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ARS Home » Southeast Area » Athens, Georgia » U.S. National Poultry Research Center » Egg and Poultry Production Safety Research Unit » Research » Research Project #444742

Research Project: Identify Environmental and Management Drivers of Foodborne Pathogen Ecology Under Pastured Poultry Rearing Systems

Location: Egg and Poultry Production Safety Research Unit

Project Number: 6040-32000-012-008-S
Project Type: Non-Assistance Cooperative Agreement

Start Date: Sep 1, 2023
End Date: Jun 30, 2025

Research conducted as part of this increase will be coordinated with the Cooperator as part of the project “Reduction of Foodborne Pathogens and Antimicrobial Resistance in Poultry Production Environments”. Recently, increased demand for antibiotic-free, “natural” products has pushed consumers towards the organic food market. This has impacted the poultry industry, where broiler meat harvested from alternative poultry farming production facilities, such as organic, free range and pastured, have increased in demand. The microbial safety of conventionally-raised poultry and their products throughout the entire farm-to-fork continuum has been studied in the United States, but organic/pastured production studies related to food safety issues are limited, especially when focusing on the pre-harvest environments. Organic poultry farms are characterized by farms that rear birds without the use of antibiotics and allow the birds access to the outside, while pastured poultry operations require moveable pens/housing that are moved daily to fresh pasture. In our previous project plan we forged relationships with several pastured poultry operations. They have allowed us frequent and consistent access to their farms and flocks upon request, and openly discuss their management practices and allow collation of a wide variety of information, such as the presence of mixed species on-farm, vaccination protocols, feeding and rearing practices, and other management factors. Initial findings for our large-scale (41 flocks from 11 farms) study demonstrated that farm environment significantly impacted poultry-related microbiomes and pathogens, as do farm management practices such as feed composition. Additionally, meteorological variables, such as minimum average temperature and maximum wind speed and farm management practices, such as feed composition during brood and chlorination of water sources, were predictive of the presence of Listeria within the pre-harvest environment. Based on these findings, the proposed work will take a two-pronged approach to continue this work: (1) at the farm level we will focus more on the specific environmental and management variables that are predictive of Salmonella prevalence, and (2) utilize experimental pastured poultry farm studies to study the effects of specific environmental/management variables on pre-harvest Salmonella prevalence in a more controlled, research setting with the ability to include true replicates in the experimental design.

All field studies will be performed under the Cooperator's IAUCU and will be reared using the American Pastured Poultry Producers Association (APPPA) guidelines ( In brief, 4 specially built broiler coops with automated feeder/waterer, temperature control, and movement capacities will each house 100 one-day old chicks within plastic bins with fresh wood shaving and given food and water ad libitum during the brood period (~2-3 weeks). After brood, chicks will be removed from the plastic bins within the coops, where they will be reared on pasture for up to 11 weeks, depending on broiler breed. While on pasture, the coops will be automatically moved every day to provide fresh pasture daily, and they will be provided food and water ad libitum. At the end of the rearing period, the cooperating farm will process the flocks in their mobile processing unit. . Under a field trial setting, multiple different aspects of broiler management, including but not limited to gut microbiology/food safety, management/performance, welfare/behavior will be studied. To assess the effect of these environmental/management variables on poultry gut microbiomes and Salmonella prevalence, fecal samples will be collected on a weekly basis starting on the first day of age. On a daily basis, farm managers will collect feed consumption data, and on a weekly basis cooperators will determine mean body weight and approximate feed conversion rate (FCR). The effect of environmental/ management variables will be examined for its effect on broiler welfare and behavior. Lameness assessment will be conducted along with recording of foot pad and feather damage as birds interact with each other and pasture. Birds will also be assessed for signs of aggression. Animal welfare parameters will be recorded using implantable telemetry loggers. Farm managers will also provide us with final product data as metadata for subsequent analyses.