Effect of an Enterococcus faecium probiotic on specific IgA following live Salmonella Enteritidis vaccination of layer chickens

ABSTRACTProbiotics and immunization are being widely adopted by the poultry industry with the goal of controlling Salmonella enterica. However, the interaction between these two management protocols has been sparsely studied. The present study aimed to understand the role of an Enterococcus faecium probiotic in the production of salmonella-specific IgA in layers immunized with a live vaccine. Four groups were used: “Control” (no vaccine or probiotic); “Probiotic” (which received an E. faecium product); “Vaccine” (immunized with two doses of a live attenuated S. Enteritidis vaccine); and “Vaccine + probiotic”. Faecal salmonella-specific IgA was analysed 7 and 20 days post-vaccination (dpv) boost. At 7 dpv, the “Vaccine” and “Vaccine + probiotic” groups had similar IgA levels. However, at 20 dpv, IgA levels were two times higher in the “Vaccine + probiotic” group compared to the “Vaccine” group. To understand the role of the intestinal microbiota in this finding, bacterial diversity in faeces was analysed b...