The role of synbiotic in controlling Salmonella infection in broilers.

Salmonellosis significantly affects poultry production sector and public health, through the emergence of multi-drug resistant (MDR) strains, which require attempts to use sustainable, safe, and effective alternatives. This study was carried out over the period spanning 2024 to 2025 and involved two steps. The first step included Salmonella isolation and characterization from 25 diseased poultry farms from various regions of Northwest Delta, Egypt, focusing on some of their virulence genes and sensitivity to antibiotics. The second experimental step involved exploring the effectiveness of synbiotic compared with traditional antibiotics in reducing Salmonella colonization and their impact on poultry performance, including growth performance, immunological parameters, and pathological changes after artificial infection. The result revealed the presence of Salmonella sp. in 16% (40/250) of examined samples, including 3 serotypes, Salmonella Papuana, Salmonella Enteritidis, and Salmonella Kentucky, with different values of MAR index ranging between 0.21 and 0.43. Marked resistances were recorded against amoxicillin, lincomycin and spiramycin (100%), followed by ampicillin (75%), while the highest sensitivity was observed toward amikacin, gentamicin, cefotaxime, colistin sulfate, and streptomycin. All Salmonella strains contained the invA and enterotoxin gene (stn), whereas spvC was detected in 75% of isolates. The study declared the impact of the supplementation of synbiotic in feed in improvement of the growth performance parameters, decreased Salmonella colonization, reduced severity of clinical signs and postmortem lesions relative to the other groups (untreated group and antibiotic treated group), in addition to its considerable improvement in hematological, biochemical, and immunological parameters and less pathological alterations than other groups.