Protective Effect of Synbiotic Supplementation Against Salmonella Typhimurium Infection in Young Broiler Chickens

Salmonella infection in poultry remains a major concern due to its economic impact and public health risks. Synbiotics have emerged as a natural strategy to improve gut health and resistance to enteric pathogens. This study evaluated the immune response and early protective effects of a synbiotic in broiler chickens using a reduced in vivo model of Salmonella Typhimurium infection. A total of 44 broiler chickens were randomly assigned to four dietary treatments: control (CT), control plus synbiotic (CT + Syn), challenged (ST), and challenged plus synbiotic (ST + Syn). Birds were challenged at 7 days of age and euthanized at day 12 for sample collection. Synbiotic supplementation reduced bacterial colonization and adhesion in the ileum, as assessed by intestinal content isolation and immunofluorescence analysis. Additionally, the synbiotics mitigated lesion severity in the intestine, liver, and heart, increased anti-inflammatory IL-10 expression, and reduced pro-inflammatory cytokines IL-1β and TNF-α. Ileal histomorphometry showed increased epithelial height in the ST + Syn birds, while intestinal permeability was not affected. Improved body weight was also observed compared to the challenged birds without supplementation. In conclusion, synbiotic supplementation provided early protection against S. Typhimurium infection by modulating immune responses, preserving intestinal morphology, and supporting weight gain in broiler chickens.