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).