The Role of Postbiotics in Poultry Health and Performance: A Review on Existing Knowledge and Further Research Needs.

The widespread use of antibiotic growth promoters (AGPs) in livestock production has contributed to the emergence of antimicrobial resistance (AMR) in pathogens. Furthermore, improper dosing and insufficient withdrawal periods lead to the presence of antibiotic residues in meat, posing significant risks to human health. Consequently, regulatory bans on AGP use in poultry and livestock have increased the susceptibility of poultry to previously controlled infectious diseases, highlighting the need for effective and safe alternatives. Postbiotics, defined as preparations of inanimate microorganisms and/or their components that confer a health benefit on the host, have emerged as one of the promising AGP alternatives. Some postbiotic preparations exert immunomodulatory, antioxidant, antimicrobial, and anti-inflammatory effects, modulate gut microbiota, and reduce enteric pathogen loads, leading to improved growth performance, health status, and resilience against heat stress, thereby supporting their role in sustainable poultry production. This review summarizes the current understanding of the effects of postbiotics on poultry health and zootechnical performance and their mechanisms of action, explicitly distinguishing empirical findings demonstrated in poultry from those extrapolated from mammalian or in vitro models. Finally, it outlines knowledge gaps in the biochemical processing and standardization of postbiotics, along with future research priorities for their use as an AGP alternative.