Black garlic (BG), a fermented form of Allium sativum L., is produced under carefully controlled conditions of temperature, humidity, and time. It contains numerous bioactive compounds that contribute to its medicinal properties, including anti-inflammatory and anticancer effects. A total of 500 one-day-old male Ross 308 broiler chickens were randomly assigned to five treatment groups, each with five replicate pens (20 birds per pen). Dietary treatments were as follows: (1) control (fed a basal diet), (2) BGP-10 (basal diet + 10 g/kg black garlic powder), (3) BGP-20 (basal diet + 20 g/kg black garlic powder), (4) BGP-30 (basal diet + 30 g/kg black garlic powder), and (5) BGP-40 (basal diet + 40 g/kg black garlic powder). Results showed that birds in the BGP-20 group exhibited significantly higher body weight gain (BWG) and feed intake (FI), along with improved feed conversion ratio (FCR) and lower mortality rates compared to other groups (P < 0.05). Additionally, supplementation of garlic powder at 20 g/kg and more led to increased red blood cell (RBC) counts, hemoglobin (HGB), hematocrit (HCT), and high-density lipoprotein (HDL) levels, while reducing triglycerides (TG), total cholesterol (TC), low-density lipoprotein (LDL), aspartate transaminase (AST), and alanine transaminase (ALT) levels in serum (P < 0.05). Antioxidant analysis revealed that birds receiving up to 20 g/kg of black garlic powder had higher glutathione peroxidase (GSH-Px) and superoxide dismutase (SOD) activity, along with lower malondialdehyde (MDA) levels than those in other treatments (P < 0.05). Furthermore, supplementation with black garlic at levels up to 20 g/kg significantly increased immunoglobulin G (IgG) and immunoglobulin M (IgM) concentrations compared to other groups (P < 0.05). In conclusion, incorporating 20 g/kg of black garlic (the fermented form of garlic) into poultry diets may enhance oxidative balance, growth performance, and immune in broiler chickens.
