The effects of rosmarinic acid and antibiotics on the intestinal morphology, function, and cecal microbiota of broiler chickens

Lay Summary Although rosmarinic acid (RA) and antibiotics (Abx) have been widely used in animal production as the growth promoters, their effects on intestinal development remain unclear. This study systematically evaluated the impacts of RA and Abx on the intestinal morphology, function, and cecal microbiota in broilers. The results showed that both RA and Abx supplementation promoted growth and improved the nutrient absorption and barrier function. However, Abx caused negative effects including reduced jejunal and ileal lengths, impaired immune organs, suppressed ileal immunoglobulins, reduced short-chain fatty acids (SCFAs) concentrations, and promoted drug-resistant bacterial proliferation. RA supplementation demonstrated superior beneficial effects by enhancing intestinal morphology, enriching cecal beneficial bacteria, and elevating SCFAs production.