Yang Yongxin, Zhao Xiaowei, Yu Shumin, Cao Suizhong
College of Veterinary Medicine, Sichuan Agricultural University, Ya'an, 625014, China; Institute of Animal Science and Veterinary Medicine, Anhui Academy of Agricultural Sciences, Hefei, 230031, China.
J Sci Food Agric. 2015 Feb;95(3):592-7. doi: 10.1002/jsfa.6791. Epub 2014 Jul 16.
Yak (Bos grunniens) is an important natural resource in mountainous regions. To date, few studies have addressed the differences in the protein profiles of yak colostrum and milk. We used quantitative proteomics to compare the protein profiles of whey from yak colostrum and milk. Milk samples were collected from 21 yaks after calving (1 and 28 d). Whey protein profiles were generated through isobaric tag for relative and absolute quantification (iTRAQ)-labelled proteomics.
We identified 183 proteins in milk whey; of these, the expression levels of 86 proteins differed significantly between the whey from colostrum and milk. Haemoglobin expression showed the greatest change; its levels were significantly higher in the whey from colostrum than in mature milk whey. Functional analysis revealed that many of the differentially expressed proteins were associated with biological regulation and response to stimuli. Further, eight differentially expressed proteins involved in the complement and coagulation cascade pathway were enriched in milk whey.
These findings add to the general understanding of the protein composition of yak milk, suggest potential functions of the differentially expressed proteins, and provide novel information on the role of colostral components in calf survival.
牦牛（Bos grunniens）是山区的一种重要自然资源。迄今为止，很少有研究涉及牦牛初乳和牛奶蛋白质谱的差异。我们使用定量蛋白质组学来比较牦牛初乳和牛奶中乳清的蛋白质谱。在产犊后从21头牦牛收集牛奶样本（产后1天和28天）。通过等压标签相对和绝对定量（iTRAQ）标记的蛋白质组学生成乳清蛋白谱。
我们在乳清中鉴定出183种蛋白质；其中，初乳和牛奶乳清中86种蛋白质的表达水平存在显著差异。血红蛋白表达变化最大；其在初乳乳清中的水平显著高于成熟牛奶乳清。功能分析表明，许多差异表达的蛋白质与生物调节和对刺激的反应有关。此外，参与补体和凝血级联途径的8种差异表达蛋白质在牛奶乳清中富集。
这些发现增进了对牦牛奶蛋白质组成的总体了解，提示了差异表达蛋白质的潜在功能，并提供了有关初乳成分在犊牛存活中作用的新信息。
