The overuse of antibiotics in poultry farming has led to a significant rise in antimicrobial resistance (AMR), highlighting the urgent need for sustainable and effective alternatives to maintain quail health and productivity. This study explored the potential of Olive leaves' extract (OLE) as a natural antibiotic alternative for quails challenged with Salmonella. OLE is rich in beneficial compounds like polyphenols, flavonoids, and oleuropein, known for their antioxidant, antimicrobial, and anti-inflammatory properties. Our research evaluated OLE's effects on growth performance, oxidative stress markers, molecular indicators of immune response, and histological variations in Salmonella-challenged quails. The results were highly encouraging: OLE significantly enhanced body weight gain, feed efficiency, and overall growth performance in treated quails compared to Salmonella-challenged controls. Moreover, OLE supplementation effectively reduced oxidative stress by lowering malondialdehyde (MDA) levels and boosting the activity of antioxidant enzymes such as superoxide dismutase (SOD) and glutathione peroxidase (GPx). At a molecular level, OLE upregulated the expression of immune-related genes, including those involved in inflammatory response and pathogen defense, indicating improved immune function. Histological analysis also revealed that OLE mitigated Salmonella-induced damage in intestinal tissues, promoting better gut health and integrity. Beyond these benefits, OLE enhanced the count of beneficial lactic acid bacteria (LAB) while decreasing pathogenic bacteria and even improved the meat color and taste quality. These findings collectively highlight the substantial potential of olive leaf extract as a sustainable and eco-friendly alternative to antibiotics in poultry production. By improving growth performance, reducing oxidative stress, modulating immune responses, and enhancing gut health, OLE offers a compelling alternative strategy to combat Salmonella infections and reduce reliance on conventional antibiotics.

To Cite This Article: Bahshwan SMA, 2025. Olive leaves' extract as an antibiotic alternative enhances the growth, oxidative stress, molecular markers, and histological variation in Salmonella-challenged Japanese quails (Coturnix japonica). Pak Vet J, 45(2): 592-604. http://dx.doi.org/10.29261/pakvetj/2025.180