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United States Department of Agriculture

Agricultural Research Service

Research Project: Sustainable Egg Supply in Alternative Housing Systems for Laying Hens

Location: Egg Safety and Quality

2011 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

The related objectives of the parent project are: 1. Evaluate bactericidal effects of critical processing parameters (e.g. influence of wash water parameters, sanitizers, and sanitizer application methods) on egg safety. Specifically, conduct research on effective sanitizers (chemical, UV, etc.) and parameters that influence efficacy (temperature, nozzle type, etc.). 2. Identify intervention strategies and processing practices for shell egg facilities and equipment that will improve sanitation standard operating procedures and reduce foodborne pathogens. 3. Develop more sensitive methods of detection and analysis and apply them in the determination and characterization of pathogen flow through the processing detection.

Barns were constructed to house layer hens in aviary and enriched caged systems, respectively. A barn with used cages (previously used) was present. A coordinator for collection of samples was hired. Parent layer breeder flocks were surveyed for the colonization by Salmonella and Campylobacter. These flocks are parents of the birds that were placed in the three housing systems. Environmental samples were taken prior to chicks being placed. The sample coordinator was trained for collection of environmental and egg shell samples. Eggs were crushed aseptically and placed into centrifuge tubes, packed with freezer blocks, and transported to the laboratory. The processing facility was toured and appropriate environmental and water samples were designated.

Monthly sampling has been conducted for each of the housing types. A quarterly sampling of the processing facility has been conducted. Environmental samples (swabs of egg collection equipment, cages, and floors) and egg samples were enriched for Salmonella and Campylobacter, respectively.

Over the three months of sampling more positive environmental samples collected from traditional cages were positive for Salmonella. More Campylobacter have been recovered from environmental samples collected from the aviary housing system than from traditional and enriched cages combined.

Salmonella was not recovered from any eggs collected at the house or in the processing facility. Unwashed egg slurry from traditional cages and a washed egg slurry from enriched cages were positive for Campylobacter.

All samples have been saved and will be analyzed subsequently. Sero-grouping and sero-typing will be performed for Salmonella. Salmonella and Campylobacter will be characterized on a molecular level.


Last Modified: 8/27/2014
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