奶牛β-乳球蛋白研究进展

Advance Research in Dairy β-Lg

β-乳球蛋白（β-Lg）是由乳腺上皮细胞合成分泌的一种特有乳清蛋白,是鲜奶中蛋白质的一种,占鲜奶蛋白质的7%~12%,是牛和其他反刍动物乳中乳清蛋白的重要组分,其功能目前尚不明确。研究已确定β-乳球蛋白在牛乳中存在多种遗传变构体,不同变构体对奶牛牛乳的组分、性质和产量有一定的影响。单核苷酸多态性（SNP,Single nucleotide polymorphism）主要是指基因组DNA某一特定核苷酸的改变（转换、颠换、插入或缺失）引起的点突变,使得群体之间和个体之间产生了差异,已被广泛应用于医学、遗传学、动植物育种等领域。利用β-乳球蛋白多态性与产奶性能在基因上的连锁关系,将乳蛋白基因作为生化标记应用到辅助育种中,可改进畜群的遗传素质,提高生产性能。

β--Lg as a particular whey protein in fresh milk （7%-12%） is secreted by mammary gland epithelium in wide variety of species such as cattle and other ruminants, and the function of the whey protein is not clear. Up to now several genetic variants and their affect the composition, quality and milk yield are detected. Single nucleotide polymorphism （SNP） describes a single-base difference （transition, transversion mutation, insertion and deletion） in DNA sequences among individuals, and SNPs analysis are extensively applied in genetic studies of human disease, breeding animals and plants. Because of the association between the polymorphisms of the β-Lg （β-Lg, GenBank accession No： DQ489319） and milk production, β-Lg gene as a candidate and biochemical markers gene was used for meliorate the heredity diathesis of the herd and enhance the milk production.