This is an HTML version of an attachment to the Official Information request 'Request for AgResearch Report'.
 
 

  
 
 
Client 
Report 
1982
Prepared for MAF Policy 
Act 
March 2006 
Key indicators of 
poultry welfare in 
New Zealand 
C. S. Bagshaw 
Information 
L. R. Matthews 
A. Rogers 
 
 
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EXECUTIVE SUMMARY 
•  There is currently a high level of interest by policy/regulatory 
authorities, the public, welfare organisations, growers and lobby 
groups in the welfare of poultry kept for meat production. 
 
•  Thus, there is an urgent need to identify key welfare indicators 
relevant to New Zealand conditions, use these measures to 
assess the welfare status of broilers under common farming 
practices, and, where necessary, revise practices in industry, and 
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standards and recommendations in the relevant welfare codes.  Act 
 
•  At the beginning of the study, a Broiler Welfare Research 
Committee (BWRC) was formed (with representation from 
Poultry Industry Association of New Zealand (PIANZ), poultry 
veterinarians and representatives from the major meat chicken 
companies in New Zealand, a scientist from AgResearch and an 
Information 
independent scientist to oversee the research programme. 
 
•  The aim of the research was to identify appropriate welfare 
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indicators for broilers, and apply them to quantify the welfare 
status of broilers in New Zealand.  
the 
 
•  This study used a suite of measures to assess welfare including: 
the incidence (and causes) of mortalities and culls; skin disorders 
under 
of the feet, hocks and breasts; gait score; and the incidence of 
back scratches, birds dead on arrival (DOA), rejects.  
 
•  The potential influence of management factors on welfare was 
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examined through information collected in a grower survey. 
 
•  The potential influence of stocking density was examined by 
correlating welfare measures with variations in stocking density 
that arose naturally during the study. 
 
 


 
 

•  The research was carried out on 36 New Zealand housed 
commercial broiler farms in each of the four seasons and within 
the context of the typical management of the birds. There were 
few differences in husbandry practices between farms. 
 
•  Overall mortality was 3.8%, which is at the lower end of levels 
typically seen in the industry overseas. Of all the birds in the 
study, 0.3% died as leg culls. 
 

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The contribution of leg culls to total mortality was relatively low 
(8%) and about half that reported for birds in two recent UK 
Act 
studies (15%). 
 
•  The proportion of birds with severe leg weakness (gait score 4 
(0.78%) and 5 (0.1%)) was about one quarter that reported for 
broilers in the UK, Denmark and Sweden.  
 
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•  Considering both the leg culling and gait scoring information 
together, our results demonstrate that leg health in New Zealand 
broilers is better than for birds in Europe. 
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the 
  Prevalence of all forms of contact dermatitis (footpad, hock burn 
and breast blisters) was within the range reported internationally. 
Incidences, such as occurred, were mostly of a relatively minor 
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nature. These data indicate that the litter in the houses is 
maintained in good condition, although there were seasonal 
variations. 
 
•  Pre-slaughter handling procedures, as assessed by Dead On 
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Arrivals and reject birds, were generally better than reported for 
other countries. The proportion of birds with back scratches 
averaged 39%. Meaningful comparisons between our data and 
the incidence of scratches reported elsewhere were not possible 
due to the lack details of the measurement criteria provided in 
other published reports 
 


 
 

•  Stocking density varied between 32.9 and 39.3 kg m-2. Stocking 
density was not correlated with any of the welfare measures, or 
variables in the epidemiological survey, suggesting that broiler 
welfare is either unaffected by stocking density, or that the range 
in densities seen in the current study was too small to enable 
correlations to be detectable. Stocking density (at the levels 
currently used in this study) would appear appropriate as the 
welfare of the birds is good. 
 
•  The welfare of broilers in New Zealand is equal to or superior to 
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that of broilers kept elsewhere. 
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TABLE OF CONTENTS 
Executive Summary .............................................................................................................. 2 
Table of contents............................................................................................................... 1 
INTRODUCTION .................................................................................................................. 3 
METHODS ............................................................................................................................ 9 
Farms ................................................................................................................................ 9 
Animals ........................................................................................................................... 10 
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Timing of measurements ............................................................................................. 10 
Measures......................................................................................................................... 11 
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Epidemiological questionnaire ..................................................................................... 11 
Mortality........................................................................................................................... 11 
Leg heath..................................................................................................................... 12 
Contact dermatitis ........................................................................................................... 13 
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Foot pad dermatitis ...................................................................................................... 13 
Hock Burn .................................................................................................................... 13 
Breast blisters (blisters) ............................................................................................... 13 
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Pre-slaughter handling .................................................................................................... 14 
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Back Scratches............................................................................................................ 14 
Dead on arrival (DOA) and rejects............................................................................... 14 
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Rejects......................................................................................................................... 14 
STATISTICAL ANALYSES ................................................................................................. 15 
Response data ................................................................................................................ 15 
Epidemiological survey data............................................................................................ 15 
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The model ....................................................................................................................... 15 
Training data ................................................................................................................... 16 
Reliabilty.......................................................................................................................... 16 
RESULTS ........................................................................................................................... 17 
Common husbandry procedures and welfare measures ................................................. 17 

 
 

Welfare measures and correlation with husbandry procedures....................................... 18 
Incidence of mortality ................................................................................................... 18 
Incidence of leg weakness........................................................................................... 25 
Incidence of contact dermatitis .................................................................................... 28 
Incidence of back scratches, DOAs (birds dead on arrival) and 
rejected birds. .............................................................................................................. 34 
DISCUSSION...................................................................................................................... 39 
References ......................................................................................................................... 52 
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References ......................................................................................................................... 52 
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INTRODUCTION 
There is currently a high level of interest by policy/regulatory 
authorities, the public, welfare organisations, growers and lobby 
groups in the welfare of poultry kept for meat production. Much of 
this interest has been brought into focus by the New Zealand 
Animal Welfare Act (1999) and associated Code development. In 
order for all interested parties to be confident that the standards of 
welfare specified in Codes and practised on farms are at 
acceptable levels, scientifically-defensible information on the 
welfare of broilers in New Zealand is required. Published scientific 
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information has been reviewed for MAF (Bagshaw and Matthews, 
2001). There is a considerable international literature on broiler 
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welfare but, unfortunately, there are no relevant published details 
on the welfare status of poultry in New Zealand. Bagshaw and 
Matthews (2001) indicated that while there are many similarities in 
the way that poultry are farmed in NZ and elsewhere, there are 
likely to be important differences (e.g. in disease status) which may 
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influence overall welfare. Thus, there is an urgent need to identify 
key welfare indicators relevant to New Zealand conditions, use 
these measures to assess the welfare status of broilers under 
common farming practices, and, where necessary, revise practices 
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in industry, and standards and recommendations in the relevant 
welfare codes.  
the 
 
In the United Kingdom a survey of the welfare status of broilers 
has been undertaken at Bristol University. The data generated by 
under 
Bristol would benchmark broiler welfare in the UK. It was proposed 
that a New Zealand study on the welfare of broilers be of a similar 
format to that in the Bristol study. It is important that the work 
carried out in NZ is internationally credible. In addition, comparing 
welfare standards between countries (e.g. UK and NZ) would be 
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useful and will be carried out when both reports are available.  
 
The main causes of poor welfare in other countries are leg 
disorders, diseases, skin disorders (primarily associated with poor 
environmental conditions) and damage during catching and 
transport to slaughter. The low levels of activity and a limited 
 


 
 

behavioural repertoire are also considered by some authors to 
indicate poor welfare (Berg et al., 2000). 
 
Leg weakness can arise from infectious and non-infectious causes 
and its prevalence can be influenced by a wide range of 
management factors (e.g. genotype, live weight, feeding level, 
lighting regime, activity levels) (Butterworth, 2004). 
 
Typically, leg weakness has been assessed using the gait scoring 
procedure developed by Kestin et al.(1992) which uses a 6 point 
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gait score (GS) scale (0 being normal, through to 5 being 
immobile). Using this system with the Ross genotype and birds 
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aged 42 to 49 days and weighing 2.6 to 2.8 kg, Kestin and 
colleagues reported that the percentage of birds with gait scores 0 
to 5 were 8.5, 22, 43, 21, 4 and 2.5, respectively. Sanotra et al. 
(2003) reported percentages of 26, 25, 25, 19, 4 and <1% in these 
GS categories for Ross and Cobb genotypes slaughtered at 35 
days of age and with a mean weight of 1.8 kg . It should be noted 
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that the percentage with gait score 0 (26%) is extremely high 
compared with other published reports.  
 
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Leg weakness might adversely affect welfare either directly (e.g. 
through pain) or indirectly (e.g. through preventing the fulfilment of 
the 
essential functions like feeding).  
There is some evidence, though not unequivocal, to suggest that 
higher gait scores (3 and over) result in broilers experiencing pain. 
under 
The evidence has been derived from two types of studies: in one, 
the effects of analgesics on behaviour have been measured; and 
in the second, the effects of gait on the propensity to exhibit 
specific important activities have been assessed. Using an 
analgesic/anti-inflammatory drug, carprofen, (McGeown et al., 
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1999) compared the time taken by broilers with gait scores of 0 or 
3 to traverse an obstacle course, with and without prior drug 
administration. Gait score 3 birds birds with and without carprofen 
negotiated the course in 18 and 38 seconds, respectively, while 
birds with sound legs took 11 seconds. The times taken for the 
sound birds and carprofen treated gait score 3 birds were not 
significantly different. Danbury et al. (2000) reported two 
 


 
 

experiments in which gait score 0 and 3 birds were offered a 
choice of carprofen and untreated food. In one study, there was no 
difference in the consumption of drug-treated and untreated food 
between gait score treatments and, in the second, the amount of 
drug-treated food eaten increased with gait score. These data 
were interpreted as indicating an increasing level of drug self-
selection (and therefore pain relief) with increasing gait score. 
However, this study requires replication before firm conclusions 
can be drawn due to: the inconsistencies between the two 
experiments; the lack of a significant difference in drug 
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concentration in the plasma between birds with sound and 
unsound legs; the correlation between consumption of drug-treated Act 
food and gait score apparently being driven entirely by a lower 
consumption rate by the gait score 0 birds; and the measures of 
gait score used in the analyses being taken at the end of the study, 
meaning that drug consumption and gait score were totally 
confounded. Further, there were no differences in the plasma 
concentrations of carprofen between birds with different gait 
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scores. 
 
Indirect measures of the welfare impacts of variations in gait score 
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include the research by Bokkers and Koene (2004) and Weeks 
and Kestin (1997) where the behaviour of birds with different gait 
the 
scores has been compared. While some aspects of broiler 
behaviour are modified in a way that suggests that lameness (GS 
2 and 3) imposes a cost on the birds (e.g. increased feeding bout 
under 
duration, reduced motivation to feed), there is no effect of 
lameness on total time spent feeding or drinking (Ross genotype; 
Weeks et al., 2000). Nonetheless, as Mench (2004) has aptly 
stated, many gait disorders must be painful as a consequence of 
the clinical manifestations involving inflammation, spinal cord 
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damage, tension on the joints or rupture of tendons. 
 
Broilers live on a litter substrate. If the litter is too damp, then the 
birds may develop contact dermatitis on the foot (footpad 
dermatitis), hock (hock burn) or breast (breast blister). Dryness of 
litter is influenced by a wide range of factors including the 
effectives of the ventilation system, climate, food composition, litter 
 


 
 

type, stocking density, drinker system and bird health (Berg, 2004). 
The mean percentage of birds seen with the various forms of 
contact dermatitis is 7 to 19% (range  up to 90%) for hock burn 
(Dawkins et al., 2004; Menzies et al., 1998), 19% for foot pad 
dermatitis (Dawkins et al., 2004), and 0.0 to 0.4% for breast 
blisters (Berg, 2004; Hall, 2001). 
 
Average total mortality in flocks is reported to vary from a low of 
about 2.5% (Butterworth, 2004), but is more likely to be in the 
range from 4 to 6.5% (Hall, 2001, Dawkins et al., 2004). About 
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15% of the total mortality arises due to culling for leg weakness, 
35% due to culling for other reasons, and 50% from natural deaths Act 
(Hall, 2001, Dawkins et al., 2004). As a proportion of the flock, leg 
culling rates have been observed in the range 0 to 4% (McNamee 
and Smyth 2000; Dawkins et al., 2004). 
 
The most common causes of leg weakness in broilers are reported 
to be femoral head necrosis (17 to 38%), limb deformities (11 to 
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14%), tibial dyschondroplasia (7 to 8%), Infections (13%), and 
spondylolisthesis (kinky back) (3 to 8%) (Butterworth, 1999; 
McNamee and Smyth, 2000).  Official 
 
Pre-slaughter handling is comprised mainly of the catching, 
the 
containment and transport of birds to slaughter. Measures to 
assess the impact of these procedures on bird welfare include 
mortalities post-transport (dead on arrival, DOA) (Mitchell and 
under 
Kettlewell, 2004), rejects or downgrades of the carcasses due to, 
for example, trauma or bruising (Scott, 1993), and other measures 
of injury (e.g. back scratches (Hall, 2001). Of course, some 
traumatic events and other variables (e.g. disease conditions, 
(Ekstrand, 1998) occurring prior to the pre-slaughter handling 
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period influence the incidence of, and therefore confound, these 
measures. Ekstrand (1998)  reported the range for DOA is typically 
0.1 to 0.6%, and for rejects/downgrades is very wide at 0.5 to 20%. 
Hall (2001) observed between 0.3 and 0.5 % of birds at slaughter 
with back scratches (Ross genotype). Frankenhuis et al. (1991) 
demonstrated that scabby hip can be caused by scratches to the 
 


 
 

back; the incidence of scabby hip varies greatly between flocks 
and can be up to 60%.  
 
Stocking density is frequently raised in discussions of broiler 
welfare, although the evidence is equivocal on the relationship 
between stocking density and welfare. Bagshaw and Matthews 
(2001) suggested that high litter temperatures rather than stocking 
density per se may contribute to poor welfare.  
 
This study used a suite of measures to assess the welfare of 
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broilers in NZ. Health status was assessed from the incidence of 
mortalities (and causes) and culls; skin disorders of the feet (Berg, Act 
1998), hocks (Butterworth, 2002) and breasts; leg health was 
assessed with a gait scoring procedure (Kestin et al 1992); 
environmental conditions were assessed by measuring the 
incidence of skin disorders; and pre slaughter handling was 
measured from the incidence of birds dead on arrival (DOA), 
rejects and back scratches.  
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The potential influence of management factors on welfare was 
examined through association of management parameters 
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(obtained in an epidemiological questionnaire) with the health and 
welfare measures. It was beyond the scope of the present study to 
the 
measure directly the behavioural repertoire of the broilers or the 
effects of stocking density on welfare. The potential influence of 
stocking density was examined by correlating welfare measures 
under 
with variations in stocking density that arose naturally during the 
study. 
 
Aims: To identify appropriate welfare indicators for broilers, and 
apply them to quantify the welfare status of broilers in New 
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Zealand.  
 
At the beginning of the study, a Broiler Welfare Research 
Committee (BWRC) was formed (with representation from Poultry 
Industry Association of New Zealand (PIANZ), poultry veterinarians 
and representatives from the major meat chicken companies in 
 


 
 

New Zealand, a scientist from AgResearch and an independent 
scientist to oversee the research programme. 
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METHODS 
In conjunction with BWRC meetings, liaison with staff from the 
University of Bristol, visits to NZ slaughter plants, and attendance 
at a gait scoring course, protocols were prepared for the collection 
of data for the following measures: mortality, leg health, contact 
dermatitis and pre-slaughter handling and catching damage. In 
addition, information on management practices was collected 
using a questionnaire. 
FARMS 
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The research was carried out on commercial broiler farms and 
within the context of the typical management of the birds.  
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To determine the number of sheds to study, historical mortality 
data was analysed to assess the most appropriate sample size 
(number of sheds) required to measure mortality reliably and to 
obtain some indication of seasonal variability in health and welfare 
of the birds. A shed refers to one growing cycle of a flock of 
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broilers from placement to slaughter. These analyses indicated 
that, ideally, 36 sheds (one shed per farm) over the four seasons 
ought to be examined each year. However, for logistical reasons 
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(i.e. availability of veterinarians, financial constraints), a total of 36 
sheds only could be used in the study (12 sheds were examined in 
the 
the first year, and 24 shed in the second year). Sheds were 
allocated to companies in proportion to the number of birds they 
process over the industry. Nine sheds were examined in each 
under 
season, three for each season in the first year and six in the 
second year.  
 
In summary, only one shed was examined on each farm in the 
study. A total of 36 farms/sheds were sampled over the 18 months 
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of the study. Each shed was visited by researchers between 1 to 3 
times, depending on slaughter dates for the flock. During the study 
a total of 85 visits to the sheds were carried out (36 sheds had one 
visit, and of those 32 had a second visit, and of those 17 sheds 
had a third visit). The experimental protocol was tested on one 
additional farm prior to the start of the project (these data were 
included in the analyses). 
 


 
 
10 
 
There were three common sets of management practice 
(designated A, B and C). They varied in terms of feeding, 
genotype, lighting regime and other factors. For commercial 
sensitivity reasons, these cannot be described in detail.  
 
Kestin et al. (1992) demonstrated that a sample size of at least 250 
birds per shed was required to measure reliably walking ability (leg 
health). In our study, samples of at least 250 birds per shed were 
used.  
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In the slaughter plant, approximately 100 birds were used to 
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measure skin disorders (Ekstrand et al., 1998) and back scratches. 
 
ANIMALS  
There were two genotypes (breeds) used in this study, Ross and 
Cobb. Table 1 shows the average number of chicks, the average 
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shed size, stocking rate and stocking density for birds of each 
breed for the sheds used in the study.   
 
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Table 1. Averages (across sheds) for the numbers of chicks at 
placement, shed sizes, stocking rates and maximum densities 
the 
attained for each genotype.  
Breed Ave. 
number Ave. shed 
Range of Max stocking 
Average stocking rate 
Average stocking 
Of chicks 
size m2 
density (kgm-2) 
Chicks m-2 
density (kgm-2) 
under 
Cobb 27235  1360 
32.9-37.5 
20 
 
36.1 
Ross 23368  1094 
34.3-39.3 
21 
36.3 
Average 25354 
1230 
32.9-39.3 
21 
36.2 
 
Timing of measurements  
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Normal farming practice was carried out on the farms in this study. 
During the time a flock was in a shed, typically a proportion of the 
flock was removed for slaughter (thinning) once or twice (and very 
occasionally three times) before the remainder of the birds in the 
flock were slaughtered (terminal slaughter). Gait scores were 
measured on a sample of birds in the shed two days before a thin 
or the terminal slaughter. When more than two thins were 
 
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scheduled, measurements were taken for two thins only (at the first 
thin and a mid thin). Additional measures were taken on a sample 
of these birds at the slaughter plant. These measurements were 
contact dermatitis (foot, hock and breast), pre-slaughter handling 
(back scratches), dead on arrival (DOA), and reject birds.  
 
MEASURES 
Epidemiological questionnaire 
A questionnaire was used to obtain information about 
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management and husbandry practices and policies for each 
shed used in the study. This provided details of factors such as Act 
number and weight of chicks placed; sex; time of year; age at 
assessment and slaughter; stocking density, thinning practices; 
brooding conditions; nutritional profile; vitamin and mineral 
levels; litter substrates; feeder and drinker design/type; water 
source; lighting programmes; age of sheds; medication policy, 
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coccidiostat usage, vaccination programmes, bird to stock 
person ratio; training /qualifications; biosecurity measures.  
 
The questionnaire was completed by the grower (farm manager) 
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on a standard form either on their own (if the questionnaire was 
sent to them) or in conversation with a research assistant, at the 
the 
first visit to the farm, when the chicks were placed in the shed. On 
the second visit to the farm, growers were asked a set of follow up 
questions specifically related to the management of the shed used 
under 
in this study. 
 
MORTALITY 
Birds that died on days 1, 3, 5, 7, in the first week, and thereafter 
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once per week (e.g. day 10 in week 2, day 17 in week 3) were kept 
for post mortem (PM) examination. Birds that died in the shed 
(“natural death”) were distinguished from those that were culled. 
Birds that were culled were separated into two groups; leg culls 
and other culls. The grower ascribed reasons for culling the birds. 
Leg culls were birds that were perceived to have a walking ability 
 
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problem by the grower, whereas other culls were birds with 
problems other than leg weakness. 
 
It was agreed to adapt the criteria for cause of death from the 
procedure used by one of the poultry veterinarians in his 
commercial practice. The mortality descriptions were agreed by all 
the veterinarians involved in the study, and a booklet containing a 
list of common pathologies, detailed descriptions and colour 
photographs was completed. This booklet was made available to 
all personnel undertaking post-mortem analyses (and is available 
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on request). 
 
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For logistical reasons, it was decided that all dead birds would be 
frozen prior to examination to allow the autopsies to be carried out 
as time permitted by the veterinarians involved. However, one 
veterinarian subsequently found it was not possible to follow this 
policy and conducted 55% of his autopsies on fresh birds.   
 
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Leg heath 
Gait scoring 
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Leg weakness was assessed using a recognised method 
developed by Kestin et al. (1992), which comprises a 6 point gait 
the 
scoring system (scores of 0 to 5, with 5 being the poorest gait). 
Techniques developed in the Bristol study were used to train 
observers. Dr Andy Butterworth ran a course on gait scoring at 
under 
Ruakura for scorers in the present study and representatives from 
the poultry industry prior to the start of the study. In addition, 
similar to the Bristol study, the reliability of gait scoring ability by 
the assessors was monitored by regular independent assessment 
of observers scoring standard video taped sequences. 
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Consistency of individual scoring and degree of agreement 
between scorers (reliability) was undertaken prior to and twice 
during the study.  
 
On the farm visit a gait scorer and recorder would gait score 250 
birds, selected at random within one shed, by reference to a pre 
 
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randomised location identifier. Birds were selected from 10 
locations, in groups of 25 to 30, by corralling at each location using 
a hinged catching pen. Each bird was individually encouraged to 
walk out of the pen and was scored as it did so. 
 
CONTACT DERMATITIS  
Standard photographs were used to describe the scoring system 
for each type of dermatitis (foot pad, hock burn, breast blisters). 
Back scratches were assessed according to number present (see 
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below). Consistency of individual scoring and degree of agreement 
were obtained for each measure before and during the study for all Act 
observers. 
 
The sample of birds scored for hock burn, breast blisters and back 
scratches were assessed after plucking and prior to evisceration. 
Once the feet had been removed (after plucking and evisceration), 
50 right feet and 50 left feet were randomly collected for scoring 
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foot pad dermatitis.  
 
Foot pad dermatitis 
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The foot pad dermatitis scores were on a five point scale of 0 (no 
the 
foot pad dermatitis) to 4 (severe foot pad dermatitis).  
 
Hock Burn 
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The hocks were assessed on a four point scale (0 to 3). Ranging 
from 0 (no hock burn) to 3 (severe hock burn). 
 
Breast blisters (blisters) 
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Breast blisters were given a score of 0 (no breast blisters), 1 
(presence of breast blisters). There was no account taken of the 
size of the breast blister. 
 
 
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PRE-SLAUGHTER HANDLING 
Back Scratches 
Scratches longer than 2.5 cm were scored according to the 
following scale: 0 ( no scratches); 1 (1 to 2 scratches); 2 (3 or more 
scratches).  No account was taken of age or depth of scratch. A 
marker 2.5 cm in length was held up near the bird being scored to 
assist observers to make their assessment of the length of the 
scratch. Consistency of individual scoring and degree of 
agreement were obtained for each measure before and during the 
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study for all observers. 
 
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Dead on arrival (DOA) and rejects 
The number of DOA and rejects for each shed were taken from 
the slaughter plant records. 
 
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Rejects 
Birds that were rejected as part of normal company policy were 
collected and ascribed a cause of death using the definitions 
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described previously on farm mortalities. 
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STATISTICAL ANALYSES 
The data analysed were welfare measures (response data) and 
epidemiological survey information, which were put into a model to 
identify significant correlations between the two. Correlations 
between welfare measures were also assessed. 
 
RESPONSE DATA 
Because there were large age and live weight differences between 
thins, on different farms, and these clearly affected the measures 
1982
of gait score and contact dermatitis, the gait and contact dermatitis 
scores were estimated on a farm basis adjusting for age 
Act 
differences using a linear mixed model. In this model, the thins 
were split into 3 age groups with farms modelled as a random 
effect. The adjusted farm effects were the best linear unbiased 
predictors (BLUPs) from the model. Scorer was included in the 
model. The contact dermatitis data, except for breast blisters, were 
not normally distributed, so for these variables, the data were log-
Information 
transformed.  
 
Official 
EPIDEMIOLOGICAL SURVEY DATA 
Some of the responses to particular questions were the same for 
the 
most farms, or for all farms within a common type of management 
practice. This precluded their use as potential explanatory 
variables. The remaining variables were used in multiple 
under 
regression models to determine which combination showed the 
best association with each welfare measure taken on the farm or 
slaughter plant.  
 
Released 
THE MODEL 
The model included season, stocking rate, stocking density, 
genotype (breed) and management practice (which includes 
factors such as nutrition, lighting schedules, and genotype). Only 
those factors which were statistically significant will be presented. 
 
 
15 

 
 
16 
BLUP analyses were used to identify the linkage of welfare 
measures to management practices. With a study such as this a 
large number of statistical tests have been carried out, which 
increased the likelihood that one or more of these would produce a 
significant result merely by chance. Results of borderline 
significance should be interpreted with caution. For this reason, 
only those associations (BLUPs) where p < 0.01 are presented.  
 
The R2 value measures the proportion of the variance in the 
response variable (welfare measure taken on the farm or slaughter 
1982
plant) explained by the explanatory terms (responses to the 
questionnaire). Because of the nature of the data and the 
Act 
analytical techniques are correlational we cannot infer any causal 
relationship between the response and explanatory variables.  
 
TRAINING DATA 
Differences between scorers were tested using an analysis of 
Information 
variance for each of the response variables used in the main study. 
 
RELIABILTY 
Official 
There were no significant differences between scorers for gait 
the 
score and they were consistent over time. The gait scorers were 
on average scoring 0.15 of a score less than the reference scores 
from Bristol University.  
under 
 
For the measures of dermatitis and back scratches, the individual 
scorers were consistent over time and were not significantly 
different from each other. 
 
Released 
Two of the veterinarians who completed 45% of the autopsies 
agreed 98% of the time. The agreement between all three 
veterinarians was 70%, which was deemed acceptable for the 
purposes of this study. 
 
 
16 

 
 
17 
RESULTS  
We firstly describe husbandry procedures that were common 
across farms, then practices that differed, then data on the welfare 
measures, then present significant correlations between welfare 
measures and the husbandry procedures. 
COMMON HUSBANDRY PROCEDURES AND WELFARE MEASURES 
A number of factors were common to the majority of the farms 
studied. Most farms had smooth concrete floor (94%), the 
1982
remaining 6% had bitumen or wooden floors. The ventilation 
systems on all farms had air extracted not blown into the shed. Act 
All sheds used pans to feed the chickens, and the lines 
between the pans were emptied out and the pans were 
disinfected before each new flock entered the shed. Most farms 
had nipple drinkers (93%), which were fed by bore water (83%), 
with chlorine added to the water (86%). A manual weighing 
Information 
system was used to weigh birds (94% of farms). All farms had a 
formal rodent control policy. The sheds were washed and 
disinfected before the placement of a new flock on all farms, 
and the majority of growers applied the disinfectant with a spray 
Official 
(86%). Growers either replaced or laundered their work clothes 
the 
(86%) and replaced or cleaned and disinfected their boots 
(97%) prior to the placement of a new flock. Trafficked and non-
trafficked areas outside the shed were very clean (97% sheds). 
under 
The cleanliness outside the shed deteriorated on some farms 
by the second visit (first thin), with 72% of farms having very 
clean trafficked areas, and 66% farms having very clean non-
trafficked areas. Most growers changed their boots before 
entering the shed (86%) on the first visit (when the birds were 
Released 
placed in the shed), however by the second visit (first thin) 
fewer growers changed their boots before entering the shed 
(64%). 
 
For all farms, feed was supplied to the growers from company 
feed mills, and all of the feed contained antibiotics (100%) and 
 
17 

 
 
18 
enzymes. For all flocks feed was provided ad libitum to chicks 
less than 7 days old. The majority of flocks were not vaccinated 
at the hatchery (83%) or the farm (94%). Eight percent of the 36 
study farms examined were diagnosed with a disease (such as 
E.coli.) during this study. All sheds had automated lighting 
systems.  
 
Wood shavings were used in all of the sheds, there was no new 
litter added before the first thin, and in a few sheds (16%) litter 
was added before the second thin. 
1982
 
At the first thin, 14% of sheds examined had system failures Act 
and another 8% of sheds had system failures by the second 
thin (e.g. 3 sheds had a feeder line failure, and 2 sheds had 
water leaks). There were no behavioural enrichment devices 
provided for the chickens in any of the sheds. 
 
Information 
As there was so little variation in these procedures across farms, 
no correlation between them and welfare measures was expected, 
and none was found. There were many other husbandry 
procedures which varied between farms. Correlational analyses 
Official 
between these procedures and the welfare measures were under 
the 
taken and the results are described when there was a significant 
effect detected. 
 
under 
WELFARE MEASURES AND CORRELATION WITH HUSBANDRY 
PROCEDURES  
Incidence of mortality 
A total sample of 35,892 deaths was recorded by the growers for 
Released 
the flocks studied. Averaged over all the farms, the percentage 
mortality was 3.8%, the percent of birds that died of ‘natural 
causes’ was 2.7%, the percent of birds that were culled due to leg 
weakness (leg culls) was 0.3% and the percent of birds that were 
culled for reasons other than leg weakness (other culls) was 0.8%.  
 
 
18 

 
 
19 
Farm mortality and Post mortem examination birds 
Cause of death data are presented from 31 of the farms (there 
were no data from five of the farms (4 out of 6 farms for 
management type A) due to unforeseen technical reasons. The 
post-mortem information comprised data for 6503 birds (18% of 
the recorded farm deaths). Post-mortems were carried out on 
14.8% of ‘natural’ farm deaths, 23.6% of leg culls and 27.5% of 
other culls. Table 2 shows percentage of weekly farm deaths by 
type of death. Overall, 71% of autopsied birds died of natural 
causes, 8% were leg culls and 21% were other culls (Table 2). 
1982
These figures did not vary much from week to week, but leg culls 
were higher and other culls lower over the last three weeks.. 
Act 
 
Table 2. Percentage of weekly farm deaths by type of death 
Week 
Week  Week 
Week 
Week  Week  Week 
Average over 
 







grow out 
“natural deaths”  
69% 
73% 74%  72%  72% 70% 74% 
71% 
Leg 
culls 
6% 
7%  8% 
8%  12% 13% 14% 
8% 
Information 
Other culls 
25% 
20% 
18% 20% 16% 16% 11% 
21% 
Total 
 
100% 100% 100% 100% 100% 100% 100% 
 
 
Of the birds that died over the 7 weeks of the flocks’ life (grow-out 
Official 
period), most occurred in the 1st week of life (35%), with only 3% 
the 
of all deaths occurring in the 7th week of life (Table 3). Of all the 
birds that died of ‘natural’ causes 34% died in the first week. 
Similarly, 24% and 42% of all leg culls and other culls, 
under 
respectively, died in the first week. The proportions of deaths in 
each category in the seventh week were 3, 5, and 2% for natural 
deaths, leg culls and other culls, respectively. 
 
Table 3. Percentage of each mortality type (‘natural’ deaths and 
Released 
culls) occurring in each week of the grow-out period. 
Week 
Week  Week 
Week 
Week  Week  Week 
 






7 Total 
“natural deaths”  
34% 
18% 15% 12% 11% 7%  3%  100% 
Leg culls 
24% 
16% 
13% 
13% 17% 12% 5%  100% 
Other culls 
42% 
18% 
12% 12%  9% 5% 2%  100% 
Average mortality  
35% 
18% 
14% 12% 11% 7%  3%  100% 
 
19 

 
 
20 
Note: Culls are birds removed by grower; average mortality is average of 
‘natural deaths and culls. 
1982
Act 
Information 
Official 
the 
under 
Released 
 
20 

 
 
21 
Table 4 shows the 10 most frequent causes of death in the 
autopsies of ‘natural deaths. The highest percentage of deaths 
was attributed to acute death syndrome (ADS) (17.6%). The 
percentage of birds with “no diagnosis” was 11.43%. The second 
highest cause of death was attributed to navel infection (9%) 
(Table 4).  
 
Table 4 Top 10 causes of death for the autopsied birds of natural 
deaths  
Post mortem condition 
% of birds autopsied 
1982
Acute Death Syndrome 
17.6 
No Diagnosis 
11.4 
Act 
Navel Infection 
9.0 
Cull Runt 
8.8 
Non Starters 
7.8 
Colisepticaemia 7.2 
Other 6.0 
Infected Yolk Sac 
5.8 
Information 
Visceral Gout 
4.8 
Too Decomposed 
          3.2 
 
Table 5 shows the percentage of all birds (live and dead) 
Official 
autopsied in the study affected by each condition. The percent of 
the 
birds dying from the two highest ranking conditions were acute 
death syndrome at 0.69% navel infection at 0.35%.  
 
Table 5. The percentage of all birds in the study affected by each 
under 
condition 
Autopsy condition  
Number of 
Overall % 
autopsies 
Acute death syndrome 
1141 
0.69 
No diagnosis 
743 
0.45 
Released 
Naval infection 
583 
0.35 
Cull runt 
574 
0.35 
Non starters  
510 
0.31 
Colisepticaemia 467 
0.28 
Other 390 
0.23 
Infected yolk sac 
375 
0.23 
 
21 

 
 
22 
Gout 315 
0.19 
Ascites 199 
0.12 
Twisted leg 
175 
0.11 
Femoral head necrosis 
140 
0.08 
Cull no obvious 
138 0.08 
abnormality 
Trauma 103 
0.06 
Joint infection 
83 
0.05 
Others 61 
0.04 
Kinky back 
47 
0.03 
1982
Dehydration 45  0.03 
Pasty vent 
27 
0.02 
Act 
Pecked 40 
0.02 
Impacted bowel 
35 
0.02 
Legs other 
33 
0.02 
Infection (other) 
24 
0.01 
Abnormalities 15  0.01 
Cellulitis 9 
0.01 
Information 
Pendulous crop 

0.00 
Hepatitis 7 
0.00 
Rickets 3 
0.00 
Septicaemia 3  0.00 
Official 
T.D.P. 2 
0.00 
Osteomyelitis 2 
 
0.00 
the 
Liver absess 
1  
0.00 
Flks 0 
0.00 
Enteritis  

0.00 
under 
Cholangiohepatitis 0 
0.00 
 
Correlations between cause of death and husbandry 
procedures 
Released 
Acute Death Syndrome 
The correlations between cause of death and husbandry 
procedures are presented for the two most common causes only 
(as the rates of occurrence of the other causes were too small to 
be useful in the model). 
 
 
22 

 
 
23 
Husbandry procedures which were correlated with acute death 
syndrome were: hock burn (Figure 1); the number of days the birds 
were fed diet 1 (the food the birds were fed for the first few weeks 
of the grow out period) (Figure 2); and use of foot baths by growers 
in the annex to the sheds (Figure 3). These three variables 
accounted for 41% (R2) of the variability (p = 0.0059).  
 
There was an increasing incidence of ADS with increasing average 
hock burn score. 

1982
50
e
ing o
om 40
Act 
ndr 30
d dy
y
ie
20
th s
ops
10
ut
 de
 a
e
0
 of
ut
c
a

0.0
0.1
0.2
0.3
0.4
0.5
%
Average hock burn scores
 
Information 
Figure 1 Percentage of autopsied birds that died of acute death 
syndrome versus average hock burn scores 
 
Official 
The trend was for fewer deaths ascribed to ADS with increasing 
time on diet 1.  
the 
g
in

50
y
 
th

40
es d
ea
m
30
si
under 
p
te d
u

ndr 20
to
y
10
f au
f ac
o

 o
0
%
0
5
10
15
20
Number of days on diet 1
Released 
 
Figure 2 Percentage of autopsied birds that died of acute death 
syndrome versus number of days fed on diet 1. 
 
In those farms with a foot bath in the annex, there appeared to be 
less ADS compared with farms were there was no foot bath in the 
annex. 
 
23 

 
 
24 
50
ing 
40
 dy
th 
s
a
e
ie
30
 de
om
e
ops
ut
ndr 20
ut
c
y
 a
 a
10
of
 of
%

0
No
Yes
Foot baths in annex
 
Figure 3 Percentage of autopsied birds that died of acute death 
syndrome versus the use of foot baths in the annex of the sheds 
1982
Navel infection 
Act 
Husbandry procedures that were correlated with navel infections 
were the type of ventilation system used in the shed, and the 
genotype of the bird. These two variables accounted for 64% (R2) 
of the variation (< 0.001).  
Sheds with cross flow ventilation had lower percentages of navel 
infection compared with sheds with other types of ventilation 
Information 
systems (Figure 4).  
40
ing
n
Official 
 dy
tio 30
s
c
ie
fe
20
the 
ops
l in
e

ut
v
 a
10
 of
f n
o

%
0
Cross flow
Other
under  Ventilation system
 
Figure 4 Percentage of autopsied birds that died of navel infection 
versus ventilation system 
 
Released 
While genotype was correlated with death rate due to navel 
infection, this factor (genotype) is inextricably confounded with 
other aspects of the management practices associated with 
particular genotypes. Thus, navel infection death rates are 
presented as a function of management practice (Figure 5). 
Management practice C had a lower percentage of navel infection 
compared with management practices A and B. 
 
24 

 
 
25 
 
40
ing 
n
 dy
tio 30
s
c
ie
fe
20
ops
l in
e

ut
v
 a
10
 of
f n
o

%
0
A
B
C
Management practice
 
Figure 5 Percentage of autopsied birds that died of navel infection 
1982
versus management practice 
Act 
 
Incidence of leg weakness  
Of the birds culled on the farm (0.3% of all birds) ostensibly due to 
a leg problem (refer to Table 2 for percentage of birds each week), 
over a quarter (28%) of the birds (Table 4) could not be ascribed a 
Information 
“cause of death” (other than culling) using the post-mortem 
techniques and criteria used in this study. Just less than a quarter 
of birds (24%) culled for leg problems were ascribed as having 
twisted legs, 10% joint infections, 9.5% femoral head necrosis and 
Official 
6.2% as having spondylolisthesis (kinky back) (Table 6). 
 
the 
Table 6 Top 10 conditions associated with leg culls on the farm  
Condition % 
of 
leg 
culls 
under No Diagnosis 
28.1 
Varus valgus deformity (sp) and twisted 
24.1 
tibia 
Joint Infection 
10.1 
Released  Femoral Head Necrosis 
9.5 
Spondylolisthesis (Kinky Back) 
6.2 
Legs Other 
4.3 
Colisepticaemia 3.3 
Trauma 2.7 
 
25 

 
 
26 
Acute Death Syndrome 
2.2 
 
The factors from the epidemiological survey which were correlated 
with percentage of birds culled for leg problems were genotype 
and target temperature at week 3 (R2 = 48%) (p < 0.001). As 
already mentioned, genotype is confounded with other 
management practices. Variation in leg culls is, thus, presented as 
a function of management practice (Figure 6). 
 
The percentage of autopsied birds that were culled due to leg 
1982
weakness was highest with management practice A.  
Act 
e
u
 d

50
lled
ss
40
n
s cu
ak 30
e
e
si
 w 20
p
to

eg 10
  l
0
f au
to
A
B
C
Information 
% o
Management practice
 
Figure 6 Percentage of autopsied birds that were culled due to leg 
weakness versus management practice 
Official 
 
the 
The graph of percentage of autopsied birds that were culled due to 
leg weakness (leg culls) against target temperature at week 3 
(Figure 7) shows two outlier points (sheds). The birds in these two 
sheds had a higher percentage of leg culls with lower than average 
under 
target temperature at week 3, compared with the other sheds in 
the study. Further, these two sheds were the only data in this data 
set for management practice A.   

le

s
25
Released ul ne ck 20
s
a
ie
15
g w 10
tops
u

le

5
 a
 t
 of
0
%
due
0
10
20
30
Target temperature at week 2
 
 
26 

 
 
27 
Figure 7 Percentage of autopsied birds that were culled due to leg 
weakness versus target temperature at week 3. 
 
Gait score 
Gait scorers in this study scored within half a score of each other, 
and scored similarly to Bristol University standards (our scorers 
were on average 0.15 of a score less than the Bristol reference 
score). 
The average flock gait score across all farms and all live weight 
1982
groups was 2.14.  
Gait score is shown by live weight category (live weight group 1, Act 
1.64 to 1.99kg; live weight group 2, 2.06 kg to 2.89 kg; and live 
weight group 3, 2.94 kg to 3.53 kg)  in Figure 8. The average 
percentage birds with gait score 0 was 0.1% for live weight group 
1, and 0.0% for groups 2 and 3. Over the three live weight groups, 
the majority of the birds had gait scores 1 or 2 (75.6%). The 
percentage of birds with gait score 2 were 70.1%, 66.4% and 
Information 
62.7% for groups 1, 2 and 3 respectively (p < 0.01).  
 
There were also significant differences between the live weight 
Official 
groups (p < 0.001) in percentage of birds with gait scores in 
categories 1, 3 and 4. The lightest birds (group 1) showed a higher 
the 
percentage of gait score 1 (16.5%) compared with heavier birds 
(group 2, 3%; group 3, 0.6%). In contrast, heavier birds, had a 
higher percentage in gait score 3 (group 2, 29%; group 3, 34%) 
under 
compared with lighter birds (group 1, 12%) (p < 0.001). There were 
very few birds with a gait score of 4 (1.3%, averaged over the three 
live weight groups). The highest percentage with gait score 4 
occurred in group 3 (2.3%) (p < 0.001). The corresponding 
percentages for groups 1 and 2 were 0.4% and 1.7%, respectively. 
Released 
The percentages of birds with gait score 5 in each weight category 
was 0.1%. There was no difference between the live weight groups 
in the percentage of birds with gait score 5 (average 0.1%). 
 
 
27 

 
 
28 
Live weight Grp 1
100
Live weight Grp 2
Live weight Grp 3
80
average

ird

60
f b
 o
e
g

***
ta
40
rcen
e
P

20
***
1982
***
0
0
1
2
3
4
5
Act 
Gait score
 
Figure 8 Percentage of birds by gait scores in 3 live weight groups 
Note: * = p < 0.05; ** = p < 0.01; *** = p < 0.001; sed are shown for each data 
point. Live weight group 1, 1.64 to 1.99kg; live weight group 2, 2.06 kg to 2.89 
kg; and live weight group 3, 2.94 kg to 3.53 kg 
There were no significant correlations between husbandry factors 
Information 
and gait score. 
 
Official 
Incidence of contact dermatitis  
the 
Foot pad dermatitis scores 
The average foot pad dermatitis score was 0.37. On average, 71% 
of birds had no foot pad dermatitis, 89.5% had scores of 0 or 1, 
under 
and 97.9% had scores of 0, 1, or 2. A higher proportion of the 
heaviest birds (live weight group 3, 83.7%) had a score of 0 
compared with the lighter birds (live weight groups 1 and 2, mean 
68%) (p < 0.05). In contrast, lower proportions of the heaviest birds 
had scores of 1 (12.9%) or 2 (2.6%) compared with lighter birds 
Released 
(score 1: live weight group 1, 21.9%; live weight group 2, 17.9%) (p 
< 0.01); score 2: live weight group 1, 9.9 %; live weight group 2, 
9.5%) (p < 0.01). Figure 9 shows the percentage of birds across 
foot pad dermatitis scores in each live weight group.  
 
28 

 
 
29 
100
Live weight Grp 1
*
Live weight Grp 2
80
 
Live weight Grp 3
rds
Average
 bi
60
 of
ge
ta

40
n
e
rc

**
e
P

20
**
1982
0
0
1
2
3
4
Foot pad Score
Act 
 
Figure 9 Percentage of birds by foot pad scores in 3 live weight 
groups  
Note: * = p < 0.05; ** = p<0.01; *** = p<0.001, sem’s are shown for each data 
point Live weight group 1, 1.64 to 1.99kg; live weight group 2, 2.06 kg to 2.89 
kg; and live weight group 3, 2.94 kg to 3.53 kg 
Information 
The factors from the epidemiological survey which were 
correlated with foot pad dermatitis scores were; hock burn, 
season, and system failures. These variables accounted for 
55% (R2) (p < 0.001) of the variation. Birds with little foot pad 
Official 
dermatitis also had low hock burn scores (Figure 10).  
 
the 
 
 
 
under 
1.5

 pa
1.0
re
 Foot
o
ge
sc 0.5
ra
Released evA 0.0
0.0
0.2
0.4
0.6
0.8
1.0
Average Hock burn scores
 
Figure 10 Foot pad dermatitis versus hock burn scores 
Foot pad dermatitis was correlated with system failures in the 
shed. Over the study, there were five system failures, four of which 
 
29 

 
 
30 
showed high foot pad dermatitis scores. Of these four system 
failures, three were feed line faults and one was a water line leak. 
Birds in one shed with a system failure giving a large water leak 
had a low incidence of foot pad dermatitis (Figure 11) 
 
1.6
ore 1.4
c
1.2
d s 1.0
 pa 0.8
1982
0.6
 Foot 0.4
ge
ra 
0.2
Act 
e
0.0
A
No
Yes
System failure
 
Figure 11 Foot pad dermatitis scores as a function of incidence of 
system failure in the shed  
 
Information 
Season was associated with foot pad dermatitis score, with 
scores in winter/spring being higher than summer/autumn 
(Figure 12).  
Official 
 
2.0
the 
or
c

1.5
d s
 pa 1.0 under 
 Foot
0.5
ge
ra
e
v
0.0
Summer/Autumn
Winter/Spring
season
 
Released 
Figure 12 Foot pad dermatitis scores versus season  
 
Hock Burn 
Average hock burn scores were less than 0.5 on a scale from 1 
(mild) to 3 (severe). On average, 72.4% of birds had no hock burn, 
 
30 

 
 
31 
97.3% had a score of 0 or 1, and 99.9% had a score of 0, 1 or 2. 
There was no difference in hock burn between the three live weight 
groups for none (0), mild (1) or severe (3) hock burn scores. There 
was a higher proportion of birds with hock burn score 2 in the 
medium live weight group (group 2, 2.06 kg to 2.89 kg) compared 
with lightest birds (group 1, 1.64 to 1.99kg) (< 0.001). Figure 13 
shows the hock burn scores for birds within each of the three live 
weight groups. 
1982
100
Live weight Grp 1
Live weight Grp 2
80
Act 

Live weight Grp 3
ird
Average
f b
60
 o
e
g
ta

40
rcen
e
P

20
**
Information 
0
0
1
2
3
Hock Burn Score
 
Official 
Figure 13 Percentage of birds by hock burn scores in 3 live weight 
groups 
the 
Note: * = p < 0.05; ** = p<0.01; *** = p<0.001, sem’s are shown for each data 
point Live weight group 1, 1.64 to 1.99kg; live weight group 2, 2.06 kg to 2.89 
kg; and live weight group 3, 2.94 kg to 3.53 kg 
 
under 
The factors from the epidemiological survey which were 
correlated with incidence of hock burn were: foot pad 
dermatitis (see Figure 10); brooding method in the shed; the 
subjective description of air quality and chicks m-2. These 
four variables accounted for 57% (R2) of the variation in the 
Released 
model (< 0.001). 
 
Average Hock burn scores were higher in sheds were there was 
half shed brooding, compared with two thirds, three quarters or full 
shed brooding (Figure 14).  
 
31 

 
 
32 
1.0
 
rn
u

0.8
 b
ck

0.6
o
res
 H
e

0.4
sco
ag
0.2
er
v
A

0.0
1/2 shed
Whole 
Brooding
shed
 
Figure 14 Hock burn scores versus brooding method used in the 
1982
shed 
 
Act 
Farms with “very good” or “average” air quality was associated with 
low average hock burn scores, whereas “good air quality” was 
associated with relatively higher average hock burn scores (Figure 
15) 
Information 

1.0
0.8
 bur
k

0.6
oc
re
 H
0.4
ge
sc
Official 
0.2
ra
e
v

0.0
A
the 
0
1
2
3
4
5
Air quality
 
Figure 15 Average hock burn scores versus air quality  
under 
Note: 1 = smelly; 2 = dusty; 3 = average; 4 = good; 5 = very good 
 
Hock burn scores appear to increase with increasing number of 
chick per metre square (Figure 16) 
Released 
 
32 

 
 
33 
 
1.0
rn
u

0.8
 b
ck

0.6
o
res
 H
0.4
e
sco
ag
0.2
er
v

0.0
A
0
5
10
15
20
25
chick m-2
 
Figure 16 Hock burn scores versus chicks per m2 
1982
Breast blisters 
Act 
On average 99% of birds had no breast blisters (score = 0) (Figure 
17). There were no differences between the live weight groups. 
Live weight Grp 1
100
Live weight Grp 2
Information 
Live weight Grp 3
80

Average
ird
f b

60
 o
e
g
ta

Official 
40
rcen
e
P

20
the 
0
no blister
blister
under  Breast blister Score
 
Figure 17 Percentage of birds by breast blister scores in 3 live 
weight groups 
Note: * = p < 0.05; ** = p<0.01; *** = p<0.001, sem’s are shown for each data 
point Live weight group 1, 1.64 to 1.99kg; live weight group 2, 2.06 kg to 2.89 
Released 
kg; and live weight group 3, 2.94 kg to 3.53 kg 
 
Factors in the epidemiological survey were not associated with the 
percent of birds with breast blisters.  
 
 
33 

 
 
34 
Incidence of back scratches, DOAs (birds dead on arrival) 
and rejected birds. 
Back scratches 
The average back scratch score was 0.64. On average, 59.4% of 
birds had no back scratches, 91.2% had a score of 0 or 1. The 
majority of birds with no back scratches were in the heaviest live 
weight group (75%), while less than half of the lightest birds had no 
back scratches (44.2%) (p < 0.001). A higher proportion of the 
lightest birds had scores of 1 (41%) and 2 (14 %) compared with 
1982
live weight group 2 (score 1, 34% and score 2, 6.9%) and live 
weight group 3 (score 1 22%; score 2 2.5%) (< 0.001). Figure18 Act 
shows the back scratch scores for birds within each of the three 
live weight groups. 
 
Live weight Grp 1
100
Information 
Live weight Grp 2
Live weight Grp 3
***
80
 
s

Average
rd
60
Official 
 of bi
ge

***
ta
40
n
e

the 
rc
e
P

20
***
0
under 0
1
2
Back Scratch Score
 
Figure 18 Percentage of birds by back scratch scores in 3 live 
weight groups  
Note: * = p < 0.05; ** = p<0.01; *** = p<0.001, sem’s are shown for each data 
Released 
point. Live weight group 1, 1.64 to 1.99kg; live weight group 2, 2.06 kg to 2.89 
kg; and live weight group 3, 2.94 kg to 3.53 kg 
 
Factors in the epidemiological survey which were correlated with 
back scratches were: season; management practices; and the 
material used to construct the shed. These three variables 
accounted for 38% (R2) of the variation in the model (= 0.0075). 
 
34 

 
 
35 
Management practice A had higher back scratch scores than B 
and C (Figure 19). 
 
 
1.0
tch
ra
 sc

s
ck
re
a
0.5
e b
sc
g
ra

1982
ve
0.0
A
A
B
C
Management practice
Act 
 
Figure 19 Average back scratch score across management 
practices 
 
Average back scratch scores were higher in winter/spring 
compared with summer/Autumn season (range from 0.43 to 0.79) 
Information 
compared with the winter/spring season (range from 0.54 to 0.78) 
(Figure 20. All female sheds had a lower average back scratch 
score compared with as hatched (mixed gender) or all male 
sheds). 
Official 
 
1
the 
tch
ra

0.8
 sc
0.6
ck
res
a
 b

0.4
under 
e
sco
ag
0.2
er
v

0
A
Summer/
Winter/
Season
Autumn
Spring
 
Figure 20 Average back scratch score across season 
Released 
 
 
 
 
35 

 
 
36 
Back scratch scores were higher in sheds with wooden framing 
(Figure 21).  
1.0
e
or
0.8
h s
tc
ra 
0.6
c
 s
k
0.4
 ba
0.2
ge
ra
e
0.0
A
1982
steel
wood
Material used to construct shed 
 
Act 
Figure 21 Average back scratch score by construction material of 
shed 
Birds dead on arrival (DOA) and rejected birds (rejects) 
Table 7 shows the percentage of birds dead on arrival (DOA) or 
rejected at the slaughter plant for each live weight group. The 
Information 
average proportion of birds dead on arrival (DOA) was 0.15% with 
the heaviest birds having the highest proportion (0.20%) (p < 
0.001). The average number of rejects was 0.22%. There was no 
Official 
difference in the proportion of reject birds between weight 
categories. The average number of DOAs and rejects combined 
the 
was 0.37%, with no difference in proportions between the weight 
categories. 
 
under 
Table 7. The percentage of birds dead on arrival (DOA) or rejected 
at the slaughter plant by live weight group 
DOA & 
Live weight 
DOA% 
SEM 
Reject%
SEM 
Reject% SEM 
Group 1 
0.12 
0.03 
0.22 
0.04 
0.34 
0.06 
Released 
Group 2 
0.16 
0.02 
0.23 
0.06 
0.39 
0.06 
Group 3 
0.20 
0.04 
0.18 
0.03 
0.38 
0.04 
Average 0.15 
0.02 
0.22 
0.03 0.37  0.04 
Note: SEMs are shown for each data point. Live weight group 1, 1.64 to 
1.99kg; live weight group 2, 2.06 kg to 2.89 kg; and live weight group 3, 2.94 
kg to 3.53 kg 
 
 
36 

 
 
37 
Factors in the epidemiological survey were not associated with the 
percent of birds dead on arrival at the slaughter plant.  
 
The factors in the epidemiological survey which were correlated 
with proportion of birds rejected were; hock burn, expected age of 
slaughter and litter depth at placement (R2 = 42.6, p = 0.0037). 
 
Rejection rates increased at higher average hock burn scores 
(Figure 22). 
 
1982
d
0.10
te
c
je

Act 
s
f re
rd 0.05
t o
bi
n
e
rc
e

0.00
P
0.0
0.1
0.2
0.3
0.4
Average hock burn scores
Information 
 
Figure 22 Percentage of rejected birds versus average hock burn 
scores 
 
Official 
Percentages of rejected birds increased with increases in expected 
age of slaughter (Figure 23). 
the 
 
0.3
ed
ct
e
ej
under 
0.2
f r
rd
t o
bi 0.1
en
c
er

0.0
P
25
35
45
55
Expected age at slaughter
Released 
 
Figure 23 Percentage of rejected birds versus expected age of 
slaughter  
 
Percentages of rejected birds increased with litter depth at 
placement (Figure 24). 
 
37 

 
 
38 
 
0.3
jected
e

0.2
f r
rds
t o
bi 0.1
rcen
e

0.0
P
0
2
4
6
8
10
Litter depth at placement
 
Figure 24 Percentage of rejected birds versus litter depth at 
1982
placement  
 
Act 
Information 
Official 
the 
under 
Released 
 
38 

 
 
39 
DISCUSSION  
 
This study has used the best measures available to objectively 
assess the management and welfare of broiler chickens in New 
Zealand, and establishes a baseline for welfare standards in the 
industry.  
 
Some of the husbandry procedures are common across the 
industry, include: type of flooring (concrete); and litter type (wood 
1982
shavings); ventilation system (extraction); use of pans for feeding 
and nipple drinkers; rodent control; hygiene policies; types of and Act 
frequency of use antibiotics; and enzymes added to feed; type of 
feed available to chicks less than 7 days old; and absence of 
specific behavioural enrichment strategies.  
 
Variations in the welfare measures recorded in the present study 
were correlated with each other and with variations in the 
Information 
procedures identified in the epidemiological survey. It is important 
to remember that some of the significant correlations may have 
occurred by chance, and if a reasonable (logical) explanation 
Official 
cannot be found for the correlations, it is not sensible to attribute 
them any significance. That said, these results remain useful in 
the 
identifying potential causes of variation in the welfare status of 
broilers. 
 
under 
Overall mortality was 3.8%, which is at the lower end of levels 
typically seen in the industry overseas, and a little higher than the 
best that has been reported (Butterworth, 2004). Of all the birds in 
the study, 0.3% died as leg culls. The contribution of leg culls to 
total mortality was relatively low (8%) and about half that reported 
Released 
for birds in two recent UK studies (15% in UK) (Hall, 2001, 
Dawkins et al. 2004). Further, the proportion of birds with severe 
leg weakness (gait score 4 and 5) in our NZ research was about 
one quarter that reported for broilers in the UK, Denmark and 
Sweden (1.4% versus 5 to 6.5%; Kestin et al. 1992; Sanotra et al. 
2003).  Moreover, these studies are the only published ones that 
have used the same gait scoring procedure as used in our 
 
39 

 
 
40 
research. Considering both the leg culling and gait scoring 
information together, our results demonstrate that leg health in 
New Zealand broilers is better than for birds in Europe.  
 
In the UK studies mentioned above, there appears to be a higher 
proportion of “other culls” (35% UK versus 21% NZ) and a lower 
proportion of “natural deaths” (50% UK versus 71% NZ) relative to 
total mortality compared with the New Zealand industry.  This 
suggests that there are differences between NZ and the UK not 
only in leg health, but also in the conditions leading to culling for 
1982
non-leg related disorders and/or natural deaths. The post-mortem 
data can potentially provide insights into likely differences in non-Act 
leg related conditions between NZ and elsewhere but, 
unfortunately, there are no other studies with appropriate autopsy 
data to make a detailed comparison. Further, we should exercise 
caution when interpreting the New Zealand industry post mortem 
data for the natural deaths, as the proportion of birds autopsied (for 
natural deaths, 14%) was much lower than the proportions 
Information 
autopsied for leg and other culls, about 25%). Further, there were 
a relatively high proportion of post mortems accorded “no 
diagnosis” for birds in all categories (mortality, leg cull and other 
Official 
cull). The reason for this may have been due to the process of 
freezing the birds (which had to occur for logistical reasons) 
the 
altering some of the internal structures, making it more difficult for 
an accurate diagnosis of death. In addition, histological and other 
examinations of tissue were not undertaken due to financial 
under 
constraints of the project. 
 
Generally speaking, the range of conditions seen in the autopsies 
of the natural deaths and other culls in our study is similar to that 
seen elsewhere (Butterworth, 2004; Julian, 2004), and the 
Released 
prevalence of ascites (0.12%) was similar to that quoted elsewhere 
(0.15%, Butterworth, 2004), whilst kinky back (0.03% NZ versus 
0.3 % elsewhere), acute death syndrome (0.69% NZ versus >2% 
elsewhere), pendulous crop (0.00% NZ versus 0.1 % elsewhere) 
were lower in our study.  Other diseases such as enteritis and 
cellulitis were rare or absent in our post-mortem samples. 
 
 
40 

 
 
41 
Of the birds autopsied, acute death syndrome (ADS) (also known 
as sudden death syndrome) was the highest ranking cause of 
death (17.6%). Bagshaw and Matthews (2001) reported that 
incidence of ADS (or sudden death syndrome) may be effected by 
fast growth rate, nutrition and other environmental factors. In the 
current study, there was a lower incidence of ADS on farms with a 
foot bath in the annex. On those farms without a foot bath in the 
annex, the growers changed boots; therefore it is unlikely that 
hygiene was a factor in incidence of ADS. Indeed, the presence of 
a foot bath cannot be assumed to reduce ADS from this study. The 
1982
significance of the correlation between ADS and hock burn score is 
not clear, particularly since factors usually associated with hock 
Act 
burn (e.g. density and season (Imaeda, 2000) were not correlated 
with ADS.  The lower rate of ADS with increased time on diet 1 
could be an area for further fruitful research. 
 
Of the birds autopsied, 9% died from navel infection. The 
percentage of birds with navel infection was correlated with 
Information 
genotype and ventilation system in the shed. There were higher 
percentages of birds which were autopsied with navel infections 
under management practice types A and B compared with type C. 
Official 
The difference between management practices is likely due to 
factors which are highly confounded such as nutrition, lighting 
the 
schedules, stockmanship, and genotype.  Further exploration of 
the differences in management practices between the three 
systems might yield useful information on ways to reduce the 
under 
incidence of navel infection. Navel infection was generally lower in 
cross-flow ventilation sheds compared with other types of 
ventilation in sheds (e.g. roof, side and tunnel). However, there 
were insufficient numbers of any other types of ventilation system 
to make a direct comparison between different systems. 
Released 
 
The high rate of non diagnosis of pathologies for the leg culls 
(28%) implies that we should exercise caution when interpreting 
these data. Of the leg culls autopsied, the most common pathology 
identified was deformed limbs (Varus valgus and twisted tibia) 
(24%), with the next three most common conditions being 
infections (joint (10%) and femoral head necrosis (9.5%)) and 
 
41 

 
 
42 
kinky back (6%). These pathologies are typical of those seen 
elsewhere, but the relative frequency of the infectious causes 
appears lower in the New Zealand birds than elsewhere (e.g. 
femoral head necrosis rates in the UK of 17 to 38%; (Butterworth, 
1999; McNamee and Smyth, 2000). Conversely, deformed limbs 
occurred relatively more often in the New Zealand industry than in 
the UK (11 to 14 % Butterworth, 1999; McNamee and Smyth, 
2000). In absolute terms, this latter observation does not imply that 
deformed legs are a greater welfare problem for New Zealand 
birds as the culling rate for leg disorders in New Zealand is only 
1982
about half or less than half that seen elsewhere (e.g. Dawkins, 
2004; Hall, 2001; McNamee and Smyth, 2000).   
Act 
 
The percentage of autopsied birds that were culled for leg 
weakness was correlated with type of management practice 
(higher in type A) and target temperature at week 3 (occurring in 
type A sheds).  In this data set, management practice A was 
represented by two sheds only, therefore clear conclusions cannot 
Information 
be drawn from these results. However, further investigations may 
help to understand if there is any causal link between leg 
weakness and target temperature at week 3, or other specific 
Official 
management practices.  
 
the 
The gait scoring procedure used was highly reliable and consistent 
over time. On average, there were relatively few birds with a 
normal or near normal gait (8.1%, gait scores 0 and 1 combined), 
under 
with two-thirds having a gait score of 2, 23% with a gait score of 3, 
and 1.4% with gait scores of 4 or5). There was a clear effect of live 
weight on gait score, with proportionately fewer of the heaviest 
(also older) birds in categories 1 and 2, and proportionately more 
with gait scores 3 and 4. Kestin et al. (2001) has also reported 
Released 
poorer gait scores with heavier birds, and demonstrated that the 
effect is due to weight rather than age. 
 
A number of UK researchers (Danbury et al., 2000; Hocking et al., 
1999; McGeown et al., 1999;) have attempted to assess the 
welfare impacts of different gait scores by measuring time budgets 
and determining if the degree of pain experienced varies with gait 
 
42 

 
 
43 
score (see Introduction). While it would be surprising if lame birds 
didn’t experience some pain (at least for some pathologies and 
particularly at high gait scores), the interpretation of these data is 
not unequivocal 
 
In addition, a single gait score can be associated with a range of 
different pathologies (Mench, 2004) and there may be varying 
levels of pain associated with different pathologies. This has also 
not been examined scientifically. Others have attempted to assess 
the welfare implications of high gait score by looking at walking 
1982
speed and time budgets of animals with different gait scores (e.g. 
Weeks et al, 2000; Bokkers and Koene, 2004). High gait score 
Act 
birds walk more slowly through obstacle courses, rest for longer 
periods and have a reduced visitation rate to feeders and drinkers. 
These results suggest impaired walking ability but do not resolve 
the issue of the presence or degree of pain experienced. We do 
not know if pathologies causing a particular gait score in New 
Zealand broilers are the same as those causing altered gait in 
Information 
birds in other countries. Thus, it is difficult to know if, or what, 
proportion of say gait score 3 birds in New Zealand are 
experiencing pain (as seems likely for a proportion of gait score 3 
Official 
birds in the UK). It would be instructive to conduct studies in New 
Zealand of gait score before and after pain relief to determine the 
the 
relationship between gait score and pain in broilers under New 
Zealand conditions.  Further, more detailed studies of the 
pathology leading to gait abnormalities in New Zealand broilers 
under 
would provide additional insights into the likely welfare impacts 
caused by those pathologies. 
 
Because both leg culling rates and the occurrence of gait scores 4 
and 5 (about 1%) were relatively low in our study, it seems that 
Released 
severe leg weakness is less of a problem in the New Zealand 
industry than elsewhere. As birds with gait scores 4 and 5 are 
likely to experience poor to very poor welfare (including pain) it is 
desirable to cull birds in these categories as soon as possible, 
thereby reducing their incidence in the flock to as close to zero as 
is practically possible. Research and practical management 
procedures to achieve this goal are a priority.  
 
43 

 
 
44 
 
While research conducted overseas has implicated a large variety 
of management factors in the aetiology of leg weakness (e.g. 
stocking density, lighting cycles and intensity, ambient temperature 
and humidity, ammonia levels, litter quality and floor type; (Reiter 
and Bessei, 1998) no significant correlations between such factors 
and gait score were seen in our study. Possible reasons for the 
absence of correlations in the present study include: these factors 
do not influence leg weakness under New Zealand conditions; 
and/or there was too little variation in the relevant 
1982
management/husbandry procedures. 
Act 
 
Contact dermatitis is thought to be caused by a combination of 
moisture and chemical irritants in the litter of broiler houses 
(Ekstrand et al., 1998). Thus, the incidence of contact dermatitis is 
an indicator of the condition of litter substrate, and this in turn 
provides a measure of the suitability of the environmental 
Information 
conditions in the houses. Berg (2004) reported that a number of 
risk factors for contact dermatitis in temperate climates have been 
identified. These are: litter material; litter type; floor type; stocking 
Official 
density; drinker system and feed composition. 
 
the 
The majority (71%) of birds in this study had no foot pad dermatitis, 
which is similar to the levels reported in the literature (e.g. 
Dawkins, 2004), although it is difficult to compare directly the 
under 
results from our study with others as the measurement protocols 
differed. Previously used protocols have been lacking in precision 
and not often tested for reliability and consistency in their 
application. In our study, an average of 89.5% of birds had scores 
of 0 or 1 (none or mild). These results imply that litter conditions 
Released 
are well maintained in NZ, although the incidence was slightly 
higher in winter/spring months when humidity is higher. During the 
winter/spring season, four of the sheds had a system failure and 
these birds had relatively high foot pad dermatitis. In contrast, 
during the summer/autumn season, one shed had a system failure 
these birds had relatively low foot pad dermatitis. Thus, although 
 
44 

 
 
45 
the seasonal data were confounded by system failures, the higher 
incidence during wetter times of the year it is consistent with other 
studies showing that the relative humidity inside and outside the 
house has an influence on litter quality, with the highest prevalence 
of foot pad dermatitis occurring in the autumn/winter months in 
Europe (Berg, 2004).  
The incidences of foot pad dermatitis and hock burn were 
correlated, as has been observed by others (Greene et al., 1985).  
 
A higher proportion of the heavier (older) birds had no foot pad 
1982
dermatitis, suggesting that this condition improves over the grow-Act 
out period. David Marks (pers comm.) suggests that this could 
occur as a result of an earlier bacterial infection healing over the 
life of the bird when litter quality is good. 
 
The majority of birds (72%) in this study had no hock burn, which is 
similar to the levels reported in the literature (Menzies et al., 1998), 
Information 
although it is difficult to compare directly the results from our study 
with others as the measurement protocols differed. Previously 
used protocols have been lacking in precision and not often tested 
Official 
for reliability and consistency in their application. An average of 
97.3% of birds had no or mild hock burn. These data indicate that 
the 
litter conditions are well maintained in NZ. There was no difference 
in the percentage of birds with hock burn across the live weight 
groups for none, mild and severe scores. However, birds of 
under 
medium weight had higher hock burn scores compared with the 
lightest or heaviest birds in the study. The reason for this is 
unclear. 
 
Average hock burn scores were correlated with foot pad dermatitis, 
Released 
the type of brooding in the shed, air quality, and chick m-2 at 
placement. Average hock burn scores tended to increase with 
average foot pad scores and this relationship was discussed 
earlier. Average hock burn scores are higher in sheds where there 
is half shed brooding, compared with two thirds, three quarters or 
full shed brooding. Average hock burn scores varied little across 
 
45 

 
 
46 
the subjective scores of air quality. However there appeared to be 
slightly lower average hock burn scores when the air quality was 
deemed very good (score 5). There was a trend toward increased 
hock burn with increased density of chicks at placement but not 
density at the time of assessment. There are no obvious 
explanations for these correlations. 
 
The incidence of breast blisters was extremely low (0.5%), is 
consistent with that reported internationally (Berg, 2004), and 
implies that litter conditions were well maintained.  
1982
 
Act 
The incidence of contact dermatitis (foot pad dermatitis, hock burn 
and breast blisters) is similar to that reported internationally and 
implies that New Zealand broiler sheds have good environmental 
conditions. In this study, there were no correlations found between 
litter depth or type, floor type, or stocking density, drinker system 
and welfare measures. The litter material used in most sheds in 
Information 
our study was wood shavings, and this has been found to result in 
lower incidence of foot pad dermatitis compared with straw 
(Ekstrand et al., 1997). Nipple drinkers with cups were used in the 
Official 
sheds in our study, and this type of drinker system has been 
shown to reduce the risk of wet litter and the risk of contact 
the 
dermatitis (Berg, 2004). 
 
Back scratches, birds dead on arrival (DOA) and reject birds were 
under 
used in this study as indicators of catching and other damage 
during the pre-slaughter period, although the activities and factors 
prior to this period may influence and, therefore, confound these 
measures.  
 
Released 
The frequency of occurrence of back scratches is only infrequently 
reported in the literature, and the incidence of scratches and 
associated conditions varies widely from 0.3 to 60% (Hall 
2001;Feddes et al., 2002; Frankenhuis et al., 1991). The average 
incidence of back scratches in the present study was 41%, being 
much higher than the lowest overseas estimates. It is not clear why 
 
46 

 
 
47 
there would be such a difference, although it is possible that the 
low rates mentioned elsewhere are underestimates. This could 
occur if the measurement systems used were not reliable. For all 
the data reported by others,(e.g. Hall, 2001), the definitions of 
scratches have been imprecise and there have been, no 
assessments of the reliability or consistency of the scoring systems 
used.  Thus, it is difficult to make meaningful comparisons between 
our data and the incidence of scratches reported elsewhere.  Back 
scratching during the grow out period is an important welfare issue 
as it can lead to scabby hip syndrome and other lesions of the skin 
1982
(Proudfoot and Hulan, 1985). The welfare impacts of scratches 
that occur during catching and pre-slaughter handling are not 
Act 
known, but would likely cause some pain or discomfort.  
 
In our study, a higher percentage of lighter birds had back 
scratches compared with the heaviest birds. There are many 
factors which could contribute to this difference including stocking 
Information 
density (heavier birds were at a lower density due to prior thinning 
of a portion of the flock), feather cover (older birds have better 
feather cover), behaviour (older are less flighty), and gender of the 
bird (males are more likely to scratch and have later development 
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of feathers). The significant correlations between back scratch 
incidence and management practices and season could be 
the 
attributable to behavioural differences in these particular 
environments, but additional research would be required to 
ascertain any causal relationships. Average back scratch scores 
under 
were correlated with the type of construction material of the shed; it 
is likely that this correlation occurred by chance. 
 
The average percent of birds dead on arrival was 0.15% and the 
average percent of bird rejected at the slaughter plant was 0.22%, 
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both values being at the lower end of the internationally reported 
levels (Ekstrand, 1998), suggesting that the pre-slaughter handling 
of birds in New Zealand is well conducted. 
 
Rejected birds at the slaughter plant were correlated with average 
hock burn scores, expected age of slaughter and litter depth when 
 
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48 
the chicks were placed in the shed. As average hock burn score 
increased there was an increase in percentage of rejected birds. 
However, it is important to note that the variation in hock burn 
scores was very small, and there were very small increases in the 
percentage of rejected birds (less than 0.1%). There was a trend 
towards increasing percentage of rejected birds with increasing 
expected age of slaughter, but the meaning of this is not clear as 
there was no relationship between live weight and reject rate. Litter 
depth varied from 3 to 12.5cm, but explanations for an effect of 
litter depth at placement on reject rates is not apparent.  
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Act 
Apart from a relatively high incidence of back scratches, the 
measures taken indicate good standards of pre-slaughter handling 
of broilers are achieved in New Zealand.  
 
Stocking density and animal welfare has often been a contentious 
issue in the literature. Bagshaw and Matthews ( 2001) reported in 
Information 
a literature review that stocking density per se does not appear to 
be a major direct cause of most welfare problems, traditionally 
associated with high stocking density rates. From the published 
Official 
information it appears that other environmental conditions are 
more directly implicated. In this study, stocking density varied 
the 
between 32.9 and 39.3 kg m-2. Stocking density was not correlated 
with any of the welfare measures, or variables in the 
epidemiological survey, suggesting that broiler welfare is either 
under 
unaffected by stocking density or that the range in densities seen 
in the current study was too small to enable correlations to be 
detectable. Stocking density (at the levels currently used in this 
study) would appear appropriate as the welfare of the birds is 
good. 
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49 
CONCLUSIONS AND FURTHER RESEARCH 
1.  General flock health is good as demonstrated by the relatively 
low total mortality rate and low incidence of infectious 
pathologies in birds culled for leg disorders. 
2.  There is a very low rate of culling for leg disorders in New 
Zealand broilers and substantially fewer birds with severe leg 
weakness (gait score 4 and 5). Most birds had gait scores of 1 
or 2. Considering both the leg culling and gait scoring 
information together, our results demonstrate that leg health in 
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New Zealand broilers is better than for birds in Europe. Given 
the high level of international concern with leg weakness in 
Act 
broilers, particularly in relation to the degree of pain 
experienced, it would be pertinent to undertake further 
research on the welfare impacts at different gait scores and of 
the common pathologies. The frequencies of various 
pathologies associated with leg weakness appears different for 
our broilers, implying that, in order to make further research on 
Information 
questions such as pain relevant to our conditions, it should be 
undertaken in New Zealand. 
3.  Prevalence of all forms of contact dermatitis (footpad, hock 
Official 
burn and breast blisters) appears within the range reported 
internationally. Incidences, such as occurred, were mostly of a 
the 
relatively minor nature. These data indicate that the litter in the 
houses is maintained in good condition, with small seasonal 
variation 
under 
4.  Pre-slaughter handling procedures as assessed by Dead On 
Arrivals and reject birds were generally better than reported for 
other countries. The proportion of birds with back scratches 
averaged 39%. Meaningful comparisons between our data and 
the incidence of scratches reported elsewhere were not 
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possible due to the lack details of the measurement criteria 
provided in other published reports. The welfare impacts of 
back scratches under New Zealand conditions, and procedures 
to reduce their incidence, would merit further study. 
5.  In this study, stocking density varied between 32.9 and 39.3 kg 
m-2. Stocking density was not correlated with any of the welfare 
 
49 

 
 
50 
measures, or variables in the epidemiological survey, 
suggesting that broiler welfare is either unaffected by stocking 
density, or that the range in densities seen in the current study 
was too small to enable correlations to be detectable. 
Controlled studies using a wider range of stocking densities 
would need to be undertaken to identify any effects of stocking 
density on welfare. Stocking density (at the levels currently 
used in this study) would appear appropriate as the welfare of 
the birds is good. 
6.  Correlations undertaken between the welfare measures and 
1982
rather simple features of the husbandry system or 
environmental conditions revealed some significant and 
Act 
interesting results. Some of these appeared logical and 
reasonable (e.g. correlation between foot pad dermatitis and 
season) and provide valuable insights into possible ways to 
improve welfare through alteration of husbandry procedures. 
Variations in more complex factors such as management type 
Information 
(A, B, C), which includes genotype, were sometimes 
associated significantly with variation in welfare measures. For 
example, management practice type C had a higher incidence 
of ADS and a lower incidence of navel infection compared with 
Official 
the other types of management practice. This, again, suggests 
that there would be considerable opportunity to improve broiler 
the 
welfare through identifying cause and effect relationships, such 
as they may exist, that underlie such correlations. It is 
recognised that this is not a trivial task due to the large number 
under 
of highly confounded (and commercially sensitive) variables 
that make up, for example, a particular type of management 
practice. 
7.  One of the often-expressed concerns with intensive indoor 
broiler growing conditions is the lack of behavioural activity 
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(both in the range of activities and time spent engaged in them) 
of broilers. The current study did not attempt to assess this 
aspect of broiler welfare, but we did record in the survey that 
there are no procedures in place to encourage a wider 
behavioural repertoire of birds in sheds. 
 
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51 
8.  Apart from the expected correlation between two of the 
measures of contact dermatitis (footpad dermatitis and hock 
burn), there were no significant correlations between the 
various welfare measures. This suggests that each measure 
was assessing independent welfare traits and, thus, all should 
be used in studies where a comprehensive description of 
broiler welfare status is required (e.g. in audits). 
9.  This study has demonstrated that the welfare of broilers in New 
Zealand is equal to or superior to that of broilers kept 
elsewhere. 
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Act 
Information 
Official 
the 
under 
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52 
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the 
 
Acknowledgements 
We would like to thank the Broiler Welfare Research Committee for 
under 
their lively discussions and support for this study. Thanks to the 
scorers in the field, in particular Diane Sutton, Frankie Hubbard, 
Katie Carnie. A special thanks to Dr Andy Butterworth, for his 
discussions and running the gait scoring workshop. 
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