Effectiveness of probiotic supplementation on growth performance, gut microbiota, and Salmonella reduction in broiler chicks challenged with Salmonella Typhimurium.

Salmonella infection poses a major threat to poultry production, affecting both animal health and food safety. With rising concerns over antimicrobial resistance, probiotics have gained attention as effective non-antibiotic interventions to control enteric pathogens while supporting gut health. This study evaluated the efficacy of a locally isolated probiotic blend comprising Ligilactobacillus salivarius BF12, and Pediococcus acidilactici strains BF9 and BYF20 (ProCU) in comparison with a commercial Clostridium butyricum-based probiotic (TOP GUT) in broiler chicks challenged with Salmonella Typhimurium (ST). A total of 196 chicks were assigned to seven groups receiving different treatments with or without Salmonella challenge. Parameters assessed included growth performance, intestinal histomorphometry, cecal Salmonella load, and microbiota composition and function. Before challenge, ProCU increased fecal lactic acid bacteria (LAB) and enriched amino acid and carbohydrate metabolism pathways. Post-challenge, TOP GUT significantly reduced Salmonella load and maintained growth, while ProCU showed a limited effect on pathogen reduction. Both probiotics improved intestinal morphology, increased Lactobacillus and Akkermansia abundance, and upregulated oxidative stress defense genes. Notably, TOP GUT also enriched Parabacteroides and other Bacteroidetes members and prolonged microbial metabolic activity. These findings emphasize strain-specific probiotic effects and suggest that continuous supplementation, particularly with spore-forming strains, may enhance gut health and reduce the Salmonella burden in poultry.