Antimicrobial peptides as sustainable alternatives to antibiotics in livestock production: implications for animal health in tropical and sub-tropical systems.

The global expansion of livestock production to meet the rising demand for animal-derived foods has been accompanied by extensive reliance on antibiotics for growth promotion, disease prevention, and therapeutic purposes. This long-term practice has raised serious concerns regarding antimicrobial resistance, drug residues in animal products, and the disruption of microbial ecosystems, particularly in tropical and developing regions where regulatory control is often limited. In response to these challenges, antimicrobial peptides (AMPs) have developed as promising and sustainable alternatives to traditional antibiotics in livestock production systems. AMPs are naturally occurring or synthetic short peptides characterized by broad-spectrum antimicrobial activities, rapid modes of action, and a relatively low propensity for inducing microbial resistance. Beyond their direct antimicrobial impacts, AMPs exhibit immunomodulatory, anti-inflammatory, and gut-protective properties that are highly relevant to animal health and productivity under tropical conditions. This narrative review provides an integrated general idea of the classification, sources, and mechanisms of action of antimicrobial peptides, with particular emphasis on their practical applications in poultry, ruminant, and aquaculture production systems. The roles of AMPs in improving growth performance, enhancing intestinal integrity, modulating gut microbiota, and strengthening immune responses are critically discussed. In addition, the review addresses key challenges associated with the stability, cost, formulation, and regulatory acceptance of AMPs in tropical animal nutrition and the feed additive industry. Finally, future research directions are highlighted to support the effective translation of antimicrobial peptides into sustainable and field-applicable alternatives to antibiotics.