Metabolic profiling of plasma from sows before parturition and during lactation using a liquid chromatography-mass spectrometry-based approach.

During transition from late gestation to lactation, the sow undergoes large and sudden metabolic changes to adapt from anabolic to catabolic metabolism. Little is known about changes in nutrient uptake and intermediary metabolism of transition sows. This study was undertaken to screen the metabolic profile for qualitative changes in nutrient uptake and metabolism during transition. Four sows were fitted with permanent catheters in artery femoralis (AF), portal vein (PV), and hepatic vein (HV) (sampling sites). Sows were fed a standard lactation diet from 15 d prior to 28 d after parturition. Blood samples were taken 1.5 h after feeding on days -10, -3, 3, and 17 relative to parturition and plasma metabolites were analyzed by a liquid chromatography-mass spectrometry-based approach. Principal components analysis was performed to visualize the metabolic profiles and to screen for intermediary metabolites altered during the transition period. The metabolic profile of sows on day 3 after parturition was distinct from other days. Plasma betaine, Pro, and some unidentified lipid compounds contributed to the separation on day 3; betaine and Pro were lowered by 30% at day 3 compared to day -10 and day -3 (P < 0.001). Plasma choline, Pro, creatine, and unidentified lipid compounds contributed to the separation due to sampling sites. Plasma choline was lowest in HV, intermediate in AF, and highest in PV (P < 0.001) plasma, indicating net absorption from the gastrointestinal tract (PV vs. AF) and liver metabolism (HV vs. PV). The majority of unidentified metabolites found using the loadings plots that were affected by day or sampling site or both were revealed as lipid compounds, that is, bile acid, cholesterol, glycerol, phosphatidyl, sphingomyelin, or acylglycerol derivatives. In conclusion, the intermediary metabolism of sows, especially for fat, changed during transition, and a deeper understanding and detection of involved metabolites are needed to optimize sow feeding during transition.