Probiotics As Alternatives to Antibiotics in Poultry: A Comprehensive Review of Mechanisms and Impacts on Antimicrobial Resistance (2021–2025)

The recent ban on the use of antibiotic growth promoters in poultry production worldwide, prompted by increased antimicrobial resistance, has hindered the pursuit of sustainable sources. Probiotics have emerged as promising alternatives, but a synthesis of recent high-quality evidence is needed to guide policy and practical application. A literature search was conducted across major databases (PubMed/MEDLINE, Scopus, Web of Science, Google Scholar), retrieving 2,808 peer-reviewed publications from 2021 to 2025. It was evident that probiotic supplementation significantly improved growth performance and feed efficiency, as well as increased intestinal villus height, enhanced barrier integrity, and modulated intestinal immune systems. Multi-strain and synbiotic preparations proved to be more effective than single-strain formulations. Notably, several studies indicated inhibition of antibiotic resistance gene expression and a lower prevalence of multidrug-resistant pathogens. Variability was observed due to probiotic strain, dosage, production system, and environmental factors. Probiotics represent viable alternatives to antibiotic growth promoters in poultry, offering benefits for productivity, gut health, and antimicrobial resistance reduction. Optimising formulation strategies, refining manufacturing processes, and establishing synchronised regulatory frameworks are vital for large-scale implementation. Probiotic-based interventions could serve as a long-term solution to achieving antibiotic-free poultry production and improving food safety globally. Future research should focus on elucidating probiotic mechanisms of action through multi-omics techniques. Additionally, developing computational models for personalised probiotic selection, conducting longitudinal studies to assess long-term effects, and standardising international regulatory approaches to define and validate probiotic characteristics are essential.