Source: AGRICULTURAL RESEARCH SERVICE submitted to
EVALUATION OF MANAGEMENT OF LAYING HENS AND HOUSING SYSTEMS TO CONTROL SALMONELLA AND OTHER PATHOGENIC INFECTIONS, EGG CONTAMINATION, AND PRODUCT QUALITY
Sponsoring Institution
Agricultural Research Service/USDA
Project Status
TERMINATED
Funding Source
Reporting Frequency
Annual
Accession No.
0430344
Grant No.
(N/A)
Project No.
6040-32420-002-00D
Proposal No.
(N/A)
Multistate No.
(N/A)
Program Code
(N/A)
Project Start Date
Feb 1, 2016
Project End Date
Jan 18, 2021
Grant Year
(N/A)
Project Director
JONES D R
Recipient Organization
AGRICULTURAL RESEARCH SERVICE
(N/A)
ATHENS,GA 30613
Performing Department
(N/A)
Non Technical Summary
(N/A)
Animal Health Component
(N/A)
Research Effort Categories
Basic
50%
Applied
50%
Developmental
0%
Classification

Knowledge Area (KA)Subject of Investigation (SOI)Field of Science (FOS)Percent
5033210110040%
7123270110060%
Goals / 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.
Project Methods
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 02/01/16 to 01/18/21

Outputs
PROGRESS REPORT Objectives (from AD-416): 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 (from AD-416): 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. This is the final report for this project; please refer to new project 6040-32420-003-000D, "Reducing Pathogen Contamination Risks and Improving Quality Attributes of Eggs and Egg Products through Housing System Management and Egg Handling Practices." Egg contamination by Salmonella Enteritidis and Typhimurium in experimentally infected laying hens in cage-free indoor housing. A study was completed to determine the frequency at which these highly invasive and prevalent Salmonella serovars were deposited inside the edible contents of eggs laid by infected laying hens in a housing system which is becoming increasingly prominent in the egg industry. Egg handling and ambient temperature impacts on physical and microbial quality during extended storage. The impact of handling practices in the shell egg processing facility, as well as post-processing ambient storage temperature on physical and microbial quality of eggs during 6 months of storage is being assessed. The study is necessary for USDA AMS to set shell egg import and export certification standards. Validation of USDA AMS sampling rates in official shell egg processing facilities. A study is underway, in conjunction with Purdue University, to determine if current USDA AMS sampling rates (1 in every 100 cases) are effective and efficient at maintaining USDA AMS shell egg grading standards. Development of instrument enhanced grading parameters for shell eggs in USDA AMS shell egg processing facilities. The validation stage of a long- term study, in conjunction with AMS and Purdue University, is currently underway to determine machine settings for large capacity shell egg processing equipment that will ensure packaged product meets shell egg grade standards. Internal organ colonization and horizontal transmission by Salmonella Enteritidis and Kentucky by experimentally infected laying hens in cage- free housing after prior vaccination. A study was completed to determine the frequency at which these Salmonella serovars were deposited in the egg contents laid by previously vaccinated, experimentally infected cage- free laying. Detection of Salmonella, Campylobacter, and Listeria in cage-free aviary environmental swabs. A study was completed to determine the naturally occurring pathogens, as well as the ability to detect low level Salmonella Enteritidis inoculation, in a variety of laying hen environmental swabs. Drag swabs and manure scraper swabs, as well as nest box swabs and egg belt, wall, and concrete flooring dust samples were compared. Comparison of egg physical, functional and microbial quality from around the world. Eggs imported from Turkey and India, as well as domestic eggs, were assessed for Salmonella prevalence, as well as egg quality. A full complement of physical and functional egg quality characteristics was monitored. 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 pullet housing system was compared for microbiological impact. Each month, drag swabs were assessed for Salmonella spp. prevalence and enumeration of coliforms. Internal organ colonization and vertical transmission by Salmonella Braenderup (SB) by experimentally infected laying hens in cage-free housing. A study was completed to determine the ability of the egg- associated human outbreak strain of SB to colonize organs and vertically transmit into eggs from inoculated cage-free laying hens. Development of training materials for shell egg processing facility pre- operational sanitation assessment. In collaboration with USDA AMS and Purdue University, video footage collected during FY 19 is being utilized to develop online training content for both AMS shell egg graders and egg processors. Twelve free-access training videos are now available with over 5,800 views. The project is ongoing. Influence of Northern Fowl Mites (NFM) on pathogen shedding, egg and environmental microbiology, and egg quality. NFM were introduced in a cage-free laying flock to determine if fecal shedding of Salmonella and Campylobacter spp. was influenced. Additionally, environmental swabs, egg shell emulsions, and egg contents were monitored for the two pathogens. Egg shape and volume, shell strength, egg weight, Haugh unit, vitelline membrane strength, and hard-cooked yolk strength were evaluated every 12 wks throughout the production cycle. Determination of compounds utilized in shell egg processing in the US. USDA FSIS requested ARS assistance in determining chemicals which make direct egg contact during shell egg processing in the US. ARS coordinated efforts with USDA AMS to collect information on chemical usage at all official shell egg processing facilities. The extensive list was provided to FSIS, along with copies of all associated safety data sheets. This information was utilized to update FSIS Directive 7120.1 Rev 55. 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. Egg shape and volume, weight, shell strength, Haugh unit, and vitelline membrane strength, as well as hard-cooked yolk strength and color were assessed from 20⿿50 wk of age. Laying hen skeletal health impact on response to Salmonella Enteritidis (SE) 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 SE and monitored for infection in liver, spleen, ceca, and magnum/isthmus junction to determine if skeletal health impacted the infection response. Determining equivalency of peracetic acid (PAA) as a shell egg sanitizing rinse. A study was conducted to determine what concentrations of PAA were equivalent to the mandatory 100-200 ppm chlorine (Cl) post-wash rinse in reducing shell surface levels of 3 Salmonella spp. and Enterobacter cloacae. It was determined 50-100 ppm PAA reduced surface bacterial levels similar to 100-200 ppm Cl. AMS has adjusted policy to allow for this level of usage in the voluntary grading program. Influence of genetic strain and housing system on egg and environmental microbiology and physical egg quality. The impact of 4 hen housing systems and 3 genetic strains of laying hens on egg and environmental microbiology was assessed from 20-68 wk of age. Samples were collected every 8 wk from a collaborative commercial style research farm. Total aerobes, Enterobacteriaceae, and yeasts and molds were enumerated. Salmonella, Campylobacter, and Listeria prevalence was also determined. Egg samples were evaluated for egg shape, shell characteristics, interior quality, and yolk physical characteristics. Influence of genetic strain and housing system on pathogen shedding. The impact of 4 housing systems and 3 genetic strains of laying hens on Salmonella, Campylobacter, and Listeria shedding. Beginning at hatch to 68 wk of age, fecal samples were collected monthly and assessed for pathogen prevalence. Deposition of Salmonella Enteritidis (SE) inside eggs produced by genetic lines of laying hens housed in conventional cages or enriched colonies. A study to determine the frequency of SE deposition in the contents of eggs laid by experimentally infected hens representing 4 genetically distinct commercial lines (in 2 different housing systems) was completed. Hen housing system influence on egg functional quality. The influence of hen housing system on functional characteristics of eggs were examined. Eggs from a single genetic brown egg strain of laying hen were collected bi-monthly from 20-68 wk of age and assessed for foaming, emulsification, and coagulation functions in food matrices. Consumer quality traits were also compared. Effectiveness of manure drag swab pooling on the detection of Salmonella spp. A study was concluded to determine the effectiveness of various pooling schemes on the detection of Salmonella spp. in federally required manure drag swab samples in laying hen barns. This study was conducted in conjunction with FDA. Duration of fecal shedding of Salmonella Heidelberg and Typhimurium by experimentally infected laying hens housed in enriched cages at different stocking densities. A study of the frequency and duration of fecal shedding of these pathogens by hens housed in enriched colony cages at two different stocking densities was completed. Effect of early lay phase and genetic strain in cage-free production system on egg physical and functional parameters. A study was conducted to assess when during early lay phase (19-25 wk of age) consistent egg physical and functional quality data could be attained. Three genetic lines each of brown and white egg layers were compared. A full profile of egg physical and functional quality measurements was conducted. Survival and multiplication of genetically characterized Salmonella Enteritis (SE) strains in egg yolk and albumen. A study of the growth of SE isolates (with defined genetic differences in their ability to infect chickens and deposit inside forming eggs) in experimentally contaminated egg contents was completed. Invasion of internal organs by Salmonella Enteritidis (SE) in commercial genetic lines of laying hens housed in conventional or enriched colony cages. A study to determine the frequency at which SE infected tissues of inoculated laying hens representing 4 commercial lines (housed in two different caging systems) was completed. On-farm holding of pullets during quarantine conditions and resulting egg quality. The influence of various strategies for holding pullets on-farm during disease quarantine conditions and the resulting impact on egg physical quality was studied. A full profile of physical egg quality parameters was assessed during the on-farm holding phase and subsequent move to cage-free aviary housing. Record of Any Impact of Maximized Teleworking Requirement: Due to pandemic restrictions both with USDA ARS and within the egg industry, in-plant sanitation research has been placed on hold. The two projects are soft funded and appropriate communication and extensions with the funding entity have taken place. ACCOMPLISHMENTS 01 Internal organ colonization and horizontal transmission by Salmonella Enteritidis and Salmonella Kentucky in experimentally infected laying hens in cage-free indoor housing. The ongoing transition of the commercial egg industry toward the use of non-cage housing options has raised new questions about the food safety consequences of egg production practices. ARS researchers in Athens, Georgia, assessed the horizontal transmission of Salmonella infection and invasion of internal organs after experimental inoculation of laying hens housed on wood shavings in isolation rooms simulating commercial cage-free barns with nest boxes and perches. After S. Enteritidis oral infection, both intestinal colonization and internal organ invasion (particularly to livers and ovaries) were detected in most orally inoculated hens, as well as in many uninoculated hens (exposed by horizontal contact with inoculated birds). After S. Kentucky oral infection, intestinal colonization was likewise observed at high frequencies in both inoculated and uninoculated hens, but invasion to internal organs was seldom detected. These results demonstrated that Salmonella infection can spread rapidly and extensively among hens in cage-free indoor housing, including a high frequency of internal organ invasion for the epidemiologically important serovar, S. Enteritidis.

Impacts
(N/A)

Publications

  • Gast, R.K., Jones, D.R., Guraya, R., Anderson, K.E., Karcher, D.M. 2020. Horizontal transmission and internal organ colonization by Salmonella Enteritidis and Salmonella Kentucky in experimentally infected laying hens in indoor cage-free housing. Poultry Science. 99:6071-6074.
  • Gast, R.K., Jones, D.R., Guraya, R., Anderson, K.E., Karcher, D.M. 2021. Internal organ colonization and horizontal transmission of experimental Salmonella Enteritidis and Salmonella Kentucky infection in vaccinated laying hens in indoor cage-free housing. Journal of Applied Poultry Research. 30:100132.
  • Jones, D.R., Garcia, J.S., Gast, R.K., Ward, G.E. 2021. Equivalency of peroxyacetic acid to chlorine as a shell egg sanitizing rinse. Poultry Science. https://doi.org/10.1016/j.psj.2021.101069.


Progress 10/01/19 to 09/30/20

Outputs
Progress Report Objectives (from AD-416): 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 (from AD-416): 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. Internal organ colonization and horizontal transmission by Salmonella Enteritidis and Salmonella Kentucky by experimentally infected laying hens in cage-free indoor housing after prior vaccination. A study was completed to determine the frequency at which these highly prevalent Salmonella serovars were deposited inside the edible contents of eggs laid by groups of previously vaccinated, experimentally infected laying hens in a housing system which is becoming increasingly prominent in the egg industry. Detection of Salmonella, Campylobacter, and Listeria in cage-free aviary environmental swabs. A study was completed to determine the detection of naturally occurring pathogens, as well as the ability to detect low level Salmonella Enteritidis inoculation in a variety laying hen environmental swabs. Drag swabs and manure scraper swabs (the currently mandated environmental swab types), as well as nest box swabs and egg belt, wall, and concrete flooring dust samples were collected for the comparison. Comparison of egg physical, functional and microbial quality from around the world. Eggs imported from Turkey and India, as well as domestic eggs, were held for 42-45 days post-lay under refrigeration before assessing for Salmonella prevalence, as well as egg quality. A full complement of physical and functional egg quality characteristics were monitored. 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 pullet housing system was compared for microbiological impact. Each month, drag swabs were assessed for Salmonella spp. prevalence and enumeration of coliforms. Up to 5 colonies from each positive coliform sample were randomly selected, cleaned, and stored for identification to determine microbial diversity at the end of the project. This study was replicated and completed. Internal organ colonization and vertical transmission by Salmonella Braenderup by experimentally infected laying hens in cage-free housing. A study has been initiated to determine the ability of the egg-associated human outbreak strain of Salmonella Braenderup to colonize organs and vertically transmit into eggs laid by experimentally inoculated cage-free laying hens. Development of training materials for shell egg processing facility pre- operational sanitation assessment. In collaboration with USDA AMS and Purdue University, video footage collected during FY 19 is being utilized to develop online training content for both USDA AMS shell egg inspectors and egg processors. Six training videos are now available free access. The project is ongoing. Accomplishments 01 Internal organ colonization and horizontal transmission by Salmonella Enteritidis and Salmonella Kentucky by experimentally infected laying hens in cage-free indoor housing after prior vaccination. Laying flocks are often vaccinated to protect against Salmonella Enteritidis infections which can be transmitted to humans when infected hens lay contaminated eggs, but the ongoing transition of the commercial egg industry toward the use of non-cage housing options has raised new questions about the food safety consequences of egg production practices. ARS researchers in Athens, Georgia, assessed the horizontal transmission of Salmonella infection and invasion of internal organs after experimental infection of previously vaccinated laying hens housed on wood shavings in isolation rooms simulating commercial cage- free barns with nest boxes and perches. One-third of the hens in each room received either S. Enteritidis or S. Kentucky (a common environmental strain but not associated with egg-borne disease transmission) and all were evaluated 12 d after infection to detect the presence of Salmonella in internal organs. After S. Enteritidis infection, pathogen colonization was detected in the intestines, livers, and spleens of 67% of orally inoculated hens and also in the intestines and livers of some uninoculated birds (exposed by horizontal contact). Significantly fewer hens were colonized by S. Kentucky. These results demonstrate that vaccines may not always provide complete exclusion of Salmonella, especially highly invasive serovars like S. Enteritidis, so a comprehensive risk reduction effort should be used to supplement vaccination of hens in cage-free housing systems to prevent extensive horizontal dissemination of Salmonella infection.

Impacts
(N/A)

Publications

  • Gast, Richard K. and Robert E. Porter, Jr., 2020. Salmonella infections. Pages 719-753 in Diseases of Poultry, 14th edition. D. E. Swayne, ed. John Wiley and Sons, Hoboken, New Jersey.
  • Jones, D.R., Gast, R.K., Regmi, P., Ward, G.E., Anderson, K.E., Karcher, D. M. 2020. Pooling of laying hen environmental swabs and efficacy of Salmonella spp. detection. Journal of Food Protection. 83(6):943-950.
  • Weimer, S.L., Robison, C.I., Tempelman, R.J., Jones, D.R., Karcher, D.M. 2019. Laying hen production and welfare in enriched colony cages at different stocking densities. Poultry Science. 98:3578-3586.


Progress 10/01/18 to 09/30/19

Outputs
Progress Report Objectives (from AD-416): 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 (from AD-416): 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. 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 01 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. 02 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.

Impacts
(N/A)

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.


Progress 10/01/17 to 09/30/18

Outputs
Progress Report Objectives (from AD-416): 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 (from AD-416): 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. Influence of genetic strain and housing system on egg and environmental microbiology. A study was concluded assessing the impact of 4 hen housing systems and 3 genetic strains of laying hens on egg and environmental microbiology. Samples were collected every 8 wk from a collaborative commercial style research farm. Indicator populations (total aerobes, Enterobacteriaceae, and yeasts and molds) were enumerated. Pathogen (Salmonella, Campylobacter, and Listeria) prevalence was also determined. The project was conducted from 20 � 68 wk of age. Influence of genetic strain and housing system on pathogen shedding. A study was conducted to determine the impact of 4 housing systems and 3 genetic strains of laying hens on Salmonella, Campylobacter, and Listeria shedding. Beginning at hatch, fecal samples were collected monthly and assessed for pathogen prevalence. The assessment was conducted from hatch � 68 wk of age. Deposition of Salmonella Enteritidis inside eggs produced by commercial genetic lines of laying hens housed in conventional cages or enriched colonies. A study to determine the frequency at which this epidemiologically important Salmonella serovar was deposited in the edible contents of eggs laid by experimentally infected hens representing four genetically distinct commercial lines (in two different housing systems) was completed. Egg physical quality across hen housing systems and genetic strains. A study was completed to assess the impact of 4 hen housing systems and 3 genetic strains of laying hens on egg physical quality parameters. Bi- monthly egg samples were evaluated for egg shape, shell characteristics, interior quality, and yolk physical characteristics. This study was conducted from 20 � 68 wk of age. Hen housing system influence on egg functional quality. A study was completed examining the influence of hen housing system on functional characteristics of eggs. Eggs from a single genetic brown egg strain of laying hen were collected bi-monthly and assessed for foaming, emulsification, and coagulation functions in food matrices. Consumer quality traits were also compared. The study was conducted from 20 � 68 wk of age. Effectiveness of manure drag swab pooling on the detection of Salmonella spp. A study was concluded to determine the effectiveness of various pooling scheme on the effective detection of Salmonella spp. in federally required manure drag swab samples in laying hen barns. This study was conducted in conjunction with the Food and Drug Administration. Accomplishments 01 Egg processing and storage conditions impact on egg physical quality during extended storage. The international trade of shell eggs has become more important in recent years in order to feed a growing worldwide population, meet food manufacturing demands, and address supply issues during disease outbreaks or product recalls. The primary barriers for the export and import of shell eggs are: whether to wash eggs and egg storage temperature. ARS researchers at Athens, Georgia, undertook a study to compare egg quality factors as influenced by egg washing and storage temperature. Three lots of nest run (unwashed) white shell eggs were collected on consecutive days from a commercial in-line egg production facility. The treatment and storage conditions were selected to encompass the primary egg handling and storage conditions utilized throughout the world: washed; washed, oiled; and unwashed stored at 4�C; and unwashed stored at 22�C. Eggs were assessed weekly from 0 � 15 wk. Percent egg weight loss was greatest for the unwashed 22�C eggs (15.72 %) and least for washed, oiled 4�C (0. 33 %). Less than 24 h at 22�C had a greater impact on yolk shape measurements decline than 15 wk at 4�C. After 15 wk, average Haugh unit scores (objective egg grade assessment) for all refrigerated treatments were still Grade A, unwashed 22�C dropped from Grade AA to almost Grade B in 1 wk. Room temperature storage of eggs rapidly declines egg quality. All refrigerated treatments maintained similar levels of egg quality throughout storage. Washing and oiling eggs before refrigerated storage did suppress the rate of egg weight loss. Maintaining eggs at refrigerated temperature has the greatest impact on maintaining egg quality, whether or not eggs were washed before entering refrigeration. 02 Invasion of internal organs by Salmonella Enteritidis in commercial genetic lines of laying hens housed in conventional cages or enriched colonies. The transmission of S. Enteritidis to humans inside contaminated eggs laid by infected hens is a leading public health concern, but the effects of different poultry housing systems on the microbial safety of eggs produced by different genetic lines of chickens are not fully understood. ARS researchers at Athens, Georgia, assessed the invasion of internal organs by 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 orally inoculated with S. Enteritidis and samples of liver, spleen, ovary, oviduct, and intestinal tract were removed from euthanized hens for bacteriologic culturing one week later. S. Enteritidis was recovered from intestinal samples at a significantly higher frequency from the white egg lines than from the brown egg lines in both conventional cage and enriched colony housing systems. For one brown egg line, the frequency of intestinal S. Enteritidis recovery was greater in conventional cages than in enriched colonies. However, there were no significant differences between hen lines or housing systems in S. Enteritidis isolation from any other internal organs. These results demonstrate that colonization of the intestinal tract by S. Enteritidis sometimes varies between genetic lines of egg-laying hens and that different housing systems can affect this colonization for some lines. 03 Survival and multiplication of genetically characterized Salmonella Enteritis strains in egg yolk and albumen. The survival and growth of S. Enteritidis strains in the edible contents of contaminated eggs plays such a major role in causing human illness that prompt refrigeration of eggs to prevent bacterial multiplication has been identified as the most important risk reduction practice to protect consumers. ARS researchers at Athens, Georgia, compared the abilities of ten S. Enteritidis strains, each of which had been previously characterized for several significant genetic and cellular characteristics, to grow rapidly in egg yolk and to survive for several days in egg albumen during storage at 25� C. Very small numbers of S. Enteritidis cells multiplied to levels more than 10 million times greater by 24 hours of incubation and larger numbers of S. Enteritidis cells remained at nearly constant levels in albumen through 96 hours of incubation, with relatively little overall variation observed between strains after incubation in either yolk or albumen. However, significant differences that were detected between individual strains suggested that possessing a gene that coded for fimbrial protein structures on the bacterial cell surface may have been useful for growth inside egg yolk, whereas maintaining a gene that coded for antibiotic resistance may have reduced bacterial survival in egg albumen. These results demonstrate that a few defined genetic characteristics of S. Enteritidis strains can affect their survival and growth properties in eggs, but the extent of variation between strains is likely insufficient to influence the effectiveness of egg refrigeration.

Impacts
(N/A)

Publications

  • Gast, R.K., Waltman, D.W. 2018. Salmonellosis. Diagnosis of major poultry diseases. Y.J. Saif and H. Toro, eds.pp. 55-59. Servet Publishing, Zaragoza, Spain.
  • Chousalker, K., Gast, R.K., Martelli, F., Soboleva, T., Pande, V. 2018. Review of egg-related salmonellosis and reduction strategies. Critical Reviews in Microbiology. 44:290-293.
  • Gast, R.K., Guraya, R., Jones, D.R., Guard, J.Y., Anderson, K.E., Karcher, D.M. 2017. Frequency and duration of fecal shedding of Salmonella serovars Heidelberg and Typhimurium by experimentally infected laying hens housed in enriched colony cages at different stocking densities. Avian Diseases. 61:366-371.
  • Jones, D.R., Ward, G.E., Regmi, P., Karcher, D.M. 2018. Impact of egg handling and conditions during extended storage on egg quality. Poultry Science. 97:716-723.
  • Gast, R.K., Guard, J.Y., Guraya, R., Locatelli, A. 2018. Multiplication in egg yolk and survival in egg albumen of genetically and phenotypically characterized Salmonella Enteritidis strains. Journal of Food Protection. 81:876-880.
  • Jones, D.R., Karcher, D., Regmi, P., Robison, C.O., Gast, R.K. 2018. Hen genetic strain and extended cold storage implications on physical egg quality from cage-free aviary housing system. Poultry Science. 97: 2347- 2355.


Progress 10/01/16 to 09/30/17

Outputs
Progress Report Objectives (from AD-416): 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 (from AD-416): 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. Impact of genetic strain in commercial aviary housing system on egg quality and functionality. A study was completed to assess the physical and functional quality of eggs from 4 genetic strains of laying hens housed in commercial aviary systems. Eggs are stored for 12 wk and assessed every 4 wk. The study was conducted for a full 50 wk production cycle. Duration of fecal shedding of Salmonella Heidelberg and Salmonella Typhimurium by experimentally infected laying hens housed in enriched cages at different stocking densities. A study of the frequency and duration of fecal shedding of these pathogen by groups of hens housed in enriched colony cages at two different stocking densities was completed. Affect of early lay phase and genetic strain in cage-free production system on egg physical and functional parameters. A study was conducted to assess when during early lay phase consistent egg physical and functional quality data could be attained. Beginning at 19 wk of age, eggs were evaluated each week thru 25 wk of age. Three genetic lines each of brown and white egg layers were compared. A full profile of egg physical and functional quality measurements were conducted each week. Influence of genetic strain and housing system on egg and environmental microbiology. A study was initiated to determine the impact of 4 hen housing systems and 3 genetic strains of laying hens on egg and environmental microbiology. Samples are being collected every 8 wk from a collaborative commercial style research farm. Indicator populations (total aerobes, Enterobacteriaceae, and yeasts and molds) are enumerated. Pathogen (Salmonella, Campylobacter, and Listeria) prevalence is also being determined. The project will be conducted from 20 � 68 wk of age. Influence of genetic strain and housing system on pathogen shedding. A study is in progress to determine the impact of 4 housing systems and 3 genetic strains of laying hens on Salmonella, Campylobacter, and Listeria shedding. Beginning at hatch, fecal samples are collected monthly and assessed for pathogen prevalence. The assessment will be conducted from hatch � 68 wk of age. Egg physical quality across hen housing systems and genetic strains. A study is in progress assessing the impact of 4 hen housing systems and 3 genetic strains of laying hens on egg physical quality parameters. Bi- monthly egg samples are evaluated for egg shape, shell characteristics, interior quality, and yolk physical characteristics. This study will be conducted from 20 � 68 wk of age. Hen housing system influence on egg functional quality. A study is in progress examining the influence of hen housing system on functional characteristics of eggs. Eggs from a single genetic brown egg strain of laying hen are collected bi-monthly and assessed for foaming, emulsification, and coagulation functions in food matrices. Consumer quality traits are also compared. The study will be conducted from 20 � 68 wk of age. Survival and multiplication of genetically characterized Salmonella Enteritis strains in egg yolk and albumen. A study of the growth of a set of S. Enteritidis isolates (with defined genetic differences in properties related to their ability to infect chickens and deposit inside forming eggs) in experimentally contaminated egg contents was completed. Invasion of internal organs by Salmonella Enteritidis in commercial genetic lines of laying hens housed in conventional or enriched colony cages. A study to determine the frequency at which this epidemiologically important Salmonella serotype infected tissues of experimentally infected laying hens representing four genetically distinct commercial lines (housed in two different caging systems) was completed. Effectiveness of manure drag swab pooling on the detection of Salmonella spp. A study is underway to determine the effectiveness of various pooling scheme on the effective detection of Salmonella spp. in federally required manure drag swab samples. This study is being conducted in conjunction with the Food and Drug Administration (FDA). Egg processing and holding conditions impact on egg physical quality during extended storage. A study is underway to determine the influence of various shell egg processing methods and storage temperature on egg physical quality during extended storage. Each week, eggs from various processing and holding conditions are assessed for physical quality characteristics. This study is conducted in partnership with the egg industry, as well as USDA Agricultural Marketing Service (AMS), to address international shell egg import and export limitations. On-farm holding of pullets during quarantine conditions and resulting egg quality. A study was conducted to determine the influence of various strategies for holding pullets on-farm during disease quarantine conditions and the resulting impact on egg physical quality. A full profile of physical egg quality parameters were assessed during the on- farm holding phase and subsequent move to cage-free aviary housing. Accomplishments 01 Duration of fecal shedding of Salmonella (S.) Enteritidis by experimentally infected laying hens housed in enriched cages at different stocking densities. ARS researchers in Athens, Georgia, determined that housing laying hens in enriched colony cages at a higher stocking density increased the frequency at which they shed S. Enteritidis in their feces after being experimentally infected, but housing hens in conventional cages caused an even higher frequency of shedding. In recent years, alternatives to conventional cage-based housing for poultry flocks have become increasingly common in the commercial egg industry, but the impact of different housing systems on important public health problems, such as S. Enteritidis contamination of eggs laid by infected hens, are not yet fully understood. In this study, laying hens were housed in colony cages enriched with perches and enclosed nesting areas at two different stocking densities (defined by the amount of floor space available to each bird), or in conventional cages at the higher density, and infected orally with S. Enteritidis. Samples of voided feces were collected from trays beneath the cages at weekly intervals and tested for the pathogen. The frequency of S. Enteritidis isolation from feces was significantly greater when infected hens were housed in enriched colony cages at the higher stocking density in comparison to the lower density, but S. Enteritidis was isolated from fecal samples at a greater overall frequency from hens in conventional cages than from either group housed in enriched cages. These results demonstrate that hen stocking density can affect the susceptibility of hens to intestinal colonization by S. Enteritidis, but some other characteristic which distinguishes conventional and enriched colony cage systems also exerts an influence. 02 Duration of fecal shedding of Salmonella (S.) Heidelberg and Salmonella Typhimurium by experimentally infected laying hens housed in enriched cages at different stocking densities. ARS researchers in Athens, Georgia, determined that housing laying hens in different cage systems or at different stocking densities affected the frequency at which infected hens shed S. Heidelberg, but not S. Typhimurium, in their feces. Although alternatives to conventional cage-based housing for poultry flocks have become increasingly common in the commercial egg industry, their impact on the important food safety problem of Salmonella contamination of eggs remains incompletely understood. In this study, laying hens were housed in colony cages enriched with perches and enclosed nesting areas at two different stocking densities (defined by the amount of floor space available to each bird), or in conventional cages at the higher density, and infected orally with either S. Heidelberg or S. Typhimurium (Salmonella serovars known to cause egg-transmitted human illness). When samples of voided feces were collected from trays beneath the cages at weekly intervals, S. Heidelberg was found in the feces of infected hens for more weeks after inoculation and at a higher overall frequency than was S. Typhimurium. Housing did not influence the frequency of S. Typhimurium shedding, but hens in both higher stocking density cage groups (enriched colony and conventional) shed S. Heidelberg at a greater frequency than did hens in enriched colony cages at the lower density. These results demonstrate that stocking density can influence the fecal shedding of Salmonella by laying hens for some (but not all) serovars or strains.

Impacts
(N/A)

Publications

  • Gast, R.K., Guraya, R., Jones, D.R., Anderson, K.E., Karcher, D.M. 2017. Frequency and persistence of fecal shedding of Salmonella Enteritidis by experimentally infected laying hens housed in enriched colony cages at different stocking densities. Frontiers in Veterinary Science. 4:47.
  • Hudson, L., Harrison, M., Berrang, M.E., Jones, D.R. 2016. Alternative antimicrobial commercial egg washing procedures. Journal of Food Protection. 79(7):1216-1220.
  • Gast, R.K. 2016. Microbiology of Shell Egg Production in the United States. In Producing Safe Eggs, Steven C. Ricke and Richard K. Gast, eds. Academic Press, London, UK. p. 25-44.
  • Gast, R.K., Guraya, R., Jones, D.R., Guard, J.Y., Anderson, K.E., Karcher, D.M. 2017. Colonization of internal organs by Salmonella serovars Heidelberg and Typhimurium in experimentally infected laying hens housed in enriched colony cages at different stocking densities. Poultry Science. 96:1402-1409.
  • Gast, R.K. 2017. Sampling and detection of Salmonella in eggs. In Achieving Sustainable Production of eggs: Volume 1: Safety and Quality, J. Roberts, Ed. Burleigh Dodds, Cambridge, UK. p.141-160.
  • Gradl, J.A., Curtis, P.A., Jones, D.R., Anderson, K.E. 2017. Assessing the impact of egg sweating on Salmonella Enteritidis penetration into shell eggs. Poultry Science. 96:2393-2399.
  • Jones, D.R. 2017. The effects of housing systems for laying hens on egg safety and quality. In Achieving Sustainable Production of eggs: Volume 1: Safety and Quality, J. Roberts, Ed. Burleigh Dodds, Cambridge, UK. p. 195-210.
  • Hofacre, Charles, L., Randall Singer, and Richard K. Gast, 2017. Foodborne Salmonella control. In: A Practical Guide for Biosecurity in the Poultry Industry, 2nd edition. Jacksonville, FL. Robert L. Owen, ed., pp. 53-59.
  • Waltman, W. Douglas and Richard K. Gast, 2016. Salmonella enterica. In Isolation and Identification of Avian Pathogens, 6th edition, S. M. Williams, L. Dufour-Zavala, M. W. Jackwood, M. D. Lee, B. Lupiani, W. M. Reed, E. Spackman, and P. R. Woolcock, eds.American Association of Avian Pathologists, Athens, GA. pp. 103-112.
  • Gast, R.K., Jones, D.R. 2017. Salmonella and impact on egg production. In Egg Production: Innovations and strategies for improvement, Patricia Hester, ed., Academic Press, Cambridge, MA. pp. 513-522.


Progress 10/01/15 to 09/30/16

Outputs
Progress Report Objectives (from AD-416): 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 (from AD-416): 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. Impact of genetic strain on Salmonella shedding in commercial aviary housing systems. Study was initiated to determine the impact of 4 genetic strains of laying hens on Salmonella shedding from day of hatch through a full egg production cycle. Fecal shedding is monitored monthly through rearing and laying phases. Impact of genetic strain in commercial aviary housing system on egg quality and functionality. Study was initiated to assess the physical and functional quality of eggs from 4 genetic strains of laying hens housed in commercial aviary systems. Eggs are stored for 12 weeks and assessed every 4 weeks. The study will be conducted for a full production cycle. Impact of genetic strain in commercial aviary housing system on egg microbiology. Study was initiated to assess the impact of genetic strain on the levels of total aerobe, Enterobacteriaceae, and yeast and molds in shell emulsions. Nestbox, system, and floor eggs are assessed separately. The prevalence of Salmonella is also being determined. Invasion of internal organs by Salmonella Heidelberg and Salmonella Typhimurium in experimentally infected laying hens housed in enriched colony cages at different stocking densities. A study to determine the frequency at which these epidemiologically important serotypes of Salmonella colonize the internal organs of experimentally infected hens (housed at a range of stocking densities in different caging systems) was completed. Persistence of fecal shedding of Salmonella Enteritidis by experimentally infected laying hens housed in enriched cages at different stocking densities. A study of the frequency and duration of fecal shedding of the pathogen by groups of hens housed in enriched colony cages at two different stocking densities was completed. Persistence of fecal shedding of Salmonella Heidelberg and Salmonella Typhimurium by experimentally infected laying hens housed in enriched cages at different stocking densities. A study of the frequency and duration of fecal shedding of these pathogen by groups of hens housed in enriched colony cages at two different stocking densities was partially completed. Accomplishments 01 Invasion of internal organs by Salmonella (S.) Enteritidis in experimentally infected laying hens housed in enriched colony cages at different stocking densities. ARS researchers in Athens, Georgia, determined that housing laying hens in enriched colony cages at different stocking densities significantly affected the progress of experimentally introduced infections with Salmonella Enteritidis, although an even greater difference was observed when hens were housed at a higher stocking density in conventional cages. Most human illnesses caused by S. Enteritidis are attributed to contaminated eggs produced by infected hens, so the recently intensified interest in alternative production housing systems for commercial laying flocks (including various types of cage-based and cage-free options) has raised many questions about the influence of poultry housing and management systems on Salmonella infections and egg contamination. This ARS research examined some of the microbiological consequences of housing laying hens in colony cages, enriched with perches and enclosed nesting areas, at different stocking densities (defined by the amount of floor space available to each bird). Groups of hens were housed at two different stocking densities (and a third group was placed in conventional cages at the higher density). S. Enteritidis infection was initiated and the birds were euthanized the following week so tissues samples could be collected and tested. S. Enteritidis was recovered more frequently from livers and ovaries of hens in enriched colony cages at the higher stocking density than at the lower density. However, S. Enteritidis was also recovered more often from spleens of hens in conventional cages than from those in enriched colony cages at the higher stocking density. These results demonstrate that stocking density can influence the susceptibility of hens to S. Enteritidis, but other characteristics of the various housing systems may also play important roles.

Impacts
(N/A)

Publications

  • Gast, R.K., Guraya, R., Jones, D.R., Anderson, K., Karcher, D.M. 2016. Colonization of internal organs by Salmonella Enteritidis in experimentally infected laying hens housed in enriched colony cages at different stocking densities. Poultry Science. 95:1363-1369.