The Microbiome-Metabolome Response in the Colon of Piglets Under the Status of Weaning Stress

Weaning is stressful for piglets involving nutritional, physiological, and psychological challenges, leading to an increase in the secretion of cortisol, changes in gut microbiome and metabolites, whereas the underlying relationships remain unclear. To elucidate this, 14 Meishan female piglets were divided into the weaning group and the suckling group at the age of 21 days paired by litter and body weight. After 48 h of experiment, weaned piglets had lower body weight, but higher salivary cortisol level than that of their suckling litter mates (P< 0.05). The composition of the colonic bacterial community and metabolites were different between the two groups, and the first predominant genus of the suckling and weaned piglets colonic microbiome wereBacteroidesandPrevotellaceae-NK3B31 grouprespectively. The suckling piglets had higher proportions of phylumBacteroidetesandLentisphaerae, and genusBacteroidesandLactobacillusin the colonic microbial community, but lower abundance of genusPrevotellaceae-NK3B31 groupthan that of the weaned piglets (P< 0.05). Accordingly, there were 15 colonic metabolites differed between the two groups, in which 2 metabolites (phenylacetic acid and phenol) negatively related to the abundant ofLactobacillusgenus (P< 0.05), while 9 metabolites (acetic acid, arabitol, benzoic acid, caprylic acid, cholesterol, dihydrocholesterol, galactinol, glucose phenol, phenylacetic acid, and oxamic acid, glycerol, propionic acid) positively associated with the proportion ofPrevotellaceae-NK3B31 groupgenus (P< 0.05). Furthermore, the salivary cortisol level negatively associated with the abundance of phylumLentisphaerae, but positively associated with the phylumBacteroidetesand the genusPrevotellaceae-NK3B31 group(P< 0.05) respectively. These results provide us with new insights into the cause of the gut microbiome and stress, and the contributions of gut microbiome in metabolic and physiological regulation in response to weaning stress.