Ach	acetylcholine
SP	substance P
NO	nitric oxide
VIP	vasoactive intestinal peptide
ENS	enteric nervous system
FDA	USA Food and Drug Administration
CFDA	China Food and Drug Administration
SCFAs	short-chain fatty acids
SPF	specific pathogen free
ELISA	enzyme-linked immunosorbent assay
RDP	ribosomal database project
PCoA	principal co-ordinates analysis
SRA	sequence read archive
OTUs	operational taxonomic units