The Impact of P-biotics on the Future of Sustainable Poultry Production: A Systematic Review of Prebiotics, Probiotics, Postbiotics, and Synbiotics

Abstract

Antimicrobial resistance linked to the long-term use of antibiotic growth promoters (AGPs) in poultry has intensified the search for effective, microbiome-based alternatives that can sustain performance without compromising food safety or animal welfare. This article aims to evaluate how recent advances in p-biotics (pre-, pro-, post-, and synbiotics) are shaping the future of sustainable poultry production. To achieve this, a systematic review was conducted using studies published between 2020 and 2025 on broilers and layers from literature databases such as Web of Science, Scopus, Google Scholar, and ScienceDirect. The PRISMA method was adopted, where 39 articles met the criteria for this review article after several exclusion criteria. The review shows that p-biotics consistently modulate gut microbiota, reinforce intestinal integrity, and enhance immune competence. Notably, the data reveal a consistent 10% to 15% improvement in feed conversion ratios and body weight gain under optimized probiotic and synbiotic regimens, directly addressing the production drops typically seen after antibiotic withdrawal. Probiotics and synbiotics, particularly Bacillus and Lactobacillus based formulations and oligosaccharide containing combinations, promote beneficial microbial populations, suppress enteric pathogens, and, in several studies, improve meat or egg quality and reduce dependence on AGPs. Postbiotic preparations from inactivated bacterial and yeast sources deliver comparable health and performance benefits while lowering the risk associated with live cultures. Evidence also indicates that p-biotics can lessen environmental burden by improving nutrient utilization and reducing nitrogen and phosphorus excretion, aligning poultry systems with broader sustainability targets. Nonetheless, considerable heterogeneity in strains, dosages, delivery routes, and experimental designs limits cross study comparability and hinders the development of standardized, context specific recommendations. Moving forward, research priorities must focus on conducting strain-specific field trials to validate efficacy across different poultry types, establishing standardized dosage protocols optimized for distinct commercial feeding phases (starter, grower, and finisher), and investigating the stability and viability of these p-biotics during high-temperature feed pelleting processes.