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.

中文翻译：

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澳大利亚网箱蛋农场的沙门氏菌：从孵化到产蛋结束的观察。

对单笼笼养母鸡群在其一生中进行沙门氏菌的监测。两个鸡群的雏鸡孵化时沙门氏菌均为阴性，饲养期间仍为阴性。雏鸡在15周龄时被运送到生产农场。从两个生产棚收集的人群前尘埃拭子中沙门氏菌阳性样本的比例很高（分别为80％和90％）。定期采样鸡群，直到70-72周龄。在这两个农场中，沙门氏菌阳性样本的比例和鸡蛋的平均负荷均很低。灰尘样品的分析显示沙门氏菌在8周内仍残留在灰尘中。灰尘的总水分含量和水分活度似乎会影响细菌的持久性。在鸡蛋分级设备上，洗蛋前只有吸盘呈沙门氏菌阳性（沙门氏菌阳性样品的平均比例为0.13±0.07；平均负荷为18.6±12.31 MPN / ml）。鸡蛋清洗实验表明，虽然清洗减少了蛋壳表面沙门氏菌的总负荷，但未观察到壳孔的影响。这些结果表明，尽管农场受到环境污染，但沙门氏菌对鸡蛋的污染仍然很低，并且可以通过洗涤进一步减少。