Salmonella in commercially manufactured feeds

Area of Science:

• Animal Science
• Food Safety
• Microbiology

Background:

• Salmonella contamination in animal feed poses a significant risk to animal health and the food supply chain.
• Understanding contamination sources and contributing factors within feed mills is crucial for effective control strategies.

Purpose of the Study:

• To investigate the prevalence and sources of Salmonella contamination in feed mills.
• To evaluate the impact of sampling time, season, and location on contamination rates.
• To assess the utility of Enterobacteriaceae counts as an indicator for Salmonella contamination.

Main Methods:

• Collected 886 samples (ingredients, dust, feed) from 3 feed mills over 2 seasons and 3 days of the week.
• Samples analyzed for Enterobacteriaceae counts (EC) and Salmonella presence.
• Sampling occurred hourly across 5 mill locations: receiving, mixer, pellet mill, coolers, load-out.

Main Results:

• Feed ingredients and dust were identified as major sources of Salmonella.
• No significant seasonal difference in contamination rates (spring vs. summer).
• Higher Salmonella rates were observed on Fridays, suggesting potential management-related influences.
• Pellet mill data showed uneven Salmonella distribution, highlighting dust control importance.
• Salmonella-positive samples had significantly higher EC than negative samples.

Conclusions:

• Feed ingredients and dust are critical reservoirs for Salmonella in feed mills.
• Sampling timing (e.g., end of the week) and mill location (e.g., pellet mill area) are important considerations for Salmonella control.
• Enterobacteriaceae counts serve as a potential indicator for Salmonella contamination in feed.