Resistance to anticoccidial drugs: alternative strategies to control coccidiosis in broilers Herman Peek Utrecht 2010 Resistance to anticoccidial drugs: alternative strategies to control coccidiosis in broilers Herman Peek ISBN : 978-90-393-5272-4 Cover : Marije Brouwer Lay-out : Division Multimedia, Faculty Veterinary Medicine, University Utrecht Printed by : Riddderprint Offsetdrukkerij b.v., Ridderkerk Edited by : Animal Health Service (GD), Deventer Resistance to anticoccidial drugs: alternative strategies to control coccidiosis in broilers Resistentie tegen anticoccidiosemiddelen: alternatieve strategieën voor de controle van coccidiose bij vleeskuikens (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. J.C. Stoof, ingevolge het besluit van het college voor promoties in het openbaar te verdedigen op donderdag 18 februari 2010 des middags te 2.30 uur door Hermanus Wilhelmus Peek geboren op 2 december 1952 te Harmelen Promotor: Prof. dr. J.A. Stegeman Co-promotor: Dr. W.J.M. Landman The research was financially supported by the Commodity Board for Poultry and Eggs (PPE), the Commodity Board for Animal Feed (PDV) and the Animal Health Service (GD). Paranimfs: Brenda Vermeulen Gerda Peek CONTENTS Chapter 1 Introduction 1 General introduction and aim of the thesis 2 Coccidiosis in poultry: anticoccidial products and alternative prevention strategies (a review) 5 Chapter 2 Anticoccidial drug resistance in the field 105 Resistance to anticoccidial drugs of Dutch avian Eimeria spp. field isolates originating from 1996, 1999 and 2001 106 (Avian Pathology, 32, (2003), pp. 392-401) Anticoccidial drug sensitivity profiles of German, Spanish and Dutch Eimeria spp. field isolates 125 (Tijdschrift voor Diergeneeskunde, 129, (2004), pp. 210-214) Chapter 3 Influence of ibuprofen, a mucolytic enzyme and a mannanoligosaccharide preparation (MOS) on a coccidiosis infection in broilers 139 Effect of ibuprofen on coccidiosis in broiler chickens 140 (Avian Diseases, 48, (2004), pp. 68-76) Dietary protease can alleviate negative effects of a coccidiosis infection on production performance in broiler chickens 157 (Animal Feed Science and Technology, 150, (2009), pp. 151-159) The effect of an in-feed mannanoligosaccharide preparation (MOS) on a coccidiosis infection in broilers 171 (Animal Feed Science and Technology, 134, (2007), pp. 347-354) Chapter 4 Influence of live coccidiosis vaccination on the occurrence of anticoccidial drug resistance 181 Higher incidence of Eimeria spp. field isolates sensitive for diclazuril and monensin associated with the use of live coccidiosis vaccination with Paracox™-5 in broiler farms 182 (Avian Diseases, 50, (2006), pp. 434-439) Chapter 5 Improvement of live anticoccidial vaccines 197 Cross protection studies between E. acervulina and E. maxima, and E. tenella (submitted) 198 Chapter 6 Summarizing discussion 215 Samenvatting 227 Dankwoord 239 Curriculum vitae 241 List of publications 243 Chapter 1 Introduction General introduction Introduction Coccidiosis is a parasitic disease affecting mainly the intestinal tract. It is caused by members of the genera Eimeria and Isospora belonging to the phylum Apicomplexa, and characterized by a complex life cycle. It affects many species of mammals and birds, and is of great economic significance in farm animals, especially poultry. Most animals are parasitized by more than one species of Eimeria, which usually differ in pathogenicity and tissue tropism. Although multiple species of coccidia have been identified, new operational taxonomic units are being discovered regularly. Most knowledge on coccidiosis has been obtained from poultry, in which the disease has been studied most intensively as in this species the parasite causes the most devastating losses due to the large number of birds per flock and high stock densities The economic importance of coccidiosis can be related to decreased profit caused by higher feed conversion, growth depression, increased mortality and the costs of prevention and treatment. Worldwide the annual costs inflicted by coccidiosis to commercial poultry have been estimated at € 2 billion, stressing the urgent need for more efficient strategies to control the parasite (Williams, 1999; Shirley et al., 2004; Dalloul & Lillehoj, 2006). The traditional control of coccidiosis mainly relies on chemoprophylaxis which appeared to be effective for the last decades. However the increased occurrence of resistance against all anticoccidial drugs has left the poultry industry with a renewed challenge for coccidiosis prevention and control and propelled the search for alternative strategies amongst which vaccination is of major importance. Aim of the thesis Manuscripts documenting the occurrence of resistance against all commonly used anticoccidial drugs abroad, together with the high incidence of clinical coccidiosis in the field (60-90% of flocks) in the Netherlands, were the reasons to start investigations on the occurrence of resistance of Dutch and other European Eimeria spp. field isolates (Chapter 2). This was preceded by an extensive literature review focusing on anticoccidial products and alternative prevention strategies (Chapter 1). In this review, first, a general overview of coccidial infections with Eimeria spp. in farm and game birds including history, classification, life cycle and the determination and diagnosis of the disease is given. This is followed by an outline on the host and site specificity of Eimeria spp., different commercialized anticoccidial products (categories, mode of action, the occurrence and management of resistance) and the influence of feed (structure, composition, ingredients, toxins and administration) on the course of coccidiosis infections. Additionally, alternative anticoccidial strategies such as biosecurity, management, homeopathy, phytotherapy, aromatherapy, pre- and probiotics and vaccination are presented. The review is finalized with conclusions and future perspectives. CHAPTER 1 Based on the literature study one alternative coccidiosis control strategy, namely a mannanoligosaccharide (a prebiotic) was chosen for further experimental studies in broiler chickens. Additionally, two other products i.e. ibuprofen (a non-steroidal anti- inflammatory drug- NSAID) and a mucolytic enzyme (protease) were also used in experimental research aiming at assessing their anticoccidial potential. Ibuprofen was chosen because as cyclooxygenase inhibitor it was expected to reduce the pathology of coccidiosis lesions through impairment of the production of prostaglandins, and because it was reported that another NSAID (indometacin) was able to reduce oocyst shedding (Allen, 2000). The mucolytic enzyme was studied as it was speculated that a protease might impair the attachment of Eimeria to the mucus layer through its degradation (Chapter 3). In view of the poor anticoccidial effect found in the studies performed with mannanoligosaccharide, ibuprofen and the mucolytic enzyme, further research focused on vaccination against chicken Eimeria, which despite some drawbacks was shown to be highly effective against outbreaks of clinical coccidiosis (Williams, 2002). Another reason to focus on vaccination was the inefficacy of rotation and shuttle programs to solve the coccidiosis resistance problem, which is explained by the fact that resistance is stable even in the absence of drug selection pressure (Gardiner & McLoughlin, 1963; Ball, 1968; Williams, 1969; McLoughlin, 1970; Chapman, 1986). A welcome side effect of vaccination is the improved sensitivity of Eimeria spp. field isolates for anticoccidial drugs reported by some researchers. This phenomenon may play a key role in reducing the anticoccidial drug resistance problem. However, large-scale field studies documenting this were lacking. Therefore, in Chapter 4, the relation between the coccidiosis prevention program (vaccination with a live attenuated anticoccidial vaccine or anticoccidial drugs in feed) and anticoccidial drug sensitivity profiles of Eimeria spp. field isolates for diclazuril and monensin was studied. Major disadvantages of live anticoccidial vaccines are: 1/ propagation has to be performed in the natural host, 2/ yield of oocysts is lowered for attenuated precocious vaccines due to precocity characteristics and 3/ all relevant Eimeria spp. must be included in the vaccine further increasing production costs. Coccidiosis vaccines could be produced more efficiently if cross protection between Eimeria spp. would be relevant enough to reduce the number of species included in the vaccine and/or reduce the vaccination doses. Therefore, cross protection studies between an E. acervulina vaccine line and E. tenella, and E. maxima were performed in Chapter 5. The thesis is finalized with a summarizing discussion with conclusions and perspectives for future research. 3 GENERAL INTRODUCTION References Allen, P.C. (2000). Effects of treatment with cyclooxygenase inhibitors on chickens infected with Eimeria acervulina. Poultry Science, 79, pp. 1251-1258. Ball, S.J. (1968). The stability of resistance to glycarbylamide and 2-chloro-4-nitrobenzamide in Eimeria tenella in chicks. Research in Veterinary Medicine, 9, pp. 149-151. Chapman, H.D. (1986). Eimeria tenella: stability of resistance to halofuginone, decoquinate and aprinocid in the chicken. Research Veterinary Science, 40, pp. 139-140. Dalloul, R.A. & Lillehoj, H.S. (2006). Poultry coccidiosis: recent