Assessment of three alternative methods for bacterial disinfection of hatching eggs in comparison with conventional approach in commercial broiler hatcheries

The disinfection of commercial hatching eggs before incubation is a common strategy to reduce potential vertical transmission of bacterial and fungal infections from the eggshell to one-day-old chicks that may prevail in poultry products and eventually reach the end consumer. The present investigation focuses on the parallel testing and application of four different disinfection methods (conventional and alternative) under commercial hatchery conditions against natural eggshell bacterial contamination. Hatching eggs from two ROSS 308 broiler breeder flocks were selected and divided into six different groups: two groups were not disinfected and served as negative controls, and four were independently disinfected following product specifications and protocols. From each group, a sample of 100 hatching eggs was selected for bacterial re-isolation, utilizing a modified shell rinse method. Colony-forming units (cfu) from the shell rinse suspensions were determined and analyzed to establish cfu values for each tested egg. These values were analyzed to determine the bacterial disinfection capacity of the four disinfection methods under commercial hatchery conditions. The tested methods were hydrogen peroxide + alcohol, peracetic acid, low energy electron beam, and the gold standard in practice: formaldehyde. Among these methods, formaldehyde, peracetic acid, and low energy electron beam showed a significant difference when compared to the non-disinfected groups whereas hydrogen peroxide + alcohol did not. The bacterial disinfection capacity of the tested methods was compared as well to the gold standard method formaldehyde fumigation and only low energy electron beam achieved similar disinfection levels as formaldehyde. According to our data, three methods significantly reduce the bacterial load on the eggshell of hatching eggs under commercial hatching conditions, including potential alternative methods such as low energy electron beam that perform similar to the gold standard in practice.