This scoping review examines evidence on the use of medicinal plants, including thyme, rosemary, peppermint and fenugreek, as potential alternatives to antibiotic growth promoters in poultry production. The review brings together findings from 38 randomised controlled and quasi-experimental studies examining outcomes including body weight gain, feed conversion ratio, mortality and gut microbiota. Thyme, rosemary and peppermint were the most widely studied and were associated with improvements in growth performance, gut microbiota and, in some studies, mortality. The review found that thyme powder at 5 to 6 g/kg showed potential to improve growth performance and gut microbiota in healthy chickens. Other studies reported reductions in intestinal bacteria, including Escherichia coli and Salmonella, following specific thyme-based interventions. However, the authors note that further research is needed to assess the effects of these interventions on antimicrobial resistance, particularly in chickens infected with multidrug-resistant bacteria.
The review considers these findings from a One Health perspective, highlighting the links between antibiotic use in poultry production, antimicrobial resistance, food safety and the environment. It identifies medicinal plants as a potential approach to reducing reliance on antibiotic growth promoters, while recognising that their contribution to AMR prevention and more sustainable poultry production requires further investigation. Future research should assess their effectiveness in different settings, optimal formulations and doses, economic feasibility, and potential impact on AMR in poultry production.
