16S_V3_v4
Total bacterial DNA for microbiota analysis was extracted from samples collected from the caeca using a FastDNATM Spin Kit for Soil (MP Biomedicals, LLC, Santa Ana, CA, USA). The quantity and quality of the DNA were evaluated using a Nanodrop ND 1000 spectrophotometer (Nanodrop Technologies Inc., Wilmington, DE, USA).  Next Generation Sequencing (NGS) of bacterial DNA was carried out as reported by Luise et al. (2021)11. The library formation and sequencing of the 16S rRNA gene were performed with MiSeq Reagent Kit V3V4 on MiSeqIllumina platform.