The escalating challenge of antimicrobial resistance (AMR) in livestock production, exacerbated by the global restrictions on antibiotic growth promoters, has intensified the search for natural alternatives. Essential oils (EOs), derived from aromatic plants, have emerged as promising phytogenic feed additives due to their multifaceted bioactive properties, including antimicrobial, antioxidant, anti-inflammatory, and immunomodulatory effects. This review explores the applications of EOs in livestock health and production, spanning poultry, swine, ruminants, and aquaculture. Key mechanisms involve disruption of microbial cell membranes, modulation of gut microbiota, enhanced nutrient digestibility, and rumen fermentation optimization, leading to improved growth performance, feed efficiency, and reduced methane emissions in ruminants. As feed additives, EOs from sources like oregano, thyme, cinnamon, garlic, and rosemary promote digestive enzyme secretion, mitigate enteric pathogens (e.g., Salmonella, E. coli, Clostridium), and support disease prevention against respiratory infections, mastitis, and parasitism. Species-specific benefits include enhanced egg production and immunity in poultry, better weight gain in swine, and improved milk yield in dairy animals. Advanced delivery systems, such as nanoencapsulation, address challenges like volatility and palatability, enhancing bioavailability and efficacy. Despite promising in vitro and in vivo evidence, variability in EO composition, optimal dosing, and long-term safety require further standardization. This review highlights EOs’ potential as sustainable tools for antibiotic-free livestock systems, emphasizing future research directions for clinical translation and regulatory approval.

Highlights

• EOs are natural alternatives to antibiotics in livestock due to antimicrobial, antioxidant and immunomodulatory properties.
• Nanoencapsulation can help overcome EO volatility and palatability issues
• EOs improve growth performance, feed efficiency, gut health and optimize rumen fermentation.
• Oregano, Thyme, Cinnamon, Garlic, and Rosemary Eos effectively control pathogens while preventing various livestock diseases.
• Use of EOs provides better egg production in poultry, weight gain in swine, and higher milk yield in dairy animals.