New consumer trends and genetic improvements have brought about a new generation of commercial layers capable of producing high-quality table eggs for a period of more than 100 weeks. This long stay on the farm also significantly increases the risk of several infectious diseases, such as Salmonella spp., impacting negatively on Public Health.

There are live Salmonella vaccines available on the market that mainly stimulate both local cellular and humoral immunity; and inactivated Salmonella vaccines, that through intramuscular application, induce the development of general humoral immunity characterised by the formation of circulating neutralising antibodies (IgY) and memory cells.

The aim of this field study was to assess whether longer-lasting protection adapted to current market needs is provided with the use of a commercial inactivated bivalent Salmonella vaccine in combination with commercial live Salmonella vaccines.