AABArchives Animal BreedingAABArch. Anim. Breed.2363-9822Copernicus GmbHGöttingen, Germany10.5194/aab-58-85-2015Effects of age at first access to range area on pecking behaviour and plumage quality of free-range layer chickensPetekM.petek@uludag.edu.trTopalE.CavusogluE.Department of Zootechnics, Faculty of Veterinary Medicine, University of Uludag, Bursa, TurkeyM. Petek (petek@uludag.edu.tr)9March2015581859114July201412January2015This work is licensed under a Creative Commons Attribution 3.0 Unported License. To view a copy of this license, visit http://creativecommons.org/licenses/by/3.0/This article is available from https://aab.copernicus.org/articles/58/85/2015/aab-58-85-2015.htmlThe full text article is available as a PDF file from https://aab.copernicus.org/articles/58/85/2015/aab-58-85-2015.pdf
The aim of this study was to investigate the effects of age
on pecking behaviour and plumage quality of free-range laying hens during first access to range.
Six hundred 16-week-old layer pullets obtained from a commercial company
were housed in a experimental free-range house. The experimental house
consisted of a slat-and-litter floor with range area and was divided into
three similar pens. The pullets were randomly assigned to a control and two
experimental groups according to age at first access to range area. The
birds were allowed into the range area for the first time at 18, 20 and 22 weeks of age in
the groups of treatment I, treatment II and control, respectively. Pecking behaviour
and plumage quality of the birds were measured for 8-week intervals from
24 to 48 weeks of age. Total feather damage significantly increased with age in all
groups (P < 0.040, P < 0.006, P < 0.001).
Compared to the control group, birds allowed into the range area earlier had
less feather damage. The feather score of the tail body region in all groups was significantly
greater (more damage) than in the others (P < 0.001).
There were no significant differences for the total pecking behaviour of the
birds in the groups at 24, 32, 40 and 48 weeks of age. Incidents of gentle
feather pecking in every period were more frequent, while aggressive pecking
was less frequent (P < 0.026, P < 0.007, P < 0.001). It can be
said that access to range area as early as possible at the beginning of
the laying period may be useful to reduce the negative effect of feather pecking
in free-range layer chickens.
Introduction
Injurious pecking is a common term used to describe feather pecking, vent
pecking, cannibalism and toe pecking in laying hens. It is also a serious
welfare concern because the pulling-out of feathers causes pain, stress,
injuries and increased susceptibility to disease (Petek and McKinstry, 2010).
Injurious feather pecking can represent a big problem in all housing
systems, even in free-range housing systems, with both economic implications
for farmers and welfare implications for birds (Tauson et al., 2005; Sherwin et
al., 2010, 2013).
Beak trimming and dim lighting are still the most effective husbandry
practice used by the poultry industry and have long been employed to help
reduce the deleterious effects of feather pecking and subsequent cannibalism
(Petek and McKinstry, 2010). However, these are under criticism in terms of the
welfare point of view (Brunberg et al., 2011). Some countries have banned the hot-blade
technique, which is most common technique for beak trimming. A general ban on
the use of all techniques, including infrared, for beak trimming is expected by 2018 in several EU countries (Anonymous, 2013). In recent
years, there has been increasing focus on alternative methods to reduce injurious
pecking in laying hens. Some scientific evidence suggests that feather
pecking and cannibalism could be largely prevented by the use of appropriate
husbandry techniques without the use of beak trimming (Savory, 1995; Morris,
2007; Picket, 2008; Petek, 2013). There have been some on-farm studies on pecking and the
welfare of laying hens in the literature (Nicol et al., 2003; Sherwin et al., 2010, 2013;
Gilani et al., 2013). Recently, a set of husbandry advisory tools was developed to
reduce injurious pecking in free-range layer chickens in the UK (Weeks et al.,
2011; Lambton et al., 2013).
It is clear that the risk of feather pecking in free-range layer chickens
might be lower when an outdoor grazing area is provided. Mahboup et al. (2004)
reported that the percentage of time spent on grassland and feather damage
were inversely correlated. Lambton et al. (2010) showed that there was a
detrimental effect of allowing range access before onset of laying and the risk of
vent pecking might also be reduced by delaying the onset of laying and
subsequently encouraging range use. A recent study also tested the effect of
range access during rearing on feather pecking and ranging behaviour. That
study found no effect of age of first range access on the amount of feather
pecking (Gilani et al., 2014). In general, the conventional timing of first access
to range area for free-range layer chickens is 22 or 24 age
of weeks because of the period of adaptation of pullets to nest boxes and
other housing environments. However there is a major concern about this
period, because it may lead to an increase in feather pecking and cannibalism in layer
chickens. This study was carried out to investigate the effects of age at
first range access on pecking behaviour and plumage quality of free-range
layer chickens.
Material and methods
Research was performed at the Research and Experimental Farm of Uludag University
in Bursa, Turkey, and experimental procedures were employed in
accordance with the principles and guidelines set out by the Committee of
Uludag University on animal care. Six hundred 16-week-old Lohman Brown layer pullets
obtained from a commercial company were reared in an
experimental free-range house. At the beginning of the experiment, pullets
were randomly distributed into three groups of 200 birds (control and two
experimental groups) according to age at first range access.
Management
The indoor and outdoor (range) areas of the experimental house were divided into three
similar pens (6×6 m). The indoor part of each pen consisted of litter
(one-third of floor space) and a slatted floor (white plastic slats, 100×60 cm). A rice hull layer of about 10 cm was used as a litter material. Birds in all groups were
allocated equal space for feeders, drinkers and nest boxes. Automatic
nest boxes (group nests; 1 m2 of nest space for every 100 hens), hanging
feeders (each 30 cm in diameter with 10–15 kg capacity) and bell drinkers
were provided for the birds in all groups. All birds were beak trimmed by
method of hot blade (at first week of age) and mean stocking density within
the groups was 6 birds per 1 m-2 indoor and 5 birds per 10 m-2 outdoors.
Birds in all groups were fed with a pullet grower diet containing 2850 kcal kg-1
metabolizable energy and 15 % crude protein until 20 weeks of
age. The standard layer diet was supplied (2700 kcal kg-1 metabolizable energy
and 18 % crude protein) between weeks 21 and 48 (NRC, 1994). Water and
feed were provided ad libitum.
The birds were allowed into the range area for the first time at 18, 20 and 22 weeks of
age in the groups of experiment I, experiment II and control, respectively. The groups were
physically and visually separated from each other so that the birds in the
18 weeks of treatment did not affect the behaviour of the birds in the other
treatments. During the experimental period, birds in all groups had continuous
access to outdoor range during daylight hours. The daily photoperiod
consisted of 16 h of light and 8 h of darkness. The lighting intensity was
arranged as 3.0 lx m-2.
Data
The control and experimental groups were monitored in 8-week intervals by
the same person to assess the poultry welfare with plumage quality (physical
assessment) and pecking behaviour (behavioural assessment) of the birds from
24 to 48 weeks (Sejian et al., 2011). The physical and behavioural assessments
in the control and treatment groups were carried out in slatted, litter and range
areas. Three observations in each area in each group were made, and each of
them was designed in the same way as the other groups.
Plumage quality
A distance scoring system, which is a more animal-friendly, less stressful, and effective and easier way to determine feather damage, was used
to assess plumage quality in hens (Bright et al., 2006; Lambton et al., 2013). Three areas of the birds' bodies were scored (neck, back and rump) from
0 (well-feathered body part with no or very little damage) to 4 (severe
damage to feathers, several or large naked areas and/or broken skin).
Moreover, two areas of flight feathers (tail and wing) were also scored
from 0 (intact feathers) to 4 (all feathers missing or broken and/or
evidence of bleeding from broken skin). To determine plumage quality, the
birds were selected at random for scoring by choosing a hen, counting five
hens to the left, and feather-scoring that fifth hen in the slatted, litter
and range areas. Ten birds from each area were scored to measure plumage
quality. Two birds from each area were caught and examined to assess the vent and
cannibalism score. Flock prevalence of feather pecking in control and
treatment groups was calculated as a percentage of birds with damaged
feathers from the total birds scored.
Behavioural observations
Behaviour observations were recorded with focal animal sampling (Martin and
Bateson, 1986) in the afternoon (14:00–16:00) by the same person from a 2 m distance from the observation area. The observations were carried out
on slats, on litter and on range in accordance with a 5 min observation
period after a standstill for 2 min to maintaining a clear view of the
observation area. The number of bouts/pecks of gentle
feather pecking (GFP) were recorded, as well as the number of pecks for severe feather pecking
(SFP), tail pecking (TP) and aggressive pecking (AP). Also, the
existence of vent pecking (VP) and cannibalistic pecking (CP) as pecking
behaviour were measured in this study (Table 1). At the start and end of
5 min observation period, the number of
birds in each area was counted and recorded.
Ethogram of behavioural observations*.
BehaviourDescriptionGentle feather peckingFeather pecking without removal of feathersSevere feather peckingFeather pecking leading to feather lossTail peckingFeather pecking leading to feather loss in tailAggressive peckingForceful downward peck at the head, neck or any part of bodyVent peckingTissue pecking in ventCannibalistic peckingTissue pecking in any part of body
* Savory (1995), Petek and McKinstry (2010)
Analysis
Total feather score was defined as the sum of the scores for all body parts.
Rates of feather pecking behaviour were calculated as pecks or bouts (in
the case of GFP) per bird per observation period (5 min) where average the
number of birds before and after observation period (the average rates of
feather pecking behaviour : pecks (bouts)/number of birds before and after
observation : 5 min). All of the data were analysed by means of an ANOVA test
procedure which is part of SPSS version 13.00 (SPSS, Inc. 2004). The mean
separation was performed using the Duncan test (Snedecor and Cochran, 1989).
Results
Results from flock prevalence of feather damage and total feather scores of
control and treatment groups are presented in Table 2. Based on the study,
there were no significant differences for total feather score between control
and treatment groups at 24 weeks of age. The total feather score significantly increased with
age and varied among the groups at 32, 40 and 48 weeks of age
(P < 0.040, P < 0.006, P < 0.001). The final feather
score of control group was the worst, with total scores of 0.93
(P < 0.001). The mean proportion of birds affected by any feather damage in
control, treatment I and treatment II was respectively 70.00, 76.66 and 70.00 at 24 weeks
of age and 100.00, 73.30 and 90.00 % at 48 weeks of age.
Flock prevalence (FP)1 and total feather scores
(TFS)2 in control and treatment groups.
1 The mean proportion of birds within each flock affected by any feather
damage. 2 Mean ±SE, lower score means better plumage quality; a-c
within columns; values with different superscript letters differ
significantly (P < 0.05, P < 0.001).
The average feather scores for all body regions of the birds in each group are
displayed in Table 3. All differences among the feather score of neck, back,
rump, tail and wing at 24, 32, 40 and 48 weeks of age in any group were
found to be statistically significant (P < 0.05, P < 0.01,
P < 0.001). All differences for same body region calculated at 24,
32, 40 and 48 weeks in control group were found to be significantly
important as well (P < 0.001). Differences for the feather score of
neck and rump was found to be significantly important in treatment I
(P < 0.05). There were important differences in the feather score
of the same body region collected during different periods of the experiment in treatment
II, except for the tail region (P < 0.05, P < 0.05,
P < 0.05, P < 0.01, respectively).
Average feather score for all body regions of the birds in each
group.
a-c Within columns, values with different superscript letters differ
significantly (P < 0.05, P < 0.001); ns: not
significant.A-B Within rows, values with different superscript letters differ
significantly (P < 0.05, P < 0.01,
P < 0.001).
The mean rate of pecking behaviour in all groups and the general proportion
to type of different pecking behaviour are shown in Table 4. There were no
significant differences for the mean rate of pecking behaviour between
control and treatment groups. The average number of pecks in the control,
treatment I and treatment II were found to be, respectively, 0.183, 0.069 and 0.168 for the first
observation period (at 24 weeks of age); 0.155, 0.108 and 0.098 at 32 weeks
of age; 0.155, 0.046 and 0.104 at 40 weeks of age; and 0.110, 0.057 and 0.064
in the final observation period (at 48 weeks of age).
In addition, on the basis of type of feather-pecking activity, significant
differences were observed throughout the experiment (P < 0.026,
P < 0.007, P < 0.001, respectively). The average number of
pecks for GFP, SFP, AP and TP were calculated as, respectively, 0.219, 0.150, 0.112 and
0.078 at 24 weeks of age; 0.274, 0.099, 0.015 and 0.093 at 32 weeks of age;
0.305, 0.089, 0.012 and 0.017 at 40 weeks of age; and 0.212, 0.054, 0.006 and
0.039 in the final period of experiment. No significant groups of
x type of feather pecking interaction were determined for all time periods of
this study.
The mean rate of pecking behaviour in the groups and mean proportion of
different pecking behaviour (number/5 min).
Groups24 w32 w40 w48 wControl0.1830.1550.1550.111Treatment I0.0690.1080.0460.057Treatment II0.1680.0980.1040.064Type of feather peckGFP0.2190.274a0.305a0.212aSFP0.1500.099b0.089b0.054bAP0.1120.015c0.012c0.006cTP0.0780.093b0.017b0.039bANOVAGroups0.2270.6920.3810.321Type of feather peck0.3510.0260.0070.001Interaction between groups0.3230.9500.8950.699× type of feather pecking
Plumage condition of laying hens is very important for the body of the bird, and
it may seriously affect the welfare of bird. Insufficient feather coverage
on a hen causes a gradual decreasing production and the economy laying period.
Also, the plumage condition might be an input level of the laying
hen's welfare. One of the major factors for reducing plumage quality is feather
pecking. The causes of and preventative measures for feather pecking and
cannibalism are very complicated and multi-factorial elements
(Rodenburg et al., 2013). Some of the predisposing factors are overcrowding, excessive light
and temperature, insufficient or improperly placed feeders or drinking space,
nutritional imbalances including mineral deficiencies, feeding of only
pelleted or concentrated feed, feeding high-energy diets heavy in corn or
low in fibre, and injuries (Green et al., 2000; Nicol et al., 2003, 2013; Sedlačková
et al., 2004; De Haas et al., 2014). Moreover, the high prevalence of
these behaviours and feather damage within flocks mainly depends upon
whether or not beak trimming is applied (McAdie and Keeling, 2000). An alternative housing system for hens such as
free range with an aviary system shows much higher incidences of injurious
pecking than in those hens housed in a conventional caged system. Among all production systems, vent pecking is most widespread in free
range (Sherwin et al., 2010). Giving birds fermented feed
results in a poorer plumage condition than given them dry feed (Engberg
et al., 2009). Gilani et al. (2012) found that dark brooding had no detrimental effect
on feather pecking on commercial farms.
A more critical factor should be the reduction in the propensity for feather
pecking during the rearing phase of layer hens. In this study there were no
significant differences for the plumage quality of birds between the groups
at 24 weeks of age. This is after the first group had been outside for a
month already. However, the rapid changes in plumage quality were observed
in all groups from the beginning onwards. By 32 weeks, all groups
developed feather pecking behaviour and the plumage condition declined.
Further decreases in plumage condition take place between 32 and 48 weeks.
Although the rearing environment may play an important role in the later
development of pecking problems, generally the plumage condition is perfect
and injurious pecking is minimal when birds are transferred from rearing to
laying houses (Blokhuis and Van der Haar, 1992; Huber-Eicher and Wechsler,
1998). All the layers in the control group had feathers that were more or less damaged
in the final period of the study, whereas flock prevalence of feather pecking
in treatment I and treatment II were 73 and 90 %, respectively. In contrast to previous reports (Leenstara et al., 2012), birds having access to range
area later resulted in more feather damage. Compare to this study, Gilani et al. (2013)
found that percentage of flock with missing feathers was 12 % at 16 weeks
and 49 % at 35 weeks.
In this study, the final plumage quality of the birds for all body regions
significantly worsened in all groups. Based on the results, more
feather damage (greater scores, more damage) was observed to the tail and
rump than to other regions of the body in all groups (P < 0.05). Also, the
best plumage quality of the body in each group was measured for the neck region.
In this study, there were significant differences for the type of feather-pecking activity of laying hens throughout the experiment, except for
initial stage of experiment (P < 0.026, P < 0.007,
P < 0.001). Similar to the findings of Lambton et al. (2013), gentle feather
pecking was the most frequently observed behaviour, followed by severe
feather pecking, tail pecking and aggressive pecking. It has been reported
that gentle feather pecking was observed in 89.2 and 73 % of flocks
at 25 and 40 weeks, respectively, in UK free-range and organic farms (Lambton
et al., 2010). Farm-level factors examined in Dutch organic farm flocks showed moderate
plumage damage in 19 % of flocks and severe damage in 52 % of flocks
(Bestman and Wagenaar, 2003). Gentle feather pecking is pecking that results
in little or no feather damage and produces no or only a mild response in
the recipient layer (McAdie and Keeling, 2000). It is important that
gentle feather pecking was rarely correlated with feather damage in any
body area (Lambton et al., 2013). Fewer instances of aggressive pecking in this study
may be as a result of less feeding competition, because feeding competition
may lead to an increase in pecking activity, especially aggressive pecking.
On the other hand, cannibalistic behaviour and vent pecking were not
observed in our trial. This was probably due to the genetic strain of bird
and the fact that they were kept in more spread-out groups (Petek and McKinstry,
2010). Most forms of feather-pecking activity increase in both prevalence
and rate with age. Previous studies have similarly noted increased
feather pecking with bird age (Nicol et al., 2003; Gilani et al., 2013), especially at
higher stocking densities (Zimmerman et al., 2006) and if flocks were fed on
pelleted feed (Lambton et al., 2010). In the current study, the rate for all types of
pecking behaviour decreased with age, as previously reported by Chow and
Hogan (2005). Shimmura et al. (2008) reported that most free-range hens
spent their time outside foraging and that the proportion of feather pecking
decreased in free-range layer chickens during their access to range, and a
similar tendency was observed also in aggressive pecking.
The results of this study clearly showed that increasing use of range is
important to reduce pecking behaviour since the more frequent total pecking
behaviour and more feather damage were observed in the control group
compared to the experimental groups. As reported previously, greatest
range use is achieved by allowing the hens range usage as early as possible
(Anonymous, 2011).
In conclusion, injurious feather pecking and cannibalism may have a serious
effect on poultry welfare. When searching for an on-farm solution to reduce
this harmful behaviour, it is important to identify the potential risk
factors involved in the development of feather pecking on every flock.
Integrated application of an appropriate husbandry management program and
multidisciplinary research might be very useful in reducing the levels of
feather pecking. The decision about the time until first access to range is a
husbandry practice, and access to range area as early as possible at the beginning of the
laying period may be a useful tool to reduce negative
effects of injurious pecking in free-range layer chickens, with beneficial
effects on both welfare and productivity. However, even with these measures,
feather pecking and cannibalism will remain a significant problem.
Acknowledgements
This study was supported with a grant from the Scientific Research Project
Directorship of Uludag University (project no: UAP(V)-2011/56).
Edited by: K. Wimmers
Reviewed by: two anonymous referees
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