The objective of this study was to reveal the effects of parity on the milk protein expression by analyzing the changes of milk protein expression between the first and the third parity.Milk proteins of the dairy cows from 1st and 21st after calving were separated and identified by two-dimensional electrophoresis combination HPLC tandem ion trap spectrometry. The results showed that 4 proteins in 1st from the third parity were up-regulated in comparison with that of primiparity, and on 21st postpartum the proteins expressed were not significantly changed. The differentially expressed proteins included IgG IgM and transferrin with immune function, and albumin with molecule transport.The findings might provide the valuable information for exploration of the mechanism of milk secretion and the effects of parity on milk secretion.%采用二维凝胶电泳结合液相色谱串联质谱的方法分析了第一胎和第三胎奶牛,产后第1天和第21天乳蛋白表达的差异.结果表明,与初产奶牛第1天乳蛋白表达模式相比,第三胎奶牛第1天的乳蛋白表达图谱上有4个蛋白表达量上调;而两个胎次第21天乳蛋白的表达模式无差异.这些差异表达蛋白包括具有免疫活性的免疫球蛋白G、免疫球蛋白M、乳铁蛋白及具有运输功能的白蛋白.这些发现揭示了胎次对泌乳初期奶牛低丰度乳蛋白表达的影响机制.
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