Quality assurance in the egg production chain to reduce the bacterial contamination of the eggshell

Washing eggs in sterile plastic bags with diluent is an efficient sample preparation method for the determination of the bacterial contamination on eggshells. The total count of aerobic bacteria and the total count of Gramnegative bacteria on the eggshell can be used to detect critical contamination points in the egg production chain. The number of eggs to be sampled in a point of the production chain was determined on a statistical basis and fixed on 40 for non-graded eggs and on 20 for graded eggs. In two production chains, one cage production and one organic production system, critical contamination points were identified. The influence of the housing system on the bacterial contamination of the eggshell at the stable was studied. A positive correlation was found between the initial bacterial eggshell contamination and the concentration of bacteria in the air of the poultry houses. With the exception of heavily soiled shells, like shells from ground eggs, there is a poor correlation between the level of bacterial contamination and the visual eggshell contamination.