Reduction of turkey hatching egg shell contamination with ultraviolet irradiation

Abstract

The effects of ultraviolet light (UV) at 254 nm on indigenous eggshell surface aerobic bacteria, Salmonella, Escherichia coli, gram positive bacteria as well as inoculated Salmonella typhimurium chicken and E. coli O157:H7 were evaluated. Various UV application methods and exposure times were utilized. Initial experiments evaluated the effects of UV light combined with individual egg rotation on indigenous bacterial populations using a minimal UV intensity of 10.8 mW/cm² and exposure time for the eggs was 0.75 min and 9 revolutions. This experiment was replicated 5 times. Significant log₁₀ reductions were reported in almost all trials with different media. Experiments were also conducted in order to determine an appropriate exposure time that would be applicable in a commercial environment. Eggs were inoculated with inoculums of marker strains of Salmonella typhimurium chicken and E. coli O157:H7 and exposed to minimal UV intensities of 10 mW/cm² for either 2, 6, and 10 minutes using the flat treatment or 0.75 min: 9 revolutions and 3 min: 9 revolutions using the roller treatment. Two replicates for each bacterial isolate were performed. Optimal exposure times based on log₁₀ reduction results identified times of flat: 6 min and roller: 3 min: 9 revolutions. Two experiments were also conducted in the field using both UV application methods (minimum UV intensity of 10 mW/cm2 for roller: 3min: 9 revolutions; flat: 6.5min) in order to evaluate reductions of indigenous bacterial populations and several hatchery parameters. Significant reductions of bacterial populations, percent pipped eggs and cull poults were seen on the UV treated eggs compared to the control. Significant differences were not seen between the UV treatments. Differences were not reported for percent positive internal contamination of dead embryos or meconium samples. Improvements were reported in percent good poults at hatch and hatch of fertile eggs for UV treated eggs in both trials and were significant in the second.