| The healthy development of dairy industry is affected by the quality of milk,and the composition and content of milk protein are important indicators to measure the nutritional quality of milk.A1 and A2 β casein are the two most common types of β casein in milk.Compared with A1 milk,A2 milk is easy to be absorbed and has higher nutritional value.It is difficult to completely separate A1 and A2 β casein in milk by using the existing technology.Therefore,artificial selection and isotypic mating were mainly used to change the genetype frequency of dairy cows,and A2 homozygous genotype dairy herds were cultivated to obtain A2 milk source.At present,the detection methods for A1/A2-β casein genotype cows mainly use the reaction of first generation sequencing and multiple ligase detection,which has many problems such as high detection cost and low efficiency.Therefore,in order to reduce detection cost,improve detection efficiency and guide the grouping and breeding of A2 dairy cows,this study established an accurate,affordable and efficient detection method with Holstein dairy cows as the research object,and obtained the following results:DNA of Holstein cows was extracted from blood and hair follicles by kit method.PCR primers and specific probes were designed according to the sequence of β casein gene and SNP sites in the gene.Standard plasmid containing A1/A2-β casein gene was constructed as positive control and blank control was set up.Fluorescence quantitative PCR system and program were established successfully.By fluorescence signal scanning,β casein genotyping could be obtained accurately.This study successfully established a TaqMan fluorescent quantitative PCR assay for the identification of A1/A2-β casein genotypes in dairy cows,which can shorten the time and cost of the assay and achieve100% accuracy,providing technical support for the breeding of A2 cows and contributing to the rapid development of the A2 cow and related products industry. |
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