Association of polymorphisms in IGF2, CLU and STAT5A genes with milk production characteristics in Chinese Holstein cattle

Reflecting the quality of milk at the molecular level is a frontier technology. The aim of this study was to analyze the polymorphisms of bovine insulin-like growth factor 2 (IGF2), signal transducer and activator of transcription 5A (STAT5A) and clusterin (CLU) genes in the raw milk from 507 Chinese Holstein cow using polymerase chain reaction (PCR)-restriction fragment length polymorphism techniques and to evaluate their correlations with the milk protein content (MPC), milk fat content (MFC), milk lactose content (MLC) and milk total solids content (MTSC). In IGF2 gene, genotype GG was the most frequent genotype (51.68%) followed by the genotype GT (38.03%) and TT (10.29%). And the genotype TT of IGF2 gene was superior to the other genotypes in MPC. In CLU gene, genotype GG was the most common genotype (63.99%) followed by the genotype GA (34.45%) and AA (1.56%). And the genotype AA of CLU gene had greater MFC and MLC, but lower MTSC than GA genotype individuals. For STAT5A gene, the frequency of genotype CC and CT was similar (45.30% and 45.08%), while the genotype TT had lowest frequency (9.62%). And the genotype TT of STA5A gene had highest MPC and lowest MLC. Thus, screening for the IGF2, CLU and STAT5A genes were available for evaluating milk quality and raw milk samples were graded according to the different genotypes.