Effects of Enterotoxigenic Escherichia coli Challenge on Jejunal Morphology and Microbial Community Profiles in Weaned Crossbred Piglets.

Pathogenic enterotoxigenic Escherichia coli (ETEC) is a major cause of bacterial diarrhea in weaning piglets, which are vulnerable to changes in environment and feed. This study aimed to determine the effects of the ETEC challenge on piglet growth performance, diarrhea rate, jejunal microbial profile, jejunal morphology and goblet cell distribution. A total of 13 piglets from one litter were selected on postnatal day 21 and assigned to treatments with or without ETEC challenge at 1 × 108 CFUs, as ETEC group or control group, respectively. On postnatal day 28, samples were collected, followed by the detection of serum biochemical indexes and inflammatory indicators, HE staining, PAS staining and 16S rDNA gene amplicon sequencing. Results showed that the growth performance decreased, while the diarrhea rate increased for the ETEC group. The jejunum is the main segment of the injured intestine during the ETEC challenge. Compared with the control, the ETEC group displayed fewer goblet cells in the jejunum, where goblet cells are more distributed at the crypt and less distributed at the villus. In addition, ETEC piglets possessed higher abundances of the genus Desulfovibrio, genus Oxalobacter and genus Peptococus and lower abundances of the genus Prevotella 2, genus Flavonifractor and genus Blautra. In terms of alpha diversity, Chao 1 and observed features indexes were both increased for the ETEC group. Our study provides insights into jejunal histopathological impairment and microbial variation in response to ETEC infection for weaned piglets and is a valuable reference for researchers engaged in animal health research to select stress models.