Polyclonal hen egg yolk antibodies could confer passive protection against Salmonella serotypes in broiler chicks

Non-typhoidal Salmonella serotypes continue to be major food safety and public health threats worldwide. In the era of emerging antimicrobial resistance, it is imperative to search for alternative strategies of infection control. Present study deals with passive protection of young chicks using polyclonal egg yolk antibodies (IgY). Laying hens were actively immunized with heat inactivated Salmonella serotypes Salmonella enterica subsp. enterica serotypes S. Enteritidis (SE) and S. Typhimurium (ST) isolated from the poultry. Serotype specific polyclonal IgY isolated from the hen egg yolk were evaluated for in vitro neutralization potential. Chicks challenged with pathogenic SE and ST were evaluated for passive protection that were co-administered with polyclonal immune IgY. Heat killed antigens (SE/ST) induced protective immune response in the immunized laying hens; and purified immune IgY inhibited the logarithmic phase of Salmonella growth. Administration of egg yolk at 5% (w/w) in the feed containing specific anti-SE or anti-ST polyclonal IgY to Salmonella-challenged chicks resulted in 37.48 and 38.54% reduction in the caecal Salmonella counts. As antimicrobial resistance is emerging as a growing public health problem, findings of this study indicate benefits of prophylactic feeding of egg yolk containing polyclonal IgY for the passive protection of chicks and minimize caecal Salmonella carriage.