Probiotic consortium from poultry strains for supporting gut immunity against pathogens

Multi-strain probiotics have gained increasing attention for their ability to enhance host health by modulating the gut microbiota, immune responses, and resistance to pathogens. This study investigated the probiotic efficacy of KMK3, a novel three-strain consortium comprising Lactobacillus brevis (TN9), Ligilactobacillus salivarius (F9/2), and Ligilactobacillus salivarius (TL4/1), in broiler chickens, with a specific focus on pathogen resistance and immune modulation. Growth kinetics revealed that L. brevis (TN9) had the shortest lag phase (2 h) and the highest maximum optical density (OD₆₀₀ ≈ 1.8), suggesting superior adaptation and growth compared to L. salivarius strains (lag phases: 6 and 4 h; OD₆₀₀: 1.5 and 1.6, respectively). KMK3 administration significantly enhanced growth performance, with a 13 % higher body weight gain and an improved Feed Conversion Ratio (FCR: 1.50) compared to the control group (FCR: 1.75). The consortium also modulated immune responses, increasing serum antibody titers against Salmonella enterica lipopolysaccharides (4.5 ± 0.2 log₁₀) and upregulating anti-inflammatory cytokine IL-10 while suppressing pro-inflammatory cytokines (IL-1β, TNF-α). Additionally, KMK3-treated chickens exhibited improved gut histopathology, including higher villus height and reduced immune cell infiltration, even under S. enterica challenge conditions. These findings highlight the ability of KMK3 to promote pathogen resistance, modulate immune mechanisms, and enhance gut health, offering insights into the molecular and functional interactions of probiotics in mitigating infectious challenges. This study highlights the therapeutic potential of multi-strain probiotics in advancing poultry health and productivity by targeting host-pathogen interactions and immune regulation.