The Effective Doses of Ultraviolet Irradiation of Eggs prior to Incubation by Amalgam Lamps

Abstract

The disinfection of eggshells prior to the incubation of the eggs is an important element of biosecurity programs and pathogen elimination in poultry production. Ultraviolet (UV irradiation is an effective method of disinfection of eggs prior to incubation. Presently the lamps where free mercury is substituted with amalgam are increasingly used as the UV source and the application of these lamps for the disinfection of eggs is an actual topic of research. The study presented was aimed at the determination of the effective doses of UV irradiation by bactericide amalgam lamps for the inactivation of pathogenic microbial species contaminating the surface of the eggs. The preliminary cultivated test strains of the following pathogens were used: Salmonella paratyphi A №225, Escherichia coli АТСС 25922, Salmonella enteritidis №64, Proteus vulgaris HX 19 222, Staphylococcus aureus ATCC 6538-P. The eggs were directly irradiated by open-type bactericide irradiator “Svetolit 90ТN” (300 Wt; 87–90 Wt of bactericide UV radiation at wavelength 254 nm). It was found that the doses of the irradiation 82.5 mJ/cm2 with the distance between amalgam lamp and eggs 20 cm and 92.3 mJ/cm2 with the distance 35 cm effectively inactivated all test species (by 99.8–99.9%) while dose 62.1 mJ/cm2 with the distance 50 cm was less effective (inactivation efficiency 95.0–99.1%). At the doses 41.3 and 30.8 mJ/cm2 and the gaps between the amalgam lamp and eggs 20 and 35 cm the least resistant to UV-irradiation strain was Staphylococcus aureus ATCC 6538-P (elimination efficiency 90.0%). The inactivation of the strain Escherichia coli АТСС 25922 was more affected by the duration of the exposure to UV than by the gap between the lamp and the eggs.