27.09.2014

The National Animal Health Monitoring Systems (NAHMS) conducted the Layers 2013 study in summer 2013 to describe management practices relevant to Salmonella Enteritidis control and prevention, estimate the prevalence of Salmonella Enteritidis, and evaluate risk factors for Salmonella Enteritidis on commercial layer farms.
In 2013, layers on 89.9 percent of farms had been vaccinated against Salmonella as pullets, and birds on 9.1 percent of farms had been vaccinated against Salmonella as pullets and as layers. Only 1.0 percent of farms had birds that had not been vaccinated as pullets or as layers. Many different vaccination protocols were used, but the highest percentage of farms that vaccinated birds against Salmonella, (39.0 percent) gave two live S. typhimurium vaccines via spray, followed by a bacterin injection. Birds received the first vaccination at the hatchery. On about half of farms in which birds had been vaccinated as pullets, layers were vaccinated at 60 to 79 weeks of age on the majority of farms that vaccinated layers.
The percentage of farms that routinely tested layer houses for Salmonella Enteritidis increased from 67.0 percent in 2008 to 99.2 percent in 2013.
In 2013, over 90 percent of farms routinely conducted environmental testing when layers were 40 to 45 weeks of age and 4 to 6 weeks postmolt (for farms that molted); less than half of farms tested during these time frames in 2008. This change is most likely because of the FDA egg safety rule, which requires layers be tested from 40 to 45 weeks of age and 4 to 6 weeks postmolt (excluding farms that exclusively produce eggs for breaking).
Overall, 69.0 percent of farms had been inspected by the FDA. About one of five farms that had been inspected by the FDA (21.3 percent) had environmental samples collected during the inspection.
Overall, 96.3 percent of farms conducted environmental tests and 5.8 percent of farms tested eggs from June 2012 through May 2013. Overall, 1.0 percent of flocks tested positive for Salmonella Enteritidis by environmental sampling from June 2012 through May 2013.