PSVII-19 Transcriptomic analysis of the liver of laying hens fed diets containing supplemental fat at early laying stages

Feeding diets containing supplemental fat to laying hens is reported to ameliorate pathogenesis of fatty liver hemorrhagic syndrome (FLHS). However, molecular mechanisms for this positive effect have not been investigated. Thus, we conducted a transcriptomic analysis of the liver of laying hens fed diets containing supplemental fat at early laying stages. Two dietary treatments included basal diets with no supplemental fat and basal diets supplemented with 3.0% tallow. A total of 256 18-week-old Hy-line Brown laying hens were allotted to 1 of 2 treatments. Diets were fed to hens for 12 weeks. At the end of the experiment (30 weeks of age), 5 hens with similar BW per treatment were euthanized to collect liver tissues. The cDNA libraries were constructed with extracted RNA from the liver tissues, and sequenced using the Illumina Nextseq 500 sequencer. Genes with False Discovery Rate (FDR) < 0.05 were defined as differentially expressed genes (DEGs). Results indicated that a total of 951 DEGs were identified, with 483 being up-regulated and 468 being down-regulated in the liver of hens fed diets containing 3.0% tallow. The KEGG analysis revealed that the DEGs belong to several biological pathways such as cellular signaling pathways, carbon metabolism, glycolysis, gluconeogenesis, TCA cycle, amino acid metabolism, drug metabolism, and glycerophospholipid metabolism. Especially for fatty acid metabolism, the DEGs associated with fatty acid degradation (ECI2, ACSL1, HADHA, EHHADH, ACOX1, CPT1) were up-regulated, whereas those related to fatty acid synthesis (ACACA, ACSL5, FASN) were down-regulated in the liver of hens fed diets containing 3.0% tallow, which indicates that supplemental fat in diets may increase fat oxidation but decrease fat synthesis in the liver. These results provide the molecular insights for hepatic lipid metabolisms by feeding diets containing supplemental fat to laying hens at early laying stages.