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ARS Home » Southeast Area » Athens, Georgia » U.S. National Poultry Research Center » Egg and Poultry Production Safety Research Unit » Research » Publications at this Location » Publication #352533

Research Project: Evaluation of Management of Laying Hens and Housing Systems to Control Salmonella and Other Pathogenic Infections, Egg Contamination, and Product Quality

Location: Egg and Poultry Production Safety Research Unit

Title: The impact of cage-free housing system on horizontal transmission of Salmonella in eggs

item Ward, Garrett
item Jones, Deana
item Gast, Richard
item ANDERSON, KENNETH - North Carolina State University
item THIPPAREDDI, HARSHAVARDHAN - University Of Georgia
item SINGH, MANPREET - University Of Georgia

Submitted to: Poultry Science Association Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 5/1/2018
Publication Date: 7/23/2018
Citation: Ward, G.E., Jones, D.R., Gast, R.K., Anderson, K., Thippareddi, H., Singh, M. 2018. The impact of cage-free housing system on horizontal transmission of Salmonella in eggs. Poultry Science Association Meeting Abstract. 97:65.

Interpretive Summary:

Technical Abstract: The current study evaluated the ability of Salmonella to penetrate nest run cage-free eggs via two inoculation methods. Nest box eggs were collected from a flock of cage-free layers (34 - 49 wks of age) with a stocking density of 0.121 m2. Two day-old nest run eggs (n = 720; stored at 4°C) were utilized. Four nalidixic (200-ppm) acid-resistant Salmonella serovars: S. Enteritidis (SE), S. Heidelberg (SH), S. Kentucky (SK), and S. Typhimurium (ST) were used in this study based on links to foodborne illness and/or frequent production environment recovery from previous research. The trial included two inoculation methods (fecal paste and dip) with an approximate target concentration of 5 log10 cfu per g or mL to evaluate penetration of serovars. Inoculated eggs were placed in 4°C storage. Weekly sampling was conducted for 5 wks with each egg sampled at 3 locations to determine shell penetration: shell rinse, shell and membrane emulsion, and egg contents. Statistical analysis was conducted using Pearson’s Chi Square test for independence. While no Salmonella spp. were detected in the egg contents, prevalence in the shell emulsion, across all serovars, diminished over time (P < 0.05). Differences in Salmonella penetration varied between serovars and inoculation treatments, where SE had higher prevalence on the shell in fecal inoculated (91.27 %) than dip inoculated eggs (82.24 %; P < 0.05). However, prevalence in the shell emulsion was not different between the two inoculation treatments for SE. ST prevalence was higher on the shell for dip inoculated (100%) versus fecal inoculated eggs (84.26 %; P < 0.05). ST prevalence for shell emulsion was greater for dip inoculated (43.52 %) versus fecal inoculated eggs (27.78 %; P < 0.05). There was no significant difference in the prevalence of SH between inoculation treatments; respectively both treatments had prevalence levels higher than 88 % throughout the duration of the study for shell rinse. SH resulted in a greater prevalence in the shell emulsions of fecal inoculated (37.14 %) versus dip inoculated eggs (14.81 %; P < 0.05). Finally, there was no difference in the prevalence of SK between inoculation treatments for both the shell rinse and the shell emulsion. Nest run cage-free eggs shell penetration by Salmonella spp. can occur throughout refrigerated storage. The contribution of fecal contamination on the surface of shell eggs to Salmonella spp. penetration should be taken into consideration when storing eggs prior to washing.