Emerging applications of postbiotics to sustainable livestock production systems

The growing challenge of drug-resistant microbes emerging from increased antibiotic use in livestock production has prompted bans and intensified research into natural feed additives for sustainable and improved animal production. While probiotics (live bacteria) have been commonly used to enhance animal health and growth, heightened concerns about probiotic stability and propensity to transfer the antibiotic resistance gene, limit their efficiency and viability. Currently, postbiotics are emerging as the more stable and natural alternative gut health promoters, in the light of their potential to increase nutrient intake, absorption, growth, fertility, and carcass quality. Postbiotics are beneficial left-over wastes (by-products and compounds) from the metabolism and digestion of probiotics and prebiotics (substrates for live bacteria) in the gut. Postbiotics include antimicrobial peptides that slow down the growth of harmful bacteria, short-chain fatty acids that help healthy bacteria flourish, amino acids, microbial cell fragments, extracellular polysaccharides, and vitamins B and K. Emerging evidence suggests that postbiotics may offer environmental benefits in mitigating microplastic contamination and reducing methane emissions in livestock production. This review examines existing gaps in the light of current knowledge on postbiotics and their impact on animal health, milk production, carcass quality, and reproductive outcomes in livestock, and proposes future research direction to foster a better understanding of the role of postbiotics in enhancing sustainable monogastric and ruminant livestock production.