Abstract

Objective:
The increasing consumption of poultry meat, driven by its high protein quality and affordability, underscores the need to enhance its microbial safety and reduce foodborne illnesses. Salmonellosis remains a significant concern, exacerbated by the excessive use of antibiotics and increasing resistance. Given the traditional use of herbal plants and the known antibacterial properties of essential oils (EOs), this study aimed to evaluate the antibacterial, immunomodulatory, and growth-promoting effects of Cinnamomum zeylanicum and Eucalyptus globulus EOs as alternatives to antibiotics in experimentally infected broiler chickens with Salmonella spp.
Materials and Methods:
Newly hatched broiler chicks (n = 135) were equally and randomly assigned to nine different groups. Experimental groups received dietary supplementation with C. zeylanicum or E. globulus EOs from day one. Birds were assessed for Salmonella Enteritidis (SE) and Salmonella Gallinarum (SG) counts in droppings, growth performance (weight gain, FCR), humoral immune response to Newcastle Disease Virus and Infectious Bursal Disease Virus, and gut morphology.
Results:
The groups treated with antibiotics and the positive control group showed markedly higher SE and SG counts than the groups administered essential oils. C. zeylanicum showed the most significant reduction in both SE (4.23 ± 0.33 log₁₀) and SG counts. Birds supplemented with EOs exhibited significantly higher weight gain at day 35 and enhanced NDV and IBDV titers. Essential oil supplementation resulted in increased villus length and mucosal surface area in various intestinal segments, including the duodenum, jejunum, and ileum, as observed through histological analysis, indicating enhanced gut function.
Conclusion:
Both C. zeylanicum and E. globulus essential oils demonstrated strong in vivo anti-Salmonella activity, enhanced growth performance, and improved immune and gut health in broilers. These findings support the application of plant-derived EOs as natural, antibiotic-free substitutes for controlling Salmonella infections in poultry.

Key words: Broilers, Cinnamomum zeylanicum, Eucalyptus globulus, Essential oils, Salmonella enteritidis, Salmonella gallinarum