2012 Annual Report 1a.Objectives (from AD-416): The proposed objectives are:. 1)to conduct on-farm surveys in organic and all natural poultry production practices to determine the prevalence and diversity of Salmonella serovars in these production systems as compared to more intensive commercial systems;. 2)to develop and evaluate intervention strategies targeting control of Salmonella during the feed withdrawal and transportation processes prior to slaughter of broiler chickens to minimize cross contamination during transport and slaughter;. 3)to evaluate post-harvest interventions to control Salmonella using novel antimicrobials in pre- and post-chiller applications, for both water and air chilling, and for finished raw products; and. 4)to develop risk assessment models that can be adapted to organic and all natural production and processing systems. The proposed research will generate multiple publications in peer-reviewed scientific journals, presentations in meetings, and annual updates as well as a complete final report to the funding agency. 1b.Approach (from AD-416): A minimum of 10 flocks from each production system will be sampled during grow-out. Chick box paper pads from each production system will be collected from a minimum of 10 boxes and will be sampled. Each flock will be sampled on at least 3 occasions and 6-10 of each sample type will be collected during each sampling occasion. Salmonella parameters will be evaluated on each sample collected:. 1)isolation frequency;. 2)serotype diversity;. 3)antimicrobial resistance pattern; and. 4)genotype diversity. 3.Progress Report: On-farm Salmonella prevalence surveys were conducted, and Salmonella enterica serovar Kentucky was the most frequent serovar found. Antimicrobial resistance genes were identified in Salmonella strains isolated both from intensive and pasture-raised poultry. The majority of the Salmonella Kentucky isolates were resistant to arsenic. Genotyping analysis revealed a high diversity and clonal distribution of Salmonella serovars in all production systems. Intervention strategies to reduce the prevalence of Salmonella have been identified, and evaluated. Prebiotics and organic acids have been shown to reduce the prevalence of Salmonella in birds. This project relates to objective 1 of the parent project. Comparing incidence of Salmonella in different production systems allowed for determining how broilers raised under different conditions of welfare (stress) respond to Salmonella infections. Additionally, this project generated information on potential intervention strategies to reduce Salmonella in broilers.