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.

The presence of extended-spectrum beta-lactamase (ESBL) producing Escherichia coli on poultry products is an important issue for veterinary and human health due to the zoonotic infection risk for producers and consumers. The present study focuses on testing the efficacy of six different disinfection methods on eggshell samples, aiming to reduce ESBL producing E. coli contamination on the hatching egg. Sterile eggshell cutouts were artificially contaminated with 10⁸ cfu/ml CTX-M-1 producing E. coli and used as a carrier model to analyze the efficacy of six disinfection methods. The contaminated samples were separated into two groups; 1) contaminated and disinfected, 2) contaminated and non-disinfected. Six independent disinfection protocols were performed following product specifications and protocols. Each eggshell sample was separately crushed, and the total viable bacterial count was calculated to determine the disinfection efficacy. Five out of six tested methods (formaldehyde gassing, hydrogen peroxide + alcohol spray, essential oils spray, peracetic acid foam, and low energetic electron radiation) demonstrated a reduction or completely eliminated the initial ESBL producing E. coli contamination. One method (essential oils as cold fog) only partly reached the expected efficacy threshold (reduction of >10² cfu/ml) and the result differed significantly when compared to the reference method i.e. formaldehyde gassing.

Hatching egg disinfection, as part of the quality assurance system, is a standard procedure in commercial hatcheries. Formaldehyde was and is broadly used but bears high risks for the personnel. In preliminary studies, the spray application of hydrogen peroxide was successfully tested and was chosen to compare its efficacy and impact on hatchability, as well as performance during fattening, and at slaughter, to formaldehyde under field conditions. The trial was set up with hatching eggs from two breeder flocks, running parallelly in three groups (H₂O₂, formaldehyde and non-disinfected control) at four different flock ages (at 38, 39, 56, 57 weeks). No significant differences were noticed in the hatchery, whereas in the rearing period higher 7-day- and total mortalities occurred during trials 1 and 2 in all non-disinfected groups and one formaldehyde-treated group, making an antibiotic treatment necessary. At slaughter, the findings in all groups were comparable. Trials 3 and 4 passed without significant differences between all groups, leading to the conclusion that hatching egg disinfection lowers the risk of infection-related losses. Meanwhile, formaldehyde fumigation and the spraying of hydrogen peroxide produced similar results in all stages.

Objective The use of low-energy electron irradiation for hatching egg disinfection was compared to formaldehyde fumigation. Material and methods To assess the efficacy, eggshells were examined for bacteria before and after disinfection. During incubation, hatching and fattening of 1400 Ross 308 broilers per group candling data, hatching rate, mortality rate and body mass development were recorded to evaluate the impact on health and performance. Additionally, data from the slaughter house and histological evaluation of organ samples were included in the health screening. Results Regarding the efficacy, irradiation and formaldehyde significantly reduced the number of bacteria compared to non-disinfected eggs. However, no significant difference was recorded between both treatments. The irradiated group performed better than the reference group concerning the number of infertile eggs, early and late dead embryos and fertile eggs. The performance during fattening was nearly identical in both groups, while mortality differed slightly between the irradiated group and the group treated with formaldehyde. Upon slaughter, there were minor variations concerning the distribution of findings between the groups, but the number of anomalies was not higher than reference values suggest. Conclusion In both groups no health problems were observed during rearing and the fattening performance met the targets of the manufacturer Aviagen for the used broiler line Ross 308. Clinical relevance Lower-energy electron irradiation proves to be an efficient and well-tolerated hatching egg disinfection procedure. Further field trials are necessary to establish low-energy electron irradiation as an alternative to formaldehyde fumigation. Gegenstand und Ziel Der Einsatz niedrigenergetischer Elektronenstrahlung zur Bruteidesinfektion wurde mit dem Verfahren der Formaldehydbegasung verglichen. Material und Methoden Zur Beurteilung der Effizienz wurden Eierschalen vor und nach Desinfektion auf Bakterien untersucht. Während Brut, Schlupf und Mast von 1400 Ross-308-Broilerküken pro Gruppe wurden Daten vom Schieren, Schlupfrate, Mortalitätsrate und Gewichtszunahmen erfasst, um den Einfluss auf Tiergesundheit und Mastleistung zu überprüfen. Zusätzlich wurden am Schlachthof erfasste Daten sowie Ergebnisse der histologischen Untersuchung von Organproben in die Gesundheitsüberprüfung einbezogen. Ergebnisse Sowohl durch Elektronenstrahlung als auch durch Formaldehydbegasung ließ sich die Anzahl an Bakterien auf der Eioberfläche im Vergleich zu nicht desinfizierten Eiern signifikant verringern. Ein signifikanter Unterschied zwischen den beiden Verfahren bestand nicht. Die mit Elektronenstrahlung behandelte Gruppe zeigte beim Schieren bessere Werte bezüglich der Anzahl unbefruchteter Eier, abgestorbener Embryonen und befruchteter Eier als die mit Formaldehyd behandelte Gruppe. Die Tageszunahmen und das Mastendgewicht waren in beiden Gruppen fast identisch, während die Mortalitätsrate leicht differierte. Bei der Schlachtung gab es Varianzen im Hinblick auf die Verteilung von Schlachtbefunden, doch war die Anzahl auffälliger Tierkörper nicht höher, als Referenzen es vermuten lassen. Schlussfolgerung In beiden Gruppen wurden im Verlauf der Aufzucht keine Gesundheitsprobleme beobachtet und die Mastleistung entspach den Zielvorgaben des Herstellers Aviagen für die verwendete Broilerlinie Ross 308. Klinische Relevanz Niedrigenergetische Elektronenstrahlung erweist sich als ein wirksames und verträgliches Verfahren zur Bruteidesinfektion. Es sind weitere Feldversuche nötig, um das Verfahren als Alternative zur Formaldehydbegasung zu etablieren. Received: 13 May 2020 Accepted: 20 August 2020 Publication Date: 04 December 2020 (online) © 2020. Thieme. All rights reserved. Georg Thieme Verlag KG Rüdigerstraße 14, 70469 Stuttgart, Germany