Abstract:

【Objective】 The purpose of this study was to investigate the influence of MHC(Major Histocompatibility Complex) gene on the predominant bacteria community in the layer gastrointestinal tract. 【Method】 The bacterial community and diversity in the crop, duodenal, jejunal, ileal and ceacal digesta at the age of 2, 4, 6 and 8 weeks of commercial layers and line 15I5 layers was studied by using 16S rDNA-based denaturing gradient gel electrophoresis (DGGE) and identification of some common and special bands in DGGE profile at 8 weeks. 【Result】 The highest level of diversity was found in cecum of commercial layers and line 15I5 layers, followed by ileum and jejunum, while the lowest levels of diversity were found in crop and duodenum. The diversity of bacteria increased with the age at every region of gastrointestinal (GI) tract. MHC gene didn’t influence the diversity of bacteria. The dendrograms revealed that MHC gene heavily influenced the bacteria composition at the age of 4 weeks and 6 weeks, followed by 8 weeks, while the highest level of similarity was found in 2 weeks. At the same time significant differences were observed between two lines in the lower GI tract than that in the upper GI tract. In addition, some amplicons in the DGGE pattern of two layer lines were identified by cloning and sequence analysis. Lactobacillus suntoryeus were predominant in the upper GI tract of two layer lines. The special bacterial in jejunal, ileal and ceacal digesta of commercial layers were Ochrobactrum spp，Clostridium sordellii，Megamonas hypermegale and plenty of uncultured bacterial. Most of the special bacteria in 15I5 layers were uncultured bacteria. 【Conclusion】 The results of this study indicate that MHC gene influence the composition of the dominant bacterial population in every region of GI tract of layers at different ages.

Key words: microbiota')">microbiota, MHC, DGGE, layer