Variations in bovine milk oligosaccharides during early and middle lactation stages analyzed by high-performance liquid chromatography-chip/mass spectrometry

Milk oligosaccharides (OS) are not only a source of nutrition for newborns, but also provide numerous important biological functions including the prevention of pathogen binding to the intestinal epithelium and serving as nutritive sources for beneficial bacteria. High-performance mass spectrometry and separation methods were used to evaluate changes of bovine milk oligosaccharides (bMO) in different lactation stages. Previously, 40 bMO were identified in bovine milk with many consisting of short oligomeric chains that were less complex than human milk oligosaccharides (hMO). The bMO are also significantly more anionic than hMO, with nearly 70% in measured abundances containing either N-acetylneuraminic acid or N-glycolylneuraminic acid, and no fucosylated OS. In this study, we examined factors that could affect the abundances of bMO including stage of lactation and breed. The total concentrations dropped rapidly in the first several days of lactation. Moreover, the anionic oligosaccharides (including N-glycolylneuraminic acid) decreased more rapidly compared with the neutral oligosaccharides.