Egg Industry Center

Research Library

Research files are added periodically on a range of topics found in this library. Library resources consist of old and new research related to the egg production and processing industry.

Egg Safety


A comparison of food safety aspects of various hen housing systems including conventional cages, enriched colony cages and cage-free aviary housing systems, this research highlights that environmental and egg microbiology. Environmental swabs and eggshell pools were collected from all housing systems and total aerobes and coliforms were determined along with the prevalence of Salmonella and Campylobacter. Aerobic and coliform counts were highest for aviary environmental drag swabs and enriched colony cage scratch pads and the aviary floor and system wire eggshell pools contained the highest levels of aerobes. Hens from all housing systems were shedding Salmonella but across the three housing systems there was no significant difference in this shedding rate. The research suggests that the use of scratch pads in enriched systems should be more thoroughly investigated for its effects on hen and egg safety.


Salmonella Oranienburg caused eight people across Illinois, Kansas and Missouri to fall ill and focused food safety professionals on a type of Salmonella that had not previously required the attention of the egg industry. Environmental swabs from one egg production facility tested positive for Salmonella Oranienburg. While the stereotype is not new, compiled information for producers was not readily available. The Egg Industry Center compiled the linked information to help producers understand the similarities and differences between S. Oranienburg and other salmonella types.

Free range and organic farm eggs were studied for microbial contamination which could affect human health. Eggshells were examined for the presence of salmonella, listeria monocytogenes, campylobacter, enterobacteriaceae, staphylococcus, enterococcus, and mesophilic aerobic bacteria. Unfortunately, the data was inconclusive as to which farming style had fewer contaminated eggs, although it did identify that the major contamination differences were due to packing companies and their hygienic conditions. Another aspect to consider with free range and organic farming is that a high density of animals could potentially cause a larger spread of pathogens and therefore it is important to have strict sanitation practices in place.

Various methods to reduce aerobic bacteria were tested in a commercial caged layer complex. A compressed air foam system (CAFS) compared disinfectants with a high pressure-water rinse (HPWR) sprayer system. Six trials were conducted treating half the barn with either chlorinated alkaline foaming cleaner (CHL/ALK), peroxyacetic acid (PAA) or glutaraldehyde (HI GLUT) blended with quaternary ammonia (QAC) while the other half of the barn utilized the HPWR. Swabs of drinker cups and cage floors were taken before and after disinfecting. The 3% PAA and HI GLUT/QAC treatments applied via CAFS were found to consistently and significantly reduce aerobic bacteria in caged layer complexes. Cleaner alone was not found to be sufficient, but should be used as a precautionary step to disinfection.

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