Fecal Microbial Structure and Metabolic Profile in Post-Weaning Diarrheic Piglets

Piglet diarrhea is the main factor affecting the growth and development of suckling or weaning piglets, which has brought great economic losses to the pig industry. Alteration of the gut microbiota is an important factor in the aetiology of piglet diarrhea, and increasing evidence suggests that diarrhea impacts not only the composition of the gut microbiota but also the fecal metabolic profile. In this study, the 16S rRNA gene sequencing combined with LC-MS-based metabolomics approach was used to evaluate the effects of post-weaning diarrhea on the gut microbial structure and fecal metabolic profile of the domestic breed Wannan Black pig. We found that piglet diarrhea was associated with increased relative abundance of the bacterial genus Campylobacter, as well as declining abundance of phylum Bacteroidetes and the species Streptococcus gallolyticus subsp. macedonicus. Meanwhile, obvious changes in the fecal metabolic profile of diarrheic piglets were also detected, particularly higher levels of polyamines (spermine and spermidine). Function enrichment analysis of differential metabolites indicated that the alterations in seven metabolic pathways might play a crucial role in piglet diarrhea. Moreover, there were substantial associations between the disturbed gut microbiota and the altered fecal metabolites, especially a strong positive relationship between spermidine and Campylobacter. These results indicate that the gut microbiota was altered in association with fecal metabolism in diarrheic conditions. These observations may provide novel insights into potential etiologies related to post-weaning diarrhea and further our understanding of the role of gut microbiota in host homeostasis and in modulating gut microbial structure.