New Production Systems: Evaluation of Organic Broiler Production in Denmark

Abstract

SUMMARY In Denmark organic production of broilers (chickens for meat production) has expanded since 1996, when only a few farmers produced approximately 6,000 broilers. At that time, the broilers were sold directly to customers. At present, the yearly production is 350,000 broilers, and professionals organize the sale. Organic broiler production should comply with the overall goals for organic farming. This new production system differs from the conventional system due to specified standards. The production period is prolonged because broilers need to be at least 81 d old when slaughtered, and these chickens are genetically programmed to be slower growing with a maximum growth rate of 30 g/d. Additionally, daily access to roughage, organic feed without coccidiostats, and outdoor pasture areas is required. In the present paper the organic production system and data concerning growth, feeding, animal health, and slaughter quality is described based on an investigation conducted on 9 Danish farms in 1998. This investigation is the first of organic broiler production in Denmark.

Full text

2003 Poultry Science Association, Inc.
New Production Systems: Evaluation
of Organic Broiler Production
in Denmark
M. A. Pedersen,* S. M. Thamsborg,†
,1
C. Fisker,‡ H. Ranvig,*
and J. P. Christensen†
*Department of Animal Science and Animal Health, Royal Veterinary
and Agricultural University, †Department of Veterinary Microbiology,
Royal Veterinary and Agricultural University, DK 1870, Fredericksberg, C,
Denmark; ‡National Department of Poultry Production, Danish Agricultural
Advisory Centre, Aarhus C, Denmark DK 8200
Primary Audience: Researchers, Veterinarians, Flock Supervisors
SUMMARY
In Denmark organic production of broilers (chickens for meat production) has expanded since
1996, when only a few farmers produced approximately 6,000 broilers. At that time, the broilers
were sold directly to customers. At present, the yearly production is 350,000 broilers, and
professionals organize the sale. Organic broiler production should comply with the overall goals
for organic farming. This new production system differs from the conventional system due to
specified standards. The production period is prolonged because broilers need to be at least 81 d
old when slaughtered, and these chickens are genetically programmed to be slower growing with
a maximum growth rate of 30 g/d. Additionally, daily access to roughage, organic feed without
coccidiostats, and outdoor pasture areas is required. In the present paper the organic production
system and data concerning growth, feeding, animal health, and slaughter quality is described
based on an investigation conducted on 9 Danish farms in 1998. This investigation is the first of
organic broiler production in Denmark.
Key words: broiler, ecological farming, feed intake, growth, ISA 657, organic farming, slow-
growing chicken
2003 J. Appl. Poult. Res. 12:493–508
DESCRIPTION OF PROBLEM
Organic (or ecological) production of broil-
ers in Denmark has expanded from about 6,000
in 1996 to more than 100,000 broilers produced
on 20 farms in 1998 [1]. In 2001, 350,000 or-
ganic broilers were produced [2]. However, this
number is small in comparison with conven-
tional production in Denmark, which produced
approximately 134 million broilers in 2000 [3].
1
To whom correspondence should be addressed: smt@kvl.dk.
Organic broiler production in Denmark
should comply with the overall goals of organic
farming, as expressed by the International Feder-
ation of Organic Agriculture Movements
(IFOAM) [4]. Some of the principle aims are to
encourage and enhance biological cycles within
farming systems, to use—as much as possible—
renewable resources in locally organized pro-
duction systems, to create a harmonious balance
between crop production and animal husbandry,

JAPR: Research Report494
and to provide livestock conditions that respect
basic aspects of innate animal behavior.
When the present investigation was com-
pleted, production was regulated by a set of stan-
dards at the national level [5] inspired by Euro-
pean Union regulation 1894 [6] that came into
force in August 2000. These rules stipulated the
use of chicken genetic lines with slower growth
(maximum growth capacity: 30 g/d), a minimum
age of 81 d before slaughter, daily access to
roughage, organic feed without coccidiostats,
and access to outdoor areas. Additionally the
participating farmers followed rules stated by the
National Board for Organic Farming, a Danish
organization for organic farmers [7]. At that
time, the rules included demands for perches,
access to outdoor areas covered with pasture,
restrictions on the stocking rate (indoor: maxi-
mum 25 kg/m
2
or 40 kg/m
2
in mobile houses,
outdoor: minimum 2 m
2
/broiler), and restrictions
on the number of birds in one group (maximum
2,000 broilers).
Because of the requirement for using slow-
growing birds, chickens from conventional pro-
duction systems, e.g., Ross 208 (growth rate up
to 60 g/d) cannot be used. In contrast, “Label
Rouge” production in France is based on slow-
growing chickens [8] and corresponds with the
rules for organic farming concerning age at
slaughter and access to outdoor areas [9]. On
the basis of results from the “Label Rouge” pro-
duction [10, 11] and results from investigations
of slow-growing chickens [12], the expected re-
sults from an organic broiler production are
chickens weighing approximately 2,200 to 2,300
g at 81 d of age. The feed requirement ranges
from 6 to 8 kg/broiler [9, 10, 11], which is larger
than in conventional production due to the longer
production period (83 to 87 d). Birds have
greater requirements for maintenance with in-
creasing age [13].
Changes in production that have influences
on animal health and welfare occur with organic
methods compared with conventional broiler
production. The risk of coccidiosis is expected
to be greater in organic broiler production. This
disease is common when no preventive treat-
ments are given [14]. Also the risk of introducing
pathogens with reservoirs in the wild fauna will
obviously increase with outdoor production,
e.g., infections such as Newcastle disease, in-
fluenza, and infectious laryngotracheitis. Con-
versely, access to outdoor areas and a longer
lifespan can positively influence the health of
broilers. For example, birds have the opportunity
to build up immunity to infections.
In this study, an investigation of 9 Danish
organic broiler farms was conducted to docu-
ment and increase knowledge of this new pro-
duction system and to evaluate results from these
farms, especially regarding growth rates, feed
conversion efficiency, health status, and slaugh-
ter quality.
MATERIALS AND METHODS
Selection of Farms and Production Periods
An on-farm investigation was conducted on
9 Danish farms with organic broiler production.
At the beginning of 1998, a total of 12 organic
farmers in Denmark had developed plans for
broiler production. Nine of these farms were
selected based on time for start of production
(May to August) and the geographic location
(Jutland and Funen). Data were obtained from
May to November in 1998.
In Denmark in general, some organic farm-
ers use production that includes 1-d-old chicks
through slaughter, whereas others have special-
ized in producing 4-wk-old chickens or in fin-
ishing broilers from 4 wk of age to slaughter.
Therefore the production period of organic
broiler production and consequently recordings
in this study can be divided into 3 periods:
1. Starting period: delivery from the hatchery
until broilers are moved to other farms or
until they are moved to a house with access
to an outdoor area (approximately at d 20
to 24).
2. Transition period: from initial move (ap-
proximately d 24) until d 50.
3. Finishing period: from d 50 until slaughter
(approximately at d 81).
History and General Farm Data
A general description of each of the 9 farms
was collected by interview. These data included
number of years in organic production, other
production on the farm (livestock or cultivation
of plants), housing facilities, and descriptions of
the land and layout.

PEDERSEN ET AL.: ORGANIC BROILER PRODUCTION 495
Data on stocking rate and housing conditions
were obtained at 3 visits during the production
period. The indoor and outdoor stocking rates
(broiler/m
2
) were calculated as the total number
of chickens at the start of the period divided by
the total floor area (m
2
) and total outdoor area
(m
2
), respectively. The feeder space per broiler
(cm/broiler) was calculated as total length (cm)
of access available on all automatic feeders di-
vided by the total number of chickens at the
start of the period. No differentiation was made
regarding the shape of the automatic feeders
(round or square trough). The number of broilers
per watering point was calculated on all farms
with bell drinkers. Finally the length of perches
per broiler was calculated as the total length of
all perches (cm) divided by the total number of
chickens at the start of the period. All recordings
were made at the beginning of each period, ex-
cept for the outdoor stocking rate and the length
of the perches per broiler, which were made in
the transition and finishing periods only.
Flock Recordings and Sampling
Feed consumption was recorded daily by the
farmer and included noting the amount of con-
centrate, whole wheat, and roughage (kg) fed to
the groups. Data on the nutritional value of the
concentrate were obtained from the feed mill.
Feed conversion (kg of feed/kg of weight gain)
was estimated on the basis of amount of feed
offered and on calculated weight gains of the
broilers. When calculating the feed intake and
feed conversion the amount of whole wheat sup-
plementation was included.
Three times during the production period (at
24, 50, and 81 d) 100 broilers were randomly
selected from each group and weighed with an
electronic balance (±1 g). However, due to prac-
tical circumstances the weighing of some groups
was not performed exactly on the days planned.
When calculating mean live weight gains within
periods, these weights were corrected to d 24,
50, and 81, respectively, by linear regression.
All weight measurements were made during the
night to avoid excitement among birds. In 16 of
24 groups, the sex of each broiler was deter-
mined at weighing during period 3.
Mortality, including those found dead or
culled, was recorded daily by the farmer. Farm-
ers were requested to submit dead birds for post-
mortem examination. At slaughter, clean, whole
chickens with no dirt, blood, foreign smell, se-
vere blood extravasations, or open fractures were
approved for quality class A or B. Additionally,
class A chickens were required to be well built
with plump musculature with no or only few
remaining feathers. Only small damaged sites,
blood extravasations, or discoloring could be
accepted, unless found on the breast and leg.
Broilers that could not be classified as A or B
(as described) were rejected. At the veterinary
inspection, pathological causes of rejection were
noted in the following groupings: 1) emaciation/
abnormal smell/discoloring, 2) ascites, 3) joints/
bones, 4) skin, 5) heart, 6) lungs, 7) liver, 8)
kidneys, 9) peritoneum/oviduct, and 10) other
illness. Data on these parameters were missing
from several groups due to different places of
slaughter, or data were not made available by
the farmer.
Statistical Analysis
Mean weight gain of broilers (g), feed con-
sumption (kg/animal), feed conversion (kg feed/
kg weight gain), and mortality (%) of up to 23
broiler groups were analyzed using the general
linear models procedure of SAS software [15].
Independent variables included farm (class vari-
able), stocking rate (SR; number of birds/unit
area), feeder space, and broilers per watering
point. Feed consumption was included as an in-
dependent variable in some analyses. One analy-
sis was made per production period, and back-
ward stepwise elimination of variables was
done. Additionally, an analysis was performed
on the uncorrected live weights (d 79 to 87) with
sex as the dependent variable.
The live weight curve was modeled using
the Gompertz function [16]: y =α×e(−β×e
(−γ×t)), where y =weight of broiler (g); α=
maximum weight of broiler (g); β,γ=Gompertz
exponents; and t =age of broiler (d). Addition-
ally, the weight gain curve was modeled using
the derived equation y′=[α×e(−β×e(−γ
×t))]′.
RESULTS AND DISCUSSION
The investigation included a total of 36,516
broilers that started in 16 groups on 4 different
farms. At age of approximately 24 d of age, the

JAPR: Research Report496
broilers were moved within the farm (55%) or
moved to another farm (45%), i.e., broilers were
divided in 23 groups on 9 different farms during
the transition period (Table 1).
Farm Descriptions and Production Planning
Two farmers had 10 to 15 yr experience with
organic farming in general, 2 farmers had 2 to
4 yr experience, and the rest had been organic
farmers for a short time (0 to 1 yr). Four were
full-time farmers, and 5 were part-time farmers.
On 4 farms the organic broiler production de-
scribed here was their first experience, whereas
the rest had 1 or 2 yr experience. Most interest-
ingly, no farmers had experience with conven-
tional broiler production beforehand. On 5
farms, broilers were the primary product; how-
ever, other products (other livestock, orchards,
vegetables, or spruce) were present on all but 1
farm. The mean area of the farms was 13.6 ha
(range: 2.5 to 22 ha). All were small farms com-
pared with the mean size of farms in Denmark,
47.7 and 49.7 ha in organic and conventional
farms, respectively [17, 18].
Two farmers specialized in production of
chickens to be sold at 4 wk of age (starter farms).
However, some of the chickens were raised on
these farms until slaughter. On 2 farms all chick-
ens were raised from1dofagetoslaughter
(whole farms). The remaining 5 farmers pro-
duced broilers from 4 wk of age until slaughter
(finishing farms) (Table 1).
All broilers produced were ISA 657 chickens
(Scan Labelle) from the same hatchery and
broiler breeder operation in Denmark (Scan-
layer, Viborg; http://www.scanlayer.dk/Labelle/
labelle.htm). Scan Labelle is a cross based on
the JA57 female. This type of chicken consti-
tutes more than 25% of the French market. The
chickens were not sorted by sex. Except for 3
groups, all broilers were slaughtered at the same
abattoir, Fjeldsted Fjerkræslagteri (Funen). Two
groups were slaughtered at “Danpo” in Ørbæk
(Funen), and the last group was slaughtered at
a small, private abattoir.
Housing Facilities and Management
Procedures
The housing conditions on the farms varied
(Table 2). Heated barns were used in the starting
period on 3 of 4 starter farms, whereas the last
used old train wagons with heating systems. At
the beginning of the starting period SR varied
from 11 to 40 broilers/m
2
, feeder space was 0.5
to 1.2 cm/broiler, and number of broilers per
watering point varied from 146 to 306.
On 5 farms, mobile houses were used for
broilers older than 4 wk (eventually supple-
mented with existing stables), 3 farms used cus-
tom-built houses, and the last farmer used ex-
isting stables only. The mean indoor SR during
transition and finishing was 16 broilers/m
2
.In
the transition period the mean feeder space per
broiler was 1.3 cm, and the mean number of
broilers per watering point was 195. The corres-
ponding means for the finishing period were 1.4
cm feeder space and 184 broilers per watering
point. The mean length of perches per broiler
was approximately 8 cm in the transition and
finishing periods. All perches were used during
the night, independent of the type of perches
(round or square cross section) or the perch cir-
cumference (5 to 15 cm). The perches were, to
some extent, used during the day as well.
All broilers had access to outdoor areas when
older than 4 wk (in the transition and finishing
periods). On 4 farms only wide-open areas cov-
ered with pasture were available. On 3 farms
open areas and areas with planted trees were
used, and on 2 farms all outdoor areas were
covered by orchards or spruce trees. The mean
outdoor SR were 3.1 broilers/m
2
in the transition
period and 3.6 broilers/m
2
in the finishing period.
When orchards or spruce trees are used for
outdoor areas, the plantings give shelter and
shade to the broilers. Tree cover reduces time
that hens spend watching for predators and en-
hances time spent feeding [19]. In general, cov-
ering enhances the willingness of hens to be
outside the house compared with areas with no
covering [20]. During farm visits it was observed
that not all broilers were out at the same time,
which was independent of the covering. How-
ever, it was obvious that nonwoody pastures
were more worn in areas where windbreaks or
buildings gave shelter. It is clear that if the total
outdoor area is to be used, and if the broilers
are to feel comfortable, then the outdoor area
must have some kind of covering.

PEDERSEN ET AL.: ORGANIC BROILER PRODUCTION 497
TABLE 1. Description of 9 farms with organic broiler production, including number of groups and number of broilers in groups (range given for each farm)
Farm
1 2 3 4 5 6 7 8 9 Total
Farm description
Full- or part-time farmer Full Part Part Full Part Part Full Part Full
Broilers primary production No No Yes Yes No Yes No Yes Yes
Farm type Whole Finishing Finishing Starter Finishing Finishing Finishing Starter Whole
Groups (n)
Starting period 4 — — 8 — — — 2 2 16
Transition period 6 1 2 4 3 2 1 2 2 23
Finishing period 6 1 2 2 3 2 1 2 3 22
Broilers per group (n)
Starting period 816–1,836 — — 1,020–2,040 — — — 5,202–8,058 2,040 35,616
Transition and finishing period 442–1,200 1,962 1,998–2,196 995–2,007 909–1,698 1,657–1,914 1,846 944–2,286 1,000–1,952 34,831

JAPR: Research Report498
TABLE 2. Description of housing facilities, outdoor areas and management procedures including stocking rate (SR), feeder space, watering points, and length of perches
in 9 farms with organic broiler production.
A
Farm Mean
Item 1 2 3 4 5 6 7 8 9 (±SD) Range
Housing
B
Starting/transition and finishing period T/CB −/M −/E H/M –/CB −/M −/CB H/M+E H/M
Outdoor area
C
Transition and finishing period O OA P+OA OA S OA P+OA OA S+OA
Starting period
Indoor SR (broilers/m
2
) 2 1–2 8 — — 20–4 0 — — — 1 1–1 8 2 0 2 7 (±8) 11–40
Feeder spacer (cm/broiler) 0.7–0.9 — — 0.5–0.7 — — — 0.8–1.2 0.9–0.9 0.7 (±0.2) 0.5–1.2
Watering points (broilers/watering point) 272–306 — — 146–291 — — — 168–217 204 250 (±59) 146–306
Transition period
Indoor SR (broilers/m
2
) 7–1 5 1 9 1 8–2 0 1 7–1 9 1 8–2 0 16–1 8 2 1 1 2–1 8 1 4–1 9 1 6 ( ±4 ) 7–2 1
Outdoor SR (broilers/m
2
) 4.3–7.4 2.4 1.9–2.0 0.9–1.3 2.4–3.0 1.7–2.0 1.1 1.3–4.5 2.8–3.5 3.1 (±2.0) 0.9–7.4
Feeder space (cm/broiler) 1.4–2.2 1.1 0.8–0.9 0.9–1.1 1.2–1.5 1.3–1.4 1.3 1.3–1.5 1.1–1.1 1.3 (±0.4) 0.8–2.2
Watering points (broilers/watering point) 147–200 109 200–222 236–287 — 138–160 231 208–236 100–195 195 (±53) 100–287
Perches (cm/broiler) 5.3–12.7 10.2 10.5–11.6 3.0–12.7 8.6–9.2 8.4–9.7 1.2 7.1–8.6 3.0–8.2 7.7 (±3.1) 1.2–12.7
Finishing period
Indoor SR (broilers/m
2
) 7–1 5 1 9 1 8–2 0 1 7–1 9 1 7–1 9 16–1 8 2 0 1 2–1 8 1 2–1 9 1 6 ( ±4 ) 7–2 0
Outdoor SR (broilers/m
2
) 4.4–7.5 2.4 1.9–2.0 1.2–1.3 2.7–3.1 1.8–2.0 1.2 3.2–4.5 2.9–6.8 3.6 (±2.0) 1.2–7.5
Feeder space (cm/broiler) 1.4–2.2 1.4 0.8–1.0 1.0–1.1 1.4–1.6 1.3–1.5 1.3 1.4–1.5 1.1–1.1 1.4 (±0.4) 0.8–2.2
Watering points (broilers/watering point) 147–196 109 197–221 250–252 — 137–157 228 207–236 99–203 184 (±44) 99–252
Perches (cm/broiler) 5.4–12.7 10.2 10.7–11.6 3.0–5.2 8.9–9.5 8.5–9.7 1.2 7.1–8.7 3.0–8.3 8.2 (±3.0) 1.2–12.7
A
Range indicates minimum and maximum values across all groups.
B
Housing conditions: H =heated barn, T =train wagons, M =mobile houses, CB =custom-built house, and E =existing stables.
C
Outdoor area: P =planted area, O =orchards, OA =open area, and S =spruce.

PEDERSEN ET AL.: ORGANIC BROILER PRODUCTION 499
TABLE 3. Composition of concentrate
Feed component (%)
Wheat +wheat bran 42
Peas 25
Rape seed 9
Barley +triticale 13
Fish meal 5
Alfalfa protein meal 2
Additives
A
4
Feeding value (per kg of feed)
ME 12 MJ/kg ∼2,864 kcal/kg
Protein and amino acids (per kg of feed)
Crude protein 20%
Methionine 3.21 g/kg
Cystine 3.02 g/kg
A
Monodicalcium phosphate (1.4%), calcium carbonate (1.0%), blood meal (1.0%), Pantium-NR (0.4%), and feed salt (0.2%).
Feeding, Growth Rates,
and Feed Conversion
Feeding. All farms used concentrate from
the same feedstuff company in Denmark [21].
Concentrate with the same composition (Table
3) was fed during all production periods. The
mean amount of feed offered (concentrate and
whole wheat) until d 81 was 6.34 kg/broiler with
0.62, 1.99, and 3.73 kg being consumed in the
starting, transition, and finishing periods, respec-
tively (Table 4). However, the feed consumption
on farms varied considerably, especially in the
finishing period (range: 3.01 to 4.29 kg/broiler).
In the transition and finishing periods, 4 and
13 groups, respectively, were fed wheat as sup-
plementation to the concentrate. In the transition
period the mean wheat consumed was 72 g/
broiler (range: 31 to 98 g, 2 to 7% of total feed
consumption), and in the finishing period it was
410 g/broiler (range: 69 to 853 g, 2 to 23%).
The supplement was fed manually indoors. On
all farms, roughage was offered on the floor in
periods when broilers did not have access to
outdoor areas. The amount varied from 8 to 20
kg of clover grass per 2,000 broilers per day.
The intake was not assessed but was likely to
be low. It was thus not included in the calculation
of feed consumption.
In the starting period, feed consumption was
significantly affected by indoor SR (P<0.001).
For example, groups at high SR consumed less
feed than groups at lower SR (Figure 1A). The
effect of the number of broilers per watering
point changed with time. In the starting period,
feed consumption increased with the number of
broilers per watering point (P<0.001), but in
the transition period it decreased (P<0.05).
The effect of farm on feed consumption was
significant (P<0.01) and almost eliminated
other effects in the transition and finishing peri-
ods (Table 5). No effect of feeder space on feed
consumption was found in any of the periods
(P>0.5).
Growth. Mean live weight gains within the
3 production periods based on live weights cor-
rected to d 24, 50, and 81 were 297, 716, and
1,119 g, respectively. Mean total weight gain
from hatching to 81 d was 2,132 g (Table 4).
When adding live weight at hatching (∼35 g),
the mean live weight at d 81 was 2,167 g. The
differences between group weight gains in-
creased with increasing age of broilers. At 24 d
of age the difference between the lowest and
highest weight gain was 100 g, at 50 d it was
196 g, and at 81 d the difference was 347 g
(Table 4).
Weight gain was significantly affected by
feed consumption in the starting (P<0.01) and
transition (P<0.001) periods. Weight gain in-
creased with increasing feed consumption (Fig-
ure 2, A and B). In the same periods weight gain
decreased with increasing indoor SR (P<0.05)
(Figure 1B) and increasing number of broilers
per watering point (P<0.05). These effects were
intensified by the negative influence on feed con-
sumption. Additionally, more feeder space in-
creased weight gain in the transition period (P
<0.05). In the finishing period no effect of feed
consumption was observed (P>0.5) because
the differences among groups (P<0.05) over-
shadowed other effects (Table 5).

JAPR: Research Report500
TABLE 4. Mean amount of feed consumption (concentrate and wheat, kg), mean live weight gain (g), and mean feed conversion per broiler in each period given as range
within each farm and total mean (±SD).
A,B
Farm
Mean
Item 123 4 5 678 9(±SD) Range
Feed consumption (kg)
Starting period (1–24 d) 0.68–0.73 — — 0.50–0.62 — — — 0.63–0.66 0.58–0.67 0.62 (±0.07) 0.50–0.73
Transition period (25–33 d) 0.57–0.58 — — 0.33–0.64 — — — — 0.47–0.61 0.54 (±0.09) 0.33–0.64
Transition period (34–50 d) 1.32–1.65 1.53 1.39–1.40 1.19–1.31 1.51–1.59 1.41–1.50 1.66 1.60–1.60 1.18–1.35 1.45 (±0.15) 1.19–1.66
Finishing period (51–81 d) 3.48–1.26 3.79 3.43–3.44 3.01–3.08 3.97–4.13 3.52–4.03 4.04 3.92–4.29 3.42–3.60 3.73 (±0.34) 3.01–4.29
Total 6.34
Live weight gain (g)
Starting period (1–24 d) 287–315 — — 234–307 — — — 325–334 330 297 (±28) 234–334
Transition period (25–33 d) 204–241 198 124–189 195–225 182–188 193–199 216 203–225 186–201 201 (±23) 124–241
Transition period (34–50 d) 456–588 537 503–504 429–548 463–480 477–496 576 586–625 496 515 (±51) 429–625
Finishing period (51–81 d) 1,073–1,140 1,148 941–1,030 1,087–1,168 1,031–1,141 1,113–1,288 1,199 1,081–1,096 1,169–1,216 1,119 (±71) 941–1,288
Total 2,132
Feed conversion
(kg feed/kg weight gain)
Starting period 2.2–2.5 — — 1.8–2.2 — — — 1.9–2.0 1.8 2.1 (±0.2) 1.8–2.5
Transition period 2.7–3.3 2.8 2.8–2.8 2.4–2.8 3.2–3.3 2.9–3.0 2.9 2.6–2.7 2.7 2.8 (±0.3) 2.4–3.3
Finishing period 3.1–3.9 3.3 3.3–3.7 2.6–2.8 3.5–4.0 3.1–3.2 3.4 3.6–3.9 2.8–3.1 3.3 (±0.4) 2.6–4.0
Total 2.9
A
Range indicates minimum and maximum values across all groups.
B
Due to practical circumstances, feed consumption and live weights could not be measured on all farms on day 25–33. The transition period is, therefore, separated into two minor periods.

PEDERSEN ET AL.: ORGANIC BROILER PRODUCTION 501
FIGURE 1. Effect of indoor stocking rate (broilers/m
2
) on A) mean feed consumption (kg) in starting period
and on B) mean live weight gain (g) in the transition period.
Mean live weight of broilers per group and
the corresponding Gompertz function is shown
in Figure 3. The estimated formula was y =3,840
×e(−4.7080 ×e(−0.02592 ⴢt)).
With this function, the expected live weights
of organic broilers at 24, 50, and 81 d of age
are 307, 1,059, and 2,157 g, respectively. When
using the derived y′, maximum daily weight gain
can be expected to be 37 g at d 60. The mean
daily weight gain fromd1to81is27g.
There was a significant effect of sex on final
body weight (P<0.001). Mean live weights of
female and male broilers were 1,974 and 2,468
g, respectively, in 16 groups at the end of the
finishing period.
Feed Conversion
Feed conversion (kg feed/kg of weight gain)
increased when age of broilers increased. The
mean feed conversion within periods was 2.1,
2.8, and 3.3, respectively (Table 4). Overall feed
conversion for the entire life cycle (d 1 to 81)
was 2.91, or 2.86 when corrected for live weight
at hatching (∼35 g).
Feed conversion was affected, in the same
way as feed consumption and live weight gain,

JAPR: Research Report502
TABLE 5. Results of general linear models analyses on feed consumption, weight gain, feed conversion, and
mortality for each production period including R
2
and P-values.
A,B
P-value
Broilers per
watering
Feeder point Feed
Item R
2
space SR
indoor
SR
outdoor
(n) Farm consumption
Feed consumption
Starting period 0.71 0.98 0.0001 — 0.0003 0.50 —
Transition period 0.86 0.83 0.39 0.23 0.02 0.002 —
Finishing period 0.76 0.48 0.44 0.42 0.34 0.004 —
Weight gain
Starting period 0.85 0.54 0.03 — 0.02 0.03 0.007
Transition period 0.77 0.03 0.02 0.67 0.01 0.89 0.0001
Finishing period 0.69 0.95 0.98 0.85 0.41 0.02 0.50
Feed conversion
Starting period 0.86 0.42 0.007 — 0.005 0.01 0.73
Transition period 0.53 0.02 0.02 0.50 0.01 0.90 0.64
Finishing period 0.90 0.96 0.96 0.76 0.48 0.02 0.002
Mortality
Starting period 0.45 0.04 0.02 — 0.14 0.92 0.78
Transition period 0.59 0.45 0.66 0.80 0.86 0.11 0.86
Finishing period 0.50 0.94 0.20 0.47 0.54 0.20 0.15
A
Variables underlined were included in the model after stepwise elimination. SR =stocking rate.
B
Analyses made on the transition period included d 34 to 50 only.
by management variables in the starting and
transition periods: indoor SR (P<0.05), feeder
space (P<0.05), and number of broilers per
watering point (P<0.01). In the finishing period,
feed conversion mainly depended on feed con-
sumption (P<0.01). Feed conversion increased
with increasing feed consumed (Figure 2C) and
with farm (P<0.05).
The results described in the last 3 sections
are concordant with the Label Rouge production
in France [7, 10] and other investigations of
slow-growing broilers [11, 12]. Mean live
weight 81 d of age was 2,167 g, just under
the live weights reported in the investigations
mentioned (2,200 to 2,400 g in mixed produc-
tion, 2,713 to 2,785 g in male-only production).
Feed consumption in the present investigation
(mean: 6.3 kg/broiler) is in accordance with [8]
but less than found in [7] and [10], which were
7.4 and 8.3 kg, respectively. The latter results
are from production of males only, which results
in higher feed consumption and corresponding
higher live weights compared with mixed pro-
duction.
On the basis of the literature [7, 8, 10], feed
requirement in organic production is suggested
to be 2.5 to 3.0 kg feed/kg of weight gain. In
the present investigation, the overall feed con-
version was 2.9 kg feed/kg of weight gain. Anal-
ysis within periods showed that the feed conver-
sion rate was especially high in the finishing
period when broilers were 50 to 81 d old
(mean: 3.3).
Management had a marked influence on the
results in the starting and transition period. In
summary, feed consumption and weight gains
were higher and feed conversion was improved
when broilers had more space available on the
floor (lower indoor SR), in front of watering
points (lower number of broilers) and in front
of feeders (higher length of trough per broiler).
Most of our observations were confirmed by
the existing literature: feed consumption [22, 23]
and live weight [23, 24] increase when feeder
space is increased, but the same studies show
that feed conversion is unchanged [23] or even
decreased [24]. Also, free access to water is
important to not cause reductions in weight gain
[25]. Increased indoor SR reduces feed con-
sumption [7, 26] and live weight [22, 26, 27,
28], but the effect on feed conversion is equivo-
cal. Feed conversion was better in 2 studies [26,
29], poorer in 2 studies [22, 27], and unchanged
in 1 study [29]. The effect of outdoor SR on

PEDERSEN ET AL.: ORGANIC BROILER PRODUCTION 503
FIGURE 2. Effect of feed consumption (kg) on mean live weight gain (g) in the A) starting and B) transition periods,
and on C) mean feed conversion (kg/kg) in the finishing period.

JAPR: Research Report504
FIGURE 3. Mean live weight (g) of broilers per group and curve modeled by the Gompertz function [16].
production results has not been investigated pre-
viously. In this investigation outdoor SR showed
no effect.
In the present investigation the feed con-
sumption per kilogram of live weight gain in-
creased during the finishing period, i.e., feed
conversion was reduced. This result is explained
by decreasing growth rate and increasing energy
requirements for maintenance [13], which re-
duced use of feed.
The present investigation showed a marked
difference in live weight (∼500 g) of female
and male broilers 81 d of age, which was also
expected, based on earlier investigations [7, 8,
10, 11, 12]. The reason for this finding is that
the growth rate curve declines earlier for female
broilers than for male broilers [30]. The same
authors point out that female broilers will deposit
fat earlier than male broilers, which means that
live weight and body composition at slaughter
are most likely dependent on sex.
Animal Health and Mortality
During the starting period, mortality ranged
between 0.9 and 15% per group (Table 6). In 3
groups on 2 farms, mortality was high (8, 12.5,
and 15%), whereas it was markedly lower in the
rest of the groups (0.9 to 2.5%). In one group
(farm 4) the high mortality (15%) was suppos-
edly caused by mistakes made at the hatchery,
probably incubation failure with suboptimal hu-
midity or temperature leading to weak 1-d-old
chickens. The hatchery accepted responsibility
for the problem. The 2 remaining cases of high
mortality (farm 1 and 4) could not be explained
and were not correlated with the diseases found
at necropsy. Mean mortality in the starting pe-
riod was 3.5%. When corrected for the 15%
group at farm 4, it was 2.7%.
In the transition period, mean mortality was
1.4%. Except for one group at farm 5 that had
a mortality rate of 10% due to coccidia problems,
mortality ranged from 0 to 2.8%. In the finishing
period mean mortality was 0.8%. Overall mor-
tality was 6.2% (or 5.5% when corrected for the
group with 15% mortality at farm 4).
Except for the starting period when decreas-
ing feeder space per broiler (P<0.05) and in-
creasing SR (P<0.05) increased mortality, the
described management procedures did not affect

PEDERSEN ET AL.: ORGANIC BROILER PRODUCTION 505
TABLE 6. The mortality (%) in organically produced broilers, shown as a range for each farm (exceptionally high mortality rates for groups are noted separately) and carcass
quality of organic broilers, described as mean proportion of broilers with A and B classification (%) and rejected broilers (%) in each period and overall means (±SD)
A
Farm Mean of
farm means
Item 1 2 3 4 5 6 7 8 9 (±SD)
Mortality (%)
Starting period 0.9–2.1
B
— — 1.0–2.5
C
— — — 1.0–2.1 0.9–1.8 3.5 (±4.4)
Transition period 0.0–1.8 0.5 0.3–1.3 0.2–1.3 2.5–2.8
D
0.6–1.3 1.4 0.2–0.3 1.0–1.1 1.4 (±2.0)
Finishing period 0.7–1.8 0.5 1.0–1.6 0.4–1.0 0.7–1.5 0.2–0.3 0.6 0.8–1.1 0.4–1.0 0.8 (±0.4)
Carcass quality
Groups (n) 3 1 2 2 3 2 1 2 3
Broilers (n) 2,555 1,940 3,963 1,990 3,285 3,479 1,776 2,992 3,831
A classification (%) 72 83 85 74 85 71 89 81 77 79 (±6)
B classification (%) 23 14 10 19 9 25 8 15 18 16 (±7)
Rejected (%) 5 3 5 7 7 4 3 4 5 5 (±2)
Breast blisters (%) 5/5/5 7 3/6 −/5 –/–/– −/10 1 −/5 5/17/17 6 (±4)
A
The proportion of broilers with breast blisters at slaughter in each group (%) is listed below. A dash indicates data not available.
B
One group 8%.
C
One group 12.5%, one group 15.0%.
D
One group 10.0%.

JAPR: Research Report506
mortality (Table 5). When groups with excep-
tionally high mortality rates were excluded from
the starting period analysis, no effect of manage-
ment procedures was found (P>0.20).
Relatively few birds were submitted for post-
mortem examination. On farm 4, four chickens
died between d 2 and 21 due to yolk sac infec-
tions. Postmortem examination of 3 broilers
from this farm could not be performed. On farm
8 coccidiosis was diagnosed in 3 chickens that
died between 24 and 26 d of age. On farm 9,
ten chickens died between d 29 and 34 from
necrotic enteritis, and 3 chickens on the same
farm died from kidney failure between d 42 and
67. A single chicken from farm 1 could not be
examined due to decomposition.
Mortalities of 0.9, 2.1, and 4.6% have been
found in the production of slow-growing chick-
ens [7, 8, 10]. In Denmark, mean mortality in
fast-growing breeds in the conventional produc-
tion system is 3.8% [3]. Therefore, mortality
of 6% (or 5.5%) in the present investigation is
unacceptably high, and efforts should be made
to minimize this problem. However, due to the
low number of dead chickens investigated, the
present study can only indicate which diseases
might be of importance in organic production
systems.
Coccidiosis is likely to pose a threat on or-
ganic farms if the houses or areas are used re-
peatedly over time and are not properly cleaned
and rotated. Increased mortality was observed
in 2 flocks without any specific causative factors
that could be identified. However, necrotic enter-
itis was diagnosed in 2 other flocks. This disease
has previously been predicted to cause increas-
ing problems in production systems that elimi-
nate the regular use of antimicrobial compounds
in feed [31, 32]. Apart from that, other mortality
was mainly due to management factors (e.g.,
kidney failure, which is often related to depriva-
tion of water) or common opportunistic patho-
gens (e.g., Escherichia coli) that are encountered
in any production system.
Carcass Quality
Classification of broilers at slaughter in-
cluded 25,811 broilers from 19 groups. The inci-
dence of breast blisters at slaughter was recorded
for 18,492 broilers from 13 groups. An average
of 79% of the broilers produced on each farm
TABLE 7. Relative frequency of pathological causes of
rejection at slaughter of organically produced broilers,
based on examination of 25,811 broilers and a level of
rejection for pathological reasons of 3.5%.
Cause %
1. Emaciation, abnormal smell, or discoloring 66.9
2. Ascites 0.5
3. Joints or bones 3.1
4. Skin 24.1
5. Heart 0.1
6. Lungs 0.0
7. Liver 2.9
8. Kidneys 0.0
9. Peritoneum or oviduct 0.5
10. Other illness 1.8
Total 100.0
were “A” broilers, 16% were classified as “B”
broilers, and 5% were rejected (Table 6). More
than 70% of the rejected broilers were rejected
due to conditions listed in Table 7. Emaciation,
abnormal smell, and discoloring were the main
reasons followed by damaged areas of skin. The
remaining rejections (30%) were due to death
during transport, insufficient bleeding, damages
from machinery, and fractures or bleeding, but
the relative frequencies were not recorded. An
average of 6% of the broilers had breast blisters,
ranging from 1 to 17% within groups (Table 6).
In the conventional production in Denmark
1.3% of broilers (calculated as kg) are rejected
[3], and the most frequent reasons for rejection
are emaciation (approximately 31% of rejections
in 2000 to 2001), skin disorders (23%), ascites
(10%), and problems with liver (14%), joints
(9%), and heart (3%) [3, 33]. As considerably
more organic broilers are rejected, it seems that
the carcass quality of organic broilers is poorer
when compared with those from the conven-
tional system. However, the pathological rea-
sons for rejection were the same as observed in
the conventional production system, although
emaciation clearly is more frequent in organic
systems and ascites and liver disorders less fre-
quent. It is unknown whether the number of
broilers rejected for other causes was dispropor-
tionately high in the present investigation.
Breast blisters are the most common cause
of rejection in the Label Rouge production [34].
Poor litter quality or acute litter deterioration
appear to be the major responsible cause of in-
creased frequency of breast blister [35], but fac-

PEDERSEN ET AL.: ORGANIC BROILER PRODUCTION 507
tors such as sex, age (∼length of exposure), and
lighting program also may play roles [36]. Inter-
actions of these factors with breed are poorly
understood. Breast blisters are almost absent
CONCLUSIONS AND APPLICATIONS
1. Facilities for organic broiler production varied from the use of available old stables with access
to wide open pastures to custom-built houses in combination with orchard or spruce plantings.
2. Production was by farmers with little prior experience with broiler production.
3. The mean feed consumption from 1 to 81 d was 6.3 kg/broiler (concentrate and whole wheat).
Until approximately 24 d of age, chicks were fed forage in house; thereafter they had access
to outdoor areas.
4. The mean live weight gain from 1 to 81 d was 2,167 g, and growth within periods (1 to 24 d,
25 to 50 d, and 51 to 81 d) was 297, 716, and 1,119 g, respectively. Overall feed conversion
was 2.9 kg feed/kg broiler live weight.
5. The management practices for stocking rate, feeding troughs, and watering points affected the
results of the production, e.g., broilers in groups with more space available on the floor (lower
indoor stocking rate), in front of watering points (lower number of broilers), and in front of
feeders (higher length of trough per broiler) had higher feed consumption, higher weight gains,
and improved feed conversion compared with groups of broilers with less space. However, this
was only the case until broilers were approximately 50 d old. Thereafter differences between
farms could not be attributed to these practices.
6. The overall mortality on farms was 6% and thus higher than in conventional flocks. No general
tendency with regard to the cause of mortality could be described on basis of the necropsies
performed, but coccidiosis and necrotic enteritis were prevalent in some groups. These diseases
may constitute a particular threat to organic production systems.
7. At slaughter, 79% of the broilers were classified as A broilers, and 16% were classified as B
broilers. The remaining 5% were rejected, primarily because of emaciation, abnormal smell, or
discoloring. Breast blisters seemed to be specific to this type of production and possibly related
to slow-growing broilers.
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Acknowledgments
This study was supported by a grant from the Familien Hede
Nielsen Foundation, Horsens. Comments by Linda Mansfield (MSU)
and Niels Kyvsgaard (KVL) on a previous version of this manuscript
are gratefully acknowledged.