Oligosaccharide Diversity: Bovine Glycans through Lactation

Non‐digestible oligosaccharides in mammalian milk are the subject of interest to the fields of glycobiology, analytical chemistry, microbiology, genetics, nutritional biology, and food science. In colostrum, oligosaccharides are the third most abundant non‐aqueous component in bovine milk after lipid and lactose; yet their abundance is dramatically lower in mature milk. We have developed separation protocols and analytical platforms to profile extracted oligosaccharides in milk from various mammals and stages of lactation. Oligosaccharides were isolated in microgram quantities using the Gilson automated solid phase extraction robot. Isolated oligosaccharides were identified, structurally characterized, and quantified using various mass analyzers including matrix assisted laser desorption/ionization Fourier transform‐ion cyclotron resonance mass spectroscopy, microchip liquid time‐of‐flight mass spectroscopy, and quadrupole liquid time‐of‐flight mass spectroscopy (Agilent Technologies Inc., Palo Alto, CA, USA). Oligosaccharides profiled in Holstein cows over the course of the first seven days of lactation showed that acidic oligosaccharides decrease relative to neutral oligosaccharides as lactation progresses. We are now using these methods to establish the environmental and genetic factors that control acidic oligosaccharide biosynthesis.