Differences in oligosaccharides composition between buffalo and Holstein milk in Guangxi, China, and their changes during lactation period

The first comprehensive oligosaccharide profiling in buffalo milk. • Buffalo milk has great diversity and 3′-FL increased during lactation. • Key oligosaccharides correlate with milk protein and fat content. • Thermal processing shows no effect on oligosaccharide content. Milk oligosaccharides (MOs) have attracted widespread attention owing to their diverse biological activities. In this study, an integrated strategy combining untargeted UPLC-Q-Orbitrap MS/MS profiling and targeted triple-quadrupole LC-MS/MS quantification was adopted to characterize the milk oligosaccharide profiles of Guangxi buffalo and Holstein cattle. A total of 38 oligosaccharide features were putatively annotated, and buffalo milk was found to have a richer variety of MOs than Holstein milk. Furthermore, 28 differentially abundant MOs were identified, 23 of which were more abundant in buffalo milk, further confirming the higher oligosaccharide diversity of buffalo milk. Subsequently, a fully validated LC-MS/MS method was established for the quantification of seven core differential MOs, and their dynamic changes across lactation stages, breed differences, and correlations with conventional milk components were systematically investigated. The results showed that 3′-sialyl-N-acetyllactosamine was a characteristic oligosaccharide in colostrum; the content of 3′-fucosyllactose increased gradually with lactation progression, while most other oligosaccharides exhibited a decreasing trend; and 6′-sialyllactose and lacto-N-neotetraose showed significant breed differences in mature milk. Additionally, significant correlations were observed between specific oligosaccharides and the contents of milk protein and milk fat, and thermal processing had no significant effect on the levels of target MOs. These findings provide a scientific basis for the quality improvement of buffalo milk and the development of functional dairy products. Download: Download high-res image (239KB) Download: Download full-size image