This study aimed to examine the effects of dietary supplementation with different concentrations of a ginger and garlic essential oils mixture (1:1) on growth performance, carcass characteristics, serum biochemical indices, lipid profile, hematological parameters, antioxidant status, immune response, caecal microbiota, histopathological changes in lymphoid and hepatic tissues, and intestinal histomorphometry of broiler chickens under heat stress. A total of 360 one-day-old Arbor Acre broiler chicks were randomly assigned to six treatment groups (n = 60 birds per group), each divided into five replicates (12 chicks per replicate). Birds received basal diets supplemented with ginger and garlic oils (1:1) at levels of 0 (T1; negative control without heat stress), (T2, control under heat stress), 0.5 (T3), 1.0 (T 4), 1.5 (T5), and 2.0mL/kg diet (T6) throughout the experiment. Results showed significant improvements in growth performance, with T5 achieving the highest final body weight (2220.83 g) and the most favorable feed conversion ratio (FCR = 1.73). Carcass yield and relative organ weights increased in a dose-dependent manner. Hematological analysis revealed no significant differences in RBC count and hemoglobin levels, but a significant reduction in WBC count was observed. Serum biochemical parameters indicated improvements in liver (ALT, AST) and kidney (creatinine, uric acid) function. Lipid profile assessment showed a significant decrease in total cholesterol, triglycerides, LDL, and VLDL, along with an increase in HDL. The immune response was enhanced, demonstrated by significant increases in IgM and IgG levels, while IgA remained unchanged. The heat stress-related genes HSP 70 and HFP 90 were upregulated to cope with higher temperatures, whereas TNF-α and IL-1β were downregulated. Additionally, antioxidant status improved significantly, with elevated SOD, CAT, TAC, GSH, and GPX levels and reduced MDA levels. Caecal microbiota analysis revealed a notable reduction in total bacterial and yeast and mold counts, as well as in E. coli and Salmonella populations, alongside an increase in lactic acid bacteria. Histological examination of the intestine, liver, and spleen revealed dose-dependent improvements in tissue architecture and intestinal morphometry, with T5 exhibiting the most pronounced effects. In conclusion, the dietary inclusion of 2. 2.0mL/kg of ginger and garlic essential oils mixture (1:1) significantly improved growth performance, health status, immune response, and gut health in broiler chickens without adverse effects, supporting its use as a natural feed additive in poultry production.

To Cite This Article: Alharbi A, Fekry NM, Osailan R, Bahshwan SMA, Al-Ghamdi FA, Al Ghamdi M, Al-Otaibi AM, Albalawi MA, Alfaleh AA, Alowaidi S, Momenah MA, Ahmed AE, and El-Saadony MT, 2025. Combinatorial effects of ginger and garlic essential oils on broiler chicken performance, digestive functions, immunity, organ function, oxidative stress, and defense genes under heat stress. Pak Vet J, 45(4): 1806-1816. http://dx.doi.org/10.29261/pakvetj/2025.xxx