The influence of stocking density on the behaviour of featherless

Arch.Geflügelk., 74 (2). S. 73–80, 2010, ISSN 0003-9098. © Verlag Eugen Ulmer, Stuttgart
The influence of stocking density on the behaviour of featherless
and normally-feathered broilers under hot ambient temperature
Der Einfluss der Besatzdichte auf das Verhalten von genetisch federlosen und normal
befiederten Masthühnern unter hohen Temperaturen
Susanna Lolli1, W. Bessei2, A. Cahaner3, L. Yadgari3 and Valentina Ferrante1
Manuskript eingegangen am 16. Mai 2008, angenommen am 7. April 2009
Introduction
Heat stress is a main problem of modern broiler production
under tropical conditions. Passive heat dissipation of normally feathered broilers is restricted to small areas of the
body surface which are not covered by feathers, such as
wattles, combs and legs, and the production of metabolic
heat in contemporary fast-growing broilers often exceeds
the potential of passive heat loss under hot conditions. It
has been reported that litter temperature increases with
increasing stocking density, due to the accumulation of
droppings that increase the bacterial fermentation in the
litter (REITER and BESSEI, 2001; YADGARI et al., 2006). Moreover, at high stocking density the entire floor surface is
covered by birds, and the heat from the litter cannot be
removed effectively by the usual ventilation systems. Thus,
broilers may suffer from heat stress even under moderate
climatic conditions. Reduced growth rate in response to increasing stocking density on deep litter is well documented
(SCHOLTYSSEK and GSCHWINDT-ENSINGER, 1983; SHANAWANY,
1988; SCHERER, 1989; GRASHORN and KUTRITZ, 1991;
WIEDMER and HADORN, 1998; YADGARI et al., 2006). When
birds are kept on wire or ventilated floor, the depression of
growth rate occurs at higher stocking densities as compared to conventional deep litter systems (SCHOLTYSSEK and
GSCHWINDT-ENSINGER, 1983; ARKENAU et al., 1997). This
underlines the crucial role of stocking density, ambient
temperature and heat dissipation in modern commercial
broiler production systems. Naked neck broilers perform
better under high ambient temperatures as compared to
normally feathered birds (HORST, 1982; MERAT, 1986, 1990;
CAHANER et al., 1993; DEEB and CAHANER, 2001; CAHANER et
al., 2008). This is due to areas without feathers on the neck
as well as reduced feather density at the entire body area.
The beneficial effect of artificially de-feathered neck areas
was also demonstrated in broiler breeders (GERKEN et al.,
2006). Featherless broilers, which do not have feathers at
any part of the body, may be even better adapted to hot ambient temperature than naked neck chickens. CAHANER et
al. (2003) and YARON et al. (2004) reported that featherless
broilers, homozygous for the Scaleless mutation (sc/sc),
did not suffer from ambient temperatures up to 35°C, and
survived even heat waves of 40°C. The superiority under
high ambient temperatures of featherless broilers compared to fully feathered and naked neck broilers as well as
normally feathered birds was confirmed by CAHANER et al.
(2008). Normally feathered chickens under heat stress
show particular behaviours, such as wing lifting, feather
ruffling, preening and dustbathing. These behaviours enhance heat loss by increasing the body surface or reducing
the isolating capacity of the feather cover. Broilers spend
considerable part of their time budget sitting/lying (BESSEI,
1992a). In this posture the temperature of the legs and of
the litter surface underneath the birds increases. While
standing up and moving a short distance the birds expose
the un-feathered surface of the legs to the ambient temperature and allow the temperature at the litter surface to cool
down (GERKEN et al., 2006). While the above mentioned
behaviours enhance passive heat loss, panting enables the
birds to dissipate heat through evaporation in the respiratory tract (MCLEAN et al., 2001).
Featherless chickens show similar behaviours as normally feathered birds. Even behaviours which are considered related to feathers, such as wing-flapping, preening
and dust-bathing is observed similarly in featherless and
feathered birds (PROVINE, 1981; VESTERGAARD et al., 1999).
Differences in the behaviour of featherless and feathered
birds are likely to provide information on the level of heat
challenge. Therefore the present study compares the
behaviour of featherless and normally feathered broilers in
response to increasing stocking density under high ambient temperature.
The great difference in optimum temperature of featherless and normally feathered birds has to be considered
when both genotypes are to be compared, and the featherless birds have to be kept at higher temperatures than normally feathered birds. As litter temperature increases with
increasing stocking density, the requirement of higher
temperatures of featherless broilers was considered in the
present study by adjusting the stocking density of the
featherless and normally feathered broilers at different
levels. Detailed results of performance and carcass quality
of the present experiment have been reported elsewhere
(YADGARI et al., 2006).
Material and Methods
1Department of Animal Science, Faculty of Vet. Med., Milan, Italy
2Institute of Animal Husbandry and Breeding (470), University of Hohenheim,
Stuttgart, Germany
3The Hebrew University of Jerusalem, Faculty of Agriculture, Rehovot, Israel
Arch.Geflügelk. 2/2010
A total of 112 normally feathered and 112 featherless broilers were used in the experiment. The birds were assigned
to six pens of the same poultry house at day-old (Table 1).
74
Lolli et al.: Behaviour of featherless and normally-feathered broilers
Table 1. Experimental design and basic information on pen area, group size, body weight, stocking density and litter temperature
Versuchsanlage und Grundlageninformationen zu Abteilgröße, Gruppengröße, Körpergewicht, Besatzdichte und Einstreutemperatur
Phenotype
Pen Area (m2)
*No. of birds/m2
*Mean body
weight (g)
*Stocking density
(kg/m2)
*Litter
temperature
Feathered
Feathered
Feathered
3.22
3.22
3.22
7.5
11.2
16.8
2349
1885
1937
16.5
21.1
32.5
31.4
34.5
36.7
Featherless
Featherless
Featherless
2.24
2.24
2.24
12.9
17.0
21.9
2337
2116
2083
28.1
35.9
45.6
36.3
37.2
36.9
*) at 44 days of age
Three pens each had a surface of 3.22 m2 (2.3 × 1.4 m) and
2.24 m2 (1.6 × 1.4 m) respectively. They were separated by
wire fences. The larger pens were used for the feathered
broilers and the smaller ones for the featherless birds.
Three different stocking densities were used within each
genetic group by varying group size from 7.5, 11.2 and 16.8
birds per m2 in the feathered broilers and from 12.9, 17.0
and 21.9 birds per m2 in the featherless broilers. This
resulted in stocking densities at the end of the experiment
of 16.5, 21.1 and 32.5 kg per m2 in the feathered and 28.1,
35.9 and 45.6 kg per m2 in the featherless broilers respectively (Table 1). Litter temperature increased with increasing stocking density from 31,4 centigrade at the lowest
stocking density to 36.9 centigrade at the highest stocking
density. All birds received the same commercial broiler diet
containing 20% crude protein and 13.4 MJ ME/kg. Water
was provided ad libitum by one automatic round drinker
per pen. The floor was covered with a layer of 8 cm wood
shavings at day old and fresh litter was supplied as required by good management practice. The ambient temperature was 35 centigrade at the beginning of the experiment and was reduced to 33 centigrade at 1 week of age
and maintained at that level thereafter. The light schedule
was 23 h of light and 1 hour of darkness. The mean body
weight per pen was recorded at the end of the experiment
(44 days of age). Each pen was video recorded at 42 days
of age for 1 hour continuously using a digital video recorder. The video tapes were analysed by scan sampling and
focal sampling technique. The behaviour was classified in
7 mutually exclusive categories: walking, standing, sitting
(birds sitting and not performing any other activities),
feeding (pecking of food and swallowing), drinking (dipping the beak in the water and raising the beak thereafter)
and preening. Dust bathing and scratching was observed
but the data are not presented because the events were too
rare to provide sound information. The number of birds
engaged in the particular behaviour was counted in 10
scans at 5 minutes intervals and reported as percentage of
the maximum frequency of counts (no. of scans × number
of birds per group). In addition five birds per pen were
randomly selected, and the mean duration of the above
mentioned behaviours was measured. A screen shot was
made at the beginning of each record and the birds to be
observed were marked. Thus it was avoided to observe the
same birds repeatedly. In addition to the above mentioned
behaviours the duration of panting (sitting or standing
with the beak widely opened) was recorded. All video
analyses were carried out by commercial software (INTERACT®, version 7.4.0; Mangold International GmbH® 94424
Arnstorf, Germany). The above mentioned behaviours
were assigned to particular keys on the keyboard. The
duration of each behavioural event was computed by the
programme.
The means of behaviours of both breeds were plotted
against stocking density (kg/m2). Since only one replicate
of each treatment was available no test statistics were
carried out.
Results
There was a clear decrease in percent of birds spent walking, standing, sitting/lying, preening, feeding and drinking in the feathered birds as stocking density increased
(Figure 1–6). The featherless broilers at their lowest density (28.1 kg/m2) showed similar activity levels of walking,
standing, sitting/lying and preening as the feathered birds
at their intermediate density (21.1 kg/m) In feathered
broilers the percentage of birds spent sitting declined with
increasing density from more than 60% to 30%. There was
a declining trend in response to stocking density in the
featherless chickens also, however, the percent of birds
spent sitting was higher at the lowest density than that of
the feathered birds at the highest density (Figure 3).
Preening in feathered broilers decreased from 10.7 to 3.2%
with increasing density (Figure 4). In the featherless broilers the level of preening declined from 6.1 to 3.7% and was
similar to that of the feathered broilers at intermediate and
low density. There was no consistent response of feeding
and drinking behaviour in response to stocking density in
featherless broilers (Figure 5 and 6). There was a tendency
of higher percentages for drinking in featherless (4.3–6.9
percent) as compared to feathered birds (1.9–4.0 percent)
(Figure 6).
The mean duration of walking increased with increasing
stocking density in normally feathered broilers. The response was obvious when stocking density was raised from
the lowest to the intermediate level (Figure 7). The featherless birds showed a slight decline of the duration of walking with increasing stocking density. There was no consistent response of the duration of standing to stocking density
in both feathered and featherless birds (Figure 8). The overall level of this trait was, however, lower in the featherless
birds. The duration of sitting/lying decreased in the feathered and the featherless broilers with increasing stocking
density (Figure 9). There was a sharp drop from 65 to 30
sec. in the feathered birds when stocking density was
raised from the low to the intermediate level. In the featherless birds the duration of sitting/lying decreased linearly
from 86 sec at the lowest to 28 sec at the highest density.
Arch.Geflügelk. 2/2010
Lolli et al.: Behaviour of featherless and normally-feathered broilers
walking
15,0
10
75
standing
12,5
8
10,0
6
7,5
4
5,0
2
2,5
15
20
25
30
35
40
45
15
50
20
Figure 1. Walking (%) of feathered (S) and featherless ( )
broilers in response to increasing stocking density
Fortbewegung (%) der befiederten (S) und unbefiederten ( )
Masthühnern bei zunehmender Besatzdichte
80
70
10
60
8
50
6
40
4
30
15
20
25
30
35
40
45
50
stocking density kg/m2
30
35
40
45
50
Figure 2. Standing (%) of feathered (S) and featherless ( )
broilers in response to increasing stocking density
Stehen (%) der befiederten (S) und unbefiederten ( ) Masthühnern bei zunehmender Besatzdichte
12
sitting/lying
25
stocking density kg/m2
stocking density kg/m2
preening
2
15
20
25
30
35
40
45
50
stocking density kg/m2
Figure 3. Sitting/lying (%) of feathered (S) and featherless
( ) broilers in response to increasing stocking density
Sitzen/Liegen (%) bei befiederten (S) und unbefiederten ( )
Masthühnern bei zunehmender Besatzdichte
Figure 4. Preening (%) of feathered (S) and featherless ( )
broilers in response to increasing stocking density
Federputzen (%) bei befiederten (S) und unbefiederten ( )
Masthühnern bei zunehmender Besatzdichte
The duration of preening and drinking was highly variable, and there was no consistent effect of either line or
stocking density (Figure 10 and 12). Feathered birds
showed higher duration of feeding than featherless birds,
regardless of the stocking density (Figure 11). The duration of panting was higher in feathered than in featherless
broilers at the highest and lowest stocking density, while a
short duration was found at the intermediate stocking
density (Figure 13). In the featherless broilers there was a
consistent increase of panting duration with increasing
stocking density.
from about 10 to 35 kg/m2 (BLOKHUIS and VAN DER HAAR,
1990; LEWIS and HURNIK, 1990; ANDREWS et al., 1997; REITER
and BESSEI, 2000a, b). Further increases in stocking density
did not produce significant changes in locomotion and
scratching activity (BESSEI, 1992a), indicating a ceiling
effect. The behavioural response to increasing stocking
density has been discussed under the aspects of physical
constraint and thermal discomfort. In the present study locomotor activity clearly declined with increasing stocking
density in the normally feathered but not in the featherless
birds. Since stocking density in the featherless birds was
much higher than in the feathered birds, physical constraint can be excluded as influencing factor. This is in
agreement with PRESTON and MURPHY (1989) who found
that physical constraint was not limiting locomotor activity
in commercial broiler houses. The most likely explanation
for the behavioural responses to stocking density of the
featherless and fully feathered broilers is the thermal effect. The litter temperature increased from 31.4 centigrade
Discussion
The effect of stocking density on the behaviour of normally
feathered commercial broilers has been studied in several
experiments. There was a significant decrease in locomotor and scratching activity when stocking density increased
Arch.Geflügelk. 2/2010
76
6,0
Lolli et al.: Behaviour of featherless and normally-feathered broilers
feeding
drinking
8
5,5
7
6
5,0
5
4,5
4
4,0
3
3,5
2
1
3,0
15
20
25
30
stocking density
35
40
45
50
Figure 5. Feeding (%) of feathered (S) and featherless ( )
broilers in response to increasing stocking density
Futteraufnahme (%) von befiederten (S) und unbefiederten ( )
Masthühnern bei zunehmender Besatzdichte
2,8
15
20
walking
25
30
35
40
45
50
stocking density kg/m2
kg/m2
Figure 6. Drinking (%) of feathered (S) and featherless ( )
broilers in response to increasing stocking density
Trinken (% von befiederten (S) und unbefiederten ( ) Masthühnern bei steigender Besatzdichte
16
standing
2,6
14
2,4
12
2,2
2,0
10
1,8
8
1,6
1,4
6
15
20
25
30
35
40
45
50
stocking density kg/m2
15
20
25
30
35
40
45
50
stocking density kg/m 2
Figure 7. Mean duration (sec) of walking in response to line
(feathered (S); featherless ( )) and stocking density
Mittlere Dauer (Sekunden) der Fortbewegung von befiederten (S)
und unbefiederten ( ) Masthühnern bei zunehmender Besatzdichte
Figure 8. Mean duration (sec) of standing in response to line
(feathered (S); featherless ( )) and stocking density
Mittlere Dauer des Stehens (Sekunden) von befiederten (S)und
unbefiederten ( ) Masthühnern bei zunehmender Besatzdichte
to about 37 centigrade as stocking density increased from
17.5 kg/m2 to 45.6 kg/m2 respectively (Table 1). The decrease of percent of walking, standing and preening with
increasing litter temperature in the feathered birds
(Figure 1; 2 and 4) can be interpreted as the attempt of the
birds to reduce the metabolic heat production associated
with physical exercise. Studies of featherless and normally
feathered birds under moderate temperature have shown
that the featherless exhibit similar heart rates as normally
feathered birds only when they are active during the light
period, but exhibit higher heart rates during resting (CAIN
and ABBOTT, 1971). It was concluded that the metabolic
heat production through physical activity balance the
greater heat loss of the featherless birds. The fact that the
featherless birds showed high levels in these behaviours
when litter temperatures was about 36 centigrade indicates that they can afford to maintain a high physical activity under these conditions due to their high heat dissipation capacity. The increase in the duration of the walking
and the relatively high level of the duration of standing of
the feathered broilers (Figure 7, 8) seem to corroborate the
above explanation. Standing and walking increase the
metabolic heat production relative to resting by 16–20%
and 53–65% respectively (VAN KAMPEN, 1976a, b). However, the magnitude of the increase in duration of walking
(from 1.7 to 2.4 sec.) is not expected to contribute remarkably to the increase of metabolic heat production. With increasing litter temperature the birds may develop a strategy where sitting phases are intermitted by short standing
and walking bouts. DEIGHTON and HUTCHINSON (1940, loc.
cit. VAN KAMPEN, 1976b) noticed a sudden increase of heat
production in chickens immediately after standing up.
Since this increase could not be explained by the energy
requirement of the physical exercise, VAN KAMPEN (1976b)
assumed that this effect was caused by the release of the
heat stored in the feather cover while the birds are sitting.
While standing, the birds can dissipate heat through the
un-feathered surface of the legs. Moving a few steps from
Arch.Geflügelk. 2/2010
Lolli et al.: Behaviour of featherless and normally-feathered broilers
90
sitting/lying
35
80
30
70
25
60
20
50
15
40
10
30
5
feeding
0
20
15
20
25
30
35
40
45
15
50
20
25
30
35
40
45
50
stocking density kg/m2
stocking density kg/m2
Figure 9. Mean duration (sec) of sitting/lying in response to
line (feathered (S); featherless ( )) and stocking density
Mittlere Dauer von Sitzen/liegen (Sekunden) von befiederten (S)
und unbefiederten ( ) Masthühnern bei zunehmender Besatzdichte
30
77
Figure 10.Mean duration (sec) of preening in response to line
(feathered (S); featherless ( )) and stocking density
Mittlere Dauer des Federputzens (Sekunden) bei befiederten (S)
und unbefiederten ( ) Masthühnern bei zunehmender Besatzdichte
drinking
preening
7,0
6,5
25
6,0
20
5,5
15
5,0
10
4,5
4,0
5
15
20
25
30
stocking density
35
40
45
50
kg/m2
15
20
25
30
35
40
45
50
stocking density kg/m2
Figure 11.Mean duration (sec) of feeding in response to line
(feathered (S); featherless ( )) and stocking density
Mittlere Dauer der Futteraufnahme (Sekunden) von befiederten
(S) und unbefiederten ( ) Masthühnern bei zunehmender Besatzdichte
Figure 12.Mean duration (sec) of drinking in response to line
(feathered (S); featherless ( )) and stocking density
Mittlere Dauer des Trinkens (Sekunden) von befiederten (S) und
unbefiederten ( ) Masthühnern bei zunehmender Besatzdichte
the former sitting place allows the birds to choose a cooler
place to settle down while the litter surface temperature of
the former sitting place declines to the level of the air temperature (GERKEN et al., 2006). Hence the beneficial effect
of standing and walking on heat dissipation may be higher
than the negative effect of additional heat production.
The effect of stocking density on percentage feeding was
rather small in the feathered broilers and highly inconsistent in the featherless birds (Figure 5). BESSEI (1992b)
and REITER and BESSEI (2000a) found no significant effects
of stocking density on percent feeding in broilers. Since the
motivation for feeding has a high priority in broilers, and
the time spent feeding represents only a minor share of the
bird’s time budget, the birds will satisfy their nutritional
demand as long as sufficient feed is available, and may not
reduce feeding activity. Increasing ambient temperature
usually increases water consumption and the water:feed
ratio. DEEB and CAHANER (2002) and VANDAI et al. (2009)
reported a rise in water:feed ratio from 1:1.5 to 1:2.5 when
the ambient temperature increased from 22 to 32 centigrade. Though the water consumption was not recorded in
the present study, it can be assumed that there was a considerable increase with increasing stocking density and litter temperature in the feathered birds. Since percent drinking decreased with increasing stocking density, the birds
must have increased their speed of drinking so that larger
amounts of water were consumed in shorter time. Since
featherless birds dissipate more heat through convection
and radiation, the loss of water through respiration (panting) is expected to be lower than in the feathered birds.
Nevertheless the percentage of drinking was higher in
featherless than in feathered birds. The absence of heat
stress in the featherless chickens might have allowed more
frequent visits to the drinker and lower drinking intensity.
It was interesting to note that featherless birds showed
preening behaviour similarly to feathered broilers. The
Arch.Geflügelk. 2/2010
78
Lolli et al.: Behaviour of featherless and normally-feathered broilers
panting
13
12
11
10
9
8
7
6
15
20
25
30
35
40
45
50
stocking density kg/m 2
Figure 13.Mean duration (sec) of panting in response to line
(feathered (S); featherless ( )) and stocking density
Mittlere Dauer des Hechelns (Sekunden) von befiederten (S) und
unbefiederten ( ) Masthühnern bei zunehmender Besatzdichte
present results confirm the report by PEREIRA et al. (2007)
that preening behaviour gradually decreased as environmental temperature increased. Some authors (KRISTENSEN
et al., 2000; WATHES, 2002) reported that preening was
associated with both high environment temperatures. The
causal relationship between ambient temperature and
preening behaviour is not fully understood. The ruffling of
the feather cover while preening would enhance heat loss
in feathered birds. But as the response of the percent
preening in the feathered birds showed the opposite tendency (Figure 4) this explanation cannot be supported.
The reduction of preening in the present study may be the
expression of a shift from comfort behaviour towards behaviours which are more efficient in facilitating heat loss.
Preening has no obvious function in featherless broilers.
Therefore is not expected that this behaviour reacts to the
experimental conditions.
The response of the duration of the behaviours to increasing stocking densities and litter temperature was generally less consistent than that of the percentages. Since
the duration of behaviours is based on observations of individual birds, the variation among individuals may hide
the effect of the experimental factors. Nevertheless, there
are consistent effects for the duration of sitting/lying and
panting. As shown in Figure 9 the duration of sitting/lying
declined with increasing stocking density in both, the
featherless and the feathered birds, but the similar re-
sponse occurred in feathered birds at lower density than in
the featherless birds. Short periods of sitting/lying in
broilers have also been reported by PRESTON and MURPHY
(1989). The authors considered disturbancies by other
birds as the causal factor for short periods of this behaviour. Since disturbancies are expected to increase with increasing stocking density, this effect cannot explain the
results of the present study. Panting is the main mechanism of active heat dissipation (FREEMAN, 1971). It is activated when the passive heat loss is not sufficient to keep
the body temperature on its normal level. ROBINSON (1979)
found a sharp increase in panting at ambient temperatures
between 30 and 35 centigrade. MCLEAN et al. (2001) found
deep panting of commercial broilers under moderate
climatic conditions from stocking density of 34 kg/m2
onwards. In the present study the reaction of the duration
of panting to increased stocking density was not consistent
in the feathered birds. However, their mean values at
stocking densities of 16.5 and 32.5 kg/m2 were higher
than that of the featherless broilers at densities of 28.1 and
45.6 kg/m2. This confirms that the increased sensible heat
loss in the featherless broilers shifts the necessity of active
heat dissipation to higher temperature.
Conclusions
The comparison of normally feathered and featherless
broilers at different stocking densities under high ambient
temperature indicate that the thermal conditions rather
than physical density influences their behaviour (Table 2).
This conclusion is based on the consistent responses of
various behaviours to increased litter temperature. These
responses could be explained as behavioural mechanisms
to dissipate metabolic heat. Since passive heat loss is much
higher in featherless than in feathered birds, the behavioural responses to increasing stocking density in feathered
birds started at a lower litter temperature than that of the
featherless broilers. These results are in line with previous
findings of CAHANER et al. (2008) and the assumption that
featherless broilers, under high ambient temperatures,
may suffer less from heat stress than feathered broilers.
Summary
Problems of heat dissipation restrict feed intake and
growth rate of conventional broilers under hot environmental conditions and high stocking density. Featherless
broilers dissipate through the whole body surface, and,
thus, are better adapted to high ambient temperatures.
Table 2. Percentages and mean duration of behaviours recorded in response to line (feathered and featherless) and stocking density
Anteile und mittlere Dauer von Verhaltensweisen in Abhängigkeit von der Linie (befiedert und unbefiedert) und der Besatzdichte
Phenotype
Den- Sum
sity of %
kg/m2
Miss%
ing % drink
Feathered
Feathered
Feathered
16.5 100.7
21.1 89.7
32.5 49.1
–0.7
10.3
50.9
4.0
3.5
1.8
Featherless
Featherless
Featherless
28.1 91.3
35.9 100.5
45.6 74.9
8.7
–0.5
25.2
6.9
4.4
5.9
%
feed
%
%
%
preen sit/lay stand
%
walk
duration
sum
duration
drink
dura- dura- dura- dura- duration tion tion tion tion
feed preen sit/lay stand walk
4.3
3.9
3.8
10.5
4.7
3.2
60
64
35
9.2
7.2
2.2
12.7
6.4
3.2
135
67
110
17
8
29
33
12.5
28
5.25
4.7
6.2
64
31
31
14
8
13.8
1.6
2.3
2.4
3.9
5.6
3.3
6.2
5.8
3.2
58
69
50
8.0
9.0
6.7
8.3
6.7
5.8
108
113
59
8.2
22
14
1
13
2.3
4.8
4.15
6.8
84
63
27
7.1
8.8
7
2.5
1.93
2.15
Arch.Geflügelk. 2/2010
Lolli et al.: Behaviour of featherless and normally-feathered broilers
The aim of the present study was to compare the behaviour
of featherless chickens and conventional feathered broilers
under high ambient temperatures and increasing stocking
densities. Three groups of featherless and normally feathered broiler type chickens each were kept in deep litter
pens. The ambient temperature was kept between 33°C.
Stocking density was 16.6; 21.1 and 32.5 kg/m2 in feathered and 28.1; 35.9 and 45.6 kg/m2 in the featherless
chickens. The temperature of the litter surface increased
with increasing stocking density, regardless of the breed,
from 31.4 to about 37 centigrade. The behaviour was
recorded at 7 weeks of age using video-recording. Percent
spent walking, standing, sitting, feeding, drinking, preening was recorded by time sampling technique. The duration of the same behaviours and of, panting was recorded
by focal animal sampling. Within the feathered broilers,
walking, standing, sitting, preening and drinking was reduced with increasing stocking density. Panting occurred
in all groups and under all stocking densities. Bouts of
panting were shorter in featherless than in feathered birds.
The featherless broilers did not consistently respond to
increasing stocking density in most behaviours. In some
cases a similar trend in response to stocking density in behaviour occurred in featherless as in the feathered broilers,
but at a higher density. The behavioural responses could be
explained by the attempt of the birds to cope with high
temperature.
The results suggest that changes in behaviour in response to stocking density are caused by the temperature
rather than physical restriction of space. It is concluded
that at high ambient temperature featherless broilers show
a better state of welfare than feathered broilers.
Key words
Behaviour, litter temperature, stocking density,
featherless chickens
79
Dauer der gleichen Verhaltensweisen sowie die Dauer des
Hechelns wurde durch Einzeltierbeobachtungen registriert. Bei den Folgefedern Masthühnern ging der Anteil an
Fortbewegung, stehen, sitzen, Federputzen und Trinken
mit zunehmender Besatzdichte zurück. Hecheln wurde
war in allen Gruppen und unter allen Besatzdichten beobachtet. Die Dauer des Lächelns war bei den genetisch
federlosen Masthühnern kürzer als bei den befiederten. Im
Gegensatz zu den befiederten Hühnern reagierten die
federlosen Masthühnern in den meisten Verhaltensabläufen nicht konsistent auf zunehmende Besatzdichte. Bei
manchen Merkmalen wurde sowohl bei den federlosen als
auch bei den befiederten der Masthühnern der gleiche
Trend in der Reaktion auf die Besatzdichte festgestellt,
wobei jedoch die Reaktion bei den federlosen Tieren bei
höheren Temperaturen einsetzte. Dieser Ergebnisse können als Anpassung der Tiere an steigende Temperaturen
interpretiert werden.
Die Veränderungen des Verhaltens mit zunehmender
Besatzdichte können eher über die die Veränderung der
Temperaturen als über die räumliche Begrenzung erklärt
werden. Die Ergebnisse weisen darauf hin, dass die unbefiederten Tiere unter hohen Umgebungstemperaturen
weniger leiden als die befiederten.
Stichworte
Verhalten, Einstreutemperatur, Besatzdichte, Nackthühner
Acknowledgement
The present study was carried out in the framework of the
cooperation of the University of Hohenheim and the Hebrew
University of Jerusalem and funded by the Government of
Baden-Württemberg, Germany.
References
Zusammenfassung
Der Einfluss der Besatzdichte auf das Verhalten von
genetisch federlosen und normal befiederten Masthühnern unter hohen Temperaturen
Die Abgabe der mit metabolischen Wärme begrenzt die
Futteraufnahme und das Wachstum von kommerziellem
Masthühnern unter warmen Klimabedingungen und unter
hohen Besatzdichten. Genetisch federlosen Masthühnern
können die Wärme übergeht die gesamte Körperoberfläche abgeben und sind deshalb besser und hohe Temperaturen angepasst. Ziel der vorliegenden Arbeit war es, das
Verhalten von genetisch federlosen und normal befiederten Masthühnern unter hohen Umweltbedingungen und
unter unterschiedlichen Besatzdichten zu vergleichen. Zu
diesem Zweck wurden je drei Gruppen von genetisch
federlosen und normal befiederten Masthühnern in eingestreuten Abteilen gehalten. Die Umgebungstemperatur
war 33°C. Die Besatzdichte betrug 16,6, 21,1 und
32,5 kg/m2 bei den befiederten und 28, ein, 35,9 und
45,6 kg/m2 bei den unbefiederten Tieren. Die Temperatur
an der Einstreu Oberfläche erhöhte sich mit zunehmender
Besatzdichten unabhängig von der Herkunft von 31,4 bis
etwa 37°C. Das Verhalten der Tiere wurde über Videoaufnahmen im Alter von sieben Wochen erfasst. Es wurde der
prozentuale Anteil der Tiere, die beim Stehen, Laufen,
Sitzen, Fressen, Trinken und Federputzen beobachtet wurden, mit Hilfe der Time sampling Technik erfasst. Die
Arch.Geflügelk. 2/2010
ANDREWS, S.M., H.M. OMED, C.J.C. PHILLIPS, 1997: The effect
of a single or repeated period of high stocking density on
the behavior and response to stimuli in broiler chickens.
Poultry Sci. 76, 1655-1660.
ARKENAU, E.F., H. MACKE, H. VAN DEN WEGHE, 1997: Einfluss
der Bodenbelüftung in Broilermastställen auf Tierleistung and Tierverluste. Züchtungskunde 69, 307-313.
BESSEI, W., 1992a: Das Verhalten von Broilern unter intensiven Haltungsbedingungen. Arch. Geflügelkde 56, 1-7.
BESSEI, W., 1992b: The effect of different floor systems on
the behaviour of broilers. Proc. 19th World’s Poultry Congress, Amsterdam (The Netherlands), 2, 743-746.
BESSEI, W., 2005: Welfare of meat producing poultry-an
overview. 7th European Symposium on Poultry Welfare,
15-19 June 2005, Lublin, (Poland). Animal Science Papers
and Reports: 23(1), 205-216.
BESSEI, W., 2006: Welfare of broilers: a review. World’s
Poult. Sci. J. 62, 455-466.
BLOKHUIS, H.J., J.W. VAN DER HAAR, 1990: Effects of stocking
density on the behaviour of broilers. Arch. Geflügelkde
54, 74-77.
CAHANER, A., N. DEEB, 2004: Breeding broilers for adaptability to hot conditions. 8 pages. In: Proc. 22nd World
Poultry Congress, Istanbul (Turkey).
CAHANER, A., N. DEEB, M. GUTMAN, 1993: Effects of the plumage-reducing naked neck (Na) gene on the performance
of fast-growing broilers at normal and high ambient temperature. Poul. Sci. 72, 767-775.
80
Lolli et al.: Behaviour of featherless and normally-feathered broilers
CAHANER, A., S. DRUYAN, N. DEEB, 2003: Improving broiler
meat production, especially in hot climates, by genes that
reduce or eliminate feather coverage. 2003 Spring Meeting of the WPSA UK Branch; British Poultry Science
44(1), 22-23.
CAHANER, A., J.A. AJUH, M. SIEGMUND-SCHULZE, Y. AZOULAY,
S. DRUYAN, A. VALLE ZÁRATE, 2008: Effects of the genetically reduced feather coverage in naked neck and featherless broilers on their performance under hot conditions.
Poul. Sci. 87, 2517-2527.
CAIN, J.R., U.K. ABBOTT, 1971: Heart rate studies with scaleless chickens. Poult. Sci. 50, 126-134.
DAI, N.V., W. BESSEI, N.H. QUANG, 2008: Effects of sodium
chloride and potassium chloride supplementation in
drinking water on performance of broilers under tropical
summer conditions. Arch. f. Geflügelk. in press.
DEEB, N., A. CAHANER, 1994: Genotype-environment interaction and heat tolerance of naked-neck broilers. Proc.
5th World Congress on Genetics Applied to Livestock
Production, Guelph, (Canada). 20, 65-68.
DEEB, N., A. CAHANER, 2001: Genotype-by-environment interaction with broiler genotypes differing in growth rate.
1. The effects of high ambient temperature and naked-neck genotype on lines differing in genetic background. Poult. Sci. 80, 695-702.
DEEB, N., A. CAHANER, 2002: Genotype-by-Environment
Interaction with Broiler Genotypes Differing in Growth
Rate. 3. Growth rate and water consumption of broiler
progeny from weight-selected versus non-selected parents under normal and high ambient temperatures. Poult.
Sci. 81, 293-301.
FREEMAN, B.M., 1971: Body temperature and thermoregulation. In: Bell, D.J. and Freeman B.M. Edts., Physiology
and Biochemistry of the Domestic Fowl. Academic Press,
London 1115-1151.
GERKEN, M., R. AFNAN, J. DÖRL, 2006: Adaptive behaviour in
chickens in relation to thermoregulation. Arch. Geflügelkde
70, 194-198.
GRASHORN, M., B. KUTRITZ, 1991: Der Einfluss der Besatzdichte auf die Leistung moderner Broilerherkünfte. Arch.
Geflügelkde 55, 84-90.
HORST, P., 1982: Genetical perspectives for poultry breeding
on improved productive ability to tropical conditions.
Proc. 2nd World Congress on Genetics Applied to Livestock Production, Madrid, Spain. 8, 887-892.
VAN KAMPEN, M., 1976a: Activity and energy expenditure in
laying hens. 2. The energy costs of exercise. J. Agric. Sci.
87, 81-84.
VAN KAMPEN, M., 1976b: Activity and energy expenditure in
laying hens. 3. The energy cost of eating and posture.
J.Agr.Sci. (Cambridge) 1976, 85-88.
KRISTENSEN, H.H., L.R. Burgess, T.G.H. DEMMERS, C.M.
WATHES, 2000: The preferences of laying hens for different
concentrations of atmospheric ammonia. Applied Animal
Behaviour Science 68, 307-318.
LEWIS, N.J., J.F. HURNIK, 1990: Locomotion of broilers chickens in floor pens. Poult. Sci. 69, 1087-1093.
MCLEAN, J., J. SAVORY, N. SPARKS, 2001: Welfare of male and
female broiler chickens in relation of stocking density.
Proc. 6th European Symposium on Poultry Welfare,
Zollikofen (Switzerland), 132-135.
MERAT, P., 1986: Potential usefulness of the Na (naked neck)
gene in poultry production. World's Poultry Science Journal 42, 124-142.
MERAT, P., 1990: Pleiotropic and associated effects of major
genes. In: Poultry Breeding and Genetics. R.D. Crawford,
ed., Elsevier Scientific Publishers, Amsterdam, The Netherlands. 429-467.
PEREIRA, D.F., I.A. NAAS, C.E.B. ROMANINI, D.D. SALGADO,
G.O.T. PEREIRA, 2007: Broiler breeder behaviour and egg
production as function of environmental temperature.
Brazilian Journal of Poultry Science 9(1), 9-16.
PRESTON, A.P., L.B. MURPHY, 1989: Movement of broiler
chickens reared in commercial conditions. Brit. Poult. Sci.
30, 519-532.
PROVINE, R.R., 1981: Wing-flapping develops in chickens
made flightless by feather mutations. Developmental
Psychobiology 14, 481-486.
REITER, K., W. BESSEI, 2000a: Effect of Stocking density of
broilers on temperature in the litter and at bird level. Arch.
Geflügelkde 64, 204-206.
REITER, K., W. BESSEI, 2000b: The behaviour of broilers in
response to group size and stocking density. Arch.
Geflügelkde 64, 93-98.
REITER, K., W. BESSEI, 2001: Effect of reduced weight load on
locomotor activity and leg disorders in broiler chickens.
Proc. 6th European Symposium on Poultry Welfare,
Zollikofen (Switzerland), 113-117.
ROBINSON, D., 1979: The influence of temperature humidity
and air speed on the occurrence of heat stress symptoms
in laying hens. 3rd Australasian Poultry and Stock Feed
Convention, Surfers Paradise, Australia, 23–28 Sept.,
184-196.
SCHERER, P.J., 1989: Einfluss unterschiedlicher Haltungsbedingungen auf das Verhalten von Broilern unter Berücksichtigung von Leistungsdaten. Thesis, ETH Zürich,
Zürich (Switzerland).
SCHOLTYSSEK, S., B. GSCHWINDT-ENSINGER, 1983: Leistungsvermögen einschließlich Befiederung und Belastbarkeit
von Broilern bei unterschiedlicher Besatzdichte in Bodenhaltung. Arch. Geflügelkde 47, 3-8.
SHANAWANY, M.M., 1988: Broiler performance under high
stocking densities. Brit. Poult. Sci. 29, 43-52.
VESTERGAARD, K.S., B.I. DAMM, U.K. ABBOTT, M. BILDSOE, 1999:
Regulation of dustbathing in feathered and domestic
chicks: the Lorenzian model revisited. Anim. Behav. 58,
1017-1025.
WATHES, C.M., 2002: Measuring and auditing broiler welfare. Eds: Weeks, C. A., Butterworth, A., 117-131.
WIEDMER, R.D., R. HADORN, 1998: Revision Tierschutzverordnung: Kurzmast-Besatzdichten lassen. Schweizerische
Geflügelzeitung. 2, 10-15.
YADGARI, L., R. KUHNREICH, S. DRUYAN, A. CAHANER, 2006: The
effects of stocking density in hot conditions on growth,
meat yield and meat quality of and feathered broilers. In
CD Proc. XII European Poultry Conference, Verona, Italy.
YADGARI, L., R. KUHNREICH, N. ASTRACHAN, Y. HADAD, S.
DRUYAN, A. CAHANER, 2007: Broilers produce more
high-quality meat in hot conditions and high stocking
densities. 3 pages. In: CD Proc. VIII Asian-Pacific Poultry
Conference, Bangkok (Thailand).
YARON, Y., Y. HADAD, S. DRUYAN, A. CAHANER, 2004: Heat
tolerance of broilers. 4 pages. In: CD Proc. 22nd World
Poultry Congress, Istanbul (Turkey).
Correspondence: Dra. V. Ferrante, University of Milan, Dept. of Animal Science,
Sec. Veterinary Animal Husbandry, Via Celoria 10, 20133 Milano, Italy; E-mail:
[email protected]
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