sequences of bacteria
samples of cecal content were randomly selected for full-length 16S rRNA sequencing. Bacterial DNA was extracted from the cecal digest using a Bacterial DNA Kit (Omega Biotek, Guangzhou, China). The purity and concentration of the DNA were assessed with the NANODrop ND-1000 spectrophotometer (Thermo Scientific, Wilmington, DE, USA), whereas the DNA quality was tested through agarose gel electrophoresis. Based on the features of the amplified 16S region, we constructed a small fragment library and performed paired-end sequencing on the Illumina NovaSeq sequencing platform. Representative sequences were generated by splicing and filtering reads using clustering or noise reduction methods; these sequences were used for annotation of the species and analysis of their abundance. We determined the differences in species composition and community structure among samples by analyzing the alpha diversity.