title: Prevalence and magnitude of helminth infections in organic laying hens (Gallus gallus domesticus) across Europe.
abstract: Helminths are associated with health- and welfare problems in organic laying hens. The present observational cross-sectional study therefore aimed to estimate the prevalence and worm burdens of intestinal helminths in organic flocks of laying hens in 8 European countries, and to identify management factors that might be associated with helminth infections, with emphasis on Ascaridia galli. Data on flock-level management factors (e.g. nutritional factors, litter quality, housing system, opening- and closing hours of popholes, pasture rotation and provision of occupational materials) were collected during a farm visit when the hens were on average 62 weeks old. Worm counts were performed for 892 hens from 55 flocks and the number of ascarid (presumably primarily A. galli) eggs per g faeces (EPG) for 881 hens from 54 flocks. The association between parasitological parameters (prevalence, worm burden and EPG) and the management factors were analysed by multivariate models. Results showed that A. galli was highly prevalent across Europe with an overall mean prevalence of 69.5% and mean worm burden of 10 worms per hen. The overall mean prevalence and worm burden for Heterakis spp. were 29.0% and 16 worms per hen, respectively, with a large variation between countries. On average, the hens excreted 576 ascarid EPG. The mean prevalence of Raillietina spp. was 13.6%. A positive correlation was found between mean A. galli worm burden and ascarid EPG. Of the analysed management factors, only pasture access time had a significant negative association with A. galli worm burden which was in contrast to the general belief that outdoor access may increase the risk of helminth infections in production animals. In conclusion, the complexity of on-farm transmission dynamics is thus a challenge when evaluating the relative importance of management factors in relation to helminth infections.
authors.affiliation: Department of Veterinary Disease Biology, Faculty of Health and Medical Sciences, University of Copenhagen, Dyrlægevej 100, Frederiksberg C, DK-1870, Denmark. Electronic address: sundar@sund.ku.dk.
authors.forename: Sundar
authors.initials: S
authors.lastname: Thapa
authors.affiliation: Department of Animal Science, Faculty of Science and Technology, Aarhus University, Blichers Allé 20, Tjele, DK-8830, Denmark. Electronic address: lenak.hinrichsen@anis.au.dk.
authors.forename: Lena K
authors.initials: LK
authors.lastname: Hinrichsen
authors.affiliation: Farm Animal Behaviour and Husbandry Section, University of Kassel, Nordbahnhofstraße 1a, Witzenhausen, 37213, Germany.
authors.forename: Christine
authors.initials: C
authors.lastname: Brenninkmeyer
authors.affiliation: Department of Animal Environment and Health, Swedish University of Agricultural Sciences (SLU), P.O. Box 234, Skara, S-532 23, Sweden.
authors.forename: Stefan
authors.initials: S
authors.lastname: Gunnarsson
authors.affiliation: Farm Animal Welfare and Behaviour Group, Animal Sciences Unit, Institute for Agricultural and Fisheries Research (ILVO), Scheldeweg 68, Melle, B-9090, Belgium.
authors.forename: Jasper L T
authors.initials: JL
authors.lastname: Heerkens
authors.affiliation: Department of Animal and Environment, Louis Bolk Institute, Driebergen, The Netherlands.
authors.forename: Cynthia
authors.initials: C
authors.lastname: Verwer
authors.affiliation: Department for Farm Animals and Veterinary Public Health, Institute for Animal Husbandry and Animal Welfare, University of Veterinary Medicine, Vienna, Austria.
authors.forename: Knut
authors.initials: K
authors.lastname: Niebuhr
authors.affiliation: ADAS UK Limited, Battlegate Road, Boxworth, Cambridgeshire, CB23 4NN England, UK.
authors.forename: Alice
authors.initials: A
authors.lastname: Willett
authors.affiliation: Department of Veterinary Science and Public Health, Faculty of Veterinary Medicine, University of Milan, Italy.
authors.forename: Guido
authors.initials: G
authors.lastname: Grilli
authors.affiliation: Department of Veterinary Disease Biology, Faculty of Health and Medical Sciences, University of Copenhagen, Dyrlægevej 100, Frederiksberg C, DK-1870, Denmark.
authors.forename: Stig M
authors.initials: SM
authors.lastname: Thamsborg
authors.affiliation: Department of Animal Science, Faculty of Science and Technology, Aarhus University, Blichers Allé 20, Tjele, DK-8830, Denmark.
authors.forename: Jan T
authors.initials: JT
authors.lastname: Sørensen
authors.affiliation: Department of Veterinary Disease Biology, Faculty of Health and Medical Sciences, University of Copenhagen, Dyrlægevej 100, Frederiksberg C, DK-1870, Denmark.
authors.forename: Helena
authors.initials: H
authors.lastname: Mejer
mesh_terms: D000822:Animal Husbandry; D000818:Animals; D002645:Chickens; D003430:Cross-Sectional Studies; D005060:Europe / Q000453:epidemiology; D005243:Feces / Q000469:parasitology; D005260:Female; D006374:Helminthiasis, Animal / Q000453:epidemiology*; D010058:Oviposition; D010270:Parasite Egg Count; D011201:Poultry Diseases / Q000453:epidemiology / Q000469:parasitology*; D015995:Prevalence
keywords: Ascaridia galli; Heterakis spp.; Management; Organic laying hens; Prevalence; Raillietina spp.; Worm burden