Lysozyme as a natural feed additive in poultry and rabbit production: implications for growth, health and sustainability - a review.

For decades, antibiotics were routinely incorporated into the diets of poultry and rabbits to enhance growth and productivity. Mounting concerns about antimicrobial resistance and food safety have driven the search for natural and safe alternatives. Lysozyme, an endogenous enzyme most abundantly found in egg white, has emerged as a promising candidate due to its antimicrobial and immunomodulatory activities. This review synthesizes current evidence on the dietary inclusion of lysozyme in poultry (broilers, layers, and quail) and rabbit production systems. Reported benefits include improved weight gain, feed efficiency, egg production, and carcass traits, alongside enhanced immune responses and healthier gut microbial profiles. Effective supplementation levels range from 50 to 200 mg/kg, depending on species and production goals. Beyond growth promotion, lysozyme contributes to gut integrity, supports the regulation of immune-related gene expression, and reduces reliance on antibiotics. Importantly, lysozyme modulates immunity by regulating cytokines, enhancing mucosal defenses, and promoting a balanced gut microbiota by suppressing pathogenic bacteria while supporting beneficial populations. Despite its potential, knowledge gaps persist regarding long-term safety, cost-effectiveness under commercial conditions, optimal species-specific dosing, and interactions with other natural feed additives. Collectively, the available data highlight lysozyme as a safe, environmentally friendly, and sustainable tool to improve health and performance in poultry and rabbit farming.