Structural determination and daily variations of porcine milk oligosaccharides

Free milk oligosaccharides (OS) are major components of mammalian milk. Swine are important agricultural species and biomedical models. Despite their importance, little is known of the OS profile of porcine milk. Herein, the porcine milk glycome was elucidated and monitored over the entire lactation period by liquid chromatography profiling and structural determination with mass spectrometry. Milk was collected from second-parity sows (n = 3) at farrowing and on days 1, 4, 7, and 24 of lactation. Twenty-nine distinct porcine milk oligosaccharides (pMO) were identified. The pMO are highly sialylated, which is more similar to bovine milk than human milk OS. Six fucosylated pMO were detected at low levels in porcine milk, making it more similar to human milk than bovine milk. In general, the pMO content was highest in milk collected at farrowing and day 1 of lactation, decreased during early lactation, but then rose at day 24; however, the pMO displayed different patterns of variation across lactation. In summary, porcine milk contains both acidic (sialylated) and neutral OS, but sialic acid containing OS predominate throughout lactation.