The Emerging Role of Dietary Bacteriophage in Monogastric Animals in the Post-Antibiotic Era—A Review

Bacteriophages, or phages, are viruses that infect and kill specific bacteria, offering a promising alternative to antibiotics in livestock production. With growing concerns over antibiotic resistance, phages have gained renewed interest due to their ability to target harmful pathogens without disturbing beneficial gut microbiota. This review explores the application of dietary phage supplementation in monogastric animals, particularly pigs and poultry. In pigs, phage use has demonstrated beneficial effects such as improved growth performance, enhanced gut health, and reduced infections from Salmonella and E. coli. Various delivery methods, including feed and water supplementation, have been studied, with microencapsulation showing promising results for stability and effectiveness. Similarly, in poultry, phages have been successfully used to control pathogens like Salmonella, Campylobacter, and avian pathogenic E. coli, improving gut health, immunity, and overall performance. Several commercial phage products are already in use, demonstrating both safety and efficacy. Despite these advantages, challenges such as a narrow host range, bacterial resistance, and regulatory limitations remain. Therefore, further research is necessary to understand phage–host interactions, optimize delivery strategies, and evaluate long-term effects under normal and disease-free conditions. This review highlights the potential of bacteriophages as safe, targeted, and sustainable alternatives to antibiotics in monogastric animal production, contributing to improved animal health and reduced antibiotic use.