevalence of toe erosion in pigs housed on floors with sparse bedding in the
lying area (OR 6.4), or pens with sparse and deep bedding all over the pen (OR 3.0).
Boars
Data were collected on 102 boars; 89 indoor and 13 outdoor. Among the indoor housed boars 95.5%
were on solid concrete floors with straw bedding and 4.5% were housed on part slatted floors. Indoor
housed boars were in individual pens in 68% of cases and group housed with sows in 22% of cases.
There was little variation between farms in floor type and provision of bedding which meant there were
few explanatory variables to be investigated.
Limb Injuries
Bursitis, capped hock and calluses score 1-3 were present on 25%, 38% and 61% of boars
respectively. There was a reduced prevalence of calluses in outdoor housed boars (OR 0.2) and a
trend for reduced prevalence in group housed indoor boars. No other associations between type of
housing and prevalence of limb lesions were detected. Within indoor housing there was no association
between the prevalence of any limb injury and the bedding depth or cleanliness. There was an
increased prevalence of calluses with increasing body condition score (OR 4.9) but no association
between the body condition of the boar and the prevalence of bursitis or capped hock.
SID 5 (Rev. 3/06)
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The boar’s response to human presence was ‘bright, alert and responsive’ in 95% of cases and 87%
had a normal gait. The prevalence of abnormal gait was higher when boars had capped hock (OR
10.6) and with increasing body condition score (OR 6.0).
Injuries inflicted by other pigs
Tail Biting
Tail biting was observed on 52% of farms. The maximum prevalence in the sample examined on a farm
was 43% but the median was 6% (IQR 0 - 6%); a total of 82% of farmers reported tail biting on their
farm. The majority of farmers reported an average prevalence of <1%. Tail biting was observed in 16%
of pens (35% of pens on affected farms). The maximum prevalence seen in a sample from one pen
was 67% but the median prevalence in affected pens was 10% (IQR 10%-20%). A total of 3% of all
pigs examined had bitten tails. The prevalence of tail damage was greatest in the growers and finishers
(3.3%) and lowest in the weaner age group (1.8%). The occurrence of new tail damage almost doubled
in the 14-22 week old pigs compared with the 6-12 week old pigs.
A total of 82% of farmers routinely docked tails. The average prevalence of tail biting on farms that
routinely tail docked was 2.6% compared with 3.4% on farms that did not tail dock. Of the farmers who
reported tail biting, 93% stated that they used preventive measures; 55% of these farmers considered
the measures successful, and 35% of farmers partially successful. The most commonly used
preventive measures were toys followed by tail docking and the addition of extra salt to the diet. The
addition of bedding as a preventive measure was only employed by 5 farmers of which 4 considered it
a successful strategy.
Where pigs were housed on bedding the prevalence of tail biting reported by the farmers was
significantly lower - weaners (OR 0.3), growers (OR 0.1) and finishers (OR 0.2). Many other variables,
such as solid floors, and low stocking densities were correlated with the presence of bedding.
Scratch Marks
Post-weaning pigs
The overall prevalence of scratch marks was 78% of 5618 pigs. The prevalence ranged from 65% in 6
week olds to 86% in 12 week olds. The greatest prevalence of scratch marks was on the head area
(56%), followed by the shoulders (55%), the trunk (46%) and finally the hindquarters (37%). When a pig
was affected it was most likely to have a lesion on all 4 locations (31%), followed by 1 location (28%), 2
locations (26%) and 3 locations (15%). The median proportion of pigs affected in a pen varied by
location of scratch marks; head 0.6, shoulders 0.6, trunk 0.4 and hindquarters 0.3. There was a
significantly greater prevalence of scratch marks in grower pigs and a significantly lower prevalence of
scratch marks in weaner pigs compared to the finisher pigs.
Scratch marks were most common on deeply bedded solid concrete floors (85%) and least common on
part slatted floors with no bedding (73%). There was a higher prevalence in scratch marks on the head,
shoulders and hindquarters of pigs on all other floor types compared with part slatted floors. There was
a higher prevalence of scratch marks on the trunk of pigs on part slatted floors compared with all floor
types except soil floors which were associated with the lowest prevalence of scratch marks to the trunk
area. There was an increase in prevalence of scratch marks on both plastic and metal slats compared
with concrete slats in the head, trunk and hind quarters. There was no significant association between
slat material and shoulder scratches.
Gilts and dry sows
The overall prevalence of scratch marks in the sows and gilts from the random farms was 73% of 1961
pigs. The prevalence was 63% in pregnant gilts, 66% in maiden gilts and 86% in dry sows. The
greatest prevalence of scratch marks was on the head (49%) followed by the shoulders (46%), the
trunk (35%) and finally the hindquarters (32%). Pigs were most likely to be affected at one location
(35%). The median proportion of pigs affected in a pen varied by location of scratch marks; head area
0.5, shoulders 0.4, trunk 0.3 and hindquarters 0.3.
Due to the nature of housing and management of gilts and sows, there were many correlated variables
which could not be entered into the model at the same time. Therefore the following results are quoted
at univariate level only. There was an increase in the prevalence of scratch marks on all locations with
increasing group size. There was a significant increase in the prevalence of scratch marks in sows
SID 5 (Rev. 3/06)
Page 13 of 20
compared with maiden and pregnant gilts. There was a decrease in the prevalence of scratch marks
around the head in pregnant gilts compared with maiden gilts (OR 0.4) and an increase in the
prevalence on the hindquarters (OR 1.4).
The lowest prevalence of scratch marks was in sows and gilts housed outdoors (56%) and the highest
prevalence was on solid concrete floors with deep and sparse bedding (81%). There was a significant
increase in the prevalence of scratch marks on all indoor floor types compared with outdoor housing.
There was a significant increase in the prevalence of scratches in all locations in sows housed in yards
compared with those housed in pens (OR 3 - 5).
There was a greater prevalence of scratch marks with decreasing body condition score.
Boars
Overall 42% of 102 boars had scratch marks on the body. The greatest prevalence of scratch marks
was on the shoulders (27%) followed by the head (19%), the hindquarters (17%) and finally the trunk
(9%). There was a trend for a greater prevalence of scratch marks when boars were group housed as
would be expected if these lesions are caused by other pigs. There was a prevalence of 55% in 20
indoor group-housed boars, 54% in 13 outdoor group housed boars and 36% in 64 boars housed
individually.
Vulva Biting
Injuries to the vulva were observed on 83% of the farms. This is similar to the 77% reported by farmers
at interview. The median prevalence of affected sows on affected farms was 15% (IQ 9-21) with a
maximum of 35% on any one farm. The median prevalence within affected pens was 30% (IQR 20-50).
There was a significantly higher prevalence of vulva damage in dry sows compared with maiden gilts
(OR 0.1) and pregnant gilts (OR 0.04). There was no difference in prevalence between maiden and
pregnant gilts. The prevalence of vulva damage in dry and lactating sows was very similar. There was
no significant association between prevalence of vulva damage and floor type or bedding depth. Indoor
pens were associated with a significantly lower prevalence of vulva biting than yards (OR 1.9). Yards
were correlated with electric sow feeders and large group sizes, both of which were associated with
vulva biting. There was no association between body condition score and the prevalence of vulva
damage.
Pen health and farm disease
Hygiene
Overall, 55% of all pigs had <25% dirty skin, 23% had 25-50% and 8% had >50% covering. Although
pigs in outdoor pens were slightly dirtier than those in indoor pens, there was no difference between
solid or slatted floor on the cleanliness of pigs kept indoors.
Health
The prevalence of discharge from the eyes was 32% in 10547 pigs of all ages. The greatest prevalence
was observed in maiden gilts (57%). In pre-weaning pigs the greatest prevalence of eye discharge was
seen on fully slatted floors and was lowest on solid floors with bedding. In older pigs the greatest
prevalence was on solid floors and the lowest prevalence was on part slatted floors. The prevalence of
nasal discharge was 0.7% of 10546 pigs. The greatest prevalence was 2% in 3 week old pigs. Routine
tooth clipping was practised on 77% of farms.
The percentage of pens with evidence of pigs with diarrhoea was 13%, in pre-weaning pens the
prevalence was approximately 28% and then decreased with age. Coughing and sneezing was heard
occasionally in 23% of pens, regularly in 7% of pens and continuously in 1% of pens. Coughs and
sneezes were most prevalent in growing pigs.
Overall, 2% of piglets were thin and small for age, 6% of piglets were small for age but otherwise well
and 0.8% of piglets were well grown but sick. There was some variation in size of pigs in 54% of
weaner and grower pens and very uneven sizes in 12% of pens.
In 17% of dry sow and gilt pens there was <25% of the group manipulating the pen, in 6% of pens 2550% of the sows were observed manipulating and 3.5% of pens there was >50% of the sows
manipulating. Lactating sows were seen manipulating the pen occasionally (18%) or regularly (8%).
SID 5 (Rev. 3/06)
Page 14 of 20
There was no effect of floor type on the prevalence of coughing/sneezing or size uniformity of pigs in a
pen. None of these pen-level health observations were associated with diseases present (but not
necessarily active) on the farm as stated by the veterinarian.
Disease
A farm level prevalence of 33 diseases was estimated from the questionnaire completed by the farm
veterinarian. Respiratory disease was reported on 93% of farms, alimentary disease on 95% of farms
and oronasally transmitted diseases were reported on 77% of farms.
It was not possible to create a farm-level floor variable which adequately represented all floor surfaces
on each farm. Therefore soil, solid, fully slatted and part slatted floor types were all added as binary
non-exclusive variables. There was no association between any floor type and any particular disease.
There were only 3 farms which did not use bedding at any point in their system and therefore the effect
of bedding with relation to disease could not be assessed.
Population Attributable Percentages
This was calculated for all outcomes with a significant association with floor type (Table 4). These
percentages rely on the prevalence of the lesion and of the floor type to calculate the percentage
change in affected pigs if all the pigs were housed on the floor type with the lowest prevalence (the
baseline B). For example, if all piglets that were housed on fully slatted floors were housed on soil with
bedding, then the percent of pigs with skin abrasions would be reduced by 13%, that is 13% of current
skin abrasions are attributable to fully slatted floors. The overall reduction in skin abrasions, if all piglets
were housed on soil and straw is the sum of the categories i.e. 89.1%% reduction.
Table 4 Population attributable percentages for outcomes that were significantly affected by floor type
(B indicates baseline category, grey cells indicate a non significant relationship)
Preweaning piglets
Outcome
Soil and
straw
Hairless
patches
Skin
abrasions
Sole
erosions
Sole
bruising
Outcome
Weaners
Bursitis
Capped hock
Callus
Heel/sole flap
Sole bruising
Sole erosion
Toe erosion
Growers
Bursitis
Capped hock
Callus
SID 5 (Rev. 3/06)
Solid with
bedding
Part slatted
All bedded
Some
bedding
No
bedding
Fully
Total
slatted reduction
B
9.6
10.6
7.7
15.2
8.4
51.5
B
12.3
15.9
18.0
29.9
13.0
89.1
B
5.5
8.5
19.1
33.8
B
8.7
19.5
19.6
35.2
Soil Deeply
bedded
solid
concrete
B
B
B
B
B
B
5.0
5.2
Deep and
sparsely
bedded
solid
concrete
Sparsely
bedded
solid
concrete
7.8
11.2
5.8
3.1
Part
slatted
no
bedding
9.9
5.9
7.2
8.1
10.4
8.0
14.3
Fully
slatted no
bedding
97.3
Total
reduction
5.7
31.1
25.3
32.2
55.2
45.9
28.4
45.7
40.4
29.1
38.1
31.9
28.4
32.1
84.6
81.9
75.4
93.3
77.8
62.5
32.1
9.0
9.3
11.0
26.1
18.1
28.5
32.1
30.7
26.7
85.2
74.4
81.4
B
B
B
B
66.9
Page 15 of 20
Heel/sole flap
Sole bruising
Sole erosion
Toe erosion
B
18.4
B
34.6
B
21.2
45.7
48.7
39.6
45.7
34.6
48.7
B
Finishers
Bursitis
Capped hock
Callus
Abnormal
gait
Deeply
bedded
solid
concrete
B
B
B
Deep and
sparsely
bedded solid
concrete
Sparsely
bedded
solid
concrete
8.9
8.3
B
11.5
Part
slatted no
bedding
Fully
slatted no
bedding
Total
reduction
13.4
10.9
15.0
26.0
17.5
23.5
48.3
28.4
38.5
11.5
36.6
59.6
Dry sows and gilts
Outdoor
Lying area
bedding
Sparse
Bursitis
Callus
Capped hock
(score 2-3)
Bedding all over pen
Deep Sparse
B
B
1.7
4.4
4.7
6.1
11.4
14.9
B
2.3
2.7
3.1
Sparse /
deep
21.6
29.8
7.4
Slatted
Total
reduction
7.9
14.3
5.5
8.9
52.8
78.4
4.6
2.4
22.5
Deep
Lactating sows
Bursitis
Capped hock
(score 2-3)
Calluses
Skin abrasions
Part slatted
Total
Fully
reduction
slatted
Outdoor
Solid
concrete
B
7.5
15.4
31.3
6.5
60.7
B
7.1
10.0
49.8
9.8
76.7
B
B
6.1
9.3
16.3
7.4
39.9
61.6
13.0
18.5
75.3
96.8
with bedding
without bedding
Objective 6. Pathology of foot and limb lesions
Two farms were used in this study; one with slatted floors and one with solid floors. Two examples of
each severity score 0-3 for sole bruising, sole erosion and skin abrasion in preweaning piglets and
capped hock and bursitis in grower pigs (6-16 weeks) were selected from each farm. Gross and histo pathological examinations were carried out on each lesion.
Lesions on pigs that originated from different floors types were pathologically identical; indicating that
different floor types did not produce different lesions with the same gross clinical presentation.
In preweaning pigs, skin abrasions were mainly superficial uninfected wounds. The pathologist
speculated that skin abrasions were likely to be associated with pain but would cause little discomfort
to the piglet once healing had begun. In contrast, external foot lesions were associated with more
internal infection and dissolution of the pedal bone. The pathologist speculated that this would be
painful since space was restricted in the foot and swelling would be painful. In addition, an infected
pedal bone is unlikely to heal.
In post weaning pigs bursitis and capped hock lesions were solid or fluid-filled (Figure 3), this was not
linked to clinical size. The pathologist’s speculation was that pain may be present at the time of
development and the lesions may persist as a protective barrier. For capped hock lesions with a clinical
score 1 there was no bursal sac, but a layer of loose connective tissue. It maybe that the proliferation of
fatty tissue that was identified in score 1 lesions was a precursor to the development of a bursal sac or
an alternative pathological response that is also associated with hard floors.
SID 5 (Rev. 3/06)
Page 16 of 20
a)
b)
Figure 3 Examples of bursitis lesions with a) fluid-filled lumen b) solid lumen
Impact of EC Directives
The council directives 2201/88/EC specifies slat and slot dimensions for concrete slatted floors for pigs
of all ages from preweaning up to adult sows. Overall in the 1,227 pens from the 93 randomly selected
farms examined for this study 13% had concrete slats. However, only 0.5% (2/338) of preweaning
piglets and 1.5% (3/195) of weaner pigs were housed on concrete slats. If the farms used in this study
are representative of the GB population council directive 2201/88/EC would have little impact of this
sector of the industry.
Within directive specifications
(n = 7 pens)
80
70
Outside directive specifications
(n = 14 pens)
60
50
40
30
20
10
0
Bursitis
Capped hock
Calluses
Abnormal gait
Figure 4 Prevalence of bursitis, capped hock, calluses and abnormal gait in 21 pens of gilts and sows
housed on concrete slats within and outside the directive
80
Within directive specifications n =7
pens
Outside directive specifications n = 122
pens
70
Prevalence of lesion (%)
60
50
40
30
20
10
0
Bursitis
Capped hock
Callus
Figure 5 Prevalence of bursitis, capped hock and calluses in grower and finisher pigs housed on
concrete slats within and outside of the directive specifications
SID 5 (Rev. 3/06)
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Concrete slats were used in 32% (136/423) of the growing and finishing pig pens. Only 5% (7/129) of
the slats were within dimensions specified by the 2201/88/EC directive. The void was too wide in 92%
(118/129) of the pens and the slat was too narrow in 25% (32/129) of the pens.
Concrete slats were used in 8% (21/271) of the sow and gilt pens. In 67% (14/21) of these pens the
dimensions of the concrete slats were outside of the directive. The void was too wide in 43% (9/21) of
pens and the slat was too narrow in 24% (5/21).
100
Cumulative percentage
90
80
70
60
50
40
30
20
10
+
30
29
28
27
26
25
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21
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0
Void width (mm)
Figure 6 Cumulative percent of grower and finisher pigs housed concrete slats of increasing void width
The small number of pens that are within the dimensions specified by the directive meant that there
was not sufficient power for complex statistical analysis. It can be seen that there is a slight trend for a
higher prevalence of calluses, capped hock and abnormal gait in sows and gilts housed in concrete
pens outside of the directive (Figure 4). However, with such a small sample size little can be concluded.
The prevalence of limb lesions in grower and finisher pigs is very similar between the two groups
(Figure 5). When considering these data the difficulty in gaining accurate measurements of void and
slat widths should be taken into account. Wear on the edge of the slat may increase the void width or
build up of dirt may reduce the width of the void by several millimetres. Slats were recorded as worn in
55% (70/127) of concrete slatted pens and a covering of dry slurry was present in 47% (59/125) of
pens. It can be seen from Figure 6 that a measurement error of 2mm could considerably affect the
number of pens that fell within or outside the directive specifications.
Discussion and conclusions
Floor materials, presence of voids and bedding and floor quality do impact on the health and welfare of
pigs of all ages. The impact varied by the outcome of interest and was not significant for all outcomes.
This study confirms many of the previously reported associations between pig health and welfare and
environment. In addition, extra information has been identified. This is the first study to examine
outdoor farmed pigs. Overall, outdoor systems with soil and deep bedding were associated with far
lower prevalences of foot and limb lesions in all ages and the population attributable percents indicate
that if the associations detected are causal and the estimated frequency of exposures is representative
of English farms then there would be a considerable reduction in foot and limb lesions if pigs were
housed outdoors.
This is not practical for all farmed pigs and we do not demand such an approach in other farmed
species. There was no one indoor floor surface that was ‘best’ for pig foot and limb injuries and even in
the same environment the age of pig led to differing disease effects e.g. in preweaning piglets fully
slatted plastic floors were associated with fewer skin abrasions and sole erosions but more sole
bruising than piglets housed on solid concrete floors, whilst lactating sows on fully slatted plastic floors
had the highest and solid concrete bedded floors the least foot and limb and body damage. .
New information linking environment and lesions in lactating sows included the association that sows
that were housed on slats had far higher prevalences of foot and limb lesions. In addition, those that
were large in proportion to their crate (a short distance between their back and the top of the crate or
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between their tail and the back of the crate) had more skin abrasions on their legs and body than those
that were small.
In dry sows group size impacts on injuries, vulva biting and scratch marks were of a higher prevalence
in yards where large numbers of sows are housed together but interestingly only scratch marks were of
a lower prevalence in outdoor paddocks compared with indoor pens.
Locomotion of gilts, dry sows and finishing pigs was less good in pigs housed on slats. This may be
because pigs walk with a stilted gait in these floors but it may also be an association with foot lesions.
The increased prevalence of bursitis, capped hock and calluses in pigs with abnormal locomotion may
be as a result of increased lying times since these limb lesions were not considered obviously painful at
post mortem.
Further new information was that capped hock, bursitis and calluses had some different associated
risks. In post weaning pigs bursitis and calluses increased as bedding depth decreased and was
absent and continued to increase as floors went to part and then fully slatted whilst capped hocks were
increased in one step when there was no deep bedding throughout the pen. In dry sows and gilts there
was an increased prevalence of bursitis and calluses housed on sparsely bedded and slatted floors but
there was no association between capped hock and floor type. In lactating sows there was an increase
in prevalence of capped hocks, calluses and skin abrasions in sows housed on slatted floors and floors
without bedding but no association with the prevalence of bursitis
Once again, tail biting was up to ten fold less likely in herds using straw in weaner – finisher pigs.
There was no significant association between prevalence of clinical signs or diseases present on the
farm and floor type. This is not surprising since infectious disease targets susceptible pigs rather than
housing conditions per se. However, the results from this study are very limited because of the cross
sectional design and more detailed cohort studies may identify differences in disease prevalence or
severity. We conclude that this section of the study should not be given much weight.
Future work
It is not acceptable to keep animals in conditions that result in physical abnormalities but the
importance of these abnormalities has to be assessed and weighed up with the practicalities of farming
livestock. This study bench marks the current situation and provides a basis for future research. Two
key questions arise
1. How does the occurrence of foot and limb lesions affect the health and welfare of pigs? This
question is not fully answered by this study, although the pathological studies indicated that infections
in the pedal bone and surrounds are highly likely to cause pain and irreversible damage. These is also
an indication that gait is worse in pigs with limb injuries (although these could be because of foot
injuries).
A cohort study monitoring piglets from birth through into the breeding herd under different flooring
conditions (including outdoors) would address this.
2. Are there floor materials that are not currently used that could be used to reduce injuries in pigs?
This is a vast question and there have been several attempts to consider alternative housing for pigs. It
is a question which may have links to farming changes and e.g. new byproducts from bio-fuel
production.
Objective 7. Preparation and submission of papers for peer review and conferences – see
section 9
References
Woodbine, K.A., Medley, G.F., Slevin, J., KilBride, A.L., Novell, E.J., Turner, M.J., Keeling, M.J., and Green, L.E.
A pig farm retrospective cohort study of hazards for breakdown with post-weaning multisystemic wasting
syndrome. (in press).
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References to published material
9.
This section should be used to record links (hypertext links where possible) or references to other
published material generated by, or relating to this project.
Submitted to Preventive Veterinary Medicine
A cross sectional study of the prevalence and associated prevalences for capped hock and the
associations with bursitis in 6,274 weaner, grower and finisher pigs from 103 British pig farms
A cross sectional study of the prevalence and associated prevalences for bursitis in 6,250
weaner, grower and finisher pigs from 103 British pig farms
Oral presentations at ISVEE 2006
Prevalence of bursitis and capped hock in weaner to finisher pigs and prevalences associated
with flooring factors: a cross sectional study of 103 GB pig farms
Prevalence of foot and limb injuries in pre-weaning piglets and prevalences associated with
indoor flooring factors; a cross sectional study
Posters SVEPM 2006
Associations between poor locomotion and severity of limb lesions in finishing pigs
Associations between foot and limb lesions and floor factors in preweaning piglets
Posters SVEPM 2005
Impact of flooring on pig health and welfare: prevalence of infectious disease
Impact of flooring on pig health and welfare: prevalence of limb lesions
Poster WAFL 2005
The effect of flooring on bursitis and capped hock; a cross sectional study of weaning to finishing
pigs
Work in preparation:
Oral presentation at Pig Veterinary Society 2007
Posters SVEPM 2007
Risk factors associated with foot lesions in growing pigs
Risk factors associated with foot, limb and body injuries in lactating sows
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