Location: Egg and Poultry Production Safety Research Unit
2019 Annual Report
Objectives
Objective 1: Assess the impact of dietary regimens, housing systems, and different chicken genetic lines on Salmonella (S.) infections of hens, Salmonella contamination of the production environment and eggs, and physical and functional egg quality.
1.a. Holistic comparison of genetic strains in commercial cage-free aviary housing.
1.b. Compare Salmonella shedding and microbial quality of eggs and environment in commercial-style conventional cage, enriched colony cage, enrichable colony cage, cage-free, and free range systems for various genetic strains of laying hens.
1.c. Assess the susceptibility of defined genetic lines of laying hens to infection with S. Enteritidis when housed in different cage-based production systems.
Objective 2: Assess the effects of key management practices using experimental and field models of different housing systems on hen health, microbial ecology of foodborne bacteria, and antimicrobial resistance associated with egg contamination.
2.a. Assess the effects of different stocking densities on S. Enteritidis infections in laying hens housed in enriched colony cages.
2.b. Assess the effects of different cage-based housing systems on infections of laying hens with Salmonella serotypes (other than Enteritidis) which are significantly associated with egg contamination.
2.c. Determine the impact of hen housing systems on prevalence, diversity, and antimicrobial resistance of Salmonella, Campylobacter, Listeria, and Enterobacteriaceae associated with the production environment and eggs.
Approach
The housing of laying hens has become a matter of state and federal regulatory concern, as well as a purchasing consideration for consumers. While the shift in European Union laying hen housing requirements resulted in a plethora of research, most have limited similarity to the management systems utilized in the U.S. This project will, through national collaborative efforts, examine the impact of U.S. commercial hen housing systems on hen health and well-being, egg and environmental microbiology, and Salmonella infection and transmission. The collaborations associated with this project allow for a comprehensive examination of hen housing systems in a cost-effective manner. Furthermore, the project incorporates the research gaps identified by federal and state regulatory groups, as well as large and small egg producers. The research project will determine the impact of hen housing systems and laying hen genetic strain on the prevalence of Salmonella, as well as other human pathogens. Additionally, this project will determine the infection rate and transmission of various Salmonella strains within these housing systems. The effects of housing and management strategies on egg quality will also be assessed. The data generated from the project can be utilized by large and small egg producers to develop informed production management plans and state and federal regulatory groups to determine regulatory needs to ensure safe, high quality eggs reach consumers.
Progress Report
Horizontal transmission of infection and invasion of internal organs by Salmonella Enteritidis and Salmonella Kentucky in a commercial line of laying hens housed in a cage-free indoor housing system. A study was completed to determine the frequency at which these highly prevalent Salmonella serovars were transmitted horizontally and invaded to internal organs in groups of experimentally infected laying hens in a housing system which is becoming increasingly prominent in the egg industry.
Influence of Northern Fowl Mites on pathogen shedding, as well as egg and environmental microbiology. Northern Fowl Mites were introduced in a cage-free laying flock to determine if fecal shedding of Salmonella and Campylobacter spp. is influenced by the presence. Additionally, environmental swabs, egg shell emulsions, and egg contents monitored for the two pathogens. This study is ongoing.
Influence of Northern Fowl Mites on egg quality. Shell and interior egg quality parameters are being assessed to determine if an infestation of Northern Fowl Mites in cage-free laying hens impacts the quality of eggs produced. Egg shape and volume, shell strength, egg weight, Haugh unit, vitelline membrane strength, and hard-cooked yolk strength are being evaluated every 12 wks throughout the production cycle. This study is ongoing.
Determination of compounds utilized in shell egg processing in the U.S. USDA Food Safety Inspection Service (FSIS) requested USDA ARS assistance in determining chemicals which make direct egg contact during shell egg processing in the U.S. USDA ARS coordinated efforts enlisting USDA Agricultural Marketing Service (AMS) National Shell Egg Supervisors to collect information on chemical usage at all official shell egg processing facilities. The extensive list was provided to USDA FSIS, along with copies of all associated safety data sheets. This information is being utilized in the development of the final rule associated with egg products processing.
Impact of nutrition interventions in cage-free aviary housing on egg quality. Hens in commercial cage-free aviaries were provided basal diets as well as those supplemented with various omega fatty acids or vitamin D. Physical egg quality was monitored monthly to determine impacts of the feeding regimens. Egg shape and volume, weight, shell strength, Haugh unit, and vitelline membrane strength, as well as hard-cooked yolk strength and color were assessed. This study was conducted from 20 – 50 wks of age.
Cage-free forage substrate material influence on pathogen shedding and environmental microbiology. Utilization of shavings or astroturf (with manure removal system) as forage material in a cage-free laying hen housing system are being compared for microbiological impact. Each month, drag swabs are assessed for Salmonella spp. prevalence and enumeration of coliforms. Up to 5 colonies from each positive coliform sample are randomly selected, cleaned, and stored for identification to determine microbial diversity at the end of the project. This study is ongoing.
Development of training materials for shell egg processing facility pre-operational sanitation assessment. In response to a USDA AMS assistance request, efforts were coordinated and conducted to collect numerous hours of video content in shell egg processing facilities before and after sanitation procedures were conducted. The video footage will be utilized to develop online training content for both USDA AMS shell egg inspectors and egg processors. The project is ongoing.
Laying hen skeletal health impact on response to Salmonella Enteritidis challenge. Mature laying hens with low and extensive keel damage scores, based on Welfare Quality Assessment and MRI assessments were individually housed. Hens were challenged with Salmonella Enteritidis and monitored for infection in liver, spleen, ceca, and magnum/isthmus junction to determine if skeletal health impacted the infection response to S. Enteritidis. Sample analysis is ongoing.
Accomplishments
1. Determining equivalency for peracetic acid as shell egg sanitizing rinse. USDA Agricultural Marketing Service (AMS) voluntary shell egg grading program requires eggs to be rinsed with a water equal or warmer than wash water temperature containing 100 – 200 ppm chlorine or its equivalence. Organic egg producers have petitioned USDA AMS to utilize peracetic acid instead of chlorine in rinse water. ARS researchers in Athens, Georgia, conducted a study to determine which concentrations of peracetic acid were equivalent to chlorine in reducing microbial levels on the shells of washed cage-free eggs. Eggs were washed according to USDA AMS guidelines for grade-shielded eggs. Four organisms (previously cultured from the egg production environment) were utilized individually via dip inoculation on the shell: Salmonella Enteritidis, S. Typhimurium, S. Bradenrup, and Enterobacter cloacae. Seven concentration of peracetic acid were compared to 100 and 200 ppm chlorine, as well as water. It was determined 50 – 100 ppm peracetic acid had similar levels of reduction as 100 – 200 ppm chlorine for the organisms assessed. Summary results have been provided to USDA AMS for policy development.
2. Contamination of eggs by Salmonella Enteritidis in commercial genetic lines of laying hens housed in conventional cages or enriched colonies. Contaminated eggs produced by infected laying hens can transmit Salmonella Enteritidis to consumers, but the influences of different poultry housing systems on the microbial safety of eggs produced by different genetic lines of chickens are not fully understood. ARS researchers in Athens, Georgia, assessed the production of eggs contaminated with S. Enteritidis in groups of experimentally infected laying hens of four commercial genetic lines (two brown egg and two white egg lines), housed in both conventional cages and colony units enriched with access to perches and nesting areas. All hens were experimentally infected with S. Enteritidis and their eggs were collected for several weeks and tested for pathogen contamination of the internal contents. S. Enteritidis was found more often inside eggs from the two white egg lines than from the brown egg lines in either type of housing. One brown egg line laid fewer contaminated eggs than any other line and the egg contamination frequencies of the two white lines differed significantly. These results demonstrate that S. Enteritidis deposition inside eggs can vary between genetic lines of egg-laying hens, but different housing systems do not appear to influence these trends.
Review Publications
Regmi, P., Robinson, C., Jones, D.R., Gast, R.K., Tempelman, R.J., Karcher, D.M. 2018. Effects of different litter substrates and induced molt on production performance and welfare quality parameters of white Leghorn hens housed in multi-tiered aviary system. Poultry Science. 97:3397-3404.
Gast, R.K., Regmi, P., Guraya, R., Jones, D.R., Anderson, K., Karcher, D.M. 2019. Colonization of internal organs by Salmonella Enteritidis in experimentally infected laying hens of four commercial genetic lines in conventional cages and enriched colony housing. Poultry Science. 98:1785-1790.
Eberle-Krish, K., Jones, D.R., Gast, R.K., Robinson, C.I., Anderson, K.E., Karcher, D.M. 2019. Microbiological impact of delayed movement of pullets. Journal of Applied Poultry Research. 20(2):318-328.
Karcher, D.M., Jones, D.R., Robinson, C.I., Eberle-Krish, K., Gast, R.K., Anderson, K. 2019. Production and well-being resulting from delayed movement of pullets to the hen facility. Journal of Applied Poultry Research. 28(2):278-289.
