Influence Of CSN1S1 Polymorphism On Milk Quality And Mozzarella Cheese Quality In Water Buffalo Milk

Buffalo is one of the main ruminants all over the world. Buffalo milk has the higher protein and fat than other breeds in milk cattle. So the buffalo milk is suited to make cheese. To improving the milk performance of Chinese buffalo and producing high quality cheese, the CSN1S1 genetic polymorphism and their relationship with milk performance and mozzarella cheese quality were studied.Blood and milk samples were taken from lactating buffalo in Nanning, Guangxi Province, China. Two milliliter individual blood samples were collected from the jugular vein of each 162 buffalo using 5-m L tubes containing anticoagulants. The collected blood samples were stored at 4 oC until analysis. Single test day milk samples were collected in a common commercial herd from October 2013 to June 2014. Milk was collected during the morning and the consecutive evening milking for each animal. After collection, each milk sample was partitioned into 2 subsamples: one subsample was immediately frozen and kept at-20oC until analysis; the remaining subsamples were mixed and collected for milk composition analysis. Milk components of all subsamples and one mixed milk sample(MMS) were analyzed using Milko Scan. PCR and sequencing are the main way to detect the polymorphism loci.Milk samples of two genotypes and MMS were taken 20 kg from lactating buffalo. Each samples were manufactured the mozzarella cheese. At last, to analysis the composition, texture analysis, functional traits, water activity, PH, titratable activity of cheese and guide of the sensory evaluation.Results show that a 333-bp DNA fragment was found after PCR amplification and the polymorphic loci was presented in 67 bp, led to the mutation of 178Ser(TCA) to 178Leu(TTA). The genotypic frequencies of CSN1S1 in the investigated Chinese water buffalo population were 90.12%, 9.88%, and 0 for BB, AB, and AA, respectively. In relation to CSN1S1, AB genotype was associated to the highest milk yield(P < 0.01) while BB genotype with the highest fat content(P < 0.05), whereas milk protein content, fat protein ratio, and lactose content were not affected(P > 0.05). The relationship between three genotypes and mozzarella cheese traits show that BB and AB types have a higher significant influence on protein than mixed sample. In terms of fat, BB type has higher influence than AB and mixed sample(P < 0.05). For the moisture content, the mixed cheese is significantly higher than AB and BB type(P < 0.05); For hardness, adhesiveness and chewiness speaking, AB type is significantly better than the BB type(P < 0.05); but for the cohesion and stickiness, the BB genotype is significantly better than the AB type(P < 0.05); In terms of drawing, AB type cheese is significantly higher than BB type and mixed type(P < 0.05); For liquidity, BB type is significantly higher than AB type cheese and mixed cheese(P < 0.05). For cheese bluish value and water activity, BB and AB was significantly stronger than the mixed cheese(P < 0.05); For p H, BB and mixed sample have significant impact on the cheese(P < 0.05); AB type cheese significantly higher on titratable acidity than BB and mixed cheese(P < 0.05).In conclusion, the CSN1S1 gene exist polymorphism, and have a significant influence on milk traits and mozzarella cheese quality.