To generate valuable data on the potential changes in egg contamination rates when laying hens are moved to more animal friendly housing systems, data will be collected using a multidisciplinary approach. Besides using historical data (from monitoring programs in Denmark and Switzerland), a longitudinal as well as a cross-sectional field trial will be conducted to gather new quantitative data on the prevalence of Salmonella and other zoonotic agents in egg-laying flocks kept in different housing systems.
Samples will be taken in 5 conventional cage layer flocks and 5 flocks of the 3 most prevalent housing types in Belgium, Germany and Denmark in the longitudinal field study, while for the cross-sectional study 25 conventional cage layer flocks and 25 flocks of the 3 most prevalent housing types will be sampled in Belgium, Germany and Switzerland.
In Greece and Turkey 5 conventional cage layer flocks and 5 free-range layer flocks will be sampled in the cross-sectional study. In Italy, 10 flocks housed in battery cages, 10 flocks of floor-raised laying hens and 10 free-range flocks will be sampled.
Also the occurrence of antimicrobial resistance in pathogenic and indicator bacteria in laying hens will be included in this study. In addition, data on the management and consequently on the use of veterinary treatments in the different housing systems will be collected. A structured questionnaire will be designed to identify risk factors for the prevalence of zoonotic bacteria. The housing system will be described in detail.
Possible additional risk factors include geographic location, season, origin of laying hens, flock size, type of feed, cleaning and disinfection protocols, presence of arthropod vectors, contact with wild birds and other animals, and health status of the flock. The same questionnaire will be used to gather information on management and the use of veterinary treatments.
Also infection studies with zoonotic pathogens (Salmonella and eventually other important pathogens identified in longitudinal and cross-sectional studies) in three different housing systems (cage, enriched cage and aviary system) will be carried out in WP2. All these data will be analysed in a quantitative risk assessment model for the evaluation of the most important risk for the consumers originating from the consumption of eggs produced in different housing systems.
The objectives of this workpackage are :
- To analyze existing data generated in other EU initiatives and to collect new data on the occurrence of zoonotic agents in laying hens kept in different housing systems as well as on the on the potential risks to the consumer due to veterinary treatments in these different housing systems.
- To develop, on the basis of the collected new data and existing data, qualitative risk assessment models that will enable us to describe and rank the risks to the consumer due to zoonotic diseases and the use of veterinary treatments
- To develop a quantitative risk assessment model to evaluate the risk for human illness due to the consumption of eggs, originating from laying hens flocks housed in different housing systems, for the most important risk (based upon the qualitative models).
