Dietary lysozyme supplement alters serum biochemical makers and milk metabolite profile of sows via gut microbiota

Abstract Lysozyme is an important antimicrobial agent with promising future in replacing antibiotics in livestok production. The aim of current study was to determine variations in sow’s gut microbiota, serum immunity and breast milk metabolite profile mediated by lysozyme supplementation.Thirty-six pregnant sows were assigned to a control group without supplementation and two treatments with 0.5 g/kg and 1.0 g/kg lysozyme provided in formula feed for 21days. Microbiota analysis based on 16s RNA high-throughput sequencing and untargeted liquid chromatography tandem mass spectrometry were applied and combined in analysis. Serum biochemical indicators and immunoglobulins were also determined. Sows received 1.0kg/t lyszoyme treatment shown significant redution in microbial diversity. Spirochaetes, Euryarchaeota and Actinobacteria significantly increased while Firmicutes showed a remarkable reduction in 1.0kg/t treated group compared with control. Pyrimidine metabolism,Purine metabolism and Amino acid related enzymes were significantly upregulated in 1.0kg/t lysozyme treated group. The richness of gram-positive bacteria were significantly down-regulated by lysozyme treatments. Serum aspartate transaminase (AST) activity was significantly un-regulated. Serum IgM levels were significantly higher in the 1.0 kg/t group compared with control, while IgA levels was significantly lower in 1.0kg/t group. Over thirty metabolites from sow’s breast milk including L-Glutamine,creatine and L-Arginine were sigficantly altered by lysozyme treatment. There existed crucial correlations among gut microbiota, serum immunity and breast milk metabolites where lactobacillus and prevotella may play a key role in lysozyme mediated host-microbial interactions. Overall, lysozyme supplementation could effectively improve the composition, metabolic functions and phenotypes of sow’s gut microbiota and it also benefit sows with better immune status and breast milk composition. Importance Enteric infections caused by pathogens have a significant negative effect on neonatal survival and animal health in swine production. The application of antibiotics in feeds at subtherapeutic levels could improve performance and overall health and is used extensively throughout the industry. However, abuse of antibiotics is contributing to the high level of drug resistance in microbial communities and rising concerns regarding human health. Here, we revealed that lysozyme supplementation could effectively improve the composition, metabolic functions and phenotypes of sow’s gut microbiota and it also benefit sows with better immune status and breast milk composition. These findings confirmed that lysozyme could be a suitable alternative to antibiotics in swine production.