The influence of the housing system on Salmonella infections in laying hens: a review

From 2012 onwards, housing of laying hens in conventional battery cages will be forbidden in the European Union and only enriched cages and non-cage housing systems such as aviaries, floor-raised, free-range and organic systems will be allowed. Although this ban aims at improving the welfare of laying hens, it has also initiated the question whether there are any adverse consequences of this decision, especially with respect to the spread and/or persistence of zoonotic agents in a flock. A zoonotic agent that is traditionally associated with the consumption of eggs and egg products is Salmonella enteritidis. This paper provides a summary of the current knowledge regarding the direct and indirect effects of different housing systems on the occurrence and epidemiology of Salmonella in laying hen flocks