Subtherapeutic levels of antibiotics are used in swine feed as growth promotants, to improve feed efficiency, and to reduce the susceptibility to bacterial infections. As a result, the use of antibiotics improves the profitability of production for swine producers. However, swine producers are currently under pressure to eliminate subtherapeutic antibiotic use throughout the production cycle. Finding safe and effective alternatives to traditional antibiotics will give swine producers viable options in the event that the removal of traditional antibiotics is needed. Research conducted at the U.S. Meat Animal Research Center determined that feeding an antimicrobial enzyme, lysozyme, to nursery pigs was as effective as traditional antibiotics in increasing growth performance, including growth, nutrient accretion and feed efficiency, and decreasing pathogen shedding. In addition, lysozyme was effective in pigs under a chronic immune stimulation. Thus, lysozyme is a suitable alternative to antibiotics in swine nursery diets, and lysozyme ameliorates the effects of a chronic immune challenge.

Key Findings:
• Lysozyme improves growth performance and feed efficiency in pigs similarly to antibiotics.
• An immune response decreases the performance of pigs in the nursery; both lysozyme and antibiotics improve growth performance in nursery pigs under a chronic immune challenge.
• Pigs consuming lysozyme have decreased shedding of Campylobacter compared to antibiotic and control fed pigs.