European Journal of Nutrition & Food Safety

Postbiotics have emerged as a rapidly developing class of microbial feed additives for poultry because they can deliver biologically active microbial structures and fermentation-associated compounds without requiring viable microorganisms in the final preparation. This narrative review summarises recent advances in the definition, production, mechanisms and poultry applications of postbiotics, with an emphasis on evidence published during 2023-2026 and on Saccharomyces cerevisiae- and Lactobacillus-derived preparations. Current evidence indicates that postbiotics can improve feed efficiency, intestinal morphology, barrier integrity, microbial balance, immune regulation and antioxidant status, although responses vary with microbial strain, fermentation conditions, inactivation method, formulation, dose, diet and challenge status. Recent studies in broilers and Rainbow Rooster chickens show that benefits may occur even when body-weight gain is unchanged, particularly through improved feed conversion, reduced serum cholesterol, suppression of enteric pathogens and enhanced villus architecture. New studies using Lactobacillus reuteri, L. acidophilus, Bacillus amyloliquefaciens and L. plantarum-derived preparations further support strain-specific effects on nutrient sensing, tight-junction expression, inflammatory pathways and caecal microbiota. However, recent meta-analytic and systematic evidence also demonstrates substantial heterogeneity, emphasising that “postbiotic” should not be treated as a uniform intervention. Future progress requires compositional standardisation, validated inactivation, dose-response studies, stability testing, multi-omics characterisation and large-scale commercial validation. Postbiotics are therefore best positioned as precision components of integrated gut-health and antibiotic-responsible poultry production systems rather than universal one-for-one replacements for antibiotic growth promoters.