Abstract: In order to elucidate the differentially expressed whey proteins between bovine colostrum and mature milk, isobaric tags for relative and absolute quantitation (iTRAQ) technique was used for proteomic analysis of the two milks. A total of 599 whey proteins were identified quantitatively, 60 of which were differentially expressed proteins. Bioinformatics analysis showed that the differentially expressed proteins were mainly involved in the biological processes of transport, subcellular localization, and single biological action, in molecular functions such as apical plasma membrane, extracellular region, and extracellular region part, and in cell components including protein binding and anion binding. Nine of the differentially expressed proteins were related to signal transduction and six of them were glycosylated whey proteins. In addition, protein-protein interaction network analysis revealed that some of these differentially expressed proteins were the key whey protein factors with high connectivity. This study provides a theoretical basis for improving bovine colostrum and mature milk quality and developing milk powder for infants and young children and functional dairy foods in the future.

Key words: bovine colostrum; mature bovine milk; whey; isobaric tags for relative and absolute quantitation; differentially expressed proteins