Salmonella on Australian cage egg farms: Observations from hatching to end of lay

• Published in: Food microbiology 2020-05, Vol.87, p.103384-103384, Article 103384
• Main Authors: McWhorter, Andrea R., Chousalkar, Kapil K.
• Format: Article
• Language: English
• Subjects: Animals; Australia; Cage; Chickens - microbiology; Chickens - physiology; Dust; Egg; Eggs - analysis; Eggs - microbiology; Farms; Female; Food Contamination - analysis; Food Contamination - statistics & numerical data; Food Handling; Layer hen; Salmonella
• ISSN: 0740-0020; 1095-9998
• DOI: 10.1016/j.fm.2019.103384

Single-aged caged layer hen flocks were monitored for Salmonella over the course of their lifetime. Chicks from both flocks were Salmonella negative at hatch and remained negative during rearing. Pullets were transported to production farms at 15 weeks of age. Pre-population dust swabs collected from both production sheds had a high percentage of Salmonella positive samples (80 and 90%). Flocks were sampled at regular intervals until 70–72 weeks of age. The proportion of Salmonella positive samples and mean load detected on eggs was low on both farms. Analysis of dust samples revealed that Salmonella persisted in dust over 8 weeks. Dust total moisture content and water activity appears to influence bacterial persistence. On egg grading equipment, only suction cups prior to egg washing were Salmonella positive (mean proportion Salmonella positive samples 0.13 ± 0.07; mean load of 18.6 ± 12.31 MPN/ml). An egg washing experiment demonstrated that while washing reduced the total Salmonella load from eggshell surfaces, no effect was observed for shell pores. These results demonstrate that despite environmental contamination on farm, Salmonella contamination of eggs is low and is further minimized by washing. •Layer hen flocks were sampled for Salmonella from hatch to the end of production.•At hatch, chicks were Salmonella negative and remained negative during rearing.•Dust and egg belt samples had the highest proportion of Salmonella positive samples.•Egg washing reduced Salmonella on eggshells but not shell pores.•Improved dust control would help reduce the bacteria on farm.