Date of Graduation

5-2025

Document Type

Thesis

Degree Name

Master of Science in Poultry Science (MS)

Degree Level

Graduate

Department

Poultry Science

Advisor/Mentor

Hargis, Billy M.

Committee Member

Graham, Danielle

Second Committee Member

Sun, Xiaolun

Third Committee Member

Latorre Cardenas, Juan D.

Keywords

Broiler chickens; Enterococcus faecium; peptides; Quorum Sensing; Salmonella

Abstract

The purpose of the present research was to evaluate Enterococcus faecium fermentation peptides (EFP) for antibacterial activity, inhibition of biofilm formation, and anti-quorum sensing properties against Salmonella Typhimurium (ST) in in vitro trials and individual body weight and ST organ colonization in therapeutic and prophylactic models in broiler chickens. Ninety-six day-of-hatch Cobb 500 broiler chickens were randomized and assigned to one of four treatments: NC) Negative Control, no EFP treatment and no ST challenge; NC+EFP) Negative Control, EFP treatment and no ST; PC) Positive Control, no EFP treatment and ST challenge, and PC+EFP) EFP treated and ST challenged. Independent trials for each model were conducted with 12 chickens per cage for a total of 24 chickens per treatment. Samples of the liver, spleen and cecal tonsils were collected in both challenged models to assess the prevalence of ST. In vitro findings indicated no significant differences in ST growth, inhibition of biofilm formation, and autoinducer-1 inhibition with the addition of different concentrations of EFP in the medium. Otherwise, no significant differences in broiler chicken performance and ST prevalence were observed between positive control and EFP-treatment groups in the therapeutic and prophylactic models (P > 0.05). Therefore, EFP does not influence the growth, biofilm inhibition, and anti-quorum sensing properties in ST. Further studies are necessary to elucidate the effects of EFP against other Gram-negatives and Gram-positive bacteria of poultry interest.

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