Impacts of the housing systems on egg and environmental microbiology

A comparison of commercial conventional cage (CC), enriched colony cage (EC), and cage-free aviary (AV) was conducted at the same production site.  Egg shell and environmental microbiology were monitored post-peak production. It is not uncommon for poultry to shed Salmonella spp. or other coliforms thus the prevalence (presence or absence) of Salmonella spp. and Campylobacter spp. were determined for every swab/egg shell pool collected from each system. Hens in all housing systems were shedding Salmonella spp. at a similar rate; the prevalence of Salmonella spp. on egg shells was very low and did not differ between housing systems. The AV had higher levels of environmental Campylobacter spp. recovery (drag swab). Salmonella spp. were detected at similar levels of prevalence in the EC and CC production environments however AV were more positive. The manure scraper had low levels of Campylobacter spp. recovery in all systems, but AV drag swabs and EC scratch pad swabs had high levels of Campylobacter spp. recovery.  AV floor shells had the greatest levels of total aerobes and coliforms.  Aerobic organisms were also elevated on AV nest box and system shells.  Previous studies indicate total aerobe levels are greater on eggs produced in high dust environments. Eggs laid on litter (in AV only) have greater shell microbial levels than eggs laid on system wires or in nest boxes. Coliforms are indicators of fecal contamination which is linked to human pathogens. In the EC system wire egg shell coliform levels were detected at levels similar to CC.  The coliform level in AV nest box egg shells was similar to the EC. The coliform levels were low for all shell samples, excluding the AV floor shells, which had the highest levels of total coliforms.