Changes in Caprine Milk Oligosaccharides at Different Lactation Stages Analyzed by High Performance Liquid Chromatography Coupled to Mass Spectrometry

Changes of the abundance of caprine milk oligosaccharides (CMO) at different lactation stages have been evaluated by hydrophilic interaction liquid chromatography coupled to mass spectrometry (HILIC-QMS) and nanoflow liquid chromatography quadrupole-time-of-flight mass spectrometry (nano-LC-Chip QTOF MS). Eight major oligosaccharides (OS) were quantified at differentJactation stages by HILIC QMS, while the use of nano-Lc-Chip QToF MS allowed expanding the study to forty-nine different OS,by monitoring neutral non- and fucosylated species, as well as acidic species containing not only N-acetyl-neuraminic acid or. N-glycolyl-neuraminic acid residues but also the combination of both sialic acids. Overall, the most, abundant OS decreased with lactation time, whereas different trends were observed for minor OS. 6'-Sialyl-lactose was the most abundant acidic OS while galactosyl-lactose isomers were identified as the most abundant neutral OS. This is the first time that a comprehensive study regarding the changes of the abundance of CMOs, both neutral and acidic, at different lactation stages is carried out.