Feather pecking and monoamines A behavioral and neurobiological approach Marjolein Suzanne Kops Kops, M.S. Feather pecking and monoamines – a behavioral and neurobiological approach Thesis Utrecht University – with ref. – with summary in Dutch ISBN: 978-90-3936-128-3 Cover art by Chaïm Becker Cover design by Chaïm Becker and Ridderprint Printed by Ridderprint, Ridderkerk © Marjolein Kops, 2014, Utrecht, the Netherlands All rights reserved. No part of this thesis may be reproduced or transmitted in any form or by any means, electric, mechanical (including photocopying, recording, or information storage and retrieval system) without prior written permission of the author or the copyright owner journal. Feather pecking and monoamines A behavioral and neurobiological approach Verenpikken en monoamines Een gedrags- en neurobiologische aanpak (met een samenvatting in het Nederlands) Proefschrift ter verkrijging van de graad van doctor aan de Universiteit Utrecht op gezag van de rector magnificus, prof.dr. G.J. van der Zwaan, ingevolge het besluit van het college voor promoties in het openbaar te verdedigen op woensdag 9 april 2014 des middags te 4.15 uur door Marjolein Suzanne Kops geboren op 27 maart 1981 te Heerlen Promotoren: Prof.dr. B. Olivier Prof.dr.dr. h.c. O. Güntürkün Co-promotoren: Dr. S.M. Korte Dr.ir. J.E. Bolhuis “Which way you ought to go depends on where you want to get to...” ― Lewis Carroll, Alice in Wonderland TABLE OF CONTENTS Chapter 1 General introduction 9 Chapter 2 Effects of feather pecking phenotype (severe feather 21 peckers, victims and non-peckers) on serotonergic and dopaminergic activity in four brain areas of laying hens (Gallus gallus domesticus) Chapter 3 Selection for low mortality in laying hens affects 35 catecholamine levels in the arcopallium, a brain area involved in fear and motor regulation Chapter 4 Central monoamine levels and behavior in young and 51 adult hens hebs from two lines selected on high (HFP) and low (LFP) feather pecking Chapter 5 Successful microdialysis in freely moving adult chickens 73 (Gallus gallus domesticus) Chapter 6 Serotonin release in the caudal nidopallium of adult laying 95 hens genetically selected for high and low feather pecking behavior: an in vivo microdialysis study Chapter 7 General Discussion 111 References 125 Author affiliations 143 Samenvatting in het Nederlands 147 List of publications 157 Acknowledgements 161 About the author 169 Chapter 1 General introduction 99 9 Chapter 1 THE PROBLEM OF FEATHER PECKING IN LAYING HENS Feather pecking (FP) remains one of the major welfare issues in laying hens. In particular the pecking at and pulling out of feathers, called severe feather pecking (SFP), inflicts damage to the plumage and causes denuded areas on the body of the recipient (Hughes and Duncan, 1972; Savory, 1995). The created bald spots will attract others to peck at the skin, and therefore SFP can easily progress into cannibalism causing mortality (Savory and Mann, 1997). SFP can be discriminated from gentle feather pecking (GFP) and aggressive pecking (Savory, 1995). GFP is a mild form of feather pecking without damage to the feathers or skin (Keeling and Jensen, 1995; Kjaer and Vestergaard, 1999). The above mentioned pecking behaviors clearly differ in the target to which they are directed. GFP and SFP are mostly directed at the back, tail and wing feathers (Riedstra et al, submitted, Savory, 1995), whereas aggressive pecking is almost exclusively directed at the top of the head or the comb. Aggressive pecking serves to establish or maintain the hierarchy and usually forces the recipient to react (Wennrich, 1975). It has been suggested that GFP is a form of explorative social pecking (Riedstra and Groothuis, 2002), although GFP can also be observed in multiple bouts with a stereotypic character (Kjaer and Vestergaard, 1999; McAdie and Keeling, 2002). SFP is, without any doubt, detrimental behavior and can be interpreted as a behavioral disorder (van Hierden et al., 2002; van Hierden et al., 2004; van Zeeland et al., 2009; Bordnick et al., 1994). Beak trimming, i.e. the removal of the sharp tip of the beak, is an effective measure to reduce the damage inflicted by SFP. Nonetheless, this method may cause welfare problems in itself since the (removed) tip of the beak contains many nerve endings enabling the discrimination between pecked objects/food (Freire et al., 2011; Gentle, 1997). Behavioral studies indicate that beak-trimmed animals may chronically suffer from painful beak deformations and chronic neuroma formation (Gentle, 1986; Duncan et al., 1989). Considering this, the European legislation has regulated beak trimming and the Netherlands will prohibit beak trimming in 2018. Similar decisions are being prepared in Germany and the United Kingdom. Beak-trimming is already prohibited in Sweden, Finland, Norway and Switzerland. Birds with an intact beak, however, produce more feather damage and mortality. Without the possibility of beak trimming, other tools are needed to reduce the damage, preferably by reducing the behavior itself and not by just reducing the harmful consequences. Moreover, conventional battery cages in Europe have been prohibited from 2012 onwards (Rodenburg et al., 2012). Now most laying hens are housed in large groups in furnished cages or in barn or free-range systems (non-cage systems) that result in more SFP than before when birds were housed with only four cage-mates in a battery cage (Allen and Perry, 1975). Indeed, large outbreaks of SFP and cannibalism have been recorded in non-cage systems (Appleby and Hughes, 1991; Gunnarsson et al., 1999). Altogether, there is general consensus that due to the larger groups of laying hens and the sharper intact beaks, the risk of severe feather pecking and cannibalism 10 General introduction will increase substantially. In order to solve this problem, unraveling the causal mechanisms of SFP in laying hens has become more important than ever. PROJECT “PREVENTING FEATHER PECKING IN LAYING HENS: FROM PRINCIPLE TO PRACTICE” SFP is a multifactorial problem and there is no simple single solution to prevent it. Forty years of research have shown that both genes (nature) and environment (nurture) play an important role in the development of SFP (Hughes and Duncan, 1972; Leonard et al., 1995; Nicol et al., 2001; Huber-Eicher and Audige, 1999; Blokhuis, 1989; Nørgaard-Nielsen et al., 1993). SFP has been suggested to develop from either redirected food pecking (Wennrich, 1974); redirected ground pecking (Blokhuis, 1986); the inability to perform dust bathing (Vestergaard et al., 1993), or redirected social pecking (Riedstra and Groothuis, 2002). Furthermore, severe feather peckers seem to have increased levels of stress (Rodenburg et al., 2009; Rodenburg et al., 2009), fear (de Haas et al., 2012; Hocking et al., 2001; Jensen et al., 2005; Rodenburg et al., 2004; de Haas et al., 2013), sometimes show more aggression (Bessei et al., 2013; Cheng and Muir, 2007) and are more likely to display a proactive coping style (Korte et al., 1997; Koolhaas et al., 1999; Cockrem, 2007). Unfortunately, none of these characterizations of SFP or feather peckers completely explains the origin of this detrimental behavior. It is supposed that the better one understands the causal factors underlying SFP, the better it can be treated and possibly prevented. Four years ago, the universities of Utrecht, Wageningen, and Groningen started the project “Preventing feather pecking in laying hens: from principle to practice”. My research was part of this larger project. The main goal of the larger project was to find predictors and indicators of FP in both experimental and commercially housed chickens at different developmental phases. The impact of both external (e.g. housing conditions and management) and internal (e.g. maternal hormones and neurochemical brain characteristics) factors on the development of SFP behavior have been addressed by two PhD-students and one post-doctoral researcher, focusing on different steps in the production chain (i.e. parent stock, rearing phase, and laying phase), see Fig. 1.1. This thesis focuses on the neurobiology of feather pecking and especially the role of the central monoaminergic system; this will be explained below. THE NEUROBIOLOGY OF FEATHER PECKING BEHAVIOR Why does abnormal behavior such as SFP occur? This is not an easy question. In humans, behavioral disorders that resemble SFP have been observed, such as body- focused repetitive (constant and recurrent) disorders, for instance, the irresistible urges to pull out hair (Trichotillomania) or to pick at skin (Excoriation disorder) (American Psychiatric Association, 1994). These maladaptive behaviors are often 11 Chapter 1 interpreted by psychiatrists to reflect obsessive-compulsive disorders (OCD) or impulsive-like disorders. It has been hypothesized that central monoaminergic systems (serotonin and dopamine) are involved in SFP (birds) and other compulsive- like behaviors (mammals) (van Hierden et al., 2004; van Zeeland et al., 2009; Dufour et al., 2010). Serotonin (5-hydroxytryptamine; 5-HT) plays a role in, amongst others, regulation of mood, reproduction and growth, impulsivity and aggressiveness (Angoa- Pérez et al., 2012; Dalley and Roiser, 2012; Stein et al., 1991; De Boer et al., 2009; Rabii et al., 1981) whereas dopamine (DA) is involved in motivational and reward- related behavior, motor control, and also higher cognitive functions (Kalenscher et al., 2006). Abnormal behaviors have been related to depletion of the serotonergic and dopaminergic systems. For instance, mice lacking the gene encoding for brain tryptophan hydroxylase 2 - resulting in 5-HT depletion - exhibit more compulsive behaviors, like excessive burying, aggressive and motor impulsive behaviors (Angoa- Pérez et al., 2012). Fig. 1.1 Schematic overview of the projects within project ‘Preventing feather pecking in laying hens: from principles to practice’. Figure shows the projects with the different phases in the laying hen production chain, the manipulations that will be applied, the indicators that will be studied in the different projects, and the implementation in practice. The topic of this thesis is depicted in pink.