Dietary supplementation of garlic leaf extract enhances growth performance and intestinal health, immunity, and gut microbiota in broiler chickens.
The poultry industry has increasingly sought natural feed additives as alternatives to synthetic growth promoters to enhance productivity and animal health in a sustainable manner. Garlic and its bioactive compounds have been widely recognised for their antimicrobial, antioxidant, and immunomodulatory properties, yet limited information is available regarding the efficacy of garlic leaf extract (GLE) in broiler diet. This study evaluated the effects of GLE as a natural dietary additive on growth performance, intestinal morphology, immune response, and gut microbiota composition in broiler chickens. A total of 160 one-day-old broilers were randomly assigned to 4 dietary treatments supplemented with 0, 125, 250, or 500 mg/kg of GLE for 35 days. Results revealed that dietary inclusion of 125 mg/kg GLE significantly increased final body weight and average daily gain compared with the control group. Supplementation with GLE also improved villus height in the jejunum and ileum suggesting enhanced nutrient absorption and intestinal integrity. The GLE treatment group exhibited significantly greater than that observed in the other experimental groups. In contrast, the concentrations of IgM and IgY did not differ significantly among treatments. Analysis of 16S rRNA gene sequences indicated that dietary GLE significantly altered the composition and structure of the intestinal microbiota, characterised by an increased relative abundance of Firmicutes, a reduction in Bacteroidetes, and enrichment of beneficial genera such as Lactobacillus. Principal coordinate and LEfSe analyses confirmed these compositional shifts. In conclusion, dietary inclusion of garlic leaf extract, particularly at 125 mg/kg, effectively enhanced growth performance, intestinal morphology, immunity, and gut microbial balance, supporting its potential as a natural feed additive in broiler production.