piglet fecal microbiota
The PCR (95 C for 5 min, followed by 27 cycles of 95 C for 30 s, 55 C for 30 s, and 72 C for 45 s and a final extension at 72 C for 10 min) which was used to amplified the the V4-V5 region of the 16S rRNA gene, the primers were 341F (5-CCTAYGGGRBGCASCAG-3) and 806R (5-GGACTACNNGGGTATCTAAT-3). The AxyPrep DNA Gel Extraction Kit (Axygen Biosciences, USA) and the QuantiFluor-ST kit (Promega, USA) were used to purified and quantified the all PCR products. The purified amplicons were sequenced on an Illumina MiSeq platform by Biozeron Biotechnology (Shanghai, China). Quantitative Insights Into Microbial Ecology (QIIME, Version 1.17) was used to demultiplexed and quality-filtered the raw FASTQ files. Under a 97% similarity cutoff, the UPARSE (Version 7.1, http://drive5.com/uparse/) was used to clustered the operational taxonomic units (OTUs), and UCHIME was used to identified and removed the chimeric sequences. Under a confidence threshold of 70%, the RDP Classifier (http://rdp.cme.msu.edu/) which against the Silva (SSU117/119)16S rRNA database was used to analyzed the phylogenetic affiliation of each 16S rRNA gene sequence