# The phage for PPLA age: effective method for Salmonella-free poultry feed

## TL;DR

This study shows that applying a bacteriophage cocktail to poultry feed effectively reduces Salmonella contamination, offering a safe alternative to antibiotics.

## Contribution

The study introduces PPLA as an effective method for delivering bacteriophages to reduce Salmonella in poultry feed.

## Key findings

- BAFASAL reduced Salmonella counts by at least three logs in in vitro feed experiments.
- In vivo trials showed no Salmonella in treated birds, while 70% of controls were infected.
- PPLA application significantly reduced Salmonella colonization in cecal contents by over four logs.

## Abstract

Salmonella is one of the most significant foodborne pathogens worldwide. Among the various sources of human Salmonella infections, poultry and poultry products are the most common. One of the primary routes of Salmonella transmission into poultry is through contaminated feed. In the present study, we evaluated the potential of bacteriophage cocktail BAFASAL applied via post-pellet liquid application (PPLA), at two concentrations—D1 – 1 × 10⁴ PFU/g and D2 – 5 × 10⁴ PFU/g—to prevent and reduce Salmonella contamination in poultry feed. In an in vitro experiment, where feed was artificially contaminated with Salmonella under laboratory conditions, both doses reduced Salmonella spp. counts by at least three logs compared to the untreated control feed. An in vivo challenge study in broiler chickens further demonstrated the protective effect of BAFASAL delivered via PPLA, confirming its effectiveness in a live animal model. After 3 days of feeding Salmonella-contaminated feed, no Salmonella was detected in crop samples from birds receiving BAFASAL/PPLA-treated feed. In contrast, Salmonella was detected in 7 out of 10 crop samples from control birds receiving untreated feed. Furthermore, analysis of cecal contents on days 18 and 35 revealed a statistically significant reduction in Salmonella colonization by more than four logs in the groups fed with feed protected by PPLA application of BAFASAL compared to the control group.

Bacteriophages, representing the most common biological entity on Earth, are viruses that infect bacteria. In recent years, there has been a revived interest in their practical application because of the antimicrobial resistance crisis. One growing commercial application of bacteriophages is animal farming and food processing to reduce the risk of pathogens passing through the food chain into humans. The use of bacteriophages may help reduce the risk of contamination of the food chain with bacteria resistant to antibiotics, among which Salmonella is recognized as a high concern pathogen for public health. Therefore, the use of bacteriophage cocktail BAFASAL to prevent Salmonella contamination in poultry feed is a promising and safe alternative to currently used antimicrobial agents and may be considered a solution in ensuring feed safety. Bacteriophage delivery to feed as post-pellet liquid application (PPLA) allows for large-scale usage in industrial poultry farms.