Proteomic analysis of whey proteins in the colostrum and mature milk of Xinong Saanen goats

Abstract

Xinong Saanen goats are among the major dairy goats in China, and their milk is one of the major milk supplies for the Chinese dairy industry. To explore the whey proteome of Xinong Saanen goat milk, we analyzed the whey proteins of goat colostrum and mature milk using proteomic techniques. We identified a total of 314 and 524 proteins in goat colostrum and mature milk, respectively. Our data showed the first 3 functional categories of signal, disulfide bond, and secreted in both milk types. The most abundant Gene Ontology annotations in both milks were the biological process of positive regulation of extracellular regulated protein kinases (ERK)1 and ERK2 cascade; the cellular component of extracellular exosome; and the molecular function of calcium ion binding. Goat colostrum whey proteins showed more disease-related pathways, and mature milk showed more pathways associated with metabolism. Moreover, we observed several pathways involved in intestinal mucosal immunity only in colostrum. Protein-protein interaction network and module analysis revealed that complement and coagulation cascades and Staphylococcus aureus infection were significant in the whey proteins of both milks, and carbon metabolism was more common for mature milk than for colostrum. These findings could provide useful information for the use of goat milk whey proteins in the Chinese dairy industry.