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

Obe, Tomi

Committee Member

Graham, Danielle

Second Committee Member

Kwon, Young Min

Keywords

Biofilm; Food safety; Microbiome; Pre-harvest poultry production; Sanitizers; Water quality

Abstract

While significant progress has been made in post-harvest control of Salmonella in the poultry industry, the development of effective pre-harvest intervention strategies remains critical for reducing foodborne pathogens. Environmental reservoirs such as poultry litter and drinking water systems (DWS) are potential harborage sites for Salmonella and other microbial communities. Understanding the microbiota of these environments, including biofilms within water lines, is essential to identifying factors contributing to Salmonella colonization and improving pre-harvest control approaches. This study aimed to evaluate the incidence and quantity of Salmonella in poultry litter and water lines, characterize the microbial populations in these environments, and assess the efficacy of various sanitizers against biofilm-forming pathogens in DWS. Samples were collected from 15 commercial conventional broiler farms, yielding 45 boot swabs from litter and 180 biofilm swabs from DWS. Microbial analyses included quantification of Salmonella, total aerobic bacterial count (APC), Enterobacteriaceae (EB), and yeast and molds (YM). The full-length 16S rRNA gene was amplified and sequenced to determine the microbial community composition. Results revealed a high Salmonella incidence of 95.6% (43 out of 45 houses) in litter samples, with an average load of 4.16 Log10 CFU/sample, compared to a lower incidence of 0.04% (8 out of 180 water lines) in biofilm samples, with an average load of 0.13 Log10 CFU/sample. Salmonella serogroups O7 (Salmonella Infantis) and O9 (Salmonella Enteritidis) were the most prevalent. Water quality significantly influenced microbial community composition, and distinct microbial profiles were observed between litter and biofilm samples, with only a few species in common. Furthermore, the antimicrobial efficacy of three sanitizers: peracid-based (PAB), peroxide-based (PB), and hypochlorite-based (HB) was evaluated against planktonic and biofilm cells of field-isolated Salmonella, Escherichia coli, and Bacillus species on polyvinylchloride (PVC), a common DWS pipe material. While all sanitizers were effective at reducing overall CFUs to varying extents, PAB demonstrated the greatest potential as a DWS sanitizer, showing superior efficacy against both planktonic and biofilm cells compared to PB and HB. This research highlights the importance of targeted microbial profiling and sanitizer efficacy testing for pre-harvest pathogen control, providing valuable insights for improving food safety in poultry production systems.

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