|ANDERSON, K - North Carolina State University|
Submitted to: Poultry Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/31/2013
Publication Date: 7/23/2013
Citation: Jones, D.R., Anderson, K.E. 2013. Housing system and laying hen strain impacts on egg microbiology. Poultry Science. 92:2221-2225.
Interpretive Summary: Eggs from alternative housing systems are becoming more commonplace in retail egg cases. Unfortunately, there is not a complete understanding of the food safety implications of the various housing systems. The current study was conducted to compare three strains of laying hens (Hy-Line Brown, Hy-Line Silver Brown, and Barred Plymouth Rock) in three housing systems (conventional cage, cage-free, and free range) and the resulting microbial populations present on the shells of eggs. Cage-free hens were housed in a poultry barn without cages or outdoor access. Free range hens had a range hut and outdoor paddock. The laying hen strains produced eggs with differing degrees of aerobic bacteria, Enterobacteriaceae, and yeasts and molds contamination within each housing system. Additionally, laying hen strains produced eggs with differing levels of aerobic bacteria and Enterobacteriaceae between housing systems. The research indicates that laying hen strain can impact egg microbiology for various housing systems and food safety should be considered when egg producers are selecting hen strains for each housing system.
Technical Abstract: Alternative hen housing is becoming more commonplace in the egg market. However, a complete understanding of the implication of alternative housing systems on egg safety has not been achieved. The current study examines the impact of housing Hy-Line Brown, Hy-Line Silver Brown, and Barred Plymouth Rock hens in conventional cage, cage-free, and free range egg production systems on shell microbiology. Eggs were collected at four sampling periods. Egg shell emulsion pools were formed and enumerated for total aerobic organisms, Enterobacteriaceae, and yeast and mold counts. Hy-Line Brown and Hy-Line Silver Brown hens produced eggs with significantly (P < 0.05 and 0.001, respectively) different levels of aerobic organisms dependent on housing system. Eggs from conventional cages had significantly different (P < 0.05) levels of aerobic contaminations dependent on hen strain with Hy-Line Silver Brown having the greatest (4.57 log cfu/mL). Hy-Line Brown and Barred Plymouth Rock hens produced eggs with significantly different (P < 0.01) levels of Enterobacteriaceae amongst housing systems with conventional cage eggs having the lowest level of contamination for the hen strains. There were no differences within each strain amongst housing systems for yeast and mold contamination. The study shows that hen strain has a dynamic effect on egg microbial levels for various housing systems and egg safety should be considered when making hen strain selections for each housing system.