Short-chain fatty acid-producing taxa enriched by competitive exclusion cultures can drive resistance to non-typhoidal Salmonella colonization in broilers

AIMS: This study evaluated the efficacy of three Competitive Exclusion (CE) products, formulated under aerobic (AER), anaerobic (ANA), and combined (MIS) conditions, in controlling Salmonella Heidelberg (SH) and Salmonella Infantis (SI) in experimentally challenged broiler chicks. METHODS AND RESULTS: Birds were inoculated with CE on the first day of life and challenged with Salmonella (SH or SI) 24 h later. Cecal colonization, fecal shedding, and microbiota modulation were monitored up to 21 days post-infection (DPI). The combined treatment (MIS) produced the most consistent results, yielding the greatest reductions in both cecal and fecal Salmonella counts. Beta diversity analyses revealed significant community restructuring across all time points (P = 0.036). CE accelerated microbial maturation, promoting early establishment of beneficial anaerobes such as Bacteroides and Subdoligranulum. Differential abundance analysis (LEfSe) confirmed strong modulatory effects, particularly enhancing key genera linked to intestinal health, including Bacteroides, Subdoligranulum, and Faecalibacterium. CONCLUSIONS: Competitive Exclusion cultures are effective in reducing Salmonella colonization in broiler chickens and represent a promising alternative to antimicrobials. The combined CE formulation (MIS) improved the performance of standard anaerobic products and enhanced the establishment of beneficial microbiota associated with colonization resistance.