Quantitative lipidomics reveals lipid perturbation in the liver of fatty liver hemorrhagic syndrome in laying hens

Fatty liver hemorrhagic syndrome (FLHS) is a metabolic disease that causes decreased egg production and even death in laying hens, which brings huge economic losses to the poultry industry. However, the pathogenesis of FLHS is unclear. The purpose of the present study was to identify the changes in lipid profile and the lipid species related to FLHS. In the present study, the FLHS disease model in Chinese commercial Jing Fen laying hens was induced by a high-energy low-protein diet. A lipidomics approach based on ultra-performance liquid chromatography-mass spectrometry coupled with multivariate statistical analysis was performed for the qualitative and quantitative analyses of the liver lipids. The results showed that a total of 29 lipid subclasses, including 1,302 lipid species, were detected and identified. Among them, the proportions of phosphatidylserine (Control/FLHS, 33.1% vs. 29.1%), phosphatidylethanolamine (22.7% vs. 15.5%), phosphatidylcholine (15.7% vs. 11.7%) and phosphatidylinositol (7% vs. 6%) were reduced, while triacylglycerol (7.1% vs. 18.3%) and diglyceride (3.9% vs. 11.7%) were increased. Between the Control and FLHS groups, distinct changes in lipid profile were observed in the score plots of principal component analysis and orthogonal partial least squares discriminant analysis. Twelve differential lipid species mainly involved in glycerophospholipid metabolism and linoleic acid metabolism were identified and considered to be related to the pathogenesis of FLHS. Fatty acid chain length and unsaturation were reduced, while the mRNA levels of elongation of very long chain fatty acids-2 (ELOVL2) were increased in the liver of laying hens with FLHS. Collectively, this study characterized the liver lipid profile and explored the changes in lipid species related to FLHS, which provided insights into the pathogenesis of FLHS from the view of lipid metabolism.