Alteration of the goat milk glycoproteins N/O-glycome at different lactation stages

Goat milk oligosaccharides represent an unexplored multi-functional ingredient for the dairy industry. Here, we qualitatively and quantitatively compared the N/O-glycome at different lactation stages via online hydrophilic interaction chromatography-tandem mass spectrometry. Complex N-glycans and high mannose N-glycans constituted 82.1% and 17.9% of the glycan pool, respectively. N-glycans with isomers containing non-bisected antenna complex structures accounted for 30.8%. N-glycans modified with Neu5Ac, Neu5Gc and fucosylated were 3.7%, 5.3% and 35.3%. The triantennary trifucosylated complex N-glycan (H5N5F3) was reported for the first time. A comparison between colostrum and mature milk revealed a 1.20-fold decrease in total N-glycans and 1.66-fold decrease in fucosylation with ongoing lactation, echoing the trend in human milk. Similarly, Neu5Ac- and Neu5Gc-modified sialylation decreased by 1.69 and 3.62 times, respectively. In the O-glycome, 46.2% of structures were O-linked core 1, 23.1% were O-linked core 2, 7.7% were O-linked core 3 and core 4. As lactation progressed, overall O-glycans content decreased by 1.26-fold. Unlike human milk, Neu5Ac- and Neu5Gc-modified sialylation increased by 4.4 and 2 times, respectively. These findings will facilitate research on the structure-function relationship of goat milk oligosaccharides and the development of formula food targeting different age groups.