Impact of Feed Withdrawal on the Broiler Gastrointestinal Tract and Identifying the Opportunity for Bacteriophage in Salmonella Mitigation

Abstract

Feed withdrawal is a common poultry industry practice to reduce carcass contamination from gastrointestinal contents during processing. While this procedure effectively eliminates gut contents, it elicits physiological and microbial alterations in the gut that may promote the colonization and proliferation of pathogens, such as Salmonella. Salmonella is a primary pathogen of concern for the poultry industry, which implements many measures in an effort to prevent infection. However, the burden of Salmonella is still large, leading the industry to search for alternative avenues for mitigation, including the use of bacteriophages. Thus, the objective of this thesis was to further characterize the physiological and microbial effects of feed withdrawal and examine the efficacy of bacteriophages to reduce Salmonella under these conditions. The first project was aimed at further describing the effects of feed withdrawal on the entire gastrointestinal tract, as well as examining the impact of feed withdrawal on the carcass and litter environment through comparisons of the microbiomes and gut physiology (Chapter 2). The objective of the second study was to assess the efficacy of SP6 bacteriophage for reducing Salmonella concentration and associated microbiome alterations with a broiler cecal in vitro model (Chapter 3). The results of this thesis suggest that feed withdrawal significantly alters the gastrointestinal tract, the carcass, and the litter, in addition to altering the cecal contents that impact the effectiveness of bacteriophage SP6 in reducing Salmonella.