library_construction_protocol: Liver  samples were taken immediately after slaughter and stored in liquid nitrogen for testing. The total RNA of the liver  was extracted using TRIzol (Invitrogen, Carlsbad, CA). Then, a NanoDrop spectrophotometer (Thermo Fisher Scientific, Wilmington, MA, USA) was used to quantify the RNA concentration, and the integrity of the RNA samples was evaluated using 1% agarose-formaldehyde gel electrophoresis. RNA concentration was measured using a NanoDrop 2000 spectrophotometer (Thermo Fisher Scientific, Waltham, MA, USA). RNA integrity was assessed using the RNA Nano 6000 Assay Kit of the Agilent Bioanalyzer 2100 system (Agilent Technologies, Santa Clara, CA, USA). Sequencing libraries were generated using the NEBNext Ultra RNA Library Prep Kit for Illumina (New England Biolabs, Ipswich, MA, USA) according to the manufacturer's recommendations, and index codes were added to attribute sequences to each sample. To select cDNA fragments with a length of approximately 240 bp, the library fragments were purified with the AMPure XP system (Beckman Coulter, Beverly, MA, USA). A 3-μl volume of USER Enzyme (New England Biolabs) was incubated with size-selected, adaptor-ligated cDNA at 37 °C for 15 min followed by 5 min at 95 °C. PCR was performed with Phusion High-Fidelity DNA polymerase, universal PCR primers, and index (X) primer. PCR products were purified (AMPure XP system), and library quality was assessed with the Agilent Bioanalyzer 2100. Index-coded samples were clustered on a cBot Cluster Generation System using TruSeq PE Cluster Kit v.4-cBot-HS (Illumina, San Diego, CA, USA) according to the manufacturer's instructions. After cluster generation, cDNA libraries were sequenced on an Illumina platform, and paired-end reads were generated.