The influence of microbial muramidase on growth and gut health of weaned piglets

Microbial muramidase (MUR) can hydrolyses bacterial peptidoglycan (PGN) in the gut, thereby reducing PGN-induced mucosal inflammation and promoting intestinal homeostasis. Based on this, it was hypothesised that dietary supplementation with microbial MUR in weaned pigs would enhance growth performance and improve gut health and microbial balance. Ninety-six pigs (28 ± 0.2 days old) were assigned to either a control group (CTR, standard diet) or a treatment group (TRT, diet supplemented with 65,000 lysozyme specific units measured with a fluorescein assay (LSU(F)/kg) from day (d) 0 (weaning) to d44. Weekly assessments included body weight (BW), feed intake, faecal scores, and antibiotic treatments. Faecal samples were collected on d9 and d28. The MUR supplementation reduced antibiotic treatments up to d28 (p < 0.01). Pigs receiving MUR had a higher final BW (d44, p = 0.01), average daily gain (d0–d44, p < 0.05) and a better feed efficiency (p < 0.05) compared to the CTR group. Microbiota analysis showed reduced alpha diversity (Chao1 index) at d9 (p = 0.02) in TRT pigs, but no differences at d28. Beta diversity differed at both time points (R2 = 0.05; p < 0.05). LEfSe analysis revealed reduced abundance of Turicibacter (LDA > 3, p < 0.01), and Colidextribacter (LDA > 3, p < 0.01) in the TRT group at both d9 and d28. Despite microbiota changes, volatile fatty acid concentrations remained unchanged, suggesting intact fermentative activity. Overall, MUR improved growth and reduced antibiotic use, possibly by affecting gut microbiota and nutrient utilisation.