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Pilot Study of Airflow in Broiler Houses for Salmonella Risk Reduction

Timmons, Jennifer
University of Maryland - College Park
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End date
Non-uniform airflow in typical commercial broiler houses can produce areas of inadequate litter surface airflow associated with increased concentrations of bacteria harmful to both poultry and humans. This project will identify practical means to correct such airflow patterns and therefore the objectives are:
  1. Collect airflow measurements along the sidewalls, ends, corners and under fans in six commercial broiler houses.
  2. Conduct modeling studies from the collected airflow data (Objective 1) to identify ways to correct areas of deficient airflow.
The results of this study will identify ways to correct areas of deficient airflow over litter surfaces in broiler houses. Practical ventilation designs, retrofits and/or devices that would correct areas of deficient airflow would provide the industry with an additional tool to address food safety issues.

A meeting will be scheduled with Delmarva poultry industry personnel and allied industry to present study results. Feedback from industry will determine if the identified ventilation designs can be incorporated economically into typical broiler houses. Also it will be determined if there is future interest to continue to collaborate and support future trials investigating identified ventilation designs under a commercial broiler house environment.

Results from this study will be used to support an integrated Agriculture and Food Research Initiative proposal. If funded, practical ventilation systems will be installed in commercial broiler houses and the impact of these ventilation systems on flock performance, surface litter moisture and water activity, surface litter bacterial levels (Salmonella and E.coli) and bacteria carcass contamination levels at the processing facility will be investigated.

Modeling concepts developed in the current proposal will be extended to more complex airflow source and sink terms, as well as modeling water activity and modeling drag-swab salmonella-responses to various airflow conditions. Utilizing this ventilation strategy at the poultry house level may be a tool for industry to improve the safety and quality of their product, and contribute to the vitality of the poultry industry on Delmarva. In addition, research results will be published in The Journal of Applied Poultry Research, Transactions of the American Society of Agricultural and Biological Engineers and UMD Poultry Perspectives newsletter (mailed to all poultry producers on Delmarva).

Results will be presented at the following: regional, and national meetings, and to poultry representatives so that this ventilation strategy may be implemented in other regions of the United States. Perhaps the efficacy of this ventilation strategy can also be investigated in other livestock animal facilities in order to improve the safety and quality of other meat products produced in the United States.

More information
Non-Technical Summary: This proposal represents a collaborative, interdisciplinary investigation of airflow patterns 2-3 inches over the litter/manure surfaces of commercial broiler houses, and modeling studies that identify ways to correct areas of deficient airflow over these surfaces. Identification of practical ventilation designs, retrofits and/or devices that would correct areas of deficient airflow (e.g., along house walls, in corners and in flow eddies under fans is now needed. The identification of remediation strategies is the critical concluding step for over twenty years of study at the University of Maryland. Literature citations include key observations concerning: a) Salmonella contamination of the litter surface and bird/carcass contamination; b) Salmonella and farm revenue; c) litter/manure surface water activity (Aw) and moisture content (MC) and the level of Salmonella and E. coli contamination in and on these surfaces; d) litter surface airflow rates and Aw and MC; and e) a national need for identification of improved Salmonella risk reduction strategies. The proposed study synergistically combines experimentation and computational modeling to efficiently develop healthier and more productive growth environments for poultry.

Approach: All houses will be selected to have identical dimensions and to be operated on a system that will allow fan settings that are identical. Furthermore, the fans will be set to two standard ventilation configurations (sidewall ventilation and tunnel ventilation) to collect airflow data. Data will be collected during times typical of both the fall/winter cool, dry season and the summer or hot humid season. Information regarding fan model, size, number of fans, etc. will be collected along with current flock information. Measurements will be collected when the house is empty (between flocks) and with birds in the house (4-6 weeks of age). Six houses will be measured and they will be distributed across the southern section of Maryland's eastern shore, with the building and fan variables being more important than geographic location. Given a house of length L and width W, measurements will be taken at 0.2L, 0.3L, 0.4L, 0.5L, 0.6L, 0.7L, and 0.8L along a side. In the first two houses, those locations will be repeated for each side of the house to evaluate whether data from both sides of the house must be collected for the remaining houses. Along the back and front, data will be collected from 0.1W, 0.3W, and 0.5W. In the first two houses, those locations will be repeated for each end of the house to evaluate whether data from both sides of the house must be collected for the remaining houses. In other words, is the airflow distribution symmetrical about the long and short axis of the house It is expected that the airflow distribution will be different on the influent and effluent ends of the house. Additionally, previous research has suggested that there are stagnant points beneath fan cowlings and in the corners. These locations will also be measured. Finally, measurements will be taken at the dead center of the house to characterize each experiment and to provide a measurement that an operator can easily take if the findings of the experiment translate into operating recommendations. Airflow will be measured (using a handheld airflow measurement device) at an elevation of 2cm above the surface in order to be comparable with Eriksson de Rezende et al. (2001) and also at 60 cm and 120cm to provide a detailed picture of its variations with height. A brace and plate to hold the measurement device will be built in-house to make repeated measurements consistent. Because velocity is very directional, a rotation device will be a built or purchased to collect the full range of velocity data from each location. The airflow will be measured a short distance away from the walls of the house. This distance will be a function of the brace and plate and the turntable devices, but it is anticipated that the distance will be approximately 15 cm. Airflow within the study poultry houses will be modeled under steady-state in three dimensions. Simulation regimes will be focused on delineating ventilation strategies with potential to correct hot spots of low airflow at the litter level.

Funding Source
Nat'l. Inst. of Food and Agriculture
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Bacterial Pathogens
Meat, Poultry, Game