2012 Annual Report 1a.Objectives (from AD-416): To evaluate three commercial laying hen housing systems in terms of bird welfare, environmental impact, and food safety. 1b.Approach (from AD-416): Three 50,000 laying hen housing complexes will be constructed by Cargill - traditional caged, furnished cage, and aviary style. After the facilities are populated, evaluations of the welfare, environmental impact, and egg microbiology will be conducted. Aerobic microorganisms, Enterobacteriaceae, Salmonella, and Campylobacter populations will be enumerated or isolated from housing and processing environments, as well as, eggs. 3.Progress Report: This research relates to inhouse project objective 3B: utilize enhanced detection methods to determine the effect of housing on egg microbiology. The first production cycle was completed for hens in traditional cages, aviary, and enriched cages. Monthly sampling was completed on eggs and environmental samples from each type of housing to determine effects of housing on microbiological impact. Aerobic microorganisms and Enterobacteriaceae were enumerated while samples were enriched for Salmonella and Campylobacter. Salmonella and Campylobacter recovery was similar for traditional and aviary systems and lowest in enriched systems. On a quarterly basis, the same populations were monitored for washed eggs and for processing facility environmental samples. Effects on egg quality were also determined on a quarterly basis. Counts and pathogen prevalence were low for environmental samples after eggs were washed. No pathogens were recovered from washed eggs regardless of housing type, including floor eggs from the aviary system. After the last monthly samples were collected in June, the houses were re-sampled to determine the efficacy of cleaning procedures. As houses were de-populated no eggs were sampled. Pathogens were not recovered after disinfection procedures were performed. On a quarterly basis, reports were delivered to Michigan State University. These reports contain general trends in data, progress within the quarter, and any concerns or additional needs. In addition, an annual meeting was held in Chicago in October 2011 and was attended by ARS PI. An additional meeting to discuss transition from the first to the second flock cycle was held in Minneapolis in April 2012 and was attended by ARS SY.