As a metabolic disease, fatty liver hemorrhagic syndrome (FLHS) has become the major factor responsible for the noninfectious cause of mortality in laying hens, which lead to huge economic losses to poultry industry. However, the pathogenesis of FLHS remains unclear. The aim of present study was to identify novel liver metabolites associated with FLHS. Twenty healthy Chinese commercial Jing Fen laying hens aged 90 d were used in present study. After acclimatization for 2 wk, the hens were divided into 2 treatments (n = 10): control group (normal diet) and FLHS group (high-energy low-protein diet). The experiment lasted for 48 d, and the laying hens were killed for blood and liver sampling at the end of the experiment. Blood biochemical indicators and liver pathological changes were examined. Meanwhile, the changes in liver metabolic profile were investigated with the application of metabolomics approach. Significant increased levels of alanine aminotransferase, aspartate aminotransferase, low density lipoprotein, total cholesterol and triglycerides, decreased high density lipoprotein (P < 0.01), and hepatic steatosis were observed in hens of FLHS group, which suggested FLHS was successfully established in this study. Distinct changes in metabolite patterns in liver between control and FLHS group were observed by partial least-squares discriminant analysis. In total, 42 liver metabolites including tyrosine, glutathione, carnitine, linoleic acid, uric acid, arachidonic acid (ARA), lactate and lysophosphatidylcholine (14: 0) were identified and considered to be related with pathogenesis of FLHS. Pathway analysis revealed that these metabolites were mainly involved in amino acid metabolism, fatty acid metabolism, ARA metabolism, glucose metabolism and glycerophospholipid metabolism. Furthermore, targeted metabolomics found that ARA metabolites such as prostaglandins and hydroxyeicosatetraenoic acids were significantly increased in FLHS group (P < 0.05). In conclusion, our data showed that liver metabolites and ARA metabolism were linked to the pathophysiology of FLHS, which provided a basis for understanding the pathogenesis of FLHS in laying hens.

In this study, a method combining molecularly imprinted polymer-solid phase extraction (MIP-SPE) and high performance liquid chromatography was developed to determine the residues of fluoroquinolone drugs in milk. During the experiments, different templates, functional monomers, porogens and template/monomer ratios were evaluated. The norfloxacin based MIP capable of recognizing four fluoroquinolones (ciprofloxacin, norfloxacin, enrofloxacin and lomefloxacin) was used to prepare the SPE cartridge. The MIP-SPE cartridge showed high adsorption capacities (≥4520 ng) and high recoveries (≥96%) to the four drugs, and could be reused for at least fifty times. Then the four drugs were fortified into blank milk samples respectively to be analyzed. The limits of detection were in the range of 10–20 ng mL⁻¹ and the recoveries were in the range of 76.8–97.7% with coefficients of variation lower than 8.3%. Furthermore, the MIP-SPE cartridge showed a better purification effect than three commercial SPE cartridges. This is the first study reporting the use of norfloxacin based MIP-SPE for determination of fluoroquinolones in milk.