Analyzing Salmonella, Campylobacter, and Generic Escherichia coli in Feed Ingredients and Poultry Feed Samples Obtained from Commercial and Integrated Feed Mills

ABSTRACT Microbial contamination in feed mills poses a significant threat to biosecurity and food microbial safety. Understanding pathogen occurrence in feed mills is crucial for minimizing contamination and producing hygienic feed. The objective of this study was to determine the prevalence of Salmonella, Campylobacter , and generic Escherichia coli ( E. coli ) in raw ingredients and finished feed from feed mills across the southeastern United States. A total of 180 samples were obtained from 14 commercial and integrated feed mills in February 2024 and February 2025. Samples were analyzed using culture methods, with presumptive-positive Salmonella and Campylobacter isolates confirmed by conventional Polymerase Chain Reaction ( PCR ). Compact Dry Plates were used to evaluate E. coli ( EC ), Total Counts Rapid ( TCR ), and Coliforms ( CF ). Data were analyzed using PROC GLIMMIX to evaluate the effects of feed mill facility, sample type, and year on pathogen prevalence. Results indicated that EC, TCR, and CF were prevalent across all mills and sample types. Twenty-three samples were presumptive-positive for Salmonella , and all were confirmed by PCR. Additionally, 42 samples were presumptive-positive for Campylobacter (23.33%); however, only 14 were confirmed by PCR (7.78%). These findings demonstrate that feed manufacturing environments remain potential sources of bacterial contamination and highlight the value of pathogen surveillance beyond routine indicator organisms. The recovery of confirmed Campylobacter further emphasizes the importance of including this pathogen in feed safety monitoring programs.