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.

Proteomic analysis of differentially expressed whey proteins in Guanzhong goat milk and Holstein cow milk by iTRAQ coupled with liquid chromatography-tandem mass spectrometry

“…Results indicated that these proteins mainly belonged to the biological process "response to stress," the cellular component "extracellular region," and the molecular function "binding." As shown in Figure 2a, most differentially expressed proteins (35%) were involved in the biological process of response to stress, followed by (Hurley and Theil, 2011;Beck et al, 2015;Sun et al, 2020). The results of the present study suggested that goat milk whey proteins differed in immune defenserelated functions such as stress, defense, inflammation, Accession number = unique entry name assigned for a given protein according to the Uniprot database (https: / / www .uniprot .org/ ).…”

“…All animals were healthy, and all milk samples were from the first batch milk in the early morning. Whey protein samples from both goat and cow milk were extracted based on a previously reported method (Sun et al, 2020). Briefly, 30 goat milk samples and 30 cow milk samples were mixed separately.…”

“…Yang et al (2017a) identified and quantified 584 whey proteins in human and cow colostrum and mature milk samples, 424 of which differed significantly in abundance between both species and different lactations. Our previous study of whey protein in goat colostrum and mature milk suggested that whey proteins in colostrum were involved in more disease-related pathways, whereas mature milk contained more proteins involved in metabolism-related pathways (Sun et al, 2020). Milk from different breeds of the same species and lactation stage also show different whey protein chemistry (Anagnostopoulos et al, 2016;Tacoma et al, 2016;Li et al, 2018).…”

“…Of the proteins identified, 100 were described for the first time in their report. Whey protein composition varies with animal species (Yang et al, 2017a;Lu et al, 2018) and lactation stage (Liao et al, 2011;Yang et al, 2015a;Sun et al, 2020). Lu et al (2018) compared the whey proteomes of human, cow, goat, and yak milks.…”

Comparative study on the microstructure and functional properties of casein in goat milk processed by different methods

“…In the latest study, the addition of quinoa extraction to goat milk yogurt enhanced the quality of the final products in terms of apparent viscosity, microstructure and organoleptic acceptability (El‐Shafei et al ., 2019). As a protein that plays an important role in functional dairy products, casein (CN) is one of the most abundant proteins in goat milk, accounting for approximately 70% of the total protein (Sun et al ., 2020), and the content of casein can change over time during the lactation period (Chen et al ., 2018; Mal et al ., 2018). CN is responsible for most of the unique physical properties of milk.…”