Lysozyme is an antimicrobial enzyme that is produced by animals and is part of the innate immune system. It is abundant in secretions such as tears, saliva, human milk, and mucus, and is also present in cytoplasmic granules of macrophages and polymorphonuclear neutrophils. Lysozyme is a naturally occurring enzyme found in bodily secretions such as tears, saliva, and milk, and functions as an antimicrobial agent by cleaving the peptidoglycan component of bacterial cell walls, which leads to cell death.

Here are some key points about lysozyme:

• It is an alternative to growth-promoting antibiotics in swine production.
• It is secreted by submucosal glands, neutrophils, and macrophages.
• It acts synergistically with other antimicrobial agents against most bacteria.
• It is a small enzyme that attacks the protective cell walls of bacteria.
• It is found in many biological organisms from bacteria and fungi to animal bodily secretions and tissues, and is considered a part of the innate immune system in most mammals.

Lysozyme has been considered as an endogenous antibiotic due to its capacity to disrupt the bacterial cell wall. It has been evaluated for its effectiveness on pigs in different models, and human lysozyme has been expressed in the milk of pigs, mice, and goats.