Morphology and Microbiota of Different Section of Intestines and Their Influences Induced by Dietary Fish Oil in Shan Partridge Ducks (Anas platyrhynchos)
Abstract：The goal of this study was to determine the differences in morphology and microbiota among 5 intestinal sections (duodenum, jejunum, ileum, cecum and rectum) of Shan partridge ducks (Anas platyrhynchos). Ducks were randomly divided into control and treatment groups, fed with basal diet and basal diet with 2% fish oil for 28 days, respectively. Histological staining and 16S rDNA V3–V4 region sequencing were applied to examine the morphology and microbiota of intestines. The highest ratio of villus height to crypt depth (VH/CD) was found in the ileum, followed by the rectum, whereas goblet cell count (GCC) was the highest in the rectum, with no differences detected between the other sections. Dietary supplementation with fish oil significantly reduced the VH/CD in the ileum, but had no significant effects on the other intestinal sections. Operational taxonomic units (OTUs) were the lowest in the duodenum and the highest in the ileum, but supplementing with fish oil reduced the number of OTUs overall. Alpha diversity analysis indicated that the lowest microbiotic diversity occurred in the duodenum, and that fish oil significantly reduced the diversity of the rectal microbiota. Taxa of Lactobacillus, Clostridia, Megamonas and Campylobacterales were chosen for further analysis on the results of linear discriminant analysis coupled with effect size (LEfSe). The results indicated that of the intestinal sections, the ileum is the primary site for digestion and absorption in Shan partridge ducks, as this section exhibited optimal morphology and contained the largest number of microorganisms that participate in these processes. Dietary supplementation with 2% fish oil compromised intestinal morphology and reduced the richness and diversity of the microbiota as a whole. This study provided reliable evidences for comprehensively evaluating the intestinal morphology and microbiota of Shan partridge duck, and the intestinal research foundation of Shan partridge duck supplemented with fish oil as well.
