Theses and Dissertations


Issuing Body

Mississippi State University


Adhikari, Pratima A.

Committee Member

Zhang, Li

Committee Member

Pulido-Landinez, Martha

Committee Member

DuBien, Janice L.

Committee Member

Kiess, Aaron S.

Date of Degree


Document Type

Dissertation - Open Access


Agricultural Sciences

Degree Name

Doctor of Philosophy (Ph.D)


College of Agriculture and Life Sciences


Department of Poultry Science


Salmonella Enteritidis (SE) infections in laying hens is a significant cause of foodborne illness linked to the consumption of contaminated eggs. This dissertation encompasses novel strategies aimed to explore appropriate in-vitro and in-vivo models to evaluate the effects of these novel strategies to reduce SE in laying hens. Firstly, we investigated the potential probiotics, prebiotics, and essential oil combinations to reduce SE in-vitro. The results showed that probiotics and prebiotics are equally effective to reduce SE. In subsequent studies, we evaluated the role of vaccination history on cecal microbiota and SE infections with various doses of oral SE challenge. Our findings showed a dose-dependent response on fecal SE shedding in vaccinated and unvaccinated laying hens. Concurrently, we found an increased abundance of phylum Synergistota in the cecal microbiota following an SE infection, as well as a surge in the relative abundance of fatty-acid producing bacteria. The emphasizing the necessity to understand microbiota changes during SE infection for developing an effective intervention. We further researched the efficacy of a Bacillus-based probiotic and a glycan-based product to reduce SE infections in laying hens. These products were effective in reducing SE in the fecal and cecal content of laying hens. However, our research also underscored the necessity of developing a precise enumerate method to accurately measure the concentration of Salmonella in fecal and tissue samples. Overall, we expect this dissertation to contribute valuable insights into developing effective strategies to reduce SE infections in laying hens. These findings, while promising, underscore the ongoing challenge to develop a robust and effective solution to address the problem of SE in laying hens.

Available for download on Friday, August 15, 2025