Associations of Breed and FUT1 Genotype with the Fecal Microbiota of Weaned Piglets

This study aimed to analyze the associations between the composition and function of the gut microbiome in weaned piglets of different breeds and Fucosyltransferase 1 (FUT1) genotypes. Ear tissue and fecal samples were collected from 163 piglets (61 Durocs, 39 Yorkshires, and 63 Landraces) for genotyping and 16S rRNA sequencing. Three genotypes were identified in the FUT1 gene: AA, GA, and GG, with the resistant AA genotype observed only in Duroc. α-diversity analysis revealed that Landrace pigs had the highest microbial diversity, whereas pigs with the AA genotype displayed the lowest diversity. At the phylum level, Bacillota and Bacteroidota were the dominant phyla across all pig breeds and genotypes. At the genus level, significant differences among different groups were observed in microbes such as Lactobacillus and Segatella. PICRUSt2-based functional prediction revealed a higher relative abundance of predicted functions related to xenobiotics biodegradation and metabolism, digestive system, nucleotide metabolism, and other metabolic processes in the AA genotype group. These findings identify breed- and genotype-associated variation in the fecal microbiota of weaned piglets and provide a foundation for future studies investigating whether FUT1-associated microbial differences are related to intestinal microbial function and resistance to F18-positive enterotoxigenic Escherichia coli.