Ascarid infections in laying hens kept in different housing systems

Abstract

The present study was undertaken to investigate the prevalence of ascarid infections in Swedish commercial laying hens in 2004 and 2008 following a recent nationwide change to alternative housing systems but before anthelmintics became available. Also, the influence on prevalence of farm and flock characteristics and management was studied in 2004. The results showed that the overall prevalence was significantly higher in 2008 (38%; n 0 64/169) compared with 2004 (24%; n 0 44/186) (P 0 0.001). Ascarid infections were rare in caged flocks, including furnished (enriched) cages, both years (2.4 to 4.3%), and were significantly more common in non-cage systems in both years (16.7 to 48.6% in 2004, and 28.6 to 77.1% in 2008 depending on the housing system). There was no significant difference in prevalence between hens kept on litter indoors and free-range/organic hens. The absence of a hygiene barrier at the entrance of the house or unit increased the risk of infection (P B 0.001), which suggests that parasite eggs were introduced horizontally to the farms. The risk of infection also increased with the age of equipment used in the barn; for example, the risk increased with an odds ratio of 7.5 (95% confidence interval 0 2.3 to 25) when comparing equipment 1 year old with equipment ]7 years old. The results of this study show that ascarid infections may re-emerge following a change to alternative housing. With the impending ban on conventional battery cages in the member states of the European Union, ascarid infections are likely to increase in importance and efficient control options such as hygiene barriers should be implemented on all farms.

Infection dynamics of Ascaridia galli in non-caged laying hens

“…All six flocks studied were introduced into the barns as replacement pullets at age 14-16 weeks between May and August 2009. Housing and feeding of commercial laying hens in Sweden has been previously described (Jansson et al, 2010).…”

“…The first faecal sample for parasitology was taken about a week after the birds arrived at the farm, to verify the hens' initial infection status. On each sampling occasion four samples of 100 g pooled fresh faeces were collected as previously described (Jansson et al, 2010). Samples were obtained in the same way throughout the study on each farm and were sent overnight by surface mail to the National Veterinary Institute (SVA), Uppsala, Sweden, for detection and identification of parasite eggs using a modified McMaster method based on saturated salt as flotation medium but with a detection level of 20 eggs per gram (epg) faeces (Permin and Hansen, 1998).…”

“…In recent years, the prevalence of roundworms in Swedish laying hens has increased substantially, especially in litter-based housing systems (Jansson et al, 2010), which is clearly linked to increased exposure to parasites with a faecal-oral route of transmission (Permin et al, 1999;Jansson et al, 2010) ing hen flocks. The situation is, however complicated by the fact that there is currently only one anthelmintic substance available for poultry (the benzimidazole substance flubendazole), which is administered to the birds for several days in the drinking water.…”

Population genetic structure of Ascaridia galli re-emerging in non-caged laying hens

“…In non-caged hens, this change was accompanied by a rapid increase of roundworm infections, especially Ascaridia galli [13]. The source of these nematodes and routes of transmission between farms have not been clearly identified, but previous studies have suggested indirect transmission between farms rather than introduction via infected replacement pullets [13,14]. To explore this further, more detailed studies based on the genetic relationships between worms collected from different flocks are warranted.…”

Environmental tolerance of free-living stages of the poultry roundworm Ascaridia galli

“…Stocking rate, removal of manure, biosecurity measures, disinfection procedures and production according to the "all in-all out" principle have apparently decreased the significance of parasitic infection (Permin et al 1998;Jansson et al 2010). Although management may control transmission of parasites with intermediate hosts in commercial free-range system (Permin et al 1999), at this time there is no effective way to prevent and eliminate the existing parasitic infections in non-cage production systems.…”