title: Blood plasma lipidome profile of dairy cows during the transition period.
abstract: BACKGROUND
  The transition period of dairy cows, around parturition and the onset of lactation, involves endocrine and metabolic changes to compensate for an increased energy requirement aggravated by reduced feed intake. Transition cows adjust to the resulting negative energy balance with the mobilization of lipids from the adipose tissues yielding increased blood levels of non-esterified fatty acids and ketone bodies like β-hydroxybutyrate.
  
  
  RESULTS
  To study the biochemical adaptations underlying this physiologic adjustment and possible pathologic derangements, we analyzed the blood plasma lipidome of transition cows by ultra-pressure liquid chromatography coupled to high-resolution quadrupole time-of-flight mass spectrometry. The resulting data were processed by principal component analysis, revealing over 60 lipid masses that change in abundance over the test period ranging from two weeks before calving to four weeks postpartum. Further characterization of analytes by tandem mass spectrometry demonstrated that the concentration of triacylglycerides in plasma drops at the day of parturition whereas the plasma level of many phosphatidylcholines and two sphingomyelins increases steadily during early lactation.
  
  
  CONCLUSIONS
  This newly identified shift in phospholipid composition delivers a potential biomarker to detect aberrant metabolic pathways in transition cows and also provides insights into how to prevent and treat associated disorders like fatty liver disease.
authors.affiliation: Institute of Pharmacology and Toxicology, Vetsuisse Faculty, University of Zurich, Winterthurerstrasse 260, 8057, Zurich, Switzerland. sandro.imhasly@vetpharm.uzh.ch.
authors.forename: S
authors.initials: S
authors.lastname: Imhasly
authors.affiliation: Department of Farm Animals, Vetsuisse Faculty, University of Zurich, Winterthurerstrasse 260, 8057, Zurich, Switzerland. cbieli@vetclinics.uzh.ch.
authors.forename: C
authors.initials: C
authors.lastname: Bieli
authors.affiliation: Institute of Pharmacology and Toxicology, Vetsuisse Faculty, University of Zurich, Winterthurerstrasse 260, 8057, Zurich, Switzerland. naegelih@vetpharm.uzh.ch.
authors.forename: H
authors.initials: H
authors.lastname: Naegeli
authors.affiliation: Institute of Food, Nutrition and Health, Swiss Federal Institute of Technology, Schmelzbergstrasse 9, 8092, Zurich, Switzerland. laura.nystroem@hest.ethz.ch.
authors.forename: L
authors.initials: L
authors.lastname: Nyström
authors.affiliation: Institute of Veterinary Pathology, Vetsuisse Faculty, University of Zurich, Winterthurerstrasse 260, Zurich, Switzerland. Maja.Ruetten@access.uzh.ch.
authors.forename: M
authors.initials: M
authors.lastname: Ruetten
authors.affiliation: Department of Farm Animals, Vetsuisse Faculty, University of Zurich, Winterthurerstrasse 260, 8057, Zurich, Switzerland. cgerspach@vetclinics.uzh.ch.
authors.forename: C
authors.initials: C
authors.lastname: Gerspach
mesh_terms: D020155:3-Hydroxybutyric Acid / Q000097:blood; D000818:Animals; D015415:Biomarkers / Q000097:blood; D002417:Cattle / Q000097:blood* / Q000502:physiology; D002851:Chromatography, High Pressure Liquid / Q000662:veterinary; D005230:Fatty Acids, Nonesterified / Q000097:blood; D005260:Female; D007774:Lactation / Q000097:blood* / Q000502:physiology; D008055:Lipids / Q000097:blood*; D036801:Parturition / Q000097:blood* / Q000502:physiology; D010713:Phosphatidylcholines / Q000097:blood; D013109:Sphingomyelins / Q000097:blood; D053719:Tandem Mass Spectrometry / Q000662:veterinary; D014280:Triglycerides / Q000097:blood
chemical_list: D015415:Biomarkers; D005230:Fatty Acids, Nonesterified; D008055:Lipids; D010713:Phosphatidylcholines; D013109:Sphingomyelins; D014280:Triglycerides; D020155:3-Hydroxybutyric Acid