Submitted to: Poultry Science
Publication Type: Abstract Only
Publication Acceptance Date: 4/15/2012
Publication Date: 7/9/2012
Citation: Jones, D.R., Anderson, K., Guard, J.Y., Gast, R.K. 2012. Microbiological differences between laying hen strains housed in various production systems. Poultry Science. 91(supp):27.
Technical Abstract: Sister flocks of three strains of laying hens were housed in conventional cage, free range, and cage free production systems. All flocks were located on a single, commercial-style research facility and provided the same dietary and lighting regimens. Once a season, a sample of shell eggs was aseptically collected from each production system and hen strain combination. In free range and cage free production, floor eggs were separated from nest box eggs. Cracked eggs were excluded from sampling. Shell emulsion pools were created and total aerobic, Enterobacteriaceae, and yeast and mold populations were enumerated. Total aerobic populations averaged between 3.5 – 4.5 log cfu/mL shell emulsion diluent for all strains across production systems. Enterobacteriaceae counts were lowest in winter for all strains and housing systems. Two strains had highest Enterobacteriaceae levels present in free range nest box eggs in the spring (3.8 – 4.2 log cfu/mL shell emulsion diluent). Yeast and mold counts were also lowest in the winter for all strain and housing combinations. Overall, average aerobic counts were similar between strains and housing systems. Enterobacteriaceae counts associated with egg shells were lowest for conventional cage production. Season of the year, hen production system, and laying hen strain all contribute to the overall microbial quality of shell eggs.