Clinic of Birds and Reptiles Faculty of Veterinary Medicine University of Leipzig
and
Animal Husbandry and Animal Ecology Group Institute of Agricultural and Nutritional Sciences Natural Sciences Faculty III Martin-Luther University Halle-Wittenberg
Genetic and environmental factors influencing the behaviour and health of laying hens with emphasis on feather pecking
Thesis for the degree of Doctor medicinae veterinariae (Dr. med. vet.) from the Faculty of Veterinary Medicine University of Leipzig
presented by Sameh Gad Abdel-hak Ramadan, M.V.Sc. from El-Dakahlia, Egypt
Leipzig, 2007
Mit Genehmigung der Veterinärmedizinischen Fakultät der Universität Leipzig
Dekan: Prof. Dr. med. vet. K. Fehlhaber
Betreuer: Prof. Dr. med. vet. Maria-Elisabeth Krautwald-Junghanns Prof. Dr. rer. nat. Eberhard von Borell
Gutachter: Prof. Dr. med. vet. Maria-Elisabeth Krautwald-Junghanns Klinik für Vögel und Reptilien, Veterinärmedizinische Fakultät, Universität Leipzig
Prof. Dr. rer. nat. Eberhard von Borell Professur für Tierhaltung und Nutztierökologie, Institut für Agrar- und Ernährungswissenschaften, Naturwissenschaftliche Fakultät III, Martin-Luther-Universität Halle-Wittenberg
Prof. Dr. med. vet. Uwe Truyen Institut für Tierhygiene und Öffentliches Veterinärwesen,Veterinärmedizinische Fakultät, Universität Leipzig
Prof. Dr. Dr. med. vet. habil Hafez Mohamed Hafez Institut für Geflügelkrankheit, Veterinärmedizinische Fakultät, Freie Universität Berlin
Tag der Verteidigung: 30. Oktober 2007
To my family
CONTENTS
1 INTRODUCTION 1
2 REVIEW OF LITERATURE 4 2.1 Behavioural biology of the bird (hen) 4 2.2 Function and anatomy of feathers 6 2.2.1. Definition of feathers 6 2.2.2 Function of feathers 6 2.2.3 Feathers and body surface 7 2.2.4 Types and anatomy of feathers 7 2.2.5 Forms of feathers damage 9 2.3 Housing systems 10 2.3.1 Main egg production systems 10 2.3.1.1 Cage systems 10 2.3.1.1.1 Conventional battery cages 10 2.3.1.1.2 Furnished/enriched cages 11 2.3.1.2 Non cage systems 12 2.3.1.2.1 The perchery (barn) system 12 2.3.1.2.2 The deep litter system 12 2.3.1.2.3 Free range system 12 2.3.1.2.4 Semi intensive system 12 2.4 Feather pecking and cannibalism 13 2.4.1. Relationship between feather pecking and cannibalism 15 2.4.2 Types of feather pecking 15 2.4.2.1 Relationship between gentle and severe feather pecking 16 2.4.3 Factors influencing the occurrence and development of feather pecking 17 2.4.3.1 Causation of feather pecking 17 2.4.3.2 External factors 18 2.4.3.3 Internal factors 21 2.4.4 Control of feather pecking 23 2.5 Behaviour patterns related to feather pecking 25 2.5.1 Dustbathing behaviour 25 2.5.2 Foraging behaviour 27 2.6 (Some experiments related to) Feather function and feather pecking 29 2.6.1 Effect of feathers manipulation on the incidence of feather pecking and cannibalism 29 2.6.2 Feather as a substrate for dustbathing 29 2.6.3 Feather eating and its role in the aetiology of feather pecking damage 30 2.6.3.1 Relationship between feather eating, feather pecking and feather attractiveness 31 2.6.4 Demand of laying hens for straw and feathers as litter substrates 32 2.6.5 Pecking at feather bunches 32 2.6.6 Demand of laying hens for feathers and wood shavings 34 2.7 Fear 34 3 ANIMALS, MATERIAL AND METHODS 36 3.1. Birds and housing 36 3.1.1 Rearing period (0-16 weeks of age) 36 3.1.2 Laying period (from 16 weeks of age) 36 3.2 Experimental design 38 3.2.1 Experiment I 39 3.2.2 Experiment II 40 3.3 Behavioural observations 40 3.3.1. Feather pecking 41 3.3.2 Other behaviour activities 41 3.4 Feather scoring 43 3.5 Tonic immobility 44 3.6 Egg production 45 3.7 Body weight 45 3.8 Statistical analysis 45
4 RESULTS 47 4.1 Feather treatment and genotype (first experiment) 47 A- Rearing period 47 4.1.1 Effect of feather treatment and genotype on the rate of feather pecking 47 4.1.2 Feather pecking directed to different body parts 49 4.1.3 Effect of feather treatment and genotype on the behavioural activities 51 4.1.4 Effect of feather treatment and genotype on feather condition. 52 4.1.5 Effect of feather treatment and genotype on body weight 54 B- Laying period 54 4.1.6 Effect of feather treatment and genotype on the rate of feather pecking 54 4.1.7 Feather pecking directed to different body parts 57 4.1.8 Location of feather pecking activity. 58 4.1.9 Behavioural activities in LT and LS during the laying period. 59 4.1.10 Effect of feather treatment and genotype on feather condition. 60 4.1.11 Effect of feather treatment and genotype on skin injuries 64 4.1.12 Effect of feather treatment and genotype on body weight 66 4.1.13 Effect of feather treatment and genotype on egg production. 67 4.2 Feather treatment and imprinting to loose feathers (second experiment) 68 A- Rearing period 68 4.2.1 Effect of feather treatment on the rate of feather pecking 68 4.2.2 Feather pecking directed to different body parts 70 4.2.3 Effects of feather treatment on the behavioural activities 70 4.2.4 Effects of feather treatment on the plumage condition 71 4.2.5 Effect of feather treatment on body weight 71 B- Laying period 72 4.2.6 Effect of feather treatment on the rate of feather pecking 72 4.2.7 Feather pecking directed to different body parts 73 4.2.8 Location of feather pecking activity 74 4.2.9 Effect of feather treatment on the behavioural activities 75
4.2.10 Effect of feather treatment on feather condition 75 4.2.11 Skin injuries 78 4.2.12 Effect of feather treatment on body weight 79 4.2.13 Effect of feather treatment on egg production 79 4.2.14 Effect of feather treatment on fear reactions of the birds (TI test) 80 4.2.15 Mortality rate 80
5 DISCUSSION 81 5.1 Feather treatment and genotype 81 5.2 Feather treatment and imprinting to loose feathers 94 5.3 Conclusions 101
6 SUMMARY 103
7 ZUSAMMENFASSUNG 105
8 REFERENCES 107
ABBREVIATIONS
°C Degree celsius Cm Centimetre cm² Square centimetre (cont) Control group (+f) With feather group (-f) Without feather group FP Feather pecking G. Gallus GLM General linear model h Hour HFP High feather pecking birds Kg/ g Kilogram/ Gram LB Lohmann Brown LFP Low feather pecking birds LS Lohmann Silver LSL Lohmann Selected Leghorn LS-Means Least squares means LT Lohmann Tradition m Metre m² Square Metre ME Metabolised energy min Minute ns Non-significant PH Poultry house s Second SE Standard Error TI Tonic immobility vs. Versus WG Winter garden Exp. Experiment
Introduction
1 INTRODUCTION In 1999 the European Commission approved the directive on the welfare of laying hens banning the traditional battery cages from 2012. This type of cages has been criticised because the space available is restricted and of the barrenness of the environment, which could not fulfil the bird’s need to express their natural behaviour and causes severe welfare disadvantages for the hens (APPLEBY 2003). Enriched cages (which provide more space, perches, nest box and litter area) will still be allowed. Therefore, there is an urgent need to develop feasible alternative housing systems for layers (SEDLACKOVA et al. 2004). These systems, however, show much higher incidence of feather pecking and cannibalism compared to cage systems (MORGENSTERN 1995; GREEN et al. 2000; PÖTZSCH et al. 2001; APPLEBY 2003; BESTMAN and WAGENAAR 2003). Feather pecking is an abnormal behaviour where laying hens peck the feathers of conspecifics, damaging the plumage or even injuring the skin, so it is considered as one of the most widespread and serious problems of today’s poultry production when hens are kept under commercial conditions (SAVORY 1995; BLOKHUIS et al. 2000). It causes reduced welfare of the bird, as it has been suggested that having feathers pulled out is painful for the recipient hen (GENTLE and HUNTER 1990) and it can lead to cannibalism (ALLEN and PERRY 1975). Moreover, it increases economical losses due to increased mortality, reduction in egg production (JOHNSEN et al. 1998; EL-LETHY et al. 2000), increased food consumption (LEESON and MORRISON 1978), and is also associated with increased (chronic) fear (HUGHES and DUNCAN 1972; QUART and ADAMS 1982). Feather pecking and cannibalism are found in battery cages as well as in modified cages, deep litter and aviary systems (ALLEN and PERRY 1975; BESSEI et al. 1984; APPLEBY and HUGHES 1991). It can occur during both the rearing and laying periods (HUGEHS and DUNCAN 1972; ALLEN and PERRY 1975; HUBER- EICHER and WECHSLER 1997, 1998). JOHNSEN and VESTERGAARD (1997) emphasised the importance of early rearing conditions (litter substrate) on the development of feather pecking behaviour, and it is possible that feather availability on litter in early life may affect subsequent pecking behaviour. Feather eating has been observed in commercial layers (SAVORY and MANN 1997), pullets prefer to eat shorter semiplumes rather than longer ones, and once feather eating has become established, a too low availability of short feathers on
______1 Introduction
pen floors may cause feather eating and pecking to be redirected to other birds (MCKEEGAN and SAVORY 1999). Various studies indicated that early pecking experience is related to later preference for dustbathing substrates in domestic chicks (VESTERGAARD and BARANYIOVA 1996). It is therefore likely that early pecking experience with inedible loose substrates lead to an imprinting like process whereby the pecked substrate becomes preferred for dustbathing later in life (VESTERGAARD and BILDS∅E 1999). With the proper early control of access to pecking and dustbathing substrates not only sand but also feathers and straw may be preferred for dust bathing (VESTERGAARD and LISBORG 1993; SANOTRA et al.1995). Chicks should be reared in such a way that they do not come to treat feathers as dust. This would be the first step to stop serious feather pecking from developing. One way of controlling the development would be to present stimuli that are much more attractive for pecking and dust bathing than feathers (VESTERGAARD and LISBORG 1993). Many studies have shown that the behaviour of individual chicks can be altered if they have the opportunity to observe the behaviour of conspecifics. For example, chicks learn to avoid an aversive object by observing the disgust response of a conspecific pecked at it. Moreover, chicks tend to feed in groups rather than individually and both foraging behaviour and the orientation of pecking behaviour are influenced by what the conspecific in the group is doing (JOHNSTON et al.1998). In cage systems, where there are only few hens per standard cage, if there is a problem with one individual hen pecking at another hen, then this affected only her cagemates. However, in loose- housing systems where thousands of hens can be housed together, misdirected pecking can be potentially more of a problem as many hens can mimic one hens’ behaviour (KEELING 1995). Provision of foraging material had significant effects on the incidence of feather- pecking interactions among hens (BLOKHUIS 1986; HUBER-EICHER and WECHSLER 1997, 1998; KLEIN et al 2000; NICOL et al 2001). In chickens, normal foraging behaviour consists of pecks directed at both edible and inedible substrates, but if chickens are housed such that ground pecking is prevented then pecks may instead be directed at the feathers of conspecifics (BLOKHUIS 1986; HUBER-EICHER and WECHSLER 1997). Feather pecking occurred less in pens with polystyrene blocks for
______2 Introduction
pecking than in pens without them. "Pulling" and "plucking" feather pecking interactions were significantly higher in pens without foraging material than they were in pens with foraging material (WECHSLER and HUBER-EICHER, 1998). There is a general consensus that a lack of appropriate foraging opportunity is a major contributor to feather pecking behaviour by chickens (MEEHAN et al 2003). Feather pecking can be viewed as foraging behaviour in which the birds first learn to peck at loose feathers on the floor and then, when there are no more feathers they develop proper feather pecking (MCKEEGAN and SAVORY 1999; FORKMAN 2003). There is also a genetic component to feather pecking. It has been documented that feather pecking differs between strains of hens (BLOKHUIS and BEUVING 1993; CRAIG and MUIR 1993, 1996). It has been demonstrated that feather-pecking traits can be selected for or against (KEELING and WILHELMSON 1997). Therefore, there is much need to understand the causes of feather pecking in order to envisage methods that can effectively prevent its development. This study was carried out to investigate the effect of feather availability on the floor on: • The bird behaviours, especially feather pecking, plumage conditions, skin injuries and performance by either collection of feathers from the pen floor or addition of new feathers that have been collected from the floor with birds of the same genotype. • The effect of genotype on the rate of feather pecking, plumage condition, skin injuries and performance. • The effect of early imprinting to loose feathers from the floor during the rearing period on the incidence of later feather pecking behaviour.
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2 REVIEW OF LITERATURES 2.1 Behavioural biology of the bird (hen) The domestic fowl is derived from the red jungle fowl (Gallus gallus) of southeast Asia (VESTEERGAARD 1994), which still inhabits the jungles of Burma and Thailand, and the domesticated bird can be regarded as a subspecies (G. gallus domesticus). Domestication is thought to have occurred about 8000 years ago, first in India and China, and then along trade routes, probably for sacrifice in religious ceremonies or for cock fighting. Domestic fowl retain much of the biology and behaviour of jungle fowl, although domestic birds employ more energy saving strategies (ITO et al. 1999; SCHÜTZ et al. 2001). Consideration of the ecology and behaviour of jungle fowl is therefore essential for predicting the requirements of the domestic fowl (HAWKINS et al. 2001; FÖLSCH et al. 2002). Several characteristics predisposed jungle fowl to domestication. They are social, which allowed them to be managed in groups. They are promiscuous, which allows any male to be mated with any female and so facilitates artificial selection. Jungle fowl have a hierarchical structure, probably based on individual recognition. Fowl have flexible dietary requirements, being omnivores, and adapt to a wide range of environments. All these traits have been used to advantage in commercial poultry production (APPLEBY et al. 1992). As prey species, jungle fowl and chickens are well designed to detect and avoid predators. They have well developed vision and sensitive hearing, where sight and sound are very important for communication and social recognition. Fowl are highly social and will form groups with stable hierarchies under appropriate conditions (ANONYMOUS 2001). Hens prefer to be with conspecifics (LINDBERG and NICOL 1996), prefer familiar birds to an empty cage and should not be housed in isolation (HAWKINS et al. 2001). Behaviours that are most important for fowl are nesting, perching and using litter for scratching, pecking and dustbathing (FAWC 1997; DUNCAN 1999; OLSSON and KEELING 2000; ANONYMOUS 2001), therefore, fowl should be housed in floor pens large enough to permit all of these behaviours. Domestic fowl show elaborate nest-searching, nest-building and other behaviour before egg laying, which is essentially the same as that of jungle fowl (FÖLSCH 1981). Hens
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are strongly motivated to obtain a suitable nest site (FREIR et al. 1997; FÖLSCH et al. 2002) and become frustrated, stressed and developed stereotypic pacing if deprived of access to one (DUNCAN and WOOD-GUSH 1972). If oviposition is delayed due to failure to find a suitable nest site, retention of the egg in the shell gland often causes deposition of extra calcium on the surface, this gives a dusted appearance. It probably also reduces gaseous exchange through the shell and hence the hatchability of fertile eggs (APPLEBY et al. 1992, 2004). Feral and wild fowl spend a large amount of time perching on branches. OLSSON and KEELING (2000) showed that thwarted access to perches increases frustration and thus reduces the welfare of the hens. Pullets prefer the highest provided perches, indicating that antipredator behaviour still exists despite of domestication (NEWBERRY et al. 2001). Providing perches reduced bird density on the floor, allows subordinate birds to escape dominant individuals, reduces agonistic interactions (CORDINER and SAVORY 2001), improved foot and plumage condition and increased leg bone strength. The beak is the main exploratory organ for the bird. It is well innervated with a collection of touch receptors at the end, which allows birds to peck accurately (GENTLE and BREWARD 1981, 1986). Jungle fowl spent 60,6% of the active part of their day pecking the ground and 34,1 % scratching the ground (DAWKINS 1989). Domestic hens also spend a large proportion of their day on pecking and scratching (HANSEN 1994). Fowl kept on a wire floor or without appropriate pecking substrate may express their motivation to forage by excessive food manipulation with the beak and by feather pecking (GREEN et al. 2000; ANONYMOUS 2001). A dustbathing bout is composed of a sequence of behavioural components (KRUIJT 1964; VESTERGAARD 1982a; van LIERE 1992), at the start of dust bathing the bird pecks, bill-rakes and scratches the ground before eventually squatting in the dust. Then the bird performs the other dustbathing patterns: vertical wing shaking, scratching while laying (during which the dust is thrown into the plumage), head rubbing, side-rubbing and lying on the side. Finally, the bird rises to its feet, raises the feathers, and removes the dust by vigorous shaking movement. Lack of loose material in some systems is often assessed as a welfare problem (VESTERGAARD 1982b; VESTERGAARED et al. 1993) in which birds deprived of loose material might suffer from frustration
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(APPLEBY et al.1993; BAXTER 1994) and stress “respond with increased corticosterone concentration” (VESTERGAARED et al. 1997) Fowl exhibit a number of “comfort behaviours” such as preening, shaking, feather ruffling and leg stretching which are important in artificial conditions as well as in natural conditions for keeping the plumage well groomed and to ensure strong leg bones. It is important to recognise that fowl will synchronise their activities and prefer to carry out specific behaviours together as a flock, so any facilities provided for them should enable them to do this (DUNCAN 1999; ANONYMOUS 2001; CHANNING et al. 2001). Birds possess pain receptors and show aversion to certain stimuli, which can be interpreted as that they experience pain (GENTLE et al.1990; GENTLE 1992). They show fearful behaviour and avoid frightening situations, implying that they experience fear (JONES and FAURE 1982; JONES 1986). They show behaviour indicative of frustration (DUNCAN 1970). These would seem to be part of the “unpleasant emotional states” defined as suffering.
2.2 Function and anatomy of feathers 2.2.1 Definition of feathers Feathers are tough and keratinised in structure that are derived from the epidermis. They distinguish birds from all other animals. Feathers are the most complex of all the structures produced by the epidermis, to which hair and wool are much less complex in comparison.
2.2.2 Function of feathers The feathers protect the skin from injury and the possible harmful effect of sunlight; therefore they are considered as a first line of defence. By trapping air in contact with the skin they act as a very effective coat of insulation to keep the bird worm in cold conditions. Moreover, birds are capable of altering the degree of insulation of feathers by fluffing them out, as is the practice in cold conditions or flattening the feathers against the body as a means of reducing the insulation properties in hot weathers. In many species the colours and sometimes extravagant shapes of feathers are served as an attractive display in courtship and mating rituals. They also act as waterproofing,
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distinguish one species from another and it is possible to separate males from females (sexing) at one day of age in certain strains of poultry through wing feathers examination, also the hackle feathers of the adult male are very distinctive and can be used to differentiate the sex of the bird. A perfect plumage is essential not only for insulation but also for flight and signalling, hence feathers serve as a barometer of general health (DESCHUTTER and LEESON 1986; MIDDLETON 1991; GOUS 1998; LEESON and WALSH 2004; YOUSAF 2005).
2.2.3 Feathers and body surface Contrary to popular belief, the feathers of most birds don’t grow randomly or uniformly over the entire skin surface of birds and about 25% of the birds’ skin is devoid of feathers (LEESON and WALSH 2004), there are in fact very few species in which feathers actually grow from the entire surface of the skin. In poultry, the feathers emerge from definite feather tracts called “pterylae”, which are separated by extensive featherless spaces called “apteria “. There are advantages to birds in not having feathers emerging from the entire body surface. As unfeathered portions would make the bird lighter, consequently, improve its ability to fly. In addition, these unfeathered portions of the skin are used as a method to cool the body effectively (GOUS 1998).
2.2.4 Types and anatomy of feathers Feathers of adult fowl are of six types, namely, contour feathers, plumules, filoplumes, powder feathers, semiplumes and bristles (BESSEI 1988; APPLEBY et al. 1992; GOUS 1998; MORSE 1999), figures (2.1, 2.2 and 2.3). The outer most covering is made up of the contour feathers. These each have a shaft, or rachis, with outer and inner vanes made up of parallel barbs held together by interlocking barbules. Contour feathers cover the body almost completely, even thought they arise only in the pterylae, and they cannot carry out their function perfectly unless they are in first-class- condition.
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Figure 2.1 Structure of flight feather (after MORSE 1999)
Regular preening is important to ensure that separated barbules remains firmly interlocked, distributes sebaceous secretions from the preen gland and helps to rearrange disturbed plumage.
Figure 2.2 Parts of chicken contour feather (after GOUS 1998)
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Beneath the contour feathers are the plumules, which form a soft downy undercoat, which provide particularly effective insulation against the cold weathers. These consist of a short rachis with radiating free barbs and barbules. Semiplumes have a similar structure but are much larger. Bristles lack barbs, are found around the eyes and base of the beak, and have tactile function. Powder feathers produce a white powder, which helps to protect the contour feathers against water. The last type of feather, the filoplume, has a short flexible hair-like rachis with barbs present only at the tip of the feather, which is richly innervated. They are believed to have a sensory system to inform the bird of the general positioning of the body feathers, preening may therefore be initiated from signals produced by the filoplumes.
Figure 2.3 Feather types: Contour feather with aftershaft (a) Bristle (b) Semiplume (c) Down feather (d) Filoplume (e), (after MORSE 1999)
2.2.5 Forms of feathers damage There are three forms of feathers damages (figure 2.4), which depend on the intensity and frequency of feather pecking as well as, the type of feathers pecked (BURCKHARDT et al. 1979). These forms are separation of the vane, cutting of barbs, which are accompanied by the absence of the vane or part of it and broken main shaft.
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C AB
Figure 2. 4 showing a different forms of feather destructions: (A) Separated vane (B) Absence of part of the vane (C) Broken main shaft
2.3 Housing systems The purpose of a poultry house is to confine the birds; to protect them from predators and environmental extremes which would cause mortality or reduce growth, feed efficiency, immunocompetence or egg production; to facilitate light control; and to facilitate bird management (DAGHIR 1995).
2.3.1 Main egg production systems Generally there are two main categories referred to as housing systems for laying hen, cage systems and non-cage systems (alternative housing systems).
2.3.1.1 Cage systems 2.3.1.1.1 Conventional battery cages Intensive battery cages have been commercially manufactured for the housing of laying hens since 1930-31 (WEBSTER 2004). Cages were originally introduced for single laying hens to allow recording of individual egg production and culling of poor layers. Later several birds were placed in each cage, and group size of 3 to 8 are now most
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common. This system consists of rows of metal and wire cages that can be arranged up to 6 tiers. A typical cage measures about 50 cm Χ 50 cm and has a sloping wire mesh floor, but European legislation sets a legal minimum space allowance of 450 cm2 per bird (EEC 1986) until 2002 and 550 cm from 2003 (EEC 1999). This housing system allows more economically beneficial egg production compared with other husbandry practice (APPLEBY et al. 2004 & TAUSON 2005). Conventional battery cages will be banned in the European Union from 2012 in order to improve hen welfare. The welfare problems of laying hens in close confinement and barren environment include the inability to move freely and perform natural behaviours such as, resting, nesting, perching, foraging and dustbathing. It has been found that hens are strongly motivated to perform these behaviours. These conditions cause the birds to experience frustration and social stress, which can lead to feather pecking among other problems. Physical injuries common in the cage systems include: plumage, foot and claw damage and bone weakness.
2.3.1.1.2 Furnished/enriched cages Furnished cages differ from conventional cages in that they provide additional space, nest sites, perches and scratching areas (ALBENTOSA and COOPER 2004). The development of these systems has continued since the 1970s to improve the behavioural repertoire of birds, presenting the get away cages (ELSON 1976; BAREHAM 1976) and modified enriched cages (APPLEBY and HUGHES 1995; ABRAHAMSSON et al. 1995, 1996). In 1996, the Scientific Veterinary Committee of the European Commission concluded that, to retain the advantage of cages and overcome most of the behavioural deficiencies, modified enriched cages are showing good potential in relation to both welfare and production (APPLEBY et al. 2004). In 1999, a directive was passed by the EU ruling that, by 2012 all laying cages shall be enriched providing at least 750 cm2 of floor space per hen, of which 600 cm2 is 45 cm high, a nest box large enough to fit multiple birds, a littered area for pecking and scratching, 15 cm of perch and 12 cm of food trough per hen, floor with a slope of eight degree or less, and a claw-shortening device (abrasive strip).
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2.3.1.2 Non cage systems There is a trend towards large group housing systems for laying hens in Europe, because of public concern for the welfare of the hens in battery cages, (table2.1).
Table 2.1 Development of laying hen flocks in alternative husbandry systems in EU Between 1991 and 2001, data in 1,000 (KOM 2003)
HUSBANDRY SYSTEM Index Year Free-range Percheries Others Total (1991 =100) 1991 3,228 5,179 4,221 12,628 100 1993 5,487 5,817 3,434 14,738 117 1995 6,720 7,504 3,769 17,993 142 1997 9,636 7,624 3,993 21,253 168 1999 13,036 9,059 5,528 27,623 219 2001 16,942 10,641 7,751 35,234 279 Source: world’s poultry science journal 2005.
2.3.1.2.1 The perchery (barn) system In this system hens are kept on a colony basis in sheds, which have raised perches or plat form available. A littered area of flooring is usually provided.
2.3.1.2.2 The deep litter system is also based on colonies, but the birds are kept at floor level. Perches are not provided. The flooring is covered partially with litter, whilst an area of slats or wire mesh is usually located over a droppings pit or manure belt.
2.3.1.2.3 Free range system Hens are kept in percheries or deep litter houses but have access to the outdoor during the day. Free range hens can also be accommodated in relatively small groups in small movable houses.
2.3.1.2.4 Semi-intensive system as free range system but hens are kept with higher stocking density. Commission of the European Communities (1985) introducing detailed rules on certain marketing standards for eggs (table 2.2).
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Table 2.2 Criteria defined by EU trading standards regulations (Commission of the European Communities, 1985) for labelling of eggs
Lable Criteria (a) Free range *Hens have continuous daytime access to open-air runs. *The ground to which hens have access is mainly covered wit vegetation. *The maximum stocking density is not greater than 1000 hens/ha of ground available to the hens or one hen/10 m2. *The interior of the building must satisfy the conditions specified in (c) or (d).
(b) Semi-intensive *Hens have continuous daytime access to open-air runs. *The ground to which hens have access is mainly covered wit vegetation. *The maximum stocking density is not greater than 4000 hens/ha of ground available to the hens or one hen/2.5 m2. *The interior of the building must satisfy the conditions specified in (c) or (d).
(c) Deep litter *The maximum stocking density is not greater than 7 hens/m2 of floor space available to the hens. *At least a third of this floor area is covered with a litter material such as straw, wood shavings, sand or turf. *A sufficient large part of the floor area available to the hens is used for collection of bird droppings. (d) Perchery *The maximum stocking density is not greater than 25 hens/m2 of floor space in that part of the building available to the hens. *The interior of the building is fitted with perches of a length sufficient to ensure that at least 15 cm of perch space for each hen.
Alternative housing systems require considerably more labour input than conventional battery cages, which in turn means their eggs will command higher prices. An assessment of egg production costs from various husbandry systems is given in table 2.3.
2.4 Feather pecking and cannibalism Feather pecking is a form of anomalous behaviour which is common in poultry. It can occur in many species including chicks, adult hens, turkeys, ducks, quail, partridge and
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pheasants and in all ages. The normal exploration and food investigation behaviours of such birds involves pecking, so it is not surprising that in a barren environment they investigate the feathers of other birds in this way (FRASER and BROOM 1990).
Table 2.3 Egg production costs in different systems for laying hens, relative to laying cages with 450 cm2 per bird. Space refers in cages to cage floor area, in houses to house floor area and in extensive systems to land area (ELSON 1985)
System Space Relative cost (%) Laying cage 450 cm2 per bird 100 Laying cage 560 cm2 per bird 105 Laying cage 750 cm2 per bird 115 Laying cage 450 cm2 per bird + perch 100 Laying cage 450 cm2 per bird + perch 100 +nest Get-away cage, two- tier aviary 10-12 birds/m2 115 Aviary 10-12 birds/m2 115 Aviary and perchery and multi-tier housing 20 birds/m2 105-108 Deep litter 7-10 birds/m2 118 Straw yard 3 birds/m2 130 Semi-intensive 1000 birds/ha 135 (140a) Free range 400 birds/ha 150 (170a) aIncludes land rental.
Cannibalism, the pecking of the skin and underlying tissues of another bird (APPPLEPY et al. 1992), followed by the consumption of blood and other tissues of conspecifics, either while they are still alive or after death (CLOUTIER et al. 2002), is a common cause of mortality and culling during the productive life cycle of laying hens that are kept in commercial housing system and, even if a pecked bird survives the attack, the wounds provide a route for infection that may lead to subsequent mortality (RANDALL 1977), where salpingitis and peritonitis are common causes of death (ABRAHAMSSON et al. 1996, 1998). It constitutes an important problem for the egg industry in terms of production and well-being (HUGHES and DUNCAN 1972; APPLEPY et al. 1988). HUGHES and DUNCAN (1972); CUTHBERSTON (1978); CLOUTIER et al. (2000) and McADIE and KEELING (2000) reported that bleeding associated with feather damage during bouts of feather pecking or from damaging pecks to other body parts such as cloaca or toes can elicit cannibalistic attacks. Chicks can learn to associate specific odours with specific colours and tastes (JONES and ROPER 1997). Moreover,
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CLOUTIER et al. (2000) found a positive correlation between feather pecking and cannibalism, and it has been shown experimentally that consumption of blood is socially transmitted (CLOUTIER et al. 2002), and cannibalism may be learned or transmitted from one individual to another (TABLANTE et al. 2000; PÖTZSCH et al. 2001). Many forms of cannibalism occur in domestic fowl, i.e. toe pecking in chicks, feather pulling in older birds from head, tail or body, and vent pecking (KOENE 1998). The latter one, also called cloacal cannibalism, is the one of the most common and severe forms of cannibalism (RIDDELL 1991; APPLEPY et al. 1992; GUNNARSSON et al. 1995) and usually leads to death within a very short period of time (CRAIG and LEE 1990; KEELING 1995). It is often occurring around the onset of lay and may be related to hormonal changes occurring at that time (HUGEHS 1973).
2.4.1 Relationship between feather pecking and cannibalism Feather pecking and cannibalism behaviours are under control of the same motivitional system where, severe feather pecking leads to cannibalism (SCHAIBLE et al. 1947; BESSEI 1983; BLOKHUIS and van Der HAAR 1992; SAVORY and MANN 1997). Contrary, many authors indicated that feather peckers and cannibals are different individuals and that the behaviours are controlled by different motivitional systems. VESTERGAARD (1994) concluded that feather pecking was controlled by the dustbathing system, whereas cannibalism was a kind of redirected feeding, i.e., controlled by the foraging system. Also, KJAER and VESTERGAARD (1999) found that light influenced feather pecking and cannibalism in a different way, as the negative effect of high light level during rearing was seen only for cannibalism but not on the plumage condition during the laying. Furthermore, the results from HOCKING et al. (2004) suggested that the two behaviours are genetically different and that behavioural studies to investigate environmental treatments to decrease cannibalism should differentiate between the two processes.
2.4.2 Types of feather pecking Feather pecking is characterised as pecking behaviour directed towards the plumage of other birds, with feathers being damaged and often pulled out (BILCIK and KEELING
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2000), where its consequences for the recipient depend on the severity of pecking such as the force and velocity of the pecking movement (KJAER 1999). It may cover several forms of pecking and authors used different terms and ways to classify them. It can be divided into two broad categories (KEELING 1994; BILCIK and KEELING 1999), gentle feather pecks are the ones where the feathers are nibbled but not pulled out and the recipient does not usually react, this type of feather pecking is likely to be normal exploratory pecking (HANSEN and BRAASTAD 1994) and, severe feather pecks or feather pulls, usually involves the feather-pecking hen either vigorously pulling at the feathers or removing one or several feathers from the recipient bird. The recipient hen often reacts with a vocalisation, or moves away or retaliates against the feather-pecking hen. Hens can become almost completely denuded as a result of this type of feather pecking. VESTERGAARD (1994) used the term feather pecking only for pecks resulting in feather damage and the terms allopreening and allopecking for other kinds of pecks directed to the feathers of other birds. WOOD-GUSH and ROWLAND (1973) used the term allopecking for occasions when one bird touches another with its peak in a manner that was not obviously aggressive. LEONARD et al. (1995) used the term allopeck for all types of pecks on the other bird and subdivided allopecking into 5 categories: allopreening (light touch, nibbling motion of the bill), light pecking (as previously described but without the nibbling motion), aggressive pecks, pulling (grasping and pulling of feathers) and toe pecks. SAVORY (1995) described five different forms of bird-to-bird pecking: aggressive pecking, gentle feather pecking, severe feather pecking, tissue pecking in denuded area, and vent pecking is aimed at the cloaca. Aggressive pecking is considered to fall into a separate behavioural category which can be easily distinguished from feather pecking (HOFFMEYER 1969) and with a different underlying motivation (VESTERGAARD1994) where, the pecks are directed to the head of another bird in a downward direction and are accompanied by a threat posture and an avoidance response by the recipient (NICOL et al 1999).
2.4.2.1 Relationship between gentle and severe feather pecking Gentle feather pecking is performed by most members in groups of young chicks (WECHSLER et al. 1998) while severe feather pecking is mostly observed at a later age
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(HUBER-EICHER and SEBÖ 2001b), and is performed by only a limited number of group members (BESSEI 1984; KEELING 1994; WECHSLER et al.1998). KJAER (1999) and NICOL et al. (1999) indicated that gentle and severe feather pecking may have a different origin and may be differentially affected by genetic and environmental factors. Gentle feather pecking at an early age does not always predict severe feather pecking at a later age (RODENBURG et al. 2003). However, within a certain age there is a positive correlation between gentle and sever feather pecking (RODENBURG et al. 2003; RIEDSTRA 2003). On the other hand, KJAER and VESTERGAARD (1999) & MCADIE and KEELING (2002) indicated that gentle and severe feather pecking depend on the same underlying mechanisms. High frequencies of gentle pecks are often directed to the same spot of the body of another bird, giving gentle feather pecking a very abnormal and stereotypic appearance, where its occurrence in the young age may subsequently develop into severe feather pecking by either increased intensity or increased severity of inter-bird pecking (McADIE and KEELING 2002). Gentle feather pecking in young chicks is regarded as a part of normal social behaviour, representing social exploration (RIEDSTAR and GROOTHUIS 2002) or allopreening (RIEDSTAR and GROOTHUIS 2002; VESTERGAARD 1994). Thus the relationship between gentle and severe feather pecking is still unclear.
2.4.3 Factors influencing the occurrence and development of feather pecking Feather pecking in layers is a multi-factorial problem, which can result from a complex interaction between the internal state of an animal and its environment (HUGHES and DUNCAN 1972; BLOKHUIS 1989; HUBER-EICHER and AUDIGE 1999; NICOL et al. 2001).
2.4.3.1 Causation of feather pecking A lot of research has been conducted to find the mechanism of development of this behaviour. One hypothesis is that feather pecking is redirected ground pecking behaviour and it might be related to foraging behaviour (HOFFMEYER 1969; WENNRICH 1975; BLOKHUIS and ARKES 1984, HUBER-EICHER and WECHSLER 1998).
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The second hypothesis considered feather pecking to be result of an abnormal development of perceptual mechanism responsible for detection of substrates for dust bathing (VESTERGAARD et al. 1993). It may be that the cause of the development of feather pecking is multifactorial (SAVORY and MANN 1997) and that the two hypotheses have features in common and are not mutually exclusive (SAVORY 1995; VESTERGAARD 1994). The third hypothesis (RIEDSTRA and GROOTHUIS 2002, 2004) argued that gentle feather pecking at an early age plays an important role in the development (social exploration) and maintenance of social relationships between chicks. The fourth hypothesis suggests that feather pecking is a socially transmitted behaviour (ZELTNER et al.2000), as introduction of chickens that showed high frequencies of feather pecking into a group of naive chicken, results in a higher incidence of feather pecking in these groups than in the control groups, thus showing that feather pecking behaviour may be spread by social interactions between chickens. In the same trend (CLOUTIER et al. 2002; McADIE and KEELING 2002) suggested that social learning might to be involved in the spread of feather pecking and cannibalism. Recent studies have underlined the role of feather eating in the development of feather pecking in laying hens (MCKEEGAN and SAVORY 1999, 2001; HARLANDER- MATAUSCHEK and BESSEI 2004, 2005). MCKEEGAN and SAVORY (1999) suggested that feather pecking develops as a consequence of feather eating. The presence of loose feathers on the floor may lead to feather eating in some birds. If there are no suitable feathers on the floor, attention may be redirected towards the feathers of conspecifics.
2.4.3.2 External factors A- Diet and feed composition / texture It has been suggested that feather pecking caused by nutritional deficiencies in certain components, i.e. inadequate levels of amino acids (methionine, arginine), dietary fibre (SIREN 1963; HUGEHS 1982; WALSTRÖM et al. 1998), sodium chloride (HUGHES and DUNCAN 1972), sodium deficiency increased pecking to objects in the environment (WOOD-GUSH and HUGHES 1973) and conspecifics (HUGHES and WHITEHEAD 1979). Low level of protein in the diet increases the risk of feather
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pecking and cannibalism, because feathers serve as compensatory source of nutrient deficient food (CAIN et al. 1984; AMBROSEN and PETERSEN 1997). An outbreak of feather pecking and cannibalism has been reported after change in dietary protein source from mainly animal to mainly plant (CURTIS and MARSH 1992). However, SAVORY et al. (1999) and MCKEEGAN et al. (2001) did not find any significant effect of different protein sources on feather pecking. SAVORY et. al (1999) and van HIERDEN et al. (2004) reported a suppression of feather pecking damage with a dietary supplementation with higher doses of the essential amino acid L-tryptophan. Feather pecking is possibly related to food consistence. JENSEN et al. (1962); SAVORY (1974); APPLEBY and HUGHES (1991); HUBER-EICHER and WECHSLER (1998); AERNI et al. (2000); EL-LETHY et al. (2000) & VAN KRIMPEN et al. (2005) reported that FP damage is more common when hens are fed on pellets rather than on mash, as time spent on feeding is reduced with pelleted food. In the line with this hypothesis, BEARSE et al. (1949) and WALSER (1997) reported a greater tendency for feather pecking with pelleted food in growing pullets and adult laying hens respectively. However, SAVORY and MANN (1997) found no significant effect of the food form on feather pecking in pullets kept in pens with litter-covered floors.
B- Housing condition Several factors are known to promote the development of feather pecking in laying hens, such as housing conditions during the rearing period with a stocking density > 10 birds per m2 and having no access to elevated perches (WECHSLER and HUBER- EICHER 1998; HUBER-EICHER and AUDIGE 1999). FP is promoted in housing condition that restricted in relation to foraging materials (HUGHES and DUNCAN 1972; SIMONSEN et al. 1980; BLOKHUIS 1989; AERNI et al. 2000; HUBER- EICHER and SEBÖ 2001a).
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C- Environmental and management factors As the occurrence of feather pecking is not only restricted to the laying period but can be also observed in growers as well there are other factors influencing this behaviour such as: 1) light intensity. It is generally agreed that an increase in the brightness of the light increases the level of feather pecking (HUGHES and DUNCAN 1972; ALLEN and PERRY 1975; KJAER and VESTERGAARD 1999). SCHUMAIER et al. (1968) found a relation between wavelength of the light and the occurrence of cannibalism. In red light, cannibalism was completely absent, 2) high stocking density; QUART and ADAMS (1982); APPPLEPY et al. (1988) & SAVORY et al. (1999), 3) large group sizes; HUGHES and DUNCAN (1972) & BILCIK and KEELING (1999). It may also be due to physical effects, as crowding leads to a restriction in movement (APPLEBY et al.1992), 4) GREEN et al. (2000) reported additional risk factors: a) less than 50% of the birds from a flock using the outdoor run, b) diet being changed three or more times during lay, c) inspection done by one person, d) no loose litter being left by the end of lay, e) hen house temperature being less than 20 °C, f) light turned up when the flock was inspected and g) bill drinker were used. However, GUNNARSSON et al. (1999) did not find significant relations between housing factors and feather pecking.
D- Physical appearance The physical appearance is thought to play a role in feather pecking and cannibalism. YNGVESSON and KEELING (2001) observed that cannibalistic hens are generally heavier and taller than the rest of the flock, and both cannibals and victims were less symmetrical in bilateral morphological traits than control hens. KJAER et al. (2001) showed a correlation between body weight and feather pecking behaviour. However, HUGHES and DUNCAN (1972); KJAER and SORENNSEN (1997); BESSEI et al. (1999)& RODENBURG et. al (2004) found a negative correlation between body weight and pecking. McADIE and KEELING (2000) suggested that hens with damaged feathers became an attractive target for feather-pecking behaviour and were more susceptible to further pecking and injurious pecking than hens with undamaged feathers.
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2.4.3.3 Internal factors A- Genetic variations Many studies found a large variation in feather pecking behaviour between lines and family groups of laying hens (HUGHES and DUNCAN 1972; CUTHBERTSON 1980; QUART and ADAMS 1982; CRAIG and LEE 1990; BLOKHUIS and BEUVING 1993; KJAER and SORENSEN 1997; KJEAR 2000; KLEIN et al. 2000; RODENBURG et al. 2003; HOCKING et al. 2004) and in plumage condition (AMBROSEN and PETERSEN 1997; WAHLSTÖRM et al. 2001). These results indicate that there is a genetic basis for feather pecking behaviour. Beside strain differences in the rate of feather pecking, there are also individual differences. Indeed, only a small proportion of birds in the flock were responsible for the most feather damage (BESSEI 1984; WECHSLER et al.1998; BILCIK and KEELING 2000). SU et al. (2005) suggested that genetic selection could be a useful tool in minimizing feather pecking behaviour in commercial stocks of laying hens. Divergent selection on feather pecking behaviour has been shown to be feasible using direct observations (KJEAR et al. 2001), where hens were selected for feather pecking (high pecking line) and against FP (low pecking line) based on number of bouts performed. Group selection (CRAIG and MUIR 1993) resulted in reduced mortality due to “beak-inflicted injuries” causing feather pecking and cannibalism after one generation of selection, and mortality greatly reduced after 6 generations of selection (MUIR 1996). BUITENHUIS et al. (2003) reported that, QTL (Quantitative Trait Loci) were detected for severe FP, gentle FP and cortisone response. FP behaviour at 6 weeks of age is regulated by different genes than FP at 30 weeks of age. Furthermore, the results open the possibility to reduce the FP problem and improve animal welfare using molecular genetics.
B- Hormonal state The increase in feather pecking around the onset of lay is hormonally mediated (HUGHES 1973) and can either be stimulated by administering a combination of oestrogen and progesterone or be blocked by giving testosterone. CUTHBERTSON
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(1978) found that, testosterone in low doses decreases feather pecking, whereas in high doses as well as in a combination with estradiol, increased feather damage.
C- Neurotransmitters Feather pecking behaviour seems to be triggered by low serotonergic neurotransmission, because increasing serotonergic tone (higher levels of tryptophan) decrease feather pecking behaviour (van HIERDEN et al. 2004). KJEAR et al. (2004) found that feather pecking was significantly reduced by the treatment with the dopamine D2 receptor antagonist haloperidol, while aggressive pecking was not affected by this treatment. KOSTAL et al. (2003) found that apomorphine stimulated floor pecking in both adult peckers and non peckers, and suppressed gentle, severe and aggressive feather pecking in peckers only.
D- Fear and stress VESTERGAARD et al. (1993) & JOHNSEN et al. (1998) suggested that feather pecking is more likely to be initiated by fearful birds. Observations in an open- field test show that laying hens that were more fearful and less social as young pullets showed higher levels of feather pecking as adult hens (RODENBURG et al. 2004). However, most studies indicate that fearfulness is a consequence of feather pecking induced by feather damage and pain (HANSEN and BRAASTAD 1994; JONES and HOCKING 1999). In addition, several studies have shown that FP in laying hens is associated with stress “indicated by increased hormone level or high heterophil / lymphocyte ratio” (VESTERGAARD et al. 1997; EL-LETHEY et al. 2000, 2001; CAMPO et 2001)
E- Imprinting It has been suggested that feather pecking is influenced by the imprinting of chicks on inferior dustbathing substrates such as feathers and straw early in life (VESTERGAARD and LISBORG 1993; VESTERGAARD 1994; SANOTRA et al. 1995).
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F- Neonatal RIEDSTRA and GROOTHUIS (2004) found that light-exposed chicks in the last week of incubation showed more feather pecking than did their dark-incubated cagemates at least during the first three weeks after hatching. Dark–incubated chicks preferred to direct feather pecks to unfamiliar peers than to familiar peers, but light-exposed chicks showed no preference. They suggested that it might be worthwhile not to expose embryos to light during the last week of incubation to reduce feather pecking when housing hatchlings in commercial condition.
2.4.4 Control of feather pecking The most common and cost effective method of prevention the serious effect of severe feather pecks is the use of beak trimming which reduces feather pulling and pecking, reduces cannibalism, improves feather condition, improves liveability and causes less nervousness, fearfulness, and chronic stress (GENTLE 1986; HUGHES and GENTLE 1995; HESTER and SHEA-MOORE 2003; DAVIS et al. 2004; AERNI et al. 2005). The procedure is carried out without an anaesthetic and involves partial amputation of the beak which is usually done with an electrical debeaking machine. There is behavioural and neurological evidence that it can cause both acute and chronic pain presumably due to neuromas (DUNCAN et al. 1989; GENTLE et al. 1990; GLATZ et al. 1992; WEBSTER 2004). Recent studies showed that neuroma development could be prevented when debeaking is carried out at an early age (1-10 days) (GENTLE et al. 1997; HESTER 2005). Beak trimming will not eliminate the abnormal behaviour entirely but the birds are less able to inflict damage. Feather pecking is also reduced by keeping birds under dim light (1 lux or less) but this practice of vision impairment can cause eye abnormalities and inhibit activity (NEWBERRY et al. 1988). In laying hens low activity is associated with osteopenia and a high risk of bone breakage during pre slaughter handling (NEWBERRY et al. 1999). Indeed, because birds cannot see each other as well at lower light intensities, antagonistic encounters and aggressive behaviour are minimized in pullets and egg laying flocks (GLATZ 2000). Low light levels during rearing impairs the birds’ ability to identify environmental cues and consequently increases exploratory pecking in order to compensate (D` EATH and STONE 1999).
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Provision of an inanimate stimulus (string device) that attracted and sustained pecking interest might not only enrich the birds’ environment but it may also divert potential injurious pecking away from their flockmates. JONES et al. (2002) found that the string devices were pecked significantly more than other hens, including whose feathers had been trimmed in order to elicit FP (McADIE and KEELING 2000). Indeed, FP was reduced in chickens from a genetic line showing high rates of this behaviour when string devices were incorporated in their cages. Furthermore, the provision of strings from one day of age or from the birds’ transfer from rearing to laying cages at 16 weeks reduced the amount of pecking-related feather damage recorded at 30 weeks of age (BLOKHUIS et al. 2001). Also, McADIE et al. (2005) concluded that the addition of a simple string devices to the pens of non-beak-trimmed high feather pecking birds decreased feather pecking behaviour, and to the cages of non-beak trimmed commercial layers significantly improved feather condition. The dark brooders separated active chicks from inactive chicks, whereby the risk of developing severe feather pecking was reduced due to an impediment of misimprinting on feathers as either food or dust. JENSEN et al. (2006) suggested that the provision of dark brooders has a long-lasting effect on the frequency of feather pecking and cannibalistic attacks, resulting in reduced mortality and an improved condition of both plumage and skin. JOHNSEN and KRISTENSEN (2001) found a significant lower frequency of severe feather pecking in the groups provided with dark brooder during the first 3 weeks of life compared to light brooders groups. Exposing chickens to litter early in early life would prevent them from perceiving feathers as a substrate for either foraging (BLOKHUIS 1986) or dust-bathing (VESTERGAARD et al. 1993), and subsequently reduces later tendencies to engage in feather pecking (NORGAARD-NIELSEN et al. 1993; HUBER-EICHER and WECHSLER 1997; NICOL et al. 2001). It is therefore advisable to offer chicks access to litter from day one on (HUBER-EICHER and SEBÖ 2001a). If straw is provided as litter substrate, special attention should be paid to its form, as long-cut straw is more efficient in reducing feather pecking than straw in shredded form (WECHSLER and HUBER-EICHER 1998). Several studies have found that lower stocking density during rearing results in less feather pecking (HUBER-EICHER and AUDIGE 1999), as well as the combination of
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lower stocking density and smaller group size (NICOL et al. 1999; SAVORY et al. 1999). High perches prevent feather damage at least during the rearing period (WECHSLER and HUBER-EICHER 1998). Grain scattered on the floor as pecking incentives during rearing period (BLOKHUIS and van DER HAAR 1992), mash diet instead of crumbles or pellets (AERNI et al. 2000; EL-LETHY et al.2000; VAN KRIMPEN et al. 2005) and feeding roughages (STEENFELDT et al., 2001; VAN KRIMPEN et al., 2005) may also reduce feather pecking. Several studies have shown that the use of the outdoor run and access to grass vegetation resulted in low incidences of FP (von BORELL et al. 2002; BESTMAN and WAGENAAR 2003; NICOL et al. 2003; MAHBOUB et al. 2004). The use of range was positively associated with the presence of trees and/or hedges on the range. NICOL et al. (2003) found that the risk of developing feather pecking was reduced 9-fold if more than 20% of the birds used their outdoor area on sunny days.
2.5 Behaviour patterns related to feather pecking 2.5.1 Dustbathing behaviour Dustbathing is a notable form of body care, which is environmental based, through which the bird is able to apply attention widely to the body including plumage inaccessible to the beak by friction against a suitable substratum (FRASER and BROOM 1990). Dustbathing occurs most often in housing system with loose material. However it can also occur in a “sham or vacuum” form in which the bird carries out the same actions on slats or wire, although more briefly (VESTERGAARD 1980; BAXTER 1994; CRAIG and SAWNSON 1994), which causes further damage to their feathers (SIMONSEN et al. 1980). Dustbathing functions to remove old stale uropyial gland oil from the plumage and thereby improve feather and downy structure and consequently enhance the insulation capacity of the plumage (BORCHELT and DUNCAN 1974; van LIERE and BOKMA 1987; van LIERE and SIARD 1991). However, dustbathing occurs in featherless birds and in birds whose oil gland had been removed (NORGAARD-NIELSEN and VESTERGAARD 1981; VESTERGAARD et al. 1999). Therefore, HOGAN (1988)
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suggested to view dust bathing as a behaviour system, which is an organization of perceptual, central and motor mechanisms that acts as a unit in some situations. A major function of dustbathing is thought to remove ectoprasites, either by dislodged of the parasites or influence the parasite loads if stale feather lipids attract parasites. Because dustbathing involves rotational and pushing motions of the legs, it could be a form of exercise that improves the leg condition in broilers (SHIELDS et al. 2004). In the fowl the perceptual mechanism of the dust system is not fully developed at hatching and is dependent on experience (VESTERGAARD et al. 1990; HOGAN et al. 1991). The young chick obtains experience by pecking (BORGHELT and OVERMANN 1975), bill raking and scratching at a substrate for dustbathing. Accordingly, there is a possibility that during the development of dustbathing behaviour chicks may form inappropriate stimulus-response association (VESTERGAARD and LISBORG 1993). In the absence of appropriate stimuli during the development of dustbathing behaviour, chicks may come to treat feathers as dust (VESTERGAARD and HOGAN 1992), and these birds peck, bill-rake and scratch their penmates before squatting on the floor and performing other patterns of dustbathing. This sequence of events is similar to that of normal dustbathing behaviour and, therefore the birds that pecked feathers had learnt to associate feathers with dustbathing during early development (VESTERGAARD and LISBORG 1993). There is a sensitive period very early in life (3 days) for the association to be formed (VESTERGAARD and BARANYIOVA 1996). HUBER- EICHER and WECHSLER (1997) found that provision of sand from day 10 on did not prevent the development of high rates of feather pecking and was too late to prevent chicks from becoming “ mis-imprinted” on feathers as a substrate for pecking and dustbathing behaviour. Therefore, access of sand from day 1 of life resulted in less feather pecking than access to sand from day 10. The imprinting process is relevant to the feather pecking problem in domestic fowl since early dust-imprinting treatment of domestic chicks may reduce feather pecking later in life and the proper early experience is essential (JOHNSEN et al. 1998). Moreover, chicks to some extent choose to dustbath on the substrate that was available to them during early development even they had access to a more suitable substrate such as sand (VESTERGAARD and LISBORG 1993; JOHNSEN and VESTERGAARD
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1996). However, NICOL et al. (2001) reported that the adult hen behaviour is flexible and that it can be strongly influenced by the nature of the current substrate. Adult fowl generally dustbath only every other day and a dustbath lasts for an average of 27 minutes. Young and adult chickens prefer peat to sand both for dust bathing and early pecking, and sand to straw, wood-shavings, and feathers (PETHERICK and DUNCAN 1989; SANOTRA et al.1995; VESTERGAARD and BARANYIOVA 1996; VESTERGAARD and BILDSOE 1999). ODEN et al. (2002) reported that there were significantly more birds dustbathing when the litter was of good quality and contained loose material.
2.5.2 Foraging behaviour When litter is available, hens use it intensively for scratching and pecking (report of the EUROPEAN COMMISSION, 1996, p.35). Exploration and foraging is an important behaviour for fowl, by which they choose materials and spend significant amounts of time interacting with it. The birds use their beaks like a sensitive hand to explore and manipulate objectives as well as to find food to eat. In the most common form, chickens scratch with both feet then move quickly backwards, pecking at any thing edible exposed by the scratching such as seeds, insects, including small stones they ingest to grind up the food in their gizzard (APPLEBY et al. 1993; HUGHES and CHANNING 1998; ROGERS 1995). Pecking is a precise, high-tech activity, requiring good coordination with the eye. In natural conditions chickens spend between half and 90% of their time foraging, making up to 15,000 pecks a day (TURNER 2003). In strawyards, 47% of the birds’ time was spent for feeding and foraging (APPLEBY and HUGHES 1991). AERNI et al. (2000) suggested that birds fed on mash used the food not only for feeding but also as a substrate for foraging, and when chicks were deprived of access to long-cut straw as foraging substrate, they reduced the time spent foraging but increased the time spent at the food trough without an increase in body-weight (El-LETHEY et al. 2000). Motivation for foraging behaviour appears to be high. Chickens scratch while feeding even if feeding is freely available in a metal trough and they forage even they don’t need to do so in order to get food (DUNCAN and HUGHES 1972; NICOL and DAWKINS 1990). That leads to the conclusion that pecking in association with food is
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so much part of the natural feeding behaviour of hens that they seem to need to peck and scratch even if they are not hungry at all (NICOL and DAWKINS 1990). When giving the choice, they strongly prefer litter to a wire floor (FAWC, 1997). BLOKHUIS and van DER HAAR (1992) showed that foraging-related behaviour, such as scratching and pecking, is apparently influenced by experiences during rearing. If there is edible matter in the substrate, pecking and scratching are considerably increased. It is also common to scatter some grain in deep litter houses and strawyards to enhance foraging, to keep the litter in good condition (BLOKHUIS and van DER HAAR 1992; AERNI et al. 2000; APPLEBY et al. 2004) and to keep feet and claws in better condition, as hens on litter have less foot damage and fewer over grown or broken claws than hens on wire (SIMONSEN et al. 1980; APPLEBY 1991). HUBER-EICHER and WECHSLER (1998) found that foraging activity depend on the quality and the availability of the foraging materials. Therefore, they suggested that chicks should be provided not only with litter but also with materials that elicit a variety of elements of foraging behaviour, and it may be also necessary to alter the quality of the materials offered during the rearing period, as chicks’ ability to act on foraging material changes during their development. The development of feather pecking is not only genetically influenced (HUGHES and DUNCAN 1972; BESSEI 1984; WALSER 1997; KJAER and SORENSEN 1997), but there are also genetically determined differences in the quality of the foraging behaviour (KLEIN et al. 2000). However, the housing conditions may have a stronger influence on foraging behaviour and the development of feather pecking than the genetic aspect. WECHSLER and HUBER-EICHER (1998) & JOHNSEN et al. (1998) found that most aggression and feather pecking occurred on the litter when chicks are crowded, since crowding inhibits the chicks from pecking and having visual contact with the litter material available to them, and the litter area become insufficient for the hens to show their preferred spacing during foraging (ODEN et al. 2002). Ground pecking or foraging behaviour when litter is provided reduces feather pecking (BAXTER 1994), as there is an inverse relationship between the time the birds spend on exploratory and manipulative foraging behaviour away from the feeder and the rate of feather pecking (HOFFMEYER 1969; WENNRICH 1975; BLOKHUIS 1986; HUBER- EICHER and WECHSLER 1997, 1998). Provision of non nutritive foraging material
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such as long straw and polystyrene blocks is effective in both preventing and reducing feather pecking behaviour by chicks. In addition, hens provided with foraging material show significantly lower rates of feather pecking than those kept without foraging material (HUBER-EICHER and WECHSLER 1998). Hens use also the dust bath for foraging (pecking and scratching) in addition to dust bathing (APPLEBY et al. 1993).
2.6 (Some experiments related to) Feather function and feather pecking 2.6.1 Effect of feathers manipulation on the incidence of feather pecking and cannibalism McADIE and KEELING (2000) suggested that hens with damaged feathers received more feather pecks than hens with undamaged feathers. In addition, damaged feathers encouraged more feather pecking than undamaged ones on the same body area, where the most preferred target for sever feather pecks being that the tail when the feathers were cut very short, followed equally by the rump which had feathers trimmed or the rump when feathers were only removed. The most preferred area for gentle feather pecks was the rump which had feathers removed. Moreover, cannibalistic attacks were directed to body areas where the feathers had been damaged, in particular to the rump when feathers were removed and cut and when the rump feathers were only removed. The authors suggested that manipulating the feathers of hens has two consequences: 1) feather pecking is directed toward the damaged feathers and the greater the damage done to the feathers, the greater the attractiveness of those feathers to feather peckers. 2) bare skin seems to elicit cannibalistic attacks. It is possible therefore that once feather pecking occurs in a flock, it becomes a cumulatively serious problem especially if the damage attracts the interest of hens that had not previously shown feather pecking. Feather pecking can spread through a flock if there is at least one hen that starts to damage feathers (McADIE and KEELING 2000)
2.6.2 Feathers as a substrate for dust bathing VESTEERGAARD and HOGAN (1992) reported that some red jungle fowl chicks could be trained to dustbath on feathers. Chicks that were trained on feathers performed
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less dustbathing during training than conspecifics that were trained on black or white sand. VESTERGAARD and LISBORG (1993) tested a model which explains feather pecking development as a process by which feathers become treated as a substrate for dust bathing, where chicks kept in wire floored cages were trained from day 3 of life to dust bath during a one hour daily training session on either a skin with feathers or on sand. They reported that by day 25-26 dustbathing was as frequent during training in feather trained chicks as in sand trained chicks. However, feather trained chicks pecked and scratched less. Sand trained chicks came to treat sand as a dustbathing substrate as well as substrate for exploration. Feather trained chicks came to treat feathers as dust bathing substrate. The result indicated that feathers are a weak stimulus not only for dustbathing but also for pecking. It is therefore most likely that the absence of dust during early development leads to the use of feathers as dustbathing substrate and thereby feather pecking. When feathers and sand are presented simultaneously feather trained chicks increased their pecking and scratching, where they pecked and scratched the sand as frequent as sand trained chicks. However, they pecked significantly more at feathers than the sand trained chicks and on average still performed 52 % of their dust bathing on feathers. On contrary, sand trained chicks never performed dustbathing on feathers and experience with feathers did not result in significant changes in any of the behaviours. The authors suggested that an association between dustbathing and feather pecking might be prevented by an early formation of a strong association between dust bathing and attractive stimuli like sand and peat.
2.6.3 Feather eating and its role in the aetiology of feather pecking damage Feather eating has been observed in both commercial layer (SAVORY and MANN 1997; MCKEEGAN and SAVORY 1999) and bantam (SAVORY and GRIFFITHS 1997) strains of domestic fowl. MCKEEGAN and SAVORY (1999) suggested that feather eating in the domestic fowl is a form of pica (consumption of non-nutritive material with non apparent function). Granivorous species does not possess the ability to break down keratin in the digestive tract and therefore feathers cannot have any nutritive value. However, the result of
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HARLANDER-MATAUSCHEK et al. (2006) show that feathers increase the speed of feed passage and, in this regard, show similar effects to insoluble fiber. Insoluble fiber stimulates peristaltic activity and hastens feed passage through the digestive tract (KROGDAHL 1986). SAVORY and MANN (1997), suggested a role for feather eating in the development of feather pecking, although no definite link was shown. On the other hand, MCKEEGAN and SAVORY (1999) found a strong association between levels of feather eating and damaging pecking. Depletion of loose feathers on the pen floor and presence of feather material in faecal droppings (up to 48 % which are indicates feather eating) were closely related to plumage damage scores in growing pullets leading to the suggestion that feather eating may have a role in the development of damaging pecking. Feathers were seen to be eaten in many situations. But, feather eating was rarely observed directly. Eating feathers from the pen floor (litter) was most common, accounting to 38% of the observed feather eating events. Thirty four percent of eaten feathers were caught in air, while 19 % were removed from other birds. Other sources of eaten feathers accounting between 1% and 5% of the total (MCKEEGAN and SAVORY 1999).
2.6.3.1 Relationship between feather eating, feather pecking and feather attractiveness The propensity of individually caged laying hens of two selected lines known as „pecker or non pecker”, to eat feathers, in which they were offered fresh semiplumes 4- 6 cm (length) plucked from freshly dead birds of the same genetic line, one at a time, in front of their cages indicated that peckers ate, picked-up and manipulated feathers significantly more often than did non peckers (p <0.05, p <0.01, and p <0.01 respectively) (MCKEEGAN and SAVORY 2001). This suggests that peckers may be responsible for the majority of feather eating as well as feather pecking. This result is in agreement with others from HARLANDER-MATAUSCHEK and BESSEI (2005)& HARLANDER-MATAUSCHEK et al. (2006). MCKEEGAN and SAVORY (2001) reported from a choice test with washed (with 70 % ethanol to remove preen oil) and unwashed semiplumes presented simultaneously in separate containers: Unwashed feathers were eaten, pecked and pecked up in preference
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to washed feathers by both peckers and non peckers. This indicates attractiveness to unwashed feathers or avoidance of washed feathers, as hens could distinguish between normal feathers and those treated in such a way as to alter their olfactory (but not visual) properties, suggesting olfactory cues may be of importance in determining the attractiveness of conspecific feathers. SANDILANDS et al. (2004) reported that lipid found on the plumage most likely arises from a combination of preen gland and sebaceous secretion. The olfactory and gustatory cues given off by a mixture of these lipids may have implications for whether or not a bird is feather pecked.
2.6.4 Demand of laying hens for straw and feathers as litter substrates GUNNARSSON et al. (2000) investigated the value of straw and feathers for laying hens that had been reared with access to grass and earth mixed with sand, but not given any intense and specific exposure to either straw or feathers previously by measuring demand functions for these items. They found that the mean elasticities of the demand were significantly different from zero (–0.48 (s.e 0.04; p <0.001) for straw and –45 (s.e 0.05; p <0.001) for feathers), as all of the laying hens worked for straw and the demand was reasonably high and the straw was used for pecking and scratching but not for dustbathing. Three out of five birds would work for feathers and their demand was strong. This means that some of the hens place a relatively high value on feathers and that others place no value on them. However, neither straw nor feathers stimulated dustbathing, and the provision of other materials may be better for the bird’s physical health in the long term as dust bathing is important for maintenance of a good plumage quality (van LIERE 1992). However, the results imply that even if a substrate does not stimulate dust bathing, caged hens have a high demand for a litter substrate (GUNNARSSON et al. 2000).
2.6.5 Pecking at feather bunches Pecking directed at bunches of feathers of an individually tested caged bird is thought to be a useful indicator of the tendency to perform feather pecking in a homepen (BESSEI et al. 1997, 1999). However, a negative relationship was recorded (RODENBURG and KOENE 2000).
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BESSEI (1986) & ALBENTOSA et al. (2003b) indicated that there is a difference between strains in terms of tendency to peck at feather bundle. There is evidence that the age at the testing is an important factor. Pecking at the feather bunch was very low at 2 weeks of age, increased at 6 weeks and reached at 14 weeks of age high levels that were subsequently sustained. This finding might reflect: 1) reduced fear and avoidance of the initially unfamiliar feather bunch with repeated exposure, 2) a developmental elevation of the birds’ motivation to peck at feathers, 3) a greater interest in the pecking device or a combination of all three factors (HOCKING et al. 2001). Also, ALBENTOSA et al. (2003b) found a decrease in pecking at fixed feather bundles when ISA Brown were tested at 11 to 13 weeks and 25 to 27 weeks of age. In the same line, CLOUTIER et al. (2000) reported that adult hens showed a relatively low response to the inanimate stimuli. RODENBURG and KOENE (2003) concluded that gentle and severe feather pecking and bunch pecking in a social test (i.e., 5 birds from one group were caught from their homepen and were transferred to the testing pen) corresponded best to feather pecking in the home pen, whereas bunch pecking in the individual context did not. However, CLOUTIER et al. (2000) & ALBENTOSA et al. (2003a) found no significant correlation between the frequency of pecking at the inanimate stimuli (bundle of feather) and the frequencies of pecking at the feathers of flock mates. Birds showed a clear preference for pecking bunches of straw over feathers (ALBENTOSA et al. 2003 a; HUBER-EICHER and WECHSLER 1997). JONES et al. (1997, 2000) & JONES and CARMICHAEL (1998) found that chicks pecked sooner and more often at lengths of yellow strings than at bunches of feathers, and white or yellow strings were preferred to red, green or blue ones or to combinations of colours. Static devices were more attractive than those that were periodically moved (JONES et al. 2000; JONES 2001). CLOUTIER et al. (2000) found that severe pecks in caged White Leghorn hens were directed more frequently at feathers than paper stimuli and at movable than stationary stimuli, but there was dispriminant response to red and blue stimuli. By contrast, YNGVESSON and KEELING (1998) reported that adult hens pecked blood-stained feathers more frequently than unstained feathers in a preference test.
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2.6.6 Demand of laying hens for feathers and wood shavings HARLANDER-MATAUSCHEK et al. (2006) used the operant conditioning technique to investigate the birds demand for feathers compared to their demand for food and litter and to evaluate if high feather pecking birds (HFP) find feathers and wood shavings more reinforcing than low feather pecking birds (LFP). They noted that both lines achieved the highest maximum price with feed as a reinforcement followed by wood shavings and feathers. Both lines found feathers and wood shaving reinforcing when presented as a food component. HFP birds paid a higher price to gain access to feathers, wood shavings and an empty feeder in the Skinner box. These results imply that the birds had a demand for feathers and wood shavings but these demands for feathers were significantly higher in HFP birds.
2.7 Fear Fear is an emotional state raised from an aversive stimulus leading to behavioural and physiological changes that assist an animal to cope with that stimulus (MOBERG 1985). Tonic immobility (TI) is an unlearned catatonic state of reduced responsiveness, which may last from a few minutes to several hours (NASH and GALLUP 1976). TI is used as a method of estimating fearfulness as it is considered to be positively related to fear (JONES 1986). Although TI has been demonstrated in many species such as insects, reptiles, amphibians, birds and mammals (RANTER 1977), the chicken has been the most commonly tested which gives a particularly robust reaction. There are strain (NASH and GALLUP 1976; NASH 1978; JONES and FAUER 1981) and genetic differences in the duration of TI have been reported in numerous studies comparing lines of laying hens (CRAIG et al 1993; CAMPO and REDONDO 1996; HOCKING et al. 2001). The response has been induced using various methods and substrates including an induction box (NASH and GALLUP 1976), a table (GALLUP et al. 1976) and cloth (BRAUD and GINSBURG 1973). JONES and FAUER (1981) strongly recommended the use of cradles and clothes for studies of tonic immobility particularly when dorsal restraint is used.
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TI reaction may have two stages. The first state is one of inhibition, it is characterised by complete immobility and lasts from induction until the first head movement. The bird is alert during the second stage and makes several head movements before righting itself. Therefore, it would be more appropriate to speak in terms of “righting time” and the term TI applies only for the first stage (JONES and FAUER 1981). The duration of TI is thought to be positively related to underlying fearfulness (GALLUP 1979; BOISSY 1995; JONES 1986, 1996). A long duration of TI is thought to be indicative of high level of fearfulness, and vice versa. SCOTT and MORAN (1992, 1993 a, b) reported that manual handling is frightening to the birds. Thereby, the duration of TI could be affected by the quality and the duration of manual handling prior to the TI treatment. The rougher the handling, the greater the duration of TI (JONES 1992). TI is sensitive to repeated testing: For example, the duration of TI decreased significantly when hens received daily trial for 7 consecutive days (GENTLE et al. 1985; NASH and GALLUP 1976) There is evidence that fear and feather pecking may be positively associated. HUGHES and DUNCAN (1972); CRAIG et al (1983) & JOHNSEN et al (1998) found that birds with the least pecking damage had the lowest fear score whereas the severely pecked hens were the most fearful. On the other hand, KEELING (1994) and JONES et al. (1995) did not find a significant relation between fear and feather pecking. CAMPO et al. (2001) found in five Spanish breeds of chickens that very poorly feathered hens showed shorter TI and were less fearful than hens with a perfect plumage.
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3 ANIMALS, MATERIAL AND METHODS 3.1 Birds and housing 3.1.1 Rearing period (0-16 weeks of age) Two experiments (experiment 1 and experiment 2) were carried out. In the first experiment, two genotypes of non beak-trimmed chicks were used, 180 Lohman Tradition (LT brown) and 180 Lohman Silver (LS white). All chicks arrived on the day of hatching and were immediately distributed into 6 groups (three groups for each genotype of 60 chicks). They were reared on traditional deep litter with long straw at a stocking density of 6.4 birds per m2. Care was taken that both genotypes arrived at the pens at the same time and that the duration of transport was the same for both. For the first 6 days, chicks had access only to an area of 150 x 130 cm nearest to the corridor, separated from the rest of the pen by a metal barrier (height 25 cm) and water was provided in a bowl (24 x 10 cm). This ensured that they stayed close to feed, water and extra heat. Additional feed was offered on a sheet of cardboard (30 x 15 cm) beside the feeder for the first 2 days after introduction. Temperature in the pen was 34 – 35 °C at the time of arrival of chicks then decreased gradually 2 °C every week and then fixed at 18 – 20 °C from 6 weeks of age for the rest of the experiment. The birds in each group had ad libitum access to a commercial starter and developer feed from 2 round feeders. Water was also provided ad libitum from 8 water nipple drinkers. The birds were exposed to 24 h light at 1-2 days (20-40 lux), 16 h light (20-30 lux): 8 h dark at 3-6 days. The light was then gradually reduced by 2 h/week and was fixed to 9 h light (4-6 lux): 15 h dark at 5 weeks of age. All chicks were marked with individual numbered leg bands at 16 weeks of age. A standard vaccination program was applied during the rearing period. All groups were moved to the laying house at the age of 16 weeks.
3.1.2 Laying period (from 16 weeks of age) During the laying period fifty hens were randomly selected from each group. All selected hens remained in the original rearing group. The six groups were randomly distributed to six identical pens at a maximum stocking rate of 6 hens/m2. Each group had access to four nests (60 cm x 30 cm x 30 cm). The nests were arranged in two rows (two nests in each) with a height of 1.0 m and 0.5 m above the floor for the
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first and second tiers respectively. Four perches were placed 50 cm above slats which allowed 15 cm space on the perch for each bird. Two round feeders were fixed 20 cm above the floor, five nipple drinkers that allowed access to one nipple for 10 hens according to EU-council directive (1999/74/EC).
Figure 3.1 Poultry house from inside showing slats, perches, feeders and passage from PH to WG
Feeder Nest boxes Passage
House Winter garden
Perches
Figure 3.2 Layout of poultry house (PH) and winter garden (WG)
Approximately 65 percent of the floor area was a deep litter area with straw; the remaining part was equipped with slats and perches. All groups were fed a standard
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layer’s mash diet composed of : crude protein 17%, crude fiber 5%, methionin 0.37 %, calcium 3.70 %, phosphorus 0.50 % and ME MJ /kg 11.40. Food and water was provided ad libitum. The droppings were automatically removed once/ week by a plastic sheet, which was located under the slats. Each pen in the poultry house (PH) was connected with an outside area (winter garden WG) via passages (0.65 m x 0.18 m x 0.24 m), through which birds could pass freely from pens to WG and vice versa. The height of the passage in the pen was at the level of the perches. The passage in the WG was 1.0 m above the ground with a ladder going down to the floor level, see figures 3.1, 3.2 and 3.3. The WG consisted of a roofed scratching room with shredded tree bark as a substrate. The stocking density in the WG was also 6 birds/m2. No daylight was allowed in the PH. Natural light was only allowed in the WG. Hens in the PH were kept on a light schedule of 14 h of light (average 5 lux) from 6.00 to 20.00 h and 10 h of total darkness. The temperature in the house ranged between 11°C and 28 °C, in the WG it was natural day temperature.
Passage
a b Figure 3.3 LS (+f) in PH (a) and LT (+f) in WG (b)
3.2. Experimental design The experiment started when birds were one day old for a period of 40 weeks in 2 replicates for each group.
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3.2.1 Experiment I The effect of availability of loose feathers from the floor was studied in this experiment. Therefore, the laying hens were assigned, according to feather treatments, into three groups for each genotype(see table 3.1): A- Control (Cont.). B- Without feathers (-f). C- With Feathers (+f).
Table 3.1 Classification of experimental groups according to feathers treatment
1 Groups Cont. -f +f 2 Genotype LT& LS LT& LS LT& LS During rearing period. Neither feathers being The feathers from the The collected feathers molted and located on floor that birds change were added the floor were removed and loose during their to the floor. nor additional new developments were feathers were given to collected. the litter. 60 Number of birds. 60 60 During laying period. The same treatment as in The same treatment as The same treatment as the rearing period. in the rearing period. in the rearing period. Number of birds. 50 50 50 1 Groups: A- Control group (cont), no feather treatment. B- Without feathers on the floor, (-f) group. C- With feathers on the floor, (+f) group 2 Genotype: LT (Lohman Tradition) and LS (Lohman Silver)
Feathers used during the first 6 weeks (as the amount of feathers were collected from the (-f) groups were low in its amount during this period) were collected from a previous experiment carried out on the same 2 genotypes (LT & LS) in the research station in Merbitz from 2 sources. The first one was collection of the moulted feathers from the floor, while the second was from defeathering of dead birds. The collected feathers of both genotypes from the first 6 weeks were washed and cleaned with distilled water to remove all manure materials, dried, disinfected and stored separately in jute sacks. During the laying period, birds of each pen and of both genotypes received the same feather treatment in the WG as in the PH. Additional amounts of stored unwashed feathers were added to the floor of the (+f) groups once/week from 20 weeks of age
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onward, as the amount of collected feathers from the (-f) groups were small in its amount and not sufficient (these feathers were collected from rearing pens after hens have been moved to the laying department).
3.2.2 Experiment II Experiment 2 was designed to study the effect of availability of loose feathers from the floor in combination with the effect of imprinting to loose feathers during the rearing period on the later feather pecking in LT hens. Three groups with LT genotype received the same feather treatments in the rearing period as in the first experiment: A- Group I: No feather treatment. B- Group II: Feathers from the floor were collected four times/week. C- Group III: Feathers from the same genotype were added to the floor before arrival of chicks, then added once per week until the end of the rearing period. During the laying period the treatments of groups (II &III) were switched, in which feathers were collected from the floor of group III and collected feathers were added to the floor of group II (see table 3.2). Behavioural activities, feather scoring, skin injuries and productive performance were measured as in the first experiment.
Table 3.2 Classification of experimental groups according to feathers treatment
Feather Group treatment Group I Group II Group III During rearing period. Neither feathers being The feathers from the The collected feathers molted and located on floor that birds change were added to the floor the floor were removed and loose during their once/ week. nor additional new developments were
feathers were given to collected 4 times/ week. the litter.
During laying period. The same treatment as Feathers were added Feathers were collected in the rearing period. to the floor once/ week. from the Floor 4 times/ week.
3.3 Behavioural observations The behaviours were recorded via direct observations. The hens of each pen group were directly observed in 2 periods per day, one in the morning (9.00-12.00) and the second
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in the afternoon (13.00-16.00). Each group was observed for 15 minutes in each period of observations, the observer was sitting outside of the pen on a high chair, with a good view over the whole pen. Before starting to observe a pen of birds, the observer sat quietly for 5 min. to get the birds accustomed to his presence.
3.3.1 Feather pecking During the observations “all occurrences” (ALTMANN 1974) of feather pecking interactions in a group were recorded (five periods of 3 min.). Feather pecks that were successively directed at the same receiver were recorded as one single interaction. An interaction ended when there were no more pecks during a period of 4 s. Repeated pecks directed to the same bird and to the same body part was defined as a bout (KJAER 2000). The number of pecks per bout (bout size) was classified into up to 4, 5 to 9 and 10 or more (WECHSLER and HUBER-EICHER 1998). Only pecks at feathered parts of conspecifics were classified as feather pecking. Pecking at legs, beak, combs or wattles were neglected as such pecks may be under the control of another system and not be linked to feather pecking. Interactions were classified as: A-“Gentle”: gentle pecks at feathers, not resulting in feathers being pulled out and neither does the receiver show a reaction to the peck. B- “severe”: forceful pecks, sometimes feathers are pulled out and the receiver of the peck may move away. C-“Aggressive”: were always severe and fast, directed mainly at the head and given in a downward direction, occasionally when the attacked bird was moving away, an aggressive pecks could also be directed to another part of its body. The body parts to which pecks were directed (head, neck, back, rump, tail, wing, belly, breast and leg, Figure 3.4) were recorded. All rates of feather pecking are given as a number. Behavioural observations were carried out at the age of 6, 10, 15 (during the rearing period), 20, 25, 30, 35 and 40 weeks (during the laying period).
3.3.2 Other behaviour activities Every 3 minutes, the ”all occurrence sampling of feather pecking interactions” was briefly interrupted for a scan sample activities of chicks. For each scan the number of chicks engaged in 8 mutually exclusive activities were recorded and defined as follows: Feeding: The chick stands next to the feeder with its head above the feed.
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Drinking: The chick’s bill was oriented to, and within 5 cm of the cup drinker. Preening: The chick is nibbling, stroking or combing its plumage with its peak (KRUIJT 1964) or it is stretching its wings or legs while standing or sitting. Standing: Standing on both feet without showing another behaviour. Sitting: The chick sits while its chest feathers touch the ground or the perch. Foraging behaviour: “ground pecking”: pecking at the ground litter; “object pecking”: pecking at the wall, feeders, drinkers; “staring at objects”: the chicks inclines its head and stretches its neck in the direction of an object; “head down”: the chick has its head in a lower position than the rump while standing or moving without showing ground pecking; and “scratching”: the chick scratches the ground /litter, the wall or the feeder.
Head Tail Neck Back Rump Underneck
Coverts
Breast Belly Leg Wing-primary feathers
Figure 3.4 The body parts used to assess feather pecking and feather scoring according to GUNNARSSON et al. (1995)
Moving: Locomotion without showing another defined behaviour. Dust bathing: The chick is showing vertical wing-shaking (a typical behaviour of dust bathing (KRUIJT 1964) or has shown vertical wing-shaking before the scan and has not
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yet finished this dustbathing bout, i.e. has not shown body /wing shaking in a standing position or moved away from the dust bathing site). The percentage of chicks engaged in each behaviour was calculated during all scan samples in each pen. During the laying period the following data were recorded: A- The location of the receiver of feather pecking (on perch, floor, slats and feeding area). B- Feather pecking and behavioural activities in the WG.
3.4 Feather scoring All birds from each pen were individually scored at 15, 32 and 39 weeks of age. For inspection of feather condition, each bird was taken from the pen and 9 individual parts (see figure 3.4) of the body (GUNNARSSON et al. 1995),”head, neck, back, rump, tail, wings (wing-primary feathers and wing coverts), abdomen, breast and legs” were carefully examined for damaged, broken, and missing feathers and bald patches.
Table 3.3 Description of scoring method used to evaluate the feather condition (modified from previous methods, BILCIK and KEELING 1999) and skin injuries. A different scale was used for flight feathers (wing primaries & tail) compared to the feather condition of the rest of the body
Scores Body feathers Flight feathers Skin injuries 0 Perfect plumage. Perfect plumage. No injuries or scratches. 1 Some feathers scruffy and/or Few separated feathers up < 5 pecks or scratches up to 5 damaged feathers. to 5, but none damaged, broken or missing. 2 > 5 damaged feathers and/or up > 5 feathers separated 5 or more pecks or scratches or to 5 broken feathers. and/or up to 5 damaged 1 wound < 1 cm diameter. feathers. 3 > 5 broken feathers and/or up All feathers separated, or > Wound > 1 cm diameter but < to 5 missing feathers. 5 feathers damaged or up 2 cm. to 3 broken. 4 Bald patch < 5 cm or < 50 % of All feathers damaged Wound > 2 cm in diameter. area. and/or > 3 feathers broken or up to 3 feathers missing. 5 Bald patch > 5 cm or > 50 % of All feathers broken or > 3 --- area. feathers missing. 6 Completely denuded area. Almost all feathers --- missing.
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Each body part was given a score from 0 (best) to 6 (worst), with special criteria used for scoring of flight feathers (the tail and the primaries) compared to the feathers of the rest of the body that were differentiated in the types, number, length, fixations and damages. The feathers under the neck and breast were excluded because of the interfering effects of feeder edge and brood patch on feather damage. A sum of all given values was taken as a total body score. Skin injuries (wounds and scratches) were also scored on a scale from 0 (no injuries) to 4 (large wound) (BILICIK and KEELING 1999) including comb, see table 3.2. A score (0 - 2) was given to the feet. Zero point was given to a normal foot, 1 point was given to inflammation of one foot and 2 points to inflammation of both feet.
3.5 Tonic immobility Tonic immobility TI reactions were examined at 40 weeks of age. 15 birds per pen were randomly selected. TI tests were carried out in separate room adjacent to the rearing pens (no visual or auditory contact). Each bird was tested individually as soon as it was caught, by placing the animal on its back with the head hanging in a U-shaped wooden cradle covered with several layers of clothing (JONES and FAURE 1981), see figure 3.5, the bird was restrained for 10 s. the observer sat in a full view of the bird, about 1 m away and fixed his eyes on the bird.
Figure 3.5 LT hen showing tonic immobility (TI)
If the bird remained immobile for 10 s after the experimenter removed his hands, a stopwatch was started to record latencies until the bird right itself. If the bird righted
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itself in less than 10 s., it was considered that tonic immobility had not been induced, and the restraint procedure was repeated. If TI was not induced after three attempts the duration of TI was considered 0 s. (ZULKIFLI et al. 2000). If the bird did not show a righting response over a 10–min test period, a maximum score of 600 s was given for righting time (CAMPO et al 2000). Testing took place between 8:30 and 14:30 h.
3.6 Egg production To evaluate the egg production, eggs produced by each pen group starting at 20 weeks of age were recorded daily, and weighed once/week to calculate the average egg weight for each group. Moreover, one day egg production from each group was subjected to an egg shell strength test at 25, 32 and 40 weeks of age.
3.7 Body weight To monitor growth rates and the effect of provision or removal of feathers from the litter, birds from each group were weighed at 16, 32 and 39 weeks of age.
3.8 Statistical analyses Data from behavioural observations, the number of feather pecking in different areas and locations, feather pecking bouts, feather scores at different parts of the body, skin injuries, body weight, egg weight, egg production, egg shell strength and tonic immobility were analysed with ANOVA using a generalized linear models (GLM- procedure, SAS Institute, 2001). To measure the effect of feather treatment (group)/genotype, week and period, Duncan’s multiple range test was used to determine significant differences between means. Differences were computed from least square means. The following model was used:
Yijkl = Gi + Wj + Perk + residualijkl Where
Y= feather pecking, feather score, skin injuries, body weight, egg weight, egg production, egg shell strength, tonic immobility or the type of behaviour observed
(feeding, drinking, foraging, preening, walking, standing and dust bathing). Gi = effect of group (feather treatment)/ genotype (i= LT, LS)
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Wj = effect of age
Perk = effect of period (k= morning or afternoon)
Residualijkl= residual factors.
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4 RESULTS 4.1 Feather treatment and genotype (first experiment) A- Rearing period 4.1.1 Effect of feather treatment and genotype on the rate of feather pecking Feather pecking was observed at less rates in the (+f) group of LT compared to the (cont) group of the same genotype (p < 0.01), with the (–f) group being intermediary between the (+f) and (cont) groups but not different from them. Groups of LS were not different in the total number of feather pecking. The LS (+f) birds exhibited high rates of FP compared to the (+f) birds of LT (p < 0.05). On the other hand there were no differences in the rates of feather pecking between the (cont.) or (–f) groups of LS compared to the corresponding groups of LT. Daytime had no effect on the rate of feather pecking within the group in both genotypes (table 4.1).
Table 4.1 Means (± SE) and p-value of total number of feather pecking and effect of daytime in relation to feather treatment for both LT and LS genotypes
Genotype P-value Group (n = 60, each) LT LS (Cont.) 8.43a (± 0.79) 9.77 (± 1.13) ns Daytime am 8.53 (±1.16) 8.20 (±1.38) pm 8.33 (± 1.11) 11.33 (±1.74)
(-f) 7.47ab (± 1.04) 8.53 (± 0. 76) ns Daytime am 7.06 (± 1.97) 8.73 (±1.36) pm 7.87 (± 0.76) 8.33(±0.73) (+f) 5.13bB (± 0.5) 7.83A (± 1.38) <0.05 Daytime am 4.80 (± 0.6) 7.06 (±1.95) pm 5.46 (±0.83) 8.60 (±1.87) P-value < 0.01 ns a,bMeans with the same letters and column are not significantly different (within the same genotype). A,B Means with the same letters and rows are not significantly different (between 2 genotypes), ns: non- significant.
Figure 4.1a shows that the LT control birds (cont) exhibited a more severe form of pecking 2.77 ± 0.57 (mean ± SE) compared to the (–f) and (+f) groups (1.46 ± 0.20, 1.13 ± 0.24, respectively, p < 0.01, p < 0.001), however, there were no differences in the gentle as well as aggressive pecks among groups of LT. There was no difference in gentle, severe and aggressive pecks among LS groups (figure 4.1b). The control groups
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of both genotypes were not different in FP forms (figure 4.1c). High rates of the severe form of FP were observed in the (-f) and (+f) groups of LS 2.27 ± 0.32, 2.46 ± 0. 51 (mean ± SE) compared to the (-f) and (+f) groups of LT 1.46 ± 0.20, 1.13 ± 0.24, respectively, (p < 05, <0.001), however, the genotype had no effect on the gentle and aggressive pecks (figure 4.1d, e).
b a LT Gentle b LS Gentle Severe ns 8 8 Severe Aggressive 6 6 Aggressive 4 4 *** 2 2 ** 0 0 Feather pecking
Feather pecking Cont. -F +F Cont. -F +F Groups Groups
c Control groups Gentle ns 8 Severe 6 Aggressive 4 2 0 Feather pecking LT LS Groups
d (-f)(-f) groupsgroups e (+f) groupsgroups Gentle Gentle 8 8 Severe 6 Severe 6 4 * 4 *** Aggressive Aggressive 2 2 0 0 Feather pecking Feather pecking LT LS LT LS Groups Groups
Figure 4.1 Feather pecking forms in LT (a), LS (b) and in comparison to corresponding groups of both genotypes (c, d and e), (*** p<0.001, * p<0.05, ns: non-significant, n = 60)
The number of bouts per bird was higher (p < 0.01) in the LT control birds (cont) compared to the (+f) group of the same genotype, as well as the number of bouts when
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the bout size was up to 4 and 10 or more (p < 0.05), with the (–f) group being intermediary between the (+f) and (cont) groups but not different from them. Peck numbers of 5-9 per bout were not different among the groups. In LS, there was no difference in the number of bouts per bird and the pecks per bout among the groups, except for the (–f) group which showed a high number of bouts compared to the (+f) group when the bout size was up to 4 (p < 0.05), with the (cont) group was in between and did not differ from any other group. The genotype had no effect on the number of bouts and the pecks per bout in the (cont) and (+f) groups of LT and LS. On the other hand the (-f) group of LT showed a less number of bouts 1.20 ±0.20 compared to the (-f) group of LS 1.86 ± 0.24 when bout size was up to 4 (p < 0.05) (see table 4.2).
Table 4.2 Effect of feather treatment and genotype on bouts of feather pecking and number of pecks per bout (Means ± SE and p-value) Feather pecking Genotype P-value Group (n = 60, each) LT LS Bouts cont. 1.96a (± 0.25) 2.20(±0.28) ns -f 1.50ab (± 0.21) 2.13 (± 0.22) ns b +f 1.10 (± 0.14) 1.53 (± 0.27) ns
P-value < 0.01 ns Pecks / bout cont. 1.60a (± 0.26) 1.63ab (± 0.25) ns abB aA Up to 4 -f 1.20 (± 0.20) 1.86 (± 0.24) <0.05 +f 0.93b (± 0.12) 1.17b (± 0.19) ns P-value <0.05 < 0.05 5 to 9 cont. 0.23 (± 0.07) 0.33 (± 0.09) ns -f 0.26 (± 0.11) 0.20 (± 0.07) ns +f 0.17 (± 0.06) 0.23 (± 0.09) ns P-value ns ns 10 or more cont. 0.13a (± 0.06) 0.23 (± 0.09) ns -f 0.03ab (± 0.03) 0.06 (± 0.06) ns +f 0.00b (± 0.00) 0.13 (± 0.07) ns P-value <0.05 ns a,bMeans with the same letters and column are not significantly different (within the same genotype). A,B Means with the same letters and rows are not significantly different (between 2 genotypes), ns: non- significant.
4.1.2 Feather pecking directed to different body parts The distributions of FP to various body regions are shown in figures 4.2 for LT and 4.3 for LS. In LT, more feather pecking was directed to the neck, back, rump and wing in the (cont) birds (0.66 ± 0.17, 0.77 ± 0.17, 1.13 ± 0.32, 2.70 ± 0.71 mean ± SE) compared to the (+f) group (0.23 ± 0.10, 0.26 ± 0.08, 0.57 ± 0.13, 1.03 ± 0.29, respectively, p = 0.04, 0.03, 0.02, 0.04, respectively), with the (–f) group being
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intermediary between the (+f) and (cont) but not different from them. In LS, the number of the FP directed to the rump in the (cont) group was higher than that in the (+f) group (p = 0.01), with the (–f) being intermediary between the (+f) and (cont) but not different from them, as other body regions were not pecked differently in the groups of the same genotype.
LT Cont.
5.00 -f +f 4.00 p=0.04 3.00 p=0.02
2.00 p=0.03
p=0.04 1.00
Feather pecking 0.00
Tail
Leg Belly Neck Back Head Wing
Rump Breast Body region
Figure 4.2 Distribution of feather pecking on various body parts in LT (mean ±SE, n = 60)
LS Cont. -f
5,00 +f 4,00 c 3,00 p=0.01
2,00 1,00 0,00 Feather peFeather king
y d ck p e m Tail Leg Hea N Back Wing Bell Ru Breast Body region
Figure 4.3 Distribution of feather pecking on various body parts in LS (mean ±SE, n = 60)
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Table 4.3 Effect of feather treatment and genotype on the total number of hens observed performing various behaviours (% Means ± SE and p-value)
Behaviour Genotype P-value Group (n = 60, each) LT LS Feeding cont. 21.03bB (± 0.85) 23.79A (± 1.55 ) 0.0060 -f 20.92b (± 1.33) 21.95 (± 1.51 ) ns +f 24.5aA (± 0.89) 22.21B (± 1.16) 0.0357 P-value 0.0003 ns Drinking cont. 4.82 (± 0.38) 4.51 (± 0.40) ns -f 4.77 (± 0.39) 5.59 (± 0.65) ns +f 5.23 (± 0.46) 5.18 (± 0.52) ns P-value ns ns Foraging cont. 30.10b (± 1.57) 29.18b (± 144) ns -f 32.41b (± 1.12) 29.28b (± 1.51) ns +f 36.56a (± 1.40) 36.35a (± 1.64) ns P-value 0.0005 0.0013 Preening cont. 12.46A (± 1.39) 7.64B (± 0.81) 0.0017 -f 10.92A (± 1.26) 7.85B (± 0.90) 0.0323 +f 9.79 (± 0.81) 8.46 (± 0.82) ns P-value ns ns Walking cont. 7.02 (± 0.67) 6.31 (± 0.39) ns -f 7.89 (± 0.54) 7.79 (± 0.79) ns +f 7.44 (± 0.82) 6.97 (± 0.57) ns P-value ns ns Standing cont. 7.64 (± 0.72) 9.28 (± 0.69) ns -f 7.08B (± 0.79) 9.54A (± 1.05) 0.0240 +f 8.51 (± 0.57) 9.44 (± 0.74) ns P-value ns ns Sitting cont. 9.18aA (± 1.58) 6.31B (± 0.74) 0.0255 -f 7.38ab (± 1.24) 5.85 (± 1.01) ns +f 5.18bB (± 0.86) 7.44A (± 1.27) 0.0308 P-value 0.0026 ns Dustbathing cont. 0.72B (± 0.13 ) 1.38A (± 0.26) 0.0364 -f 0.92 (± 0.37 ) 1.54 (± 0.42) ns +f 1.08 (± 0.38 ) 0.87 (± 0.39) ns P-value ns ns a,bMeans with the same letters and column are not significantly different (within the same genotype). A,BMeans with the same letters and rows are not significantly different (between 2 genotypes), ns: non- significant.
4.1.3 Effect of feather treatment and genotype on the behavioural activities The results are summarised in table 4.3. The higher proportion of hens was recorded as feeding and foraging in the (+f) group of LT compared to other groups of the same genotype (p = 0.0003, 0.0005, respectively). The percentage of hens performing sitting behaviour was higher in the LT (cont) group compared to the (+f) group (p = 0.0026), with (–f) being intermediary between (+f) and (cont) but not different from them. Other behaviour patterns were similar among LT groups. In LS, foraging behaviour was higher in the (+f) birds (p = 0.0013) compared to the (–f) and (cont) groups.
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The genotype affected behavioural activities concerning feeding, preening, standing, sitting and dustbathing. In the control groups, a higher proportion of hens was recorded as feeding and dustbathing in LS compared to LT hens, while the preening and sitting behaviours were higher in LT compared to LS birds. In the (–f) groups, the percentage of hens performing preening was lower in LS compared to LT, but LS hens performed more standing behaviour. In the (+f) groups, feeding behaviour was higher in LT compared to the LS genotype, but the percentage of LS hens performing sitting and dustbathing behaviours was higher compared to the LT birds. The other categorised behaviours were similar in corresponding groups of the two strains.
4.1.4 Effect of feather treatment and genotype on feather condition Results from feather scoring at the different parts of the body at the age of 15 weeks are shown in table 4.4. In LS hens, only the feathers on the rump were worse in the (cont) and (–f) groups compared to the (+f) group (p= 0.01), as feathers on other body regions were similar in all groups.
8,00 cont. a ns 7,00 b c 6,00 -f
5,00 +f 4,00 * 3,00 *** 2,00 Total feather score 1,00 0,00 LT LS
Genotype
Ls-means with the same letters are not significantly different (within the same genotype), ns: non significant, (* P < 0.05, *** P = 0.001, n = 60).
Figure 4.4 Effect of feather treatment and genotype on the whole body feather score
In LT, the (+f) group had a significantly better feather condition on the rump and wing- coverts compared to the other groups, also this group (+f) had a better feather condition on the neck compared to the (cont) group, and on the back compared to the (–f) group.
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The LT (cont) group had a more damaged plumage on wing primaries compared to the (–f) group of the same genotype.
Table 4.4 Means (± SE) and p-value for plumage conditions at 15 week of age
Body parts Genotype P-value Group (n = 60, each) LT LS Head cont. 0.12 (± 0.05) 0.12 (± 0.05) ns -f 0.08 (± 0.04) 0.10 (± 0.04) ns +f 0.06 (± 0.03) 0.16 (± 0.05) ns
P-value ns ns Neck cont. 0.42a (± 0.09) 0.26 (± 0.08) ns -f 0.28ab (± 0.06) 0.18 (± 0.05) ns +f 0.18b (± 0.06) 0.24 (± 0.07) ns P-value 0.02 ns Back cont. 0.28ab (± 0.06) 0.42 (± 0.08) ns -f 0.30a (± 0.07) 0.36 (± 0.07) ns +f 0.12b (± 0.05) 0.26 (± 0.07) ns P-value 0.03 ns Rump cont. 1.20a (± 0.05) 1.12a (± 0.05) ns -f 1.10a (± 0.05) 1.08a (± 0.06) ns +f 0.92b (± 0.06) 0.90b (± 0.06) ns P-value 0.01 0.01 Tail cont. 1.30 (± 0.08) 1.52 (± 0.08) ns -f 1.40 (± 0.08) 1.46 (± 0.09) ns +f 1.22B (± 0.07) 1.44A (± 0.08) 0.05 P-value ns ns Wing-coverts cont. 0.98a (± 0.05) 1.02 (± 0.05) ns -f 0.92aB (± 0.04) 1.16A (± 0.07) 0.004 +f 0.78bB (± 0.06) 1.04A (± 0.04) 0.0004 P-value 0.004 ns Wing primaries cont. 2.26a (± 0.08) 2.26 (± 0.08) ns -f 1.86bB (± 0.11) 2.16A (± 0.09) 0.04 +f 2.06ab (± 0.11) 2.20 (± 0.09) ns P-value 0.01 ns Belly cont. 0.04 (± 0.03) 0.06 (± 0.03) ns -f 0.02 (± 0.02) 0.02 (± 0.02) ns +f 0.02 (± 0.02) 0.08 (± 0.03) ns P-value ns ns Leg cont. 0.10 (± 0.04) 0.08 (± 0.04) ns -f 0.06 (± 0.03) 0.04 (± 0.03) ns +f 0.02 (± 0.02) 0.06 (± 0.03) ns P-value ns ns a,bMeans with the same letters and column are not significantly different (within the same genotype). A,B Means with the same letters and rows are not significantly different (between 2 genotypes), ns: non- significant.
The genotype had no effect on the plumage condition except for (tail, wing-coverts and wing primaries), where the (+f) group of LS had a poorer feather condition on the tail and wing-coverts compared to the (+f) group of LT (p = 0.05, 0.0004, respectively). LT
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Birds of the (–f) group had a better feather condition on the wing-coverts and wing primaries compared to the (–f) group of LS (p = 0.004, 0.04, respectively). Total feather score was defined as the sum of the scores for all body parts (figure 4.4). There was no difference in total feather scoring between LS groups. There are however differences among groups of LT in total feather scoring, where the (+f) group were scored best and the (cont) worst (p < 0.001). In comparison between 2 genotypes, there was no difference in total feather scoring between the (cont) groups (LT& LS), but the (–f) and (+f) LT birds were scored best, and (–f) and (+f) LS birds were scored worst.
Table 4.5 Effect of feather treatment and genotype on body weight (g) (Means ± SE) and p-value)
Body weight Genotype P-value Group (n = 60, each) LT LS Week 15 cont. 1391.34a (± 13.89) 1404.44 (± 11.91) ns
-f 1340.30bB (±13.21) 1421.68A (±12.60) <0.001
+f 1360.02abB (±11.47) 1439.76A (±12.39) <0.001
<0.01 ns a,b Means with the same letters and column are not significantly different (within the same genotype). A,B Means with the same letters and rows are not significantly different (between 2 genotypes), ns: non- significant.
4.1.5 Effect of feather treatment and genotype on body weight There were no differences in the body weights among LS groups at 15 weeks of age. However, in LT, the (cont) group had significantly higher body weights compared to the (–f) group (p < 0.01). The genotype had no effect on the body weights in control groups. But the LT (–f) and (+f) groups had significantly lower body weight compared to the LS (–f) and (+f) groups (p < 0.001) (table 4.5).
B- Laying period 4.1.6 Effect of feather treatment and genotype on the rate of feather pecking There were differences in the total number of FP among LT groups, as well as among LS groups (table 4.6). In LT, the (+f) hens exhibited the lowest rate of FP and the (cont) hens exhibited the highest rate. Contrarily, in LS, the (+f) hens exhibited the highest rate and the (–f) exhibited the lowest rate of FP. The LT (+f) and (–f) groups showed a significantly lower rate of feather pecking compared to the LS (+f) and (–f) groups.
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Daytime had an effect on the rate of feather pecking in some groups but not in others. High rates of feather pecking were observed at the afternoon period compared to the morning period only in the (cont) groups of both genotypes and (–f) group of LS.
Table 4.6 Means (± SE) and p-value of total feather pecking and effect of daytime in relation to feather treatment for both LT and LS genotypes Genotype P-value Group (n = 50, each) LT LS Cont. 11.40a (± 0.59) 12.60b (± 0.53) ns Daytime am 9.78 (± 0.63) 11.22 (± 0.56 ) pm 13.02*** (± 0.94 ) 13.98*** (±0.86 ) -f 8.57bB (± 0.37) 11.01cA (± 0.40) <0.001 Daytime am 8.38 (±0.37 ) 10.16 (±0.44 ) pm 8.76 (± 0.64) 11.86* (±0.65 ) +f 6.91cB (± 0.32) 14.17 aA (± 0.44) <0.001 Daytime am 6.54 (±0.38 ) 13.82 (±0.60 ) pm 7.28 (±0.51 ) 14.52 (± 0.64) P-value <0.001 <0.001 a,b Means with the same letters and column are not significantly different (within the same genotype). A,B Means with the same letters and rows are not significantly different (between 2 genotypes), ns: non- significant. ( p-value for the effect of day time within the group: * P < 0.05, *** P < 0.001).
Figure 4.5a shows that the LT control birds (cont) exhibited the more severe form of pecking 6.62 ± 0.43 (mean ± SE) compared to the (–f) and (+f) groups (3.55 ± 0.20, 2.96 ± 0.19, respectively (p < 001). The (cont) group also exhibited a high rate of aggressive pecks 1.60 ± 0.07 compared to (+f) 1.34 ± 0.06 ( p< 01). The (–f) group exhibited a high rate of gentle pecks 3.54 ± 0.28 compared to the (+f) hens 2.61 ± 0.19 (p <0 1). In LS, (figure 4.5b) the number of severe pecks observed in the (cont) group 7.23 ± 0.38 (mean ± SE) was higher than that observed by the (–f) 4.95 ± 0.22 (p < 001), however, the highest severe pecks were observed in the (+f) group 9.03 ± 0.36 (p < 001) compared to the other groups of the same genotype. The LS (-f) group exhibited a more gentle FP compared to the other groups, also this group observed less aggressive pecks 1.60 ± 0.06 compared to (+f) 1.81 ± 0.08 (p < 05). Figure 4.5c shows that, there were no differences in gentle, severe and aggressive pecks between the control birds of the two genotypes. Figure 4.5d shows that, the LS (–f) exhibited a high rate of gentle and severe pecks compared to the LT (–f) birds. The highest rate of gentle, severe and
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aggressive pecks were observed in the (+f) group of LS compared to those were observed in the (+f) group of LT (p < 0.01, < 0.001, < 0.01, respectively) (figure 4.5 e).
ab LT Gentle LS
Gentle Severe a 10 a 10 b 8 8 Severe Aggressive a c 6 ab a 6 b b b b b Aggressive 4 a 4 ab b ab b a 2 2 0
Feather pecking 0
pecking Feather Cont. -f +f Cont. -f +f Group Gourp
c 10 ns 8 LT 6 ns 4 ns LS 2
Feather pecking 0 Gentle severe aggrressive Control groups
de*** 10 10 LT 8 8 * *** LS 6 LT 6 4 ** ns LS 4 2 ** 2
Feather pecking
Feather peckingFeather 0 Gentle severe aggrressive 0 Gentle severe aggrressive -F groups +F groups
Figure 4.5 Feather pecking forms in LT (a), LS (b) and in comparison between corresponding groups of both genotypes (c, d and e), n= 50
There were differences among LT groups in the number of bouts per bird, where the (cont) group recorded the highest number and the (+f) group recorded the lowest number. The (cont) group showed a higher number of bouts compared to the (–f) and (+f) groups when the bout size was 5 to 9 and 10 or more.
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Table 4.7 Effect of feather treatment and genotype on bouts of feather pecking and number of pecks per bout (Means ± SE and p-value)
Feather pecking Genotype P-value Group (n = 50, each) LT LS Bouts cont. 2.47a (± 0.13) 2.72 (±0.12) ns -f 2.05bB (± 0.11) 2.54A (± 0.12) <0.01 +f 1.55cB (± 0.11) 2.82A (± 0.11) <0.001 P-value <0.001 ns Up to 4 cont. 1.96a (± 0.13) 2.05 (± 0.12) ns -f 1.85a (± 0.12) 2.08 (± 0.12) ns +f 1.37bB (± 0.10) 2.14A (± 0.13) <0.001 P-value <0.001 ns 5 to 9 cont. 0.36a (± 0.06) 0.49 (± 0.06) ns -f 0.15bB (± 0.04) 0.39A (± 0.06) <0.001 +f 0.17bB (± 0.04) 0.37A (± 0.05) <0.01 P-value <0.01 ns 10 or more cont. 0.15a (± 0.04) 0.18b (± 0.04) ns -f 0.05b (± 0.02) 0.07b (± 0.03) ns +f 0.01bB (± 0.01) 0.31aA (± 0.05) <0.001 P-value <0.001 <0.001 a,b Means with the same letters and column are not significantly different (within the same genotype). A,B Means with the same letters and rows are not significantly different (between 2 genotypes), ns: non- significant
Pecks number up to 4 per bout were lower in the (+f) group compared to the other groups of LT (p < 0.001) (table 4.7). In LS, the (+f) group showed a higher number of bouts compared to the (cont) and (–f) groups when the bout size was 10 or more (p < 0.001). The number of bouts per bird, pecks number up to 4 and 5 to 9 were not differ among groups. Among genotype, the number of bouts and the pecks per bout were similar between the (cont) groups of LT and LS. Contrarily, the LS (+f) group showed a higher number of bouts and the pecks per bout when the bout size was up to 4, 5 to 9 and 10 or more compared to the LT (+f) group. The LT (–f) group showed a lower number of bouts and pecks per bout when the bout size was 5 to 9 compared to the LS (–f) group (p < 0.01, < 0.001, respectively).
4.1.7 Feather pecking directed to different body parts The number of feather pecking directed to the tail and belly in the house PH was significantly greater in the LS (+f) group compared to the (cont) and (–f) groups of the same genotype (figure 4.6a). The LT (cont) group showed a higher frequency of FP to the head, neck, rump and leg in the PH compared to the (+f) group, as the (–f) group
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was in between and not significantly differ from them. Also, the LT (cont) showed a higher frequency of FP to the back and tail compared to the other groups (figure 4.6b).
a b LT LS b Cont. Cont. -f 4,00 4,00 *** +f -f 3,00 *** 3,00 * * ** 2,00 +f 2,00 *** ** 1,00 1,00 * 0,00 Feather pecking Feather pecking 0,00 Feather pecking
Tail Leg Tail Belly Leg Back Neck Wing Head Rump Belly Head Back Neck Wing Breast Rump Breast Body region Body region region
c c LS d LT Cont. Cont. 4,00 4,00 -f -f P=0.05 p=0.02 3,00 3,00 p=0.01 +f
pecking p=0.04 2,00 p=0.002 +f 2,00 p=0.01 p=0.02 1,00 1,00 0,00 0,00 Feather Feather pecking Tail Leg Tail Leg Belly Back Wing Neck Head Belly Rump Back Neck Wing Head Breast Rump Breast Body region region Body region
Figure 4.6 distribution of feather pecking on various body parts in the house PH LS (a), LT (b) and in the winter garden WG LS(c), LT (d). N = 50
In the winter garden WG, more feather pecking (p = 0.002) were directed to the belly in the LS (+f) group compared to the other groups of the same genotype (figure 4.6c). Figure 4.6d shows that, lower number of FP were directed to the head, neck, back, rump and tail in the LT (+f) group compared to the (cont), with the (–f) group being intermediary between the (+f) and (cont) groups but not different from them. The (–f) group showed a higher number of FP to the leg 0.66 ± 0.14 (mean ± SE) compared to the (+f) group 0.30 ± 0.09 (p = 0.04).
4.1.8 Location of feather pecking activity Table 4.8 shows a comparison of the proportion of feather pecking at different locations. The rate of FP was similar among the LS groups, except for a significant increase in the number of pecks on the floor in the (+f) group compared to the (–f) group (p = 0.001). In LT, the (cont) group exhibited a high rate of FP on the floor
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compared to the other groups (p < 0.001). Also this group showed a higher FP on the feeding area, perch and slats compared to the (+f) group, with the (–f) being intermediary between the (+f) and (cont) groups but not different from them.
Table 4.8 Effect of feather treatment and genotype on the number of feather pecks at 4 locations (mean ± SE and p-value)
Body parts Genotype P-value Group (n = 50, each) LT LS Feeding area cont. 2.52a (± 0.31) 2.61 (± 0.31) ns -f 1.98ab (± 0.23) 2.45 (±0.30) ns bB A +f 1.71 (± 0.20) 2.67 (± 0.31) 0.01 P-value 0.03 ns Floor cont. 8.15a (± 0.73) 9.0ab (± 0.63) ns -f 6.11bB (± 0.49) 7.67bA (± 0.57) 0.04 +f 4.88bB (± 0.40) 10.44aA (± 0.63) <0.0001 P-value <0.001 0.001 Perch cont. 0.35a (± 0.09) 0.52 (± 0.12) ns -f 0.24ab (± 0.07) 0.45 (± 0.10) ns +f 0.15bB (± 0.05) 0.63A (± 0.14) 0.001 P-value 0.05 ns Slats cont. 0.38a (± 0.08) 0.40 (± 0.09) ns -f 0.24ab (± 0.07) 0.44 (± 0.10) ns +f 0.17bB (± 0.05) 0.43A (± 0.09) 0.01 P-value 0.02 ns a,b Means with the same letters and column are not significantly different (within the same genotype). A,B Means with the same letters and rows are not significantly different (between 2 genotypes), ns: non- significant.
There was no difference in the number of feather pecks at any locations between the (cont) groups of both strains. However, there were more pecks observed on the floor in the LS (–f) group than the LT (–f) group (p = 0.04). The LT (+f) group observed low pecks in all locations compared to the LS (+f) group.
4.1.9 Behavioural activities in LT and LS during the laying period Feather treatments affected behavioural activities concerning foraging, preening and standing in the LT. The percentage of hens performing foraging behaviour was higher (p < 0.001) in the (+f) group compared to the other groups. Contrary, the (+f) hens performed less standing (p < 0.01) compared to the other groups. The percentage of hens engaged in preening behaviour was higher (p < 0.001) in the (-f) group compared to the (cont) and (+f) groups (table 4.9). In LS, walking activity was higher in the (cont) birds compared to the (–f) and (+f) groups (p < 0.01). A significantly higher proportion of hens was recorded as dust bathing in all LS groups compared to the corresponding
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LT groups (table 4.9). The LS (–f) hens were performing higher foraging and lower preening behaviours compared to the LT (–f) hens (p < 0.001).
Table 4.9 Effect of feather treatment and genotype on the total number of hens observed performing various behaviours (% Means ± SE and p-value)
Behaviour Genotype P-value Group (n = 50, each) LT LS Feeding cont. 13.66 (± 1.51) 10.84 (± 1.18) ns -f 13.22 (± 1.42) 11.87 (± 1.35) ns +f 15.71 (± 1.72) 12.12 (± 1.31) ns P-value ns ns Drinking cont. 6.91 (± 0.79) 8.11 (± 0.92) ns -f 6.54 (± 0.75) 7.99 (± 0.89) ns +f 6.43 (± 0.75) 7.97 (± 0.90) ns P-value ns ns Foraging cont. 28.44b (± 1.49) 30.93 (± 1.89) ns -f 24.60bB (± 1.51) 32.86A ( 1.83) <0.001 +f 35.47a (± 1.84) 33.14 (± 1.66) Ns P-value <0.001 ns Preening cont. 18.46b (±0.94) 16.50 (± 1.09) ns -f 22.80a A (± 1.35) 14.07B (± 0.88) <0.001 +f 16.77b (±1.29) 16.53 (± 0.91) ns P-value <0.001 ns Walking cont. 7.23 (± 0.51) 8.39a (± 0.39) ns -f 7.38 (± 0.53) 6.13b (± 0.50) ns +f 6.11 (± 0.40) 6.24b (± 0.53) ns P-value ns <0.01 Standing cont. 12.80a (± 1.12) 10.71 (± 1.00) ns -f 12.10a (± 1.01) 10.47 (± 0.78) ns +f 9.23b (± 0.73) 10.42 (± 0.86) ns P-value <0.01 ns Sitting cont. 7.56 (± 0.70) 7.51 (± 0.56) ns -f 9.40 (± 1.30) 7.69 (± 0.72) ns +f 6.97 (± 0.70) 6.36 (± 0.51) ns P-value ns ns Dustbathing cont. 1.73B (± 0.34) 3.94A (± 0.90) <0.01 -f 2.49B (± 0.47) 5.93A (± 0.98) <0.001 +f 2.62B (± 0.48) 5.53A (± 1.11) <0.01 P-value ns ns a,b Means with the same letters and column are not significantly different (within the same genotype). A,B Means with the same letters and rows are not significantly different (between 2 genotypes), ns: non- significant.
4.1.10 Effect of feather treatment and genotype on feather condition Tables 4.10a and 4.10b show least squares means of feather scoring at 32 and 39 weeks of age. Generally, plumage damage increased with the age during the laying period. At 32 weeks of the age, the feathers on the tail, wing primaries and belly were significantly worse in the LT (cont) group birds than the other groups of the same genotype. The LT
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(+f) group had a better feather condition on the head, back, rump, and wing-coverts compared to the other LT groups. In LS, the (–f) hens had a better feather condition on the back compared to other groups, and on the rump compared to the (+f) group. Feather condition was significantly worst on the Wing-coverts in the (cont) birds, and on the belly in the (+f) hens compared to the other groups.
Table 4.10a Plumage condition at 32 week of age for LT and LS (means ± SE and p-value)
Body parts Genotype P-value Group (n = 50, each) LT LS Head cont. 1.68a (± 0.08) 1.84 (± 0.08) ns -f 1.80a (± 0.08) 1.76 (± 0.06) ns bB A +f 1.40 (± 0.08) 1.93 (± 0.05) <0.001 P-value 0.0004 ns Neck cont. 2.52a (± 0.08) 2.50 (± 0.07) ns -f 2.30ab (± 0.08) 2.41 (± 0.07) ns +f 2.08bB (± 0.09) 2.52 A (± 0.09) 0.001 P-value 0.0003 ns Back cont. 1.64aB (± 0.08) 1.88aA (± 0.05) 0.01 -f 1.48aB (± 0.08) 1.73bA (± 0.07) 0.02 +f 1.14bB (± 0.05) 2.02aA (± 0.02) <0.0001 P-value <0.0001 0.0001 Rump cont. 1.66a (± 0.07) 1.74ab (± 0.09) ns -f 1.64a (± 0.07) 1.53b (± 0.07) ns +f 1.40bB (± 0.07) 1.78aA (± 0.08) 0.001 P-value 0.01 0.03 Tail cont. 2.32aB (± 0.07) 2.54A (± 0.07) 0.03 bB -f 2.10 (± 0.04) 2.41A (± 0.09) 0.003 bB +f 2.06 (± 0.03) 2.39A (± 0.08) 0.0001 P-value 0.0003 ns Wing-coverts cont. 1.66aB (± 0.07) 2.02aA (± 0.05) <0.001 -f 1.56a (± 0.07) 1.73b (± 0.09) ns +f 1.34bB (± 0.07) 1.80bA (± 0.08) <0.001 P-value 0.001 0.0067 Wing primaries cont. 3.46aA (± 0.08) 3.18B (± 0.07) 0.01 -f 3.20b (± 0.08) 3.10 (± 0.07) ns +f 3.16b (± 0.08) 3.07 (± 0.07) ns P-value 0.01 ns Belly cont. 1.16a (± 0.07) 1.26b (± 0.07) ns -f 0.74bB (± 0.07) 1.12bA (± 0.04) <0.0001 +f 0.58bB (± 0.07) 1.83aA (± 0.10) <0.0001 P-value <0.0001 <0.0001 Leg cont. 2.28 (± 0.08) 2.22 (± 0.06) ns -f 2.42A (± 0.07) 2.22 B (± 0.06) 0.04 +f 2.44 (± 0.09) 2.30 (± 0.07) ns P-value ns ns a,b LS- Means with the same letters and column are not significantly different (within the same genotype). A,B Means with the same letters and rows are not significantly different (between 2 genotypes), ns: non- significant.
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The genotype had an effect on the plumage conditions, as the LS (cont) group had a poorer feather condition on the back, tail, wing-coverts and better condition on the wing primaries compared to the LT (cont) group. Also, the LS (–f) group had more damaged feathers on the back, tail, belly and less damage on the leg compared to the LT (–f) group.
Table 4.10b Plumage condition at 39 week of age for LT and LS (Means ± SE and p-value)
Body parts Genotype P-value Group (n = 50, each) LT LS Head cont. 2.24aB (± 0.06) 2.71A (± 0.10) <0.0001 -f 2.06aB ((± 0.07) 2.68A (± 0.12) <0.0001 +f 1.74bB (± 0.09) 2.96A (± 0.10) <0.0001 P-value <0.0001 ns Neck cont. 3.28aB (± 0.08) 3.84aA (± 0.06) <0.0001 -f 2.92bB (± 0.10) 3.62bA (± 0.08) <0.0001 +f 2.38cB (± 0.08) 3.93aA (± 0.06) <0.0001 P-value <0.0001 0.001 Back cont. 2.24aB (± 0.08) 3.04aA (± 0.11) <0.0001 -f 2.14aB (± 0.07) 2.74bA (± 0.10) <0.0001 +f 1.60bB (± 0.07) 3.33aA (± 0.10) <0.0001 P-value <0.0001 0.0001 Rump cont. 2.24aB (± 0.07) 2.51bA (± 0.08) 0.02 -f 2.06aB (± 0.05) 2.66bA (± 0.09) <0.0001 +f 1.76bB (± 0.07) 3.32aA (± 0.10) <0.0001 P-value <0.0001 <0.0001 Tail cont. 2.34B (± 0.07) 2.71bA (± 0.09) 0.001 -f 2.22B (± 0.07) 2.55bA (± 0.08) 0.002 +f 2.28B (± 0.07) 4.46aA (± 0.10) <0.0001 P-value ns <0.0001 Wing-coverts cont. 2.46aB (± 0.08) 2.96aA (± 0.06) <0.0001 -f 2.14bB (± 0.05) 2.72bA (± 0.07) <0.0001 +f 1.88cB (± 0.05) 2.93abA (± 0.09) <0.0001 P-value <0.0001 0.03 Wing primaries cont. 3.80a (± 0.06) 3.38ab (± 0.05) ns -f 3.32bB (± 0.07) 3.68bA (± 0.08) <0.0001 +f 3.36bB (± 0.08) 3.86aA (± 0.07) <0.0001 P-value <0.0001 0.03 Belly cont. 1.70aB (± 0.11) 2.45bA (± 0.08) <0.0001 -f 1.36bB (± 0.08) 2.36bA (± 0.08) <0.0001 +f 1.10bB (± 0.09) 4.91aA (± 0.12) <0.0001 P-value <0.0001 <0.0001 Leg cont. 4.00aB (± 0.00) 3.78aA (± 0.06) 0.003 -f 4.00aB (± 0.00) 3.40bA (± 0.10) <0.0001 +f 3.86b (± 0.06) 3.72a (± 0.08) ns P-value 0.01 0.01 a,b LS-Means with the same letters and column are not significantly different (within the same genotype). A,B Means with the same letters and rows are not significantly different (between 2 genotypes), ns: non- significant.
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The LT (+f) group had a better feather condition and less damage on all body parts compared to the LS (+f) hens (except for the wing primaries and legs). At 39 week of age (table 4.10b) further deterioration of feathers was recorded in both genotypes. In LT, the (cont) group had a significantly worse plumage conditions on the neck, wings, and belly compared to the other groups. The (+f) group had a better feather conditions on the head, neck, back, rump, wing-coverts, and legs compared to the (cont) and (–f) groups. In LS, the (–f) group had a significantly less damaged feathers on the neck, back, and leg compared to the other groups. Also this group (-f) had a better feather condition on the wing-coverts compared to the (cont) group, and on the wing primaries compared to the (+f) group. The (+f) group had a poorer feather condition on the rump, tail and belly than the other groups. The genotype had a significant effect on the plumage condition. Generally, the LS birds showed more damaged feathers on all body parts compared to the corresponding LT groups (except on the wing primaries in the (cont) groups, and on the legs in the (+f) groups).
Cont. -f +f 40,00 a
35,00 b 30,00 a c a b 25,00 a a c b c b 20,00 *** * 15,00 *** 10,00 * *** 5,00 *** Total feather score feather Total 0,00 32 32 39 39
LT LS LT LS
Week of age
Ls-means with the same letters are not significantly different, ns: non-significant. *p< 0.05, ***p< 0.001.
Figure 4.7 Total feather scoring at 32 and 39 weeks of age for LT and LS (Means ± SE and p-value, n = 50)
The sum of feather scores for all body parts at 32 and 39 weeks of age is shown in figure 4.7. There was a difference in the total feather score among LT groups at 32
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(18.38 ± 0.27, 17.24 ± 0.25, 15.60 ± 0.28 mean ± SE for the (cont), (–f) and (+f), respectively, p < 0.001) and 39 weeks of age (24.30 ± 0.32, 22.24 ± 0.27, 19.96 ± 0.31 mean ± SE for the (cont), (–f) and (+f) respectively, p < 0.001) where the (cont) group was scored worst and the (+f) group scored best. In LS, at 32 weeks of age the (–f) group was scored better 18.02 ± 0.28 mean ± SE compared to the (cont) and (+f) groups 19.18 ± 0.24, 19.65 ± 0.28, respectively, (p < 001). At 39 weeks of age, there was a difference in the sum of feather scores among LS groups (27.84 ± 0.34, 26.43 ± 0.45, 33.46 ± 0.31 mean ± SE for the (cont), (–f) and (+f) respectively, p < 0.001) where, the (+f) group had poorer feather conditions and the (–f) had the best. The sum of feather scores for all body parts was higher in all LS groups compared to corresponding LT groups at 32, and 39 weeks of age.
4.1.11 Effect of feather treatment and genotype on skin injuries The results of skin injuries are shown in table 4.11. Skin injuries were significantly more recorded on the neck and wing areas for the LT (cont) group compared to the (+f) group of the same genotype. Also this group (cont) showed more injuries on the belly as well as on the sum of the whole body injuries compared to the other LT groups. More skin injuries were recorded on the feet of the (–f) group compared to the other groups (p = 0.0002). In LS, the (+f) group had more skin injuries on the rump, tail and belly areas as well as the sum of the whole body injuries compared to the other groups. The (–f) group had more injuries (p = 002) on the feet compared to the other groups. Skin injuries were affected by the genotype. More skin injuries were recorded on the rump, tail, belly and comb, as well as the sum of the whole body injuries in the LS (+f) group compared to the LT (+f) group. The LT (–f) group showed less injuries on the comb as well as less injuries in the whole body areas compared to the LS (–f) group. But the genotype had no effect on the skin injuries between the control groups of LT and LS. The sum of the injuries for the whole body is shown in figure 4.8. At 16 weeks of age there were no denuded areas found and the damages of feathers were not extensive. There were only some scratches on the comb, and no differences in skin injuries among the LT groups as well as among the LS groups.
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Table 4.11 Effect of feather treatment and genotype on skin injuries (Means ± SE and p-value)
Body areas Genotype P-value Group (n = 50, each) LT LS Head cont. 0.02 (± 0.01) 0.02 (± 0.01) ns -f 0.01 (± 0.01) 0.01 (± 0.01) ns +f 0.00 (± 0.00) 0.03 (± 0.02) ns P-value ns ns Neck cont. 0.04a (± 0.02) 0.03 (± 0.02) ns -f 0.01ab (± 0.01) 0.02 (± 0.01) ns +f 0.00b (± 0.00) 0.02 (± 0.02) ns P-value 0.03 ns Back cont. 0.02 (± 0.01) 0.01 (± 0.01) ns -f 0.00 (± 0.00) 0.01 (± 0.01) ns +f 0.01 (± 0.01) 0.04 (± 0.02) ns P-value ns ns Rump cont. 0.03 (± 0.02) 0.03b (± 0.02 ) ns -f 0.00 (± 0.00) 0.01b (± 0.01) ns +f 0.01B (± 0.01) 0.11aA (± 0.03) <0.0001 P-value ns 0.002 Tail cont. 0.02 (± 0.01) 0.02b (± 0.01) ns -f 0.01 (± 0.01) 0.01b (± 0.01) ns +f 0.01B (± 0.01) 0.50aA (± 0.09) 0.003 P-value ns <0.001 Wing cont. 0.04a (± 0.02) 0.01 (± 0.01) ns -f 0.01ab (± 0.01) 0.00 (± 0.00) ns +f 0.00b (± 0.00) 0.01 (± 0.01) ns P-value 0.03 ns Belly cont. 0.05a (± 0.02) 0.05b (± 0.02) ns -f 0.00b (± 0.00) 0.03b (± 0.02) ns +f 0.01bB (± 0.01) 1.27aA (± 0.15) <0.0001 P-value 0.01 <0.001 Leg cont. 0.02 (± 0.01) 0.03 (± 0.02) ns -f 0.03 (± 0.02) 0.02 (± 0.01) ns +f 0.03 (± 0.02) 0.03 (± 0.02) ns P-value ns ns ns Comb cont. 1.29 (± 0.05) 1.44 (± 0.07) ns -f 1.17 B (± 0.06) 1.38A (± 0.08) 0.04 +f 1.13 B (± 0.07) 1.41A (± 0.07) 0.004 P-value ns ns Feet cont. 1.22b (± 0.11) 1.17b (± 0.12) ns -f 1.49a (± 0.10) 1.50a (± 0.09) ns +f 1.07b (± 0.11) 1.24b (± 0.10) ns P-value 0.0002 0.002 Total skin cont. 1.53a (± 0.08) 1.65b (± 0.09) ns Injuries * -f 1.24bB (± 0.06) 1.49bA (± 0.08) 0.02 +f 1.20bB (± 0.08) 3.43aA (± 0.25) <0.001 P-value 0.002 <0.001 *The whole body parts except for the feet. a,b Means with the same letters and column are not significantly different (within the same genotype). A,B Means with the same letters and rows are not significantly different (between 2 genotypes), ns: non-significant.
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At the age of 32 and 39 weeks, the LT (cont) group had more skin injuries than the other LT groups (p < 0.001, p < 0.05, respectively). The LS (+f) group had more skin injuries than the other groups of the same genotype at 39 weeks of age (p < 0.001).
LT
6.00 Cont. 5.00 4.00 0.01 -f 3.00 0.01 2.00 +f 1.00 0.00 Skin injuries score injuries Skin 15 32 39 Week of age
LS
p<0.001 6,00 Cont.
5,00 -f 4,00 3,00 +f 2,00 1,00
Skin injuries score 0,00 15 32 39
Week of age
Figure 4.8 Skin injuries at different ages for LT and LS (Means ± SE, n = 50)
4.1.12 Effect of feather treatment and genotype on body weight There were no differences in the body weights among LS groups at the age of 28 and 32 weeks of age, but the (–f) group had a lower body weight at 39 weeks compared to the (+f) group (p = 0.04), with the (cont) group was in between and did not differ from any of them. In LT, the (–f) group had a significantly lower body weight at 28 week of age compared to the other groups (p = 0.02). At 32 week, the (+f) group had a higher body weight compared to the other groups (p = 0.04). There were no differences in the body
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weights among LT groups at 39 weeks of age. The genotype had a significant effect on body weight only between the (–f) groups as the LS hens had a higher body weight at 28 and 39 weeks of age compared to the LT hens (p =0.02; p =0.003, respectively). Body weights were similar in the LT (cont) and (+f) groups compared to the corresponding LS groups (table 4.12).
Table 4.12 Effect of feather treatment and genotype on body weight (g) (Means ± SE and p-value) week Genotype P-value of age Group (n = 50, each) LT LS 28 cont. 1775.96a (± 22.30) 1774.78 (±17.59) ns -f 1695.48bB (± 26.57) 1770.67A (± 14.91) 0.02 +f 1769.48a (± 25.43) 1822.88 (± 14.91) ns P-value 0.02 ns 32 cont. 1836.32b (± 22.44) 1869.76 (± 16.32) ns -f 1835.94b (± 19.72) 1886.69 (± 16.95) ns +f 1900.28a (± 23.47) 1884.70 (± 28.08) ns P-value 0.04 ns 39 cont. 1974.42 (± 43.83) 1975.69ab (± 17.96) ns -f 1933.30B (± 22.12) 2020.83aA (± 17.26) 0.003 +f 1968.94 (± 20.31) 1957.65b (± 26.91) ns P-value ns 0.04 a,b Means with the same letters and column are not significantly different (within the same genotype). A,B Means with the same letters and rows are not significantly different (between 2 genotypes), ns: non- significant.
4.1.13 Effect of feather treatment and genotype on egg production There was no difference in the number of egg production per hen per day among the LT or LS groups (table 4.13). Hens of the LT (cont) group produced higher nest eggs and lowest floor eggs compared to the other groups (p < 0.001). The LT (+f) group laid higher number of eggs on the floor compared to the other groups of the same genotype (p < 0.001). In LS, the (cont) group produced highest floor eggs in comparison with the other LS groups. There was no difference in the nest eggs among groups of the LS. The genotype had no effect on egg production. But, all the LT groups laid significantly higher number of eggs on the floor and lower numbers in the nest compared to the corresponding LS groups. There were no differences in the egg weight or egg shell strength among the LS groups as well as among LT groups. Generally, the LT groups produced heavier eggs with less shell strength compared to the corresponding LS groups (table 4.13).
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Table 4.13 Effect of feather treatment and genotype on egg production, egg weight (g), and egg shell strength (Neuton)
Egg Genotype P-value production Group (n = 50, each) LT LS Nest eggs cont. 33.37aB (± 1.05) 37.80A (± 1.21) 0.01 -f 29.77bB (± 0.97) 35.65A (± 1.07) <0.001 +f 28.15bB (± 1.05) 36.11A (± 1.12) <0.001 P-value <0.001 ns Floor eggs cont. 7.43cA (± 0.33) 4.17aB (± 0.19) <0.001 -f 9.88bA (± 0.29) 3.05bB (± 0.27) <0.001 +f 11.37aA (± 0.61) 3.07bB (± 0.16) <0.001 P-value <0.001 <0.001 Egg production cont. 0.80 (± 0.02) 0.84 (± 0.03) ns /hen/day -f 0.79 (± 0.02) 0.79 (± 0.02) ns +f 0.79 (± 0.03) 0.83 (± 0.03) ns P-value ns ns Egg weight cont. 62.79A (± 1.35) 56.82B (± 1.07) 0.001 -f 62.31A (± 1.24) 57.62B (± 1.10) 0.01 +f 62.85A(± 1.19) 57.24B (± 1.16) 0.002 P-value ns ns ns Egg strength cont. 49.16B (± 0.74) 51.87A (± 0.76) 0.01 -f 49.32B (± 0.64) 53.17A (± 0.69) 0.0001 +f 49.52 (± 0.67) 51.42 (± 0.93) ns p-value ns ns a,b Means with the same letters and column are not significantly different (within the same genotype).A,B Means with the same letters and rows are not significantly different (between 2 genotypes), ns: non- significant.
4.2 Feather treatment and imprinting to loose feathers (second experiment) A- Rearing period 4.2.1 Effect of feather treatment on the rate of feather pecking Table 4.14 shows that there was no difference among groups in the rates of feather pecking. The daytime had no effect on the total number of feather pecking between groups. High rates of feather pecking in the afternoon period were observed (within group) in all groups, however these rates did not reach significance except for the group II (p < 0.05). Figure 4.9 shows that group I exhibited the more severe form of feather pecking 1.93 ± 0.45 (mean ± SE) compared to groups II and III (0.97 ± 0.26, 0.87 ± 0.23, respectively, p < 0.05). On the other hand, there were no differences in gentle and aggressive pecks among groups. The number of bouts per bird was higher (p = 0.04) in group I compared to group III, with group II being intermediary between groups (III & I) but not different from them.
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Also, group I showed a high number of bouts compared to the other groups when the bout size was up to 4 (p= 0.02) (table 4.15).
Table 4.14 Means (±SE) and P-value of the number of feather pecking in total and during daytime in relation to feather treatment Feather Group P-value pecking Group I Group II Group III
Total 10.87 (±1.79) 11.20 (±3.54) 7.80 (±1.79) ns Daytime am 9.39 (±3.50) 6.00 (±3.50) 5.27 (±3.50) ns pm 11.80(±3.50) 16.40(±3.50)* 10.33 (±3.50) ns Means with the same letters are not significantly different, ns: non-significant, *: significantly different within the group p<0.05, n = 60.
16 14 12 Gentle 10 Severe 8 6 Aggressive 4 a Feather pecking Feather b b 2 0 Group I Group II Group III Group
Figure 4.9 Feather pecking forms (means ± SE, p< 0.05, n= 60)
Table 4.15 Effect of feather treatment on bouts of feather pecking and number of pecks per bout (means ± SE, p-value)
Feather Group P-value pecking Group I Group II Group III
Bouts 2.50a (±0.32) 1.83ab (±0.32) 1.56b (±0.27) 0.04 Pecks/ bout Up to 4 1.80a (±0.27) 1.17b (±0.22) 1.03b (±0.16) 0.02
5 to 9 0.47 (±0.12) 0.33 (±0.15) 0.36 (±0.12) ns
10 or more 0.23 (±0.11) 0.23 (±0.12) 0.17 (±0.06) ns Means with the same letters are not significantly different, ns: non-significant, n= 60.
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7 Group I 6 5 Group II 4 ** 3 * Group III 2 1
pecking Feather 0
p ly t m ail el as u T B Leg e Head Neck Back R Wing Br Body region
Figure 4.10 Distribution of feather pecking on various body parts in the rearing period (Means ± SE , n= 60), *p< 0.05, ** p<0.01
4.2.2 Feather pecking directed to different body parts The number of feather pecking directed to the back and rump was greater in group I compared to groups II and III (p <0.05, <0.01, respectively ). The distribution of feather pecking to other body regions was similar among groups (figure 4.10).
Table 4.16 Effect of feather treatment on the total number of hens observed performing various behaviours (% Means ± SE and p-value)
Behaviour Group P-value Group I Group II Group III Feeding 19.54 (±0.99) 21.64 (±1.11) 20.97 (±0.64) ns Drinking 4.87 (±0.44) 5.28 (±0.52) 4.77(±0.48) ns b b a Foraging 28.92 (±1.42) 31.85 (±1.51) 37.59 (±1.07) <0.001 a ab b Preening 10.67 (±1.04) 9.08 (±0.78) 7.69 (±0.69) <0.01 a ab b Walking 4.92 (±0.49) 4.05 (±0.45) 2.87 (±0.38) <0.01 a b b Standing 7.54 (±0.73) 5.59 (±0.47) 5.54 (±0.53) <0.05 Sitting 5.38 (±0.81) 5.33 (±0-97) 4.21 (±0.48) ns b b a Dustbathing 0.87 (±0.26) 0.82 (±0.22) 1.95 (±0.27) <0.001
Means with the same letters are not significantly different, ns: non-significant, n = 60.
4.2.3 Effects of feather treatment on the behavioural activities The percentage of hens performing foraging and dustbathing behaviours was higher in group III compared to other groups (p < 0.001). A higher proportion of hens (p <0.01) was recorded as preening and walking in group I compared to group III, with group II
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being intermediary between groups (III and I) but not different from them. Also, group I showed higher (p <0.05) standing behaviour compared to the other groups (table 4.16).
4.2.4 Effects of feather treatment on plumage condition The results of feather scoring on separate parts of the body at 15 weeks of age are shown in table 4.17. The feathers on the back and wing-coverts were significantly worse in group I than in the other groups (p < 0.001). Group III had a better feather condition on the rump compared to group I (p < 0.05), with group II being intermediary between groups (III & I) but not different from them. The sum of the feather scores for the all body parts (figure 4.11) was higher 8.98 ±0.23 (mean ± SE) in hens of group I than in hens of groups II and III (7.96 ±0.21, 7.66 ±0.19, respectively, p < 0.001).
Table 4.17 Plumage condition at 15 week of age (LS-means ± SE and P-value)
Body parts Group P-value Group I Group II Group III Age 15 weeks Head 0.28 (± 0.06) 0.16 (± 0.05) 0.20 (± 0.06) ns Neck 0.58 (± 0.09) 0.48 (± 0.08) 0.46 (± 0.07) ns Back 0.76a (± 0.08) 0.40b (± 0.07) 0.30b (± 0.08) <0.001 Rump 1.12a (± 0.05) 1.06ab (± 0.04) 0.98b (± 0.02) <0.05 Tail 1.80 (± 0.09) 1.72 (± 0.06) 1.74 (± 0.06) ns Wing-coverts 1.32a (± 0.09) 1.14b (± 0.05) 1.02b (± 0.02) <0.001 Wing primaries 2.64 (± 0.08) 2.56 (± 0.09) 2.54 (± 0.07) ns Belly 0.12 (± 0.05) 0.16 (± 0.05) 0.18 (± 0.05) ns Leg 0.36 (± 0.07) 0.28 (± 0.06) 0.24 (± 0.06) ns LS-Means with the same letters are not significantly different, ns: non-significant, n=60.
Table 4.18 Effect of feather treatment on body weight (g) (LS-means ± SE)
Week Group P-value of age Group I Group II Group III 15 1282.38 b (± 14.95) 1255.74 b (± 14.45) 1324.00 a (± 14.22) 0.0011
LS-Means with the same letters are not significantly different, n = 60.
4.2.5 Effects of feather treatment on body weight Group III had higher body weights at 15 weeks of age compared to the other groups (p = 0.0011) (table 4.18).
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a 10 b b Group I 8 Group II 6 Group III 4
Feather score Feather 2
0 15 Week of age
LS-Means with the same letters are not significantly different. P<0.05, n = 60.
Figure 4.11 Effect of feather treatment on whole body feather score at the age of 15 weeks
B- Laying period 4.2.6 Effect of feather treatment on the rate of feather pecking
Table 4.19 Means (± SE) and p-value of total feather pecking in the PH and WG areas and during daytime in relation to feather treatment
Feather Group P-value pecking Group I Group II Group III
Total 13.75ab (±85) 12.12b (±0.72) 15.30a (±0.83) <0.01 Inside PH 13.94b (±0.70) 12.86 b (±0.74) 16.24a (±0.86) <0.01 Outside
WG 13.56 (±1.55) 11.38 (1.24) 14.36 (±1.41) ns
Daytime am 12.42 (±0.64) 10.96 (±1.11) 11.98 (±1.03) ns b a pm 15.08 (±0.63) 13.28b (±0.91) 18.62 *** (±1.12) <0.05 LS-Means with the same letters are not significantly different, ns: non-significant. ( p-value for the effect of day time within the group: *** P < 0.001), n = 50.
Results from feather pecking activity are shown in table 4.19. There was a significant difference in the amount of feather pecking between birds of groups III and II, where group III exhibited higher rates of feather pecking (p < 0.01), with the group I being
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intermediary between the groups (II & III), but not different from them. In the house, feather pecking was significantly increased (p < 0.01) in group III compared to the other groups. The daytime had an effect on the rate of feather pecking (within the group) only in group III, where higher rates of FP (p < 0.001) were observed in the afternoon period. In group III higher rates of FP were observed (between groups) in the afternoon period compared to the other groups (p < 0.05). Figure 4.12 shows that group III exhibited a more aggressive form of feather pecking 1.89 ± 0.16 (mean ± SE) compared to groups I and II (1.45 ± 0.11, 1.48 ± 0.11, respectively, p < 0.05). Group II showed lower severe pecks 5.26 ± 0.40 (mean ± SE) compared to groups I and III (6.69 ± 0.46, 7.66 ± 0.54, respectively, p< 0.05, < 0.01, respectively). On the other hand, there was no difference in gentle feather pecking among groups.
10 ** Gentle 8 * 6 Severe
4 a bb Aggressive 2
Feather pecking 0 Group I Group II Group III group
Figure 4.12 Feather pecking forms (means ± SE, * p< 0.05, ** p< 0.01, n = 50)
The number of bouts per bird and the pecks per bout were similar among the groups when the bout size was up to 4 and 10 or more. But, group III showed a higher number of bouts compared to groups I and II (p < 0.05) when the bout size was 5 to 9 (table 4.20).
4.2.7 Feather pecking directed to different body parts The number of feather pecking directed to the head and belly observed in the house was higher in group III compared to groups I and II (p<0.01). A lower proportion of feather pecking was directed to the neck and rump in group II 2.2 ± 0.19, 1.14 ± 0.21 (mean ± SE) compared to group III 2.62 ± 0.20, 2.06 ± 0.46, respectively, p < 0.05), with group I being intermediary between groups II and III, but not different from them (figure 4.13).
______73 Results
Table 4.20 Effect of feather treatment on bouts of feather pecking and number of pecks per bout (means ± SE and p-value)
Feather Group P-value pecking Group I Group II Group III Bouts 2.42 (±0.14) 2.32 (±0.14) 2.50 (±0.15) ns Pecks/ bout Up to 4 1.65 (±0.13) 1.67 (±0.12) 1.48 (±0.12) ns
5 to 9 0.48b (±0.06) 0.45b (±0.06) 0.69a (±0.07) <0.05
10 or more 0.29 (±0.04) 0.20(±0.04) 0.33 (±0.05) ns LS-Means with the same letters are not significantly different, ns: non-significant, n = 50.
In the winter garden (figure 4.14) group II showed a lower frequency of feather pecking to the back compared to other groups (p < 0.05). Also, this group (II) exhibited a lower number of pecks directed to the rump compared to group III (p < 0.05), and less pecks directed to the belly compared to group I (p < 0.05).
5 Group I 4 Group II ** * 3 * **
2 Group III
1
pecking Feather 0 k p il g ly ad st e Ta Bel Leg H Neck Bac Rum Win rea B Body region
Figure 4.13 Distribution of feather pecking on various body parts in the PH (Means ± SE, * p <0.05 ** p<0.01), n = 50
4.2.8 Location of feather pecking activity Table 4.21 shows that the rate of feather pecking was similar between the groups at the feeding area, perch and slats. But there were significantly more pecks recorded on the floor in group III compared to group II (p = 0.03).
______74 Results
Group I 5 4 Group II * *
3 Group III 2 * 1 Feather pecking Feather 0
p il t a g lly s m T in Leg Head Neck Back W Be Ru Brea Body region
Figure 4.14 Distribution of feather pecking on various body parts in the WG (Means ± SE, * p <0.05) , n = 50.
Table 4.21 Effect of feather treatment on means (± SE) of feather pecks at 4 locations
Location Group P-value Group I Group II Group III Feeding area 2.84 (±0.35) 2.81(±0.32) 3.30 (±0.30) ns Floor 10.24ab (±0.90) 8.52 b (±0.75) 11.07a (±0.86) 0.03 Perch 0.47 (±0.12) 0.53 (±0.13) 0.70 (±0.18) ns Slats 0.20 (±0.06) 0.26 (±0.07) 0.22 (±0.06) ns LS-Means with the same letters are not significantly different, ns: non-significant, n = 50.
4.2.9 Effect of feather treatment on the behavioural activities The results of behaviour patterns are summarised in table 4.22. Foraging behaviour was higher in group II compared to group III (p <0.05), with group I being intermediary between groups II and III, but not different from them. The percentage of hens performing walking and standing activities was lower in group II compared to the other groups (p < 0.01, < 0.001, respectively).
4.2.10 Effect of feather treatment on feather condition Results from feather scoring at different parts of the body at 32 and 39 weeks of age are shown in table 4.23. At 32 weeks of age, group III had a significantly greater plumage damage on the head, rump, and wing primaries than other groups. Group II had a better
______75 Results
feather condition on the back and belly compared to group III, and a better plumage condition on the rump and wing-coverts compared to the other groups (I & III).
Table 4.22 Effect of feather treatment on the total number of hens observed performing various behaviours (% Means ± SE and p-value)
Behaviour Group P-value Group I Group II Group III Feeding 14.02 (±1.55) 16.56 (±1.83) 15.59 (±1.70) ns Drinking 8.93 (±1.06) 8.07 (±0.97) 8.36(±0.98) ns Foraging 26.14ab (±1.47) 29.68a (±1.50) 25.32b (±1.54) <0.05 Preening 18.69 (±1.21) 19.36 (±1.23) 18.24 (±1.06) ns Walking 7.47a (±0.49) 5.93b (±0.36) 8.23a (±0.60) <0.01 Standing 11.76a (±0.96) 9.37b (±0.64) 13.49a (±1.05) <0.001 Sitting 4.36 (±0.49) 4.05 (±0.50) 4.64 (±0.53) ns Dustbathing 4.11 (±0.66) 3.91 (±0.66) 3.16 (±0.61) ns
Means with the same letters are not significantly different, ns: non-significant, n = 50.
Table 4.23 Feather scoring at 32 and 39 week of age (LS- Means ± SE and p-value) in relation to feather treatment
Body parts Group P-value Group I Group II Group III Age 32 weeks Head 1.61b (± 0.08) 1.72 b (± 0.10) 2.06a (± 0.09) <0.001 Neck 2.08 (± 0.10) 2.10 (± 0.08) 2.32 (± 0.08) ns Back 1.55ab (± 0.10) 1.32b (± 0.07) 1.63a (± 0.08) <0.01 Rump 1.73b (± 0.06) 1.44c (± 0.07) 1.96a (± 0.09) <0.0001 Tail 2.06 (± 0.03) 2.16 (± 0.05) 2.13 (± 0.06) ns Wing-coverts 2.12a (± 0.07) 1.90b (± 0.07) 2.30a (± 0.07) <0.0001 Wing primaries 3.24b (± 0.07) 3.16b (± 0.08) 3.49a (± 0.09) <0.01 Belly 2.10ab (± 0.13) 1.74b (± 0.13) 2.26a (± 0.12) <0.01 Leg 3.00 (± 0.06) 3.06 (± 0.06) 3.04 (± 0.06) ns Age 39 weeks Head 2.29b (± 0.09) 2.46ab (± 0.10) 2.63a (± 0.10) <0.05 Neck 3.73b (± 0.07) 3.65b (± 0.07) 3.94a (± 0.04) <0.001 Back 2.62ab (± 0.08) 2.41b (± 0.08) 2.77a (± 0.07) <0.01 Rump 2.35a (± 0.07) 2.10b (± 0.04) 2.54a (± 0.08) <0.0001 Tail 2.48b (± 0.08) 2.31b (± 0.07) 2.70a (± 0.08) <0.001 Wing-coverts 2.86b (± 0.05) 2.87b (± 0.05) 3.06a (± 0.05) <0.01 Wing primaries 3.93a (± 0.04) 3.60b (± 0.09) 3.95a (± 0.06) <0.001 Belly 3.31a (± 0.07) 2.81b (± 0.10) 3.12a (± 0.06) <0.0001 Leg 3.95 (± 0.04) 3.85 (± 0.06) 4.00 (± 0.10) ns LS-Means with the same letters are not significantly different, ns: non-significant, n = 50.
More deterioration of feathers was recorded with increased age the birds. At 39 weeks of age, group III had a worse feather condition on the most body parts compared to the other groups especially on the neck, tail, and wing-coverts. Group II had a significantly
______76 Results
less feather damage on the rump, wing primaries and belly than the other groups. Group III had a poorer feather condition on the head than group I, and a poorer condition on the back than group II.
35 Group I b c a 30 Group II 25 b b a 20 Group III 15 10
Feather score Feather 5
0 32 39 Week of age
Figure 4.15 Feather score of the whole body at the age of 32 and 39 weeks, n = 50
Table 4.24 Effect of feather treatment on skin injuries at various body parts (LS- Means ± SE, p-value)
Body areas Group P-value Group I Group II Group III Head 0.03 (±0.02) 0.02 (±0.02) 0.08 (±0.03) ns Neck 0.03 (±0.01) 0.02 (±0.01) 0.04 (±0.02) ns Back 0.03 (±0.01) 0.04 (±0.02) 0.05 (±0.02) ns Rump 0.02b (±0.01) 0.04b (±0.02) 0.15a (±0.05) 0.0078 Tail 0.03 (±0.01) 0.03 (±0.01) 0.07 (±0.04) ns Wing 0.05ab (±0.02) 0.02b (±0.01) 0.12a (±0.03) 0.0141 Belly 0.10 (±0.03) 0.06 (±0.02) 0.15 (±0.05) ns Leg 0.02 (±0.01) 0.01 (±0.01) 0.03 (±0.02) ns b Comb 1.08 (±0.07) 1.05b (±0.06) 1.32a (±0.07) 0.0067 a Feet 1.00 (±0.08) 0.65b (±0.07) 0.85ab (±0.08) 0.0028 Total skin 1.41b (±0.11) 1.29b (±0.09) 2.02a(±0.15) <0.0001 Injuries * *The whole body parts except for the feet. Means with the same letters are not significantly different, ns: non-significant, n = 50.
The sum of feather scores for the all body parts was higher in group III 21.19 ± 0.19 (mean ± SE) compared to groups I and II (19.51 ± 0.37, 18.60 ± 0.32, respectively, p < 0.001) at the age of 32 weeks (figure 4.15). At 39 weeks of age, there was a difference in the total feather score among groups, where group III had the worst feather condition
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28.73 ± 0.23 (mean ± SE) compared to group I 27.56 ± 0.25 and group II (which had the best score) 26.08 ± 0.24 (p < 0.01, < 0.001, respectively).
4.2.11 Skin injuries The results of skin injuries are shown in table 4.24. More skin injuries were recorded on the rump and comb for group III (p = 0.0078, 0.0067, respectively) compared to the other groups. Group II had less injuries on the wings compared to group III (p = 0.0141), and less injuries on the feet compared to group I (p = 0.0028).
3 ** Group I 2,5 Group II 2 **
1,5 Group III
Injuries 1 0,5
0 15 32 39 Week of age
Figure 4.16 Skin injuries of the whole body at different ages (** p< 0.01), n = 50
Table 4.25 Effect of feather treatment on the body weight (g) (LS-means ± SE)
Week Group P-value of age Group I Group II Group III 32 1794.63 (± 20.02) 1754.64 (± 20.48) 1797.63 (± 21.40) ns
b a ab 39 1884.49 (± 23.17) 1980.94 (± 25.40) 1930.67 (± 21.17) 0.0043 LS-Means with the same letters are not significantly different, ns: non-significant, n = 50.
The sum of injuries for the whole body is shown in table 4.24. Group III had more injuries 2.02 ± 0.15 (mean ± SE) compared to groups I and II (1.41 ± 0.11, 1.29 ± 0.09, respectively, p<0.0001). Also this group (III) had more injuries at 32 and 39 weeks of age compared to the other groups (p < 0.01) (figure 4.16). There were no differences in skin injuries among the groups at 15 weeks of age.
______78 Results
4.2.12 Effect of feather treatment on body weight
The results are summarised in table 4.25. There were no differences in body weights among groups at the age of 32 weeks. Group II had a higher body weight at 39 weeks of age compared to group I (p = 0.0043), with group III being intermediary between groups (I & II) but not different from them.
4.2.13 Effect of feather treatment on egg production The number of produced eggs per hen per day was lower in group III compared to the other groups (p = 0.0308) (table 4.26). There was a difference in the number of eggs laid in the nest as well as on the floor among the groups, where group III laid more eggs on the floor (p < 0.0001) and less eggs in the nest (p < 0.0001) compared to other groups. Contrarily group I laid more eggs in the nest and less eggs on the floor. There were no differences in the egg weights or egg shell strengths among the groups (table 4.26).
Table 4.26 Effect of feather treatment on egg production, egg weight, and egg shell strength
Egg Group P-value Group I Group II Group III Production (%) 83.65 a (± 1.81) 83.83 a (± 1.71) 78.44 b (± 1.76) 0.0308
Floor egg 4.25 c (± 0.21) 9.22 b (± 0.36) 19.06 a (± 0.60) <0.0001
Nest egg 36.79 a (± 0.80) 32.48 b (± 0.67) 19.44 c (± 0.49) <0.0001
Shell strength 45.23 (± 0.80) 43.39 (± 0.78) 43.04 (± 0.92) ns
Weight 61.07 (± 1.05) 61.45 (± 1.13) 60.42 (± 1.02) ns
LS-Means with the same letters are not significantly different, ns: non-significant, n = 50.
Table 4.27 Duration of TI (LS-Means ± SE, p-value) in relation to feather treatment
Week Group P-value of age Group I Group II Group III 40 216.33 b (± 39.60) 168.67 b (± 43.99) 399.53 a (± 52.72) <0.001
LS-Means with the same letters are not significantly different, n = 50.
______79 Results
4.2.14 Effect of feather treatment on fear reactions of the birds (tonic immobility test) Group III reacted significantly more fearfully and exhibited a longer duration in the tonic immobility test 399.53 ± 52.72 compared to groups I and II (216.33 ± 39.60, 168.67 ± 43.99, respectively, p < 0.001) (table 4.27).
4.2.15 Mortality rate No increased mortality rates could be noticed during the whole study. One hen died from each group during the laying period in the first experiment except in the LS (+F) group 2 hens died. In the second experiment one hen died from group III during the laying period.
______80 Discussion
5 DISCUSSION 5.1 Feather treatment and genotype A- Rearing period Feather pecking Provision of non nutritive foraging material is effective in both preventing and reducing feather pecking behaviour by chicks (HUBER-EICHER and WECHSLER 1997, 1998). This suggestion supports our results in LT, as feather pecking was more pronounced in the (cont) group compared to the (+f) group. This may be attributed to attraction of (+f) birds to the feathers which have been added to the floor. These feathers were manipulated and pecked as a foraging material especially the collected feathers sometimes were attached with some litter substrates and faecal matter from other birds which may increase attractiveness of the birds to the added feathers. MCKEEGAN and SAVORY (2001) noted that if feathers are coming into contact with the litter (either by moulting or via dustbathing) they could take up other odours from the litter itself or from faeces which could contribute to feather attractiveness. Therefore, more foraging behaviour observed in this group led to less feather pecking. The (-f) and (+f) groups exhibited less severe pecks than the (cont) group. This may be attributed to more foraging behaviour in the (+f) group which used feathers as a foraging materials, also collection of feathers 4 times per week in the (-f) group may cause turning of the superficial layer of the litter and hence increased foraging behaviour however, the difference does not reach significance. This is in agreement with HOFFMEYER (1969); WENNRICH (1975); BLOKHUIS (1986) & HUBER- EICHER and WECHSLER (1997, 1998) who reported that there is an inverse relationship between the time the birds spend on exploratory and manipulative foraging behaviour away from the feeder and the rate of feather pecking. The bout size is one parameter used to evaluate the severity of feather pecking in a batch of hens (KJEAR 2000). As shown by KJAER and VESTERGAARD (1999) the bout size might tell more about the severity and risk of damage than the total number of feather pecks. The (cont) group showed large number of bouts compared to the (+f) group. This was reflected in the plumage condition which was the worst in the (cont) group and best in the (+f) group.
______81 Discussion
In LS, the total number of feather pecking, gentle, severe and aggressive pecks, as well as the number of feather pecking bouts were similar among the groups. This was reflected in the plumage condition that was similar among the groups. The overall number and bouts of feather pecking, pecks per bout and feather pecking forms were similar in the (cont) groups of both genotypes. But the (+f) group of LS showed higher rates of feather pecking than the (+f) group of LT. The LS (-f) and (+f) hens exhibited more severe pecks compared to the LT (-f) and (+f) hens. Each genotype seemed to react differently to the changes in the environmental condition such as availability of loose feathers on the floor (either collection or addition of feathers). This is in accordance with KLEIN et al. (2000) who reported that hybrids showed different behavioural reactions to the changes in their environment, i.e., when placed in an improverished environment the strains developed feather pecking at different intensities, indicating that there was a difference between the strains in feather pecking behaviour and their response to changes in the environment (KLEIN et al. 2000).
Feather pecking to different body parts The target of feather pecks depends on the relative location of the pecking and pecked birds (SEDLACKOVA et al. 2004). ALLEN and PERRY (1975) reared growers in cages and reported that in some cages most layers were pecked on the back and in others most were pecked on the wings. This supports our results that showed uneven distribution of feather pecks to the respective body parts. In LS, more pecks were directed to the rump in the (cont.) group which was reflected in the plumage condition that was the worst on the rump in this group compared to the (+f) group. In LT, the control hens pecked more to the wing, rump, back and neck than the (+f) hens. Our results showed that most feather pecks were directed to the tail, wing, rump and back. This is in agreement with WOOD-GUSH and ROWLAND (1973) who noted that most feather pecks were directed to the rump followed by, tail and back. BILICIK and KEELING (1999) noted that most feather pecks were on the tail, followed by the rump and back. Furthermore, KJEAR (2000) observed that feather pecking bouts directed to the tail had longer bout size and that more feather pecking was directed to the tail than to other regions.
______82 Discussion
Other behavioural activities Foraging is regarded as an important behaviour: hens are strongly motivated to perform scratching (FAWC 1991) and in semi-natural conditions birds spend much of their day foraging even if supplied with food (DAWKINS 1989). Provision of feathers on the floor increased foraging behaviour, which is indicated by significantly more hens in the (+f) groups of both genotypes engaged in foraging behaviour compared to other groups of the corresponding genotype. In contrast to birds in a deep-litter system which showed a foraging rate of about 25% (APPLEBY et al. 1989), there was relatively more foraging observed in the present study (about 36 % in the (+f) groups of both genotypes). However, there was no difference in foraging behaviour between the (+f) birds of both genotypes, the LS (+f) birds showed more feather pecking than the LT (+f) birds. One possible explanation of our results could be that there are genetic differences in the quality of foraging behaviour rather than the amount of time spent foraging, and it is possible that some aspects of the foraging substrate were perceived differently in the various strains because of strain-specific differences in the proportions of time spent using different foraging substrates without a difference in the total time spent foraging. This is in accordance with KLEIN et al. (2000) who found that LSL and Dekalb spent the same amount of time foraging, but Dekalb spent significantly more of that time with pecking at the polystyren blocks. Both hybrids developed feather pecking but LSL showed higher rates of feather pecking than Dekalb. In addition, VAN EMOUS (2003) reported strain differences in foraging behaviour, as LB hens showed more scratching behaviour than LSL hens. In the same trend, HUBER-EICHER and WECHSLER (1997) suggested that the development of feather pecking depends not only on the absolute level of foraging activity but also on qualitative aspects of this behaviour. There was a tendency to spent less time in sitting behaviour for the LT (+f) group compared to the other groups of the same genotype. This may be attributed to more foraging behaviour in this group which is associated with several activities such as pecking and moving from one place to another during ground pecking, scratching and food searching. This is in agreement with HUBER-EICHER and WECHSLER (1997) who defined foraging behaviour as exploratory and manipulative pecking away from the feeder or the bird is standing / moving with its head in a lower position than the rump. DUNCAN (1999) & FÖLSCH et al. (2002) reported that birds tend to roam some
______83 Discussion
distance when foraging. Also, the less time spent resting reflected the greater amount of time spent feeding and foraging (CHANNING et al. 2001). Hens in the LT (-f) group spent less time engaged in feeding behaviour compared to other groups of the same genotype. The point of interest is the relationship between body weight and feeding behaviour, as the (-f) group had decreased body weight at the end of the rearing period compared to the control group.
Condition of the integument Feather scoring is often used as a convenient measure to assess feather pecking in flocks of laying hens (HUGHES and DUNCAN 1972; NORGAARD-NIELSEN et al. 1993; GUNNARSSON et al. 1999). In LT, the (cont) group had more damaged plumage and worse feather condition compared to other groups of the same genotype. The possible explanation for our finding is that the difference in feather pecking behaviour among groups was reflected in the plumage condition. In the (cont) group more feather pecking was observed, especially the severe form of this behaviour. There is evidence that feather damage is largely caused by severe feather pecks (BILCIK and KEELING 1999). Consequently, the increased total number of feather pecking and severe pecks found in the (cont) group might explain its poor feather condition. In LS, such differences in the frequency of feather pecking and feather pecking forms were not observed, therefore no difference in the plumage condition among the groups was recorded. Generally, our results demonstrated that there was less plumage deterioration at the end of the rearing period. This finding may be because feathers are moulted three times during the rearing period (APPLEBY et al. 1992) and because feather pecking is not yet as damaging as later on (HUBER-EICHER and SEBÖ 2001b). This is in agreement with PROCTOR and LYNCH (1993) who reported that the relatively low level of feather pecking combined with a quick series of moults during the first months of life may explain why pullets reared commercially often appear to be full feathered, however, feather pecking has actually taken place during the rearing period (JOHNSEN et al. 1998). No differences were observed in the control birds of both genotypes (LT& LS) in the feather pecking rates, forms and bouts. Therefore, the total plumage score was similar
______84 Discussion
and not different between them. On the other hand, the LS (-f) and (+f) groups exhibited more severe pecks compared to the LT (-f) and (+f) groups, also the LS (+f) group showed higher rates of feather pecking compared to the LT (+f) group. This may explain why these LS groups showed a worse feather score compared to corresponding LT groups. This is in agreement with HUBER-EICHER and SEBÖ (2001a) who reported that feather scoring actually measures the amount of severe feather pecks, but because of the proportionality it also reflects the total frequency of feather pecking.
B- Laying period Feather pecking The notion that feather eating may be a precursor to subsequent damaging pecks (SAVORY and MANN 1997; MCKEEGAN and SAVORY 1999) is supported by our results which suggested that the (cont) groups of both genotypes may had lernt to peck and to eat loose feathers from the floor that were available during the rearing period, as feather moulting occurs three times during this period (APPLEBY et al. 1992), and then when there are no more feathers on the floor (during the laying period), attention may have been redirected towards the feathers of conspecifics and hence developed into feather pecking. This is indicated by increased both total amount of FP and severe FP in the control groups compared to the (–f) groups in both genotypes. These results are in agreement with MCKEEGAN and SAVORY (1999) who reported that short feathers were eaten preferentially and long feathers were partially eaten by pullets when short feathers were no longer available from the litter and once feather eating has become established, a low availability of suitable sized feathers may cause feather eating and pecking to be redirected towards other birds. Addition of feathers to the floor (+f) in LT was associated with a reduction in the total amount of FP, the severe form of this behaviour and improved plumage condition, as birds may have been imprinted to feathers on the floor that were manipulated and pecked as foraging materials, especially the added feathers were attached with some litter substrates and faecal matter from other birds. SANDILANDS et al. (2004) reported that birds may gain gustatory and nutritive feedback from preen oil when ingesting feathers. Also, JONES and ROPER (1997) reported there is an evidence that domestic fowl can smell, and chicken behaviour can be affected by olfactory cues (JONES and FAURE 1982) as chicks in a Y-maze test
______85 Discussion
preferred their own soiled wood shavings compared with clean wood shavings or those of a strange chick. Continuous additions of feathers to the litter during the laying period allowed the birds to direct their attention to loose feathers on the floor for both foraging and eating. Thereby FP was reduced and plumage condition was improved. This result is supported by MCKEEGAN and SAVORY (1999) who demonstrated that the majority of feather eating in pen housed pullets is of loose feathers from the littered floor, with fewer being pulled and eaten directly from the plumage of pen-mates. In another study with bantam, of 191 feathers that were seen to be eaten, 50% were obtained from the floor and 50% were pulled from other birds (THOMSON 1997). It was unexpected that the LS (+f) birds exhibited the highest rate of FP, the highest severe form of this behaviour as well as the worst feather score at 39 weeks of age compared to the other groups of the same genotype. Contrary to the LT (+f) birds, provision of feathers stimulated the feather pecking activity in the LS (+f) birds. The possible explanation of this result is that these birds showed less interest and less attraction to the white feathers of the same genotype from the floor and preferred the feathers of conspecifics which may be found more attractive. This is supported by the absence of significant differences in the foraging behaviour among groups of the LS genotype during the laying period. This is in agreement with BOLLIGER and VAGRA (1961) who reported possible characteristics affecting feather attractiveness including texture, colour, shape and perhaps olfactory/ gustatory stimuli provided by preen oil which coats the plumage. Another explanation could be the reflection of light on white feathers which have been added to the litter especially with increased light intensity during the laying period. Also, birds in the outside roofed area WG were exposed to high intensive natural daylight that might be reflected by the white feathers on the floor and hence increased feather pecking, as high light intensity seems to enhance the development of FP and cannibalism in laying hens (HUGHES and DUNCAN 1972; KJAER and VESTERGAARD 1999). The overall number of feather pecking bouts was different among groups of the LT genotype with the (cont) group being the highest and the (+f) group being the lowest, which has been reflected in the feather condition that was in a poorer condition in the (cont) birds and better in the (+f) birds. Although, the overall number of bouts was similar among groups of LS, the (+f) birds showed a higher number of bouts compared
______86 Discussion
to other groups when the bout size was 10 or more. This was reflected in the plumage condition that was very poor in this group. The number of feather pecks per bout was low compared to the results from KJAER (2000) who found an average of 13.8 (LSL) and 7.51 (LB) pecks per bout in hens that were kept in aviary systems, respectively. This may be attributed to the differences in the birds density (12.4 birds/ m2 in the rearing period and 17 birds/ m2 in the laying period vs. 6.4 birds/ m2 in the rearing period and 6 birds/ m2 in the laying period in the current study) and larger group size. Increasing group sizes (KEELING 1994) or increasing stocking densities (APPLEBY et al. 1989) have been linked to an increase in feather pecking behaviour. Moreover, HANSEN and BRAASTAD (1994) observed that in week 12 growers reared at a high density (13 birds per m2 ) feather pecked more than when reared at a low density (6.5 birds per m2 ). The location of the birds within the house strongly influenced feather pecking. It has been shown that less feather pecking is performed on perches than in areas with litter (NICOL et. al. 1999). The highest frequency of feather pecking was recorded on the floor in the LT (cont) group compared to other groups of the same genotype. Also, this group showed more feather pecks on the feeding area and slats compared to the other groups, which was reflected in the poor feather condition. The LS (+f) birds showed high rates of feather pecking on the floor compared to the (–f) group of the same genotype and high rates on the four locations compared to the LT (+f) birds which was reflected also in the worst plumage condition in the LS (+f) birds. Our results indicated that the highest frequency of feather pecking was recorded in the floor area, followed by the feeding area in both genotypes, perch and slats in the (LS) and by slats and perch in the (LT) groups. This is in agreement with WECHSLER and HUBER-EICHER (1998) who reported that hens situated on the floor received more feather pecks (85%) and hens on the perches were less pecked.
Durinal rhythm of feather pecking Feather treatment significantly effected the diurnal rhythm of feather pecking in some groups in that is was more frequency observed in the afternoon. This is in accordance with a study of PRESTON (1987) who found feather pecking in general to occur mostly in the afternoon. Birds showed increased activities in the afternoon with more foraging,
______87 Discussion
dustbathing, movement and feeding (VESTERGAARD 1982b; APPLEBY et al. 1992; CHANNING et al. 2001), which might be accompanied by more feather pecking. However, SAVORY (1995) reported that diurnal rhythm of feather pecking corresponds more to dustbathing than to feeding.
Feather pecking to different body parts The results from behavioural observations show that, even considering the differences in the areas of the body regions, there are differences in the number of pecks that are directed towards them. This difference in the attractiveness of the regions may be a consequence of the structure of the feathers, or on the ease of access to a particular part of the body (BILCIK and KEELING 1999). In LT, most feather pecks in the house were directed to the head region than to other body regions. This may be due to feeding competition which lead to an increase in aggressive pecking that was directed mainly to the head / neck regions. This is in accordance with HOFFMEYER (1969) & BLOKHUIS (1986) who reported that feather pecking was linked to other behaviour patterns such as feeding. Also, indoors more feather pecks were directed to the tail, back and rump and these pecks were higher in the (cont) group compared to other groups which resulted in a poor feather condition of this group. In the WG, most feather pecks were directed to the tail followed by the rump and back and these pecks were higher in the (cont) group compared to the (+f) group. Similar results for pecking to body parts were observed by (SAVORY and MANN 1997; BILICIK and KEELING 1999). Within LS, hens in the (cont) group pecked more to most of the body regions compared to (-f) group in the house and in the WG. However, the differences do not reach significance. This was reflected in a poor feather condition of this group. The (+f) hens pecked more to the tail and belly in the house and to the belly in the WG compared to hens of other groups. A possible explanation would be that the belly area was soft and the feathers on it were more delicate so that this may have encouraged the birds to pull out feathers. This is in accordance with MCKEEGAN and SAVORY (1999) who reported that downy feathers which tend to have a softer rachis were easier swallowed and were therefore preferred over other types of short feathers. Also, the caudal parts which include the tail, rump, and belly were away from the head may be safe and easy
______88 Discussion
accessible for the pecker, especially when the recipient birds performed dustbathing (VESTERGAARD 1994).
Other behavioural activities Hens of the LT (+f) group spent more time performing foraging behaviour than hens of the other groups. This may explain why these birds showed less feather pecking rates, as birds may find feathers from the floor and its attached litter and faeces a good substrate for foraging behaviour and more attractive than feathers of conspecifics. Also resting behaviour (sitting or standing) was decreased in the (+f) group compared to the other groups so these birds were less likely to receive feather pecks. This is in accordance with WECHSLER and HUBER-EICHER (1998) who concluded that hens resting on the floor were the main targets for feather peckers, whereas, hens engaged in foraging and preening were less often pecked. This confirms our results that showed more preening activities and less severe feather pecking in the LT (-f) group compared to the (cont) of the same genotype and the (-f) group of LS. The results of the behavioural observations show that there was no difference in the foraging behaviour among the groups of the LS genotype and provision of white feathers on the floor do not encourage foraging behaviour in the (+f) birds. The LS (cont) group showed more walking behaviour and more feather pecking compared to the (-f) group. The absence of feathers on the floor led to redirection of feather pecking towards other birds in the groups that had previously had feathers on the floor in the rearing period (control group), and hence more pacing and moving behaviour was observed. This explanation is in agreement with NEWBERRY et al. (1988) & RIBER et al. (in press) who reported that an increase in general activity leads to increases in feather pecking behaviour. KLEIN et al. (2000) reported that increased moving is a sign of frustration. It can be interpreted as an attempt to increase the chance of meeting the pecker birds. WOOD-GUSH (1972) observed that laying hens, when kept in barren battery cages show intensive pacing in the pre-laying phase when searching for a nest site. He also reported excessive pacing of laying hens as a response to frustration in a feeding situation. MAHBOUB et al. (2002) found that walking was associated with a high probability for the occurrence of being pecked.
______89 Discussion
Dustbathing behaviour was higher in all groups of the LS genotype compared to the corresponding groups of LT. This may explain why groups of LS showed more feather pecking rates and a poor feather condition compared to the corresponding groups of LT. This is in agreement with VESTERGAARD (1994) who suggested that feather pecking is related to dustbathing. Our behavioural observations showed that most dustbathing behaviour has occurred in the WG, where shredded tree bark was used as a substrate. Therefore, these dark substrate particles may be scattered on and among bird’s feathers during bouts of dustbathing. The contrast between white feathers of LS and these dark particles may stimulate more feather pecking than the uniformly brown feathers of LT. SAVORY and MANN (1997) reported that mean pecking damage scores at 10 weeks of age in a mixed group of light and dark coloured bantam bullets in a pen with wood shavings as a litter, was higher in dark than in light birds. However, SAVORY and MANN (1999) did not find a significant effect of the litter substrate (wood-shavings and peat) on the pecking damages. The only significant difference in pecking behaviour was evident for the light birds response to particles on dark birds in the wood shaving group. This suggests that light-coloured particles on dark plumage might be a more potent pecking stimulus than dark particles on light plumage, and the strength of this stimulus may be greater for light birds. Our explanation is in contrast to this findings. This may be attributed to the litter substrate (wood-shavings) which was used. Wood-shavings may be an inferior dustbathing substrate (SANOTRA et al. 1995) and less attractive foraging substrate (HUBER-EICHER and WECHSLER 1997). Also, birds in the WG were exposed to high intensive natural day light. It has been found that an increase of the brightness of the light increases the level of feather pecking (HUGHES and DUNCAN 1972; ALLEN and PERRY 1975; KJAER and VESTERGAARD 1999).
Condition of the integument Plumage deterioration increased with the age during the laying period in all groups of both genotypes. A rise in the level of feather pecking has been found to correspond with the rise in gonadal hormones inducing egg laying (HUGHES 1982). RODENBURG and KOENE (2003) reported that the intensity and severity of feather pecking seem to depend on age. Gentle feather pecking is mostly observed in young chickens (KJEAR and SORENSEN 1997; WECHSLER et al. 1998) and severe feather pecking is more
______90 Discussion
often seen at a later age (HUBER-EICHER and SEBÖ 2001b). This may explain the rapid changes in plumage condition of different body parts that were recorded during the laying period. Hens in the control groups had worse feather scoring than hens in the (–f) groups of both genotypes. This may be attributed to the difference in feather pecking behaviour among groups which was reflected in the plumage condition. As birds in the (cont) groups have been learnt to peck and eat feathers from the floor, and due to the lack of feathers from the floor during the laying period they pecked, pulled out and ate feathers from penmates. Therefore, feather pecking rates as well as the severe form of this behaviour were highest in the (cont) groups which led to the deterioration of feathers. This is in agreement with WECHSLER and HUBER-EICHER (1998); WECHSLER et al. (1998) & HUBER-EICHER and SEBÖ (2001a, b) who found that individuals characterised by relatively high rates of feather pecking performed more the severe form of this behaviour. The finding that most feather damage is a result of severe feather pecks is supported by the result of BILCIK and KEELING (1999) in laying hens and VESTERGAARD et al (1993) in red junglefowl. They correlated pooled numbers of feather pecks received during dustbathing with feather scores at the end of experiment and found a significant correlation. LT hens in the (+f) group had the best feather score compared to other groups of the same genotype. This may be attributed to less frequent feather pecking in this group as well as less severe feather pecks. The possible explanation of our finding is that continuous addition of feathers on the floor increased foraging behaviour which distracted the birds away from feathers of conspecifics. The finding that feather scores in the LT (+f) group were better than in the (-f) hens of the same genotype, may be due to that few birds in the (-f) group had lernt to peck feathers from the floor during the rearing period, as it is practically impossible to collect all feathers and to clear the litter from feathers at all times. Therefore, these birds peck and eat feathers from conspecifics and showed a larger bout size compared to the (+f) group which was reflected in the feather condition that was poorer in this group compared to the (+f) birds. The LS hens in (+f) group showed the worse feather scoring at 32 weeks of age compared to the (–f) group, also this group showed the worst feather score at 39 weeks of age compared to the other groups of the same genotype. This may be due to the
______91 Discussion
highest rate of FP as well as the highest severe form of this behaviour in this group compared to other groups and compared to the LT hens in the (+f) group. Therefore, feather pecking activity that was highest in this group led to the destruction of feathers. In addition, damaged feathers stimulate more feather pecks (McADIE and KEELING 2000). The ease with which feathers are pulled out may affect the relationship between pecks received and feather condition. A part from the feathers on the belly is being are easily accessibly as the target birds were often sitting on perches, thereby providing easy access to the belly from the ground. The belly region is also easy accessible during feeding, foraging or while standing on the floor. Feathers on the legs are also quite easily removed and this may explain why large bald patches resulted from relatively few pecks. Pulled out feathers were reported to be frequently swallowed and competition for pulled out feathers was occasionally observed (BILICIK and KEELING 1999). The rump and back were also denuded. SAVORY and MANN (1997, 1999) observed that juveniles most commonly peck the small oilier feathers near the tail and preen gland, and that the rump region is more exposed to feather pecking than other body regions. More skin injuries were recorded in the (cont) group compared to the LT groups, and in the LS (+f) group compared to other groups of the same genotype. This finding indicated that a higher frequency of feather pecking and more severe form of this behaviour resulted not only into a destruction of feathers but also caused injuries of the skin. This is in accordance with BESSEI (1983) who reported that cannibalism is often seen as a severe form of feather pecking. In addition, CLOUTIER et al. (2000) found a positive correlation between feather pecking and cannibalism. The pattern of skin injuries increased with the age of the birds and related to the increase in the frequency and severity of feather pecking. During the rearing period where feather pecking was not so severe to cause feather damages and denuded areas, there were only few pecks and scratches on the comb region. In contrast, more feather pecking interactions were observed during the laying period from which proportionally more were judged as severe, led to more damage of the feathers, denuded areas and skin injuries. The LT control birds had more skin injuries on the neck, wing coverts and belly compared to the LT groups. This may be attributed to the condition of the plumage that was the worst in
______92 Discussion
the hens of the control group hence the possibility to suffer skin injuries increased. The LS (+f) birds had more skin injuries on the denuded rump, belly and tail. The possible explanation of this result is that, the belly region was the main target for the pecking and pulling out of feathers, and many birds in the LS (+f) birds had a completely denuded abdomen. The skin of this region is extremely delicate. Therefore, pecks lead to excessive bleeding, which stimulates more birds to peck at this area. Also pulling out of the tail feathers, which are characterised by strong shaft and fixation in the body, is associated with bleeding which attracts more birds to peck at it. This is in accordance with HUBER-EICHER and WECHSLER (1997) & SAVORY and MANN (1997) who reported that wounded birds due to sever feather pecking are attractive for others to peck at. Also, McADIE and KEELING (2000) reported that bleeding associated with feather damage can elicit cannibalistic attacks. Although, the LT control birds and LS (+f) birds were more aggressive than other groups of the corresponding genotype, the head region showed fewer injuries with absence of significant differences among groups. This may be attributed to the flexible movement of the head away from the pecker, hiding the head down or escape of pecked bird to slatted areas (FREIRE et al. 2003) or perches in order to avoid attacks or repeated attacks. This is in accordance with MCLEAN et al. (1986); GIBSON et al. (1988) & CORDINER and SAVORY (2001) who found that low-ranked birds are avoiding dominant ones by using the perches at day-time. This theory of perch use as a method of social escape was also discussed by YNGVESSON (2002). Foot condition may deteriorate severely if the litter becomes wet in common floor systems (HILL 1986). ENGSTRÖM and SCHALLER (1993) & TAUSON and ABRAHAMSSON (1994) reported that Bumble foot syndrome (inflamed foot pad lesions) is often associated with the use of perches which are soiled by manure/litter coming in contact with the perch surface, especially when litter moisture is high (WANG et al. 1998). Perch design and genotype have clear effects on the incidence of this disorder (TAUSON and ABRAHAMSSON 1994). The feet were more damaged in the (-f) groups of both genotypes compared to other groups of the same genotype. The possible explanation of our finding is that presence of feathers on the floor may protect the foot from direct contact with wet litter and faecal matters. Therefore, the (-f) groups exhibited more foot damage.
______93 Discussion
There was no genotype effect on skin injuries between the control birds of both genotypes. But the LS (-f) and (+f) groups were recorded for more injuries compared to the LT (-f) and (+f) groups respectively. This may be attributed to more severe pecks in these groups which led to more skin injuries as recorded by many authors. Feather pecking can trigger cannibalism after severe plucking of feathers and following bleeding from the skin (KEELING 1995; SAVORY 1995). Also, this may be related to strain differences in claw strength and growth rate. VAN EMOUS (2003) reported that claws of white hens grow faster and are stronger than those of brown hens. This may explain why white birds had more injuries, especially with denuded areas that are easier to be injured with strong claws.
Effect of feather treatment and genotype on egg production Feather treatment and genotype had no effect on the number of eggs produced (eggs per hen and day). The point of interest is that there was a genotype difference in the number of eggs that were laid on the floor in relation to the provision of feathers, as provision of feathers in the LT genotype is associated with increases in the number of floor eggs. Contrary, the provision of feathers in the LS genotype is associated with a decrease in the number of floor eggs. The LS genotype produced heavier eggs with less shell strength compared to the corresponding group of LT. This is in accordance with many studies which have demonstrated shell strength differences between strains (SIEGEL et al. 1978; RENDEN et al. 1984; DE KETELAERE 2002).
5.2 Feather treatment and imprinting to loose feathers Feather pecking As suggested by SAVORY and MANN (1997), the development of bird pecking may be reinforced by the ingestion of loose feathers from the floor which is supported in the current experiment. Birds in group III (which had feathers added to the floor in the rearing period), showed high rates of feather pecking in the laying period compared to group II and feather pecking was performed more frequently in the house compared to the winter garden. This may be attributed to imprinting of these birds in group III to loose feathers from the floor that were added continuously during the rearing period and were used as a substrate for pecking, scratching and sometimes eating. Then, when feathers on the floor are absent during the laying period (as a result of collection of the
______94 Discussion
feathers), the bird’s attention was redirected to the feathers of other birds, hence developed higher rates of feather pecking, especially the severe form of this behaviour which is associated with pulling out, plucking and eating of feathers. Despite the lack of difference in the rate of gentle feather pecks among groups, our results showed that groups which are exposed to feathers during the rearing period (I& III) exhibited higher damaging pecks compared to group II, and it was obvious that the provision of feathers in group III had more pronounced effects on the severity of feather pecking than experience to moulted feathers on the floor in the group I. Group I exhibited the most severe pecks, the highest number of bouts as well as the largest bout size (number of feather pecks per bout) than other groups in the rearing period which resulted in the worst feather cover in this group. Our result is in agreement with FORKMAN (2003) who found that the birds that previously had feathers on the floor (in rearing period) showed a higher number of severe feather pecks than those that had not. However, there was no difference in the number of gentle feather pecks. The relatively low levels of feather pecking observed in the current study may be due to environmental and husbandry factors associated with the study, such as lighting. For example, KJEAR and VESTERGAARD (1999) showed that gentle feather pecking was approximately 20 times more frequent when hens were reared at 3 lux compared to 30 lux, whereas severe pecks were 2-3 times more frequent in birds reared at 30 lux. The light intensity of about 5 lux in the present study might not have been great enough to induce high rates of feather pecking. The distribution of feather pecking over the defined areas of the body showed that most feather pecking in the rearing period was directed to the tail, wing, rump and back. This is in agreement with WECHSLER et al. (1998) who observed in an experiment with grower LSL that most feather pecks were directed to the wing, tail and rump. However, there was no difference among groups in the number of pecks directed to the wing. Group I showed more damaged feathers on the wing-coverts compared to other groups. This may be attributed to enhanced walking behaviour which was observed in this group that increases the bird’s frequency to have contact with other penmates and the walls of the pen. This explanation is in accordance with BILCIK and KEELING (1999) who related the damages on the wing and tail to the abrasion against other birds or against the walls of the pen.
______95 Discussion
During the laying period, the majority of feather pecks occurred on the floor followed by feeding area, perch and slats. Birds in group III showed more feather pecking on the floor compared to group II. This may be attributed to many behaviours performed on the floor such as, sitting or standing on the floor, and dustbathing behaviour which is associated with a high frequency of feather pecking (VESTERGAARD 1994; HUBER- EICHER and WECHSELER 1998). Indoors, more feather pecking was directed to the head and neck, rump and belly. While in the winter garden, more pecks were directed to the back, rump and belly. These pecks were higher in birds that were previously exposed to loose feathers on the floor, which support the suggestion that loose feathers (either moulted or added to the floor) may play a role in the development of feather pecking (JOHNSEN and VESTERGAARD 1997; SAVORY and MANN 1997, 1999; FORKMAN 3003; HARLANDER-MATAUSCHEK and BESSEI 2004, 2005). ODEN et al. (2002) reported that aggression at feeders increased when the need for feed increased, for example, if the birds are partly denuded due to feather pecking. This finding support our results, as hens in group III, which showed the highest rate of feather pecking and worst feather condition with many denuded areas, were more aggressive and pecked more at the head than hens in other groups. The caudal area of hens in groups I & III (back, rump and belly) was subjected to more pecks. WOOD-GUSH and ROWLAND (1973) in an experiment with pen-housed Brown Leghorn indicated that the most feather pecks were delivered to the rump followed by the tail and the back. SAVORY and MANN (1999) reported that feather loss typically commence at the base of the back where litter particles tend to lie and where there are relatively short feathers, which may be both easily plucked and preferred for eating. Conceivably, the proximity of the adjacent preen gland might reinforce such a preference, and this could explain why destructive pecking is sometimes targeted at the gland. Although, the tail is subjected to a high number of feather pecks, there was no difference in the number of feather pecks directed at the tail among groups in this experiment. Feather pecking activity increased in all groups during the day, with more feather pecks occurred in the afternoon compared to the morning period. However, these rates did not reach significance except for group II in the rearing period (within the group) and in group III in the laying period (within the group and between groups). This is in
______96 Discussion
accordance with SAVORY (1995) who reported that more feather pecking was found at the end of the light period.
Other behavioural activities Provision of loose feathers to the floor in group III (rearing period) was associated with increased foraging behaviour in this group compared to other groups, as birds in group III may have been imprinted to loose feathers from the floor and used feathers soiled with litter as a foraging substrates which directed the attention of the birds away from feathers of penmates. Consequently, severe feather pecks were greatly reduced and feather condition was improved. This is in accordance with BLOKHUIS (1986) who suggested that feather pecking is redirected foraging. Hens in group I spent more time in walking and standing behaviours. This may explain why this group showed more feather pecking and worse plumage condition, as more standing behaviour and movement activities were associated with more feather pecking (WECHSLER and HUBER-EICHER 1998; WECHSLER et al. 1998; CHANNING et al. 2001). Although birds in group III spent significantly more time engaged in dustbathing behaviour compared to the other groups, this group showed less severe feather pecking and better plumage condition than group I. This finding is in contrast with VESTERGAARD et al. (1993) who observed more feather pecking during dustbathing activity. The possible explanation of our finding is that the birds of group III were experienced to loose feathers from the floor and may have found this more attractive for pecking than for feathers of penmates. However, WECHSLER et al. (1998) reported that most of the feather pecking occurred whilst the receiver was resting and the lowest whilst duatbathing. Collection of feathers from the floor in group III (laying period) was associated with a significant decrease in foraging behaviour. In contrast, addition of feathers to the floor in group II was associated with increased foraging and foraging related behaviours. This may explain why group III showed more pecks and a worse plumage condition than group II. Our results are in agreement with HUBER-EICHER and WECHSLER (1998) who found that in pens where the foraging materials were removed, the percentage of chicks engaged in foraging behaviour was significantly reduced and the rate of feather pecking interactions was significantly increased.
______97 Discussion
A lack of feathers on the floor during the laying period may be associated with frustration in the birds that were exposed to loose feathers from the floor during the rearing period. Consequently, feather pecking rates increased. This was indicated by increased walking behaviour in groups I & III compared to group II. This is in agreement with KLEIN et al. (2000) who reported that increased moving is a sign of frustration. Frustration may stimulate the redirection of pecking behaviour at feathers (LINDBERG and NICOL 1994). In addition, the birds in groups I & III spent more time engaged in resting behaviour (standing and sitting) than birds in group II. This may explain why these groups that were experienced to loose feathers from the floor in the rearing period showed more feather pecking, the severe form of this behaviour and poor plumage condition compared to group II. This is in agreement with many authors who indicated that the majority of feather pecking occurs while the recipient birds were resting (WECHSLER and HUBER-EICHERC1998; WECHSLER et al. 1998).
Feather condition Hens that were experienced to loose feathers from the floor (groups I & III) had worse feather condition than hens in group II. The possible explanation for our finding is that the difference in feather pecking behaviour among groups, especially pecks which were judged as severe were reflected in the feather condition. Absence of loose feathers on the floor resulted in a redirection of ground pecking to the feathers of penmates not only for pecking but also sometimes for eating of plucked feathers. Therefore, high rates of severe feather pecking activity in groups I & III led to the destruction of feathers. This is in accordance with VESTERGAARD et al. (1993) and BILCIK and KEELING (1999) who demonstrated that severe feather pecks and not gentle feather pecks or aggressive pecks are the cause of most of the feather damages on the body of laying hens. More deterioration of feathers was recorded at 39 weeks of age especially in the groups that were experienced to loose feathers from the floor. There was a significant difference among groups in total feather scoring, as group II was scored best and group III scored worst. This supports our suggestion that imprinting of birds to loose feathers that were added to the floor had more deteriorating effect on the feather cover compared to the feather condition of those birds that were exposed to moulted loose feathers.
______98 Discussion
However, experience to loose feathers (moulted or added) in early rearing is considered as a precursor to feather pecking. The first feather loss was observed at the belly and rump regions in groups I & III, at the legs in all groups, wing coverts and neck in group III. SAVORY and MANN (1997) observed that most feather pecks were delivered on the back and thigh in Hisex hens and White Leghorns respectively. NORGAARD-NIELSON et al. (1993) found in White Leghorns more feather pecking directed at the breast and back. According to our inside observations, the rump received the most of feather pecks followed by the belly in group III. In the WG, groups experienced to loose feathers from the floor pecked more at the back, rump and belly compared to group II. A possible explanation would be that the soft delicate skin and easy access to the belly region as well as the soft and short feathers in this region encouraged the experienced birds to loose feathers to peck, pull out and eat feathers from this region. SAVORY and MANN (1997) observed that feathers around the preen gland were often removed when pecking damage took place. Group III had the worst feather condition on the head and neck regions. This may be attributed to more aggressive pecks in this group which were mainly directed to the head / neck. This is in accordance with BILCIK and KEELING (1999) who reported that aggressive pecks were the cause of most feather damage on the head. Hens in group III showed more severe skin injuries than other groups at 32 and 39 weeks of age. This may be attributed to more feather pecking and more severity of pecks in this group (that had imprinted to feathers which were added to the floor during the rearing period), which led not only to destruction of the plumage but also denuded areas and skin injuries. This is in accordance with McADIE and KEELING (2000) who reported that, hens which have been denuded by feather pecking are therefore lacking the protection of feather cover, are more likely to be victims of cannibalism as their bare skin may be more easily damaged by scratches and pecks. In addition, the blood resulting from these injuries may also elicit cannibalistic attacks. KJEAR and ISAKESN (1998) found more injuries from pecking followed by a higher mortality from cannibalism. Consequently, more pecks directed to the rump in this group led to a lack of feather cover and more skin injuries in this region. Also, more aggression was observed in this group and resulted in more injuries in the comb region. The point of interest is that group II in contrast to the first experiment experienced significantly
______99 Discussion
lower injuries on their feet. This supports our suggestion that provision of feathers on the floor may prevent direct contact between faecal matter and feet, which subsequently reduces the incidence of bumble foot.
Egg production Egg production was affected by feather pecking rates. Group III which showed high rates of feather pecking produced less eggs (per hen per day) compared to other groups. This is in accordance with JOHNSEN et al. (1998) who found that feather pecking was associated with a decreased productivity. BIEDERMANN et al. (1993) reported that brown layers with an intact plumage had a reduced mortality, a higher egg production, and fewer cracked eggs. In addition, CHARLES (1980) reported that a poor feather cover can depress production. The point of interest is that hens in group III had significantly more eggs laid on the floor and therefore lower nest eggs compared to other groups. This is in contrast to our finding in the first experiment which suggested that the provision of feathers on the floor was associated with a significantly higher number of eggs laid on the floor in LT hens. The possible explanation of this finding is that the provision of feathers in early rearing is associated with imprinting of chicks to the feathers from the floor, and that they retain this imprinting during the laying period.
Tonic immobility Hens in group III which had the worst feather condition reacted more fearfully in the TI test than the other groups. This is in accordance with ADAMS et al. (1978); VESTERGAARD et al. (1993) & JOHNSEN et al. (1998) who reported that birds with the most feather damage were the most fearful. In contrast, birds with a better feather cover tended to be less fearful (QUART and ADAMS 1982). Also, VESTERGAARD et al. (1993) reported that individual Red Junglefowl characterized as high feather peckers were found to be the most fearful as estimated by TI reactions. Similar trends were founding in White Leghorns of the low feather pecking line which showed shorter TI fear reactions at 14 weeks of age than those of the high pecking line (BLOKHUIS and BEUTLER 1992). The duration of TI has been shown to correlate positively with fear level measured by the plasma corticosterone levels and other physiological measurements such as heterophil/lymphocyte ratio (JONES et al. 1988; CAMPO et al.2001 ; EL-LETHY et al.2001).
______100 Discussion
5.3 Conclusions The results of this study suggest that loose feathers from the floor may play an important role in the development of feather pecking behaviour in LT & LS laying hens.
Our results support the hypothesis that “feather pecking can be viewed as foraging behaviour” in which the birds first learn to peck at loose feathers on the floor and then, when there are no more feathers available, the propensity to develop severe feather pecking increases.
There were great genotype differences in response to feather availability on the floor, as collection of feathers from the floor reduced severe feather pecking and improved plumage condition in LT, but not in LS laying hens during the rearing period. However, collection of feathers resulted in reduced severe feather pecking and improved plumage and skin conditions (within both genotypes) during the laying period.
Also, quite large differences between genotypes in feather pecking behaviour were found in response to the feathers of conspecifics which have been added to the litter. Addition of brown feathers to the floor in LT hens was associated with a reduction in feather pecking, the severe form of this behaviour and improved plumage and skin conditions. Contrary, the addition of white feathers to the floor in LS was associated with the highest rate of feather pecking, the highest severe form of this behaviour as well as the worst feather and skin conditions in the laying period compared to other groups of the same genotype.
Our results suggest that imprinting of birds to loose feathers that were added to the floor had more deteriorating effects on the feather cover caused by severe feather pecks in comparison to the feather condition of those birds that were exposed to moulted loose feathers. However, experience to loose feathers from the floor (moulted or added) during early rearing can be considered as a precursor to feather pecking.
The provision of feathers on the floor during the rearing period is associated with a significantly higher number of eggs laid on the floor during the laying period in LT
______101 Discussion
hens. Also, the provision of feathers on the floor is associated with a reduction in inflamed foot pads in the current study in both genotypes.
There were no genotype differences in the number of eggs produced, although LT hens produced heavier eggs with less shell strength compared to LS hens. Hens in the group with least feather pecking and intact plumage had a higher egg production and heavier body weights than hens in the group that were severely pecked with a poorer feather cover in the second experiment.
Poorly feathered hens showed longer TI and were more fearful than hens with an intact plumage.
Further studies on the effect of feather availability on the floor (genotype, colour, light intensity and period) are needed for the clarification of our findings.
______102 Summary
6 SUMMARY Sameh Gad Abdel-hak Ramadan Genetic and environmental factors influencing behaviour and health of laying hens with emphasis on feather pecking
Clinic for Birds and Reptiles, Faculty of Veterinary Medicine, University Leipzig and Animal Husbandry and Animal Ecology Group, Institute of Agricultural and Nutritional Sciences, Natural Sciences Faculty III, Martin-Luther University Halle-Wittenberg
106 pages, 25 figures, 33 tables, 293 references Keywords: Feather availability, imprinting, feather pecking, laying hens Submitted in May 2007
The aim of this work was to investigate the effects of feather availability and imprinting to loose feathers in the litter on the incidence of feather pecking behaviour (FP), condition of the integument and fear reactions in two genotypes of laying hens. In experiment I, Lohmann Tradition (LT) and Lohmann Silver (LS) were raised from day one in 3 groups of 60 birds for each genotype in a straw-bedded pen. Each genotype was allocated to one of three feather treatments: (1) without feathers (-f) on the floor (feathers were collected 4 times/week, (2) with feathers (+f), (3) the control (cont) with no feather treatment. At 16 weeks of age, fifty randomly selected hens from each group were allocated to six identical pens. Birds of each pen and of both genotypes received the same feather treatment as in the rearing period. Experiment II studied the effect of imprinting to loose feathers from the floor. Laying hens of the same genotype (LT) were kept in three groups according to the feather treatment. A- Group I: No feather treatment. B- Group II: Feathers from the floor were collected. C- Group III: Feathers from the same genotype were added to the floor. During the laying period the treatments of groups (II & III) were switched, in which feathers were collected from the floor of Group III and collected feathers were added to the floor of Group II. Birds were observed directly for feather pecking and other behavioural activities at 6, 10, 15, 20, 25, 30, 35 and 40 weeks of age. All birds were individually scored for feather damage at 15, 32 and 39 weeks of age. Results from experiment I during the rearing period showed no difference in feather pecking forms and feather scoring among the LS groups. In LT, control birds exhibited a higher number of severe form of pecking and showed a worst feather score compared
______103 Summary
to the (–f) and (+f) groups (p<0.001). During laying period, the rate of FP and number of severe FP observed for the (cont) group were higher than observed for (–f) in LS (p<0.01, p<0.001, respectively). The LS control birds showed a poor feather condition at 32 and 39 weeks of age compared to the (-f) birds. The highest rate of FP as well as the highest number of severe FP were observed in the (+f) group of LS compared to other groups of the same genotype as well as the worst feather score at 39 weeks of age. In LT, high rates of feather pecking as well as the severe form of this behaviour were observed in the (cont) compared to (-f) or (+f) groups (p<0.001). There was a significant difference among groups of LT in the total feather scoring, where the (cont) group was scored poorest and (+f) best. The LT birds in all feather treatments had a better feather cover than the LS birds. Results from experiment II showed that high rates of severe FP and poorer feather condition are observed in group I compared to groups II or III in the rearing period (P <0.05, p<0.001, respectively). In the laying period, group III exhibited high rates of FP compared to group II (p<0.01). Group II showed lower severe pecks compared to groups I and III (p<0.05, <0.01, respectively). The plumage condition was significantly different among groups, where group III had the worst and group II the best condition. Group III recorded more skin injuries and react more fearfully as indicated by a longer duration in the tonic immobility (TI) test (p<0.001) compared to the groups I or II. It is concluded that loose feathers may play a role in the development of feather pecking behaviour in laying hens and feather pecking can be viewed as foraging behaviour. Large differences between genotypes were found in respect to the availability of loose feathers, feather pecking and plumage and integument condition. Imprinting of chicks to loose feathers from the floor may affect the incidence of feather pecking later on.
______104 Zusammenfassung
7 ZUSAMMENFASSUNG Sameh Gad Abdel-hak Ramadan Einflüsse der Genetik und Umwelt auf das Verhalten und die Gesundheit von Legehennen unter besonderer Berücksichtigung des Federpickens
Klinik für Vögel und Reptilien, Veterinärmedizinische Fakultät, Universität Leipzig und Professur für Tierhaltung und Nutztierökologie, Institut für Agrar- und Ernährungswissenschaften, Naturwissenschaftliche Fakultät III, Martin-Luther- Universität Halle-Wittenberg
106 Seiten, 25 Abbildungen, 33 Tabellen, 293 Literaturquellen Schlüssewörter: Federangebotes, Prägung, Federpicken, Legehennen Eingereicht im Mai 2007
Ziel dieser Arbeit war es, die Einflüsse des Federangebotes in der Einstreu und die Prägung auf lose Federn in der Einstreu auf die Häufigkeit des Auftretens von Federpicken (FP), den Zustand des Integuments und die Furchtreaktionen an zwei Legehennengenotypen zu untersuchen. Im Experiment I (Exp. I) wurden Lohmann Tradition (LT) und Lohmann Silver (LS) vom 1. Lebenstag an in 3 Gruppen mit je 60 Tieren pro Genotyp in eingestreuten Abteilen gehalten. Jeder Genotyp wurde einer der folgenden Behandlungen unterzogen: (1) ohne Federn (-f) in der Einstreu (Federn wurden viermal pro Woche aus der Einstreu abgesammelt), (2) mit Federn (+f), und (3) Kontrolle (cont) ohne zusätzliche Federbehandlung. Im Alter von 16 Wochen wurden jeweils 50 zufällig ausgewählte Hennen aus jeder Gruppe sechs identischen Abteilen zugeordnet. Hennen beider Genotypen aus jedem Abteil erhielten die gleiche Federbehandlung wie in der Aufzuchtphase. In Exp. II wurden Prägungseinflüsse auf lose Federn in der Einstreu untersucht. Legehennen eines Genotyps (LT) wurden in drei Gruppen gemäß der Federbehandlung gehalten. A- Gruppe I: Keine Federbehandlung. B- Gruppe II: Federn wurden aus der Einstreu abgesammelt. C- Gruppe III: Federn aus der gleichen Herkunft wurden zusätzlich in die Einstreu gegeben. Während der Legeperiode wurden die Gruppenbehandlungen umgekehrt (II und III), indem Federn aus der Gruppe III abgesammelt und der Gruppe II zugesetzt wurden. Die Hennen wurden direkt bezüglich des Federpickens und anderer Verhaltensaktivitäten im Alter von 6, 10, 15, 20, 25, 30, 35 und 40 Wochen beobachtet. Alle Hennen wurden einzeln bezüglich der Gefiederschäden im Alter von 15, 32 und 39 Wochen bonitiert.
______105 Zusammenfassung
Die Ergebnisse aus Exp. I während der Aufzuchtperiode ließen keine Unterschiede in der Art des Federpickens und der Gefiederbonitur zwischen den LS Gruppen erkennen. Die Kontrollgruppe (cont) der Linie LT führte vermehrt die schwere Form des Federpickens und hatte einen schlecheren Gefiederyustand gegenüber den (-f) und (+f) Gruppen (<0.001) aus. Während der Legeperiode war das FP und die schwere Form des FP häufiger in der (cont) Gruppe zu beobachten als bei (-f) der LS Gruppe (p<0.01, p<0.001). Die LS Kontrolltiere wiesen im Vergleich zu den (-f) Hennen einen schlechten Gefiederzustand im Alter von 32 und 39 Wochen auf. Die höchste FP Rate und auch die höchste Häufigkeit der schweren Form dieses Verhaltens wurden bei der (+f) der LS Gruppe im Vergleich zu den anderen Gruppen desselben Genotyps und generell die schlechteste Gefiedernote im Alter von 39 Wochen festgestellt. Hohe Federpickraten und die schwere Form dieses Verhaltens wurden in der (cont) LT Gruppe im Vergleich zu den (-f) und (+f) Gruppen (p<0.001) festgestellt. Es bestand ein signifikanter Unterschied in der Gefiederbenotung zwischen den LT Gruppen, wobei die (cont) Gruppe die schlechteste und (+f) die beste Benotung aufwies. Hühner der LT Linie hatten in allen Federbehandlungen eine bessere Befiederung als die LS Hühner. Die Ergebnisse aus Exp. II zeigten während der Aufzuchtphase eine erhöhte Rate an schwerem FP und schlechterer Gefiederbeschaffenheit in Gruppe I im Vergleich zu den Gruppen II und III (p<0.05, p<0.001). Gruppe III wies im Vergleich zu Gruppe II erhöhte Federpickraten während der Legeperiode auf (p<0.01). Gruppe II zeigte im Vergleich zu Gruppen I und III weniger die schwere Form des Pickens (p<0.05, 0.01). Die Gefiederbeschaffenheit war signifikant unterschiedlich zwischen den Gruppen, wobei die Gruppe III die schlechteste und Gruppe II die beste Note aufwies. Gruppe III wies vermehrt Hautverletzungen auf und reagierte furchtsamer mit längerer Verweildauer (p<0.001) während der (TI). gegenüber den Gruppen I und II. Es kann geschlussfolgert werden, dass lose Federn in der Einstreu eine Rolle bei der Entwicklung des Federpickverhaltens von Legehennen spielen und dass Federpicken als Futtersuchverhalten interpretiert werden kann. Grosse Unterschiede zwischen den Genotypen bestanden hinsichtlich der Verfügbarkeit von losen Federn in der Einstreu, des Federpickens sowie der Gefieder- und Integumentbeschaffenheit. Eine Prägung der Junghennen auf lose Federn in der Einstreu könnte das Auftreten von Federpicken zu einem späteren Zeitpunkt beeinflussen.
______106 References
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______127 Acknowledgments
ACKNOWLEDGMENTS Heartily, I want to express my sincere appreciation and deepest thanks to Prof. Dr. E. von Borell, my supervisor, for suggesting the subject, inspiring disscussions and supervion of the work. His unfailing interest, unforgetable helpful advice, continuous encouragement, guidance and criticism have made the completion of this work.
My particular thanks and gratitude gratefulness to Prof. Dr. M. Krautwald-Junghanns for her supervision, support, faithful and patiently help in overcoming all difficulties to bring this work to light.
I’m also appreciated to my colleagues, technicians and secretary in our group especially Dr. S. Schäfer, Dr. D. Schäffer, Mrs. H. Nitzer and Mrs. E. Gussek for their continuous unfailing help.
My deepst thanks to Dr. N. Mielenz and Dr. R. Schafberg for helpful advice in statistics.
My deepest thanks to all the members of the Research Centre for Animal Science, Merbitz.
Finally, many thanks to the Government of Egypt for the financial support during the scholarship.