Relative abundance of KEGG pathways of duodenal (A), jejunal (B), and ileal (C) microbiota in the control and heat-treated ducks. Only the KEGG pathways that were significantly affected in percentage by temperature are presented. P value was calculated based on the independent samples t-test. P < 0.05 was considered to be statistically significant (*), whereas P < 0.01 was considered to be extremely statistically significant (**). CD and HD represent the duodenal content samples from the control ducks and heat-treated ducks, respectively. CJ and HJ represent the jejunal contents of the control group and heat-treated group, respectively. CI and HI were the samples of ileal contents from the control ducks and heat-treated ducks, respectively. Abbreviations: MAPK, mitogen-actived protein kinase; PPAR, peroxisome proliferator-activated receptor.