Submitted to: Journal of Applied Poultry Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/27/2010
Publication Date: 10/1/2010
Citation: Musgrove, M.T., Cox Jr, N.A., Berrang, M.E., Buhr, R.J., Richardson, L.J., Mauldin, J.M. 2010. Effect of inoculation and application methods on the performance of chemicals used to disinfect salmonella contaminated broiler hatching eggs. Journal of Applied Poultry Research. 19(4):387-392. Interpretive Summary: If hatching eggs are not disinfected, Salmonella may be spread during hatching and incubation. Many chemicals have been tested for this purpose. This project was conducted to demonstrate how an experiment can be biased to make a compound seem effective or useless based on methods used. Fertile eggs were contaminated with Salmonella by three methods (immersion, fecal smear, drop) then treated with two disinfectants, respectively. Each chemical was applied by immersing eggs and by spraying. A weaker chemical was able to perform well by spray or immersion if drop inoculation was used. A strong chemical was not effective by spray or immersion if the eggs were inoculated by immersion. A fecal smear egg required a strong chemical for disinfection by spray though a weaker chemical was sufficient if the eggs were dipped in the disinfecting chemical solution. This information will be used by hatchery managers and scientists so that published literature can be interpreted more easily.
Technical Abstract: Salmonella can penetrate the shells and shell membranes of hatching eggs and this can critically affect final product contamination levels (processed broiler carcass). There have been numerous published studies on the efficacy of chemical disinfectants for hatching eggs. The objective of this study was to provide information allowing the reader to accurately assess published works on chemical efficacy to reduce Salmonella on hatching eggs. Three methods of egg inoculation were used: immersion, fecal smear, and droplet. Following inoculation, two methods of sanitizer application were used: immersion and spraying. When an immersion inoculum was used at a high level (107 cells/mL), it was difficult to demonstrate any reduction in Salmonella contamination of eggs with either chemical (hydrogen peroxide or quaternary ammonium), regardless of application method. When a fecal smear inoculation was used, hydrogen peroxide treatment reduced the number of Salmonella positive eggs with spray or immersion application; quaternary ammonium, was less effective, and showed no advantage over water. Droplet inoculation was the mildest of the methods used. With droplet inoculation (105 Salmonella), immersion and spray application of chemicals resulted in reductions of Salmonella prevalence. In fact, when using the drop inoculation method, slight reductions were noted even when water was used as the treatment. Readers should pay close attention to method and levels of bacterial inoculation as well as method of chemical application before deciding on the efficacy of a sanitizing treatment. Experimental methodologies may affect results as much as the chemical composition of the sanitizer being analyzed.