design: Fecal DNA was isolated with the QIAamp PowerFecal Pro DNA Kit (Qiagen) following the suppliers protocols. The V3V4 region of the 16S rRNA gene was amplified and processed for sequencing in accordance with the Illumina 16S Metagenomic Sequencing Library Guide (Illumina, San Diego, CA, USA). Sequencing was performed on an Illumina MiSeq platform with a 2  250-bp reagent kit at the Teagasc Sequencing Facility. Paired-end reads were merged using FLASH. Subsequent processing, including quality filtering (Q-score > 25), removal of barcode errors, and elimination of short sequences, was conducted in QIIME (v1.9.0). Denoising, chimera filtering, and operational taxonomic unit (OTU) clustering were carried out with USEARCH v7 (64-bit). OTUs were aligned with PyNAST and taxonomically classified using BLAST against the SILVA SSURef database (release 123). Bacterial diversityboth alpha and betawas assessed within QIIME. Oscillatory patterns of OTUs were evaluated using the JTK_Cycle algorithm.