SNPs identification and its correlation analysis with milk somatic cell score in bovine MBL1 gene

The objective of this study was to investigate the single nucleotide polymorphisms (SNPs) within bovine binding lectin-liver (A) gene (MBL1) and to explore its correlation analysis with milk somatic cell score (SCS) which reflects mastitis resistance in cattle. Through polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP), created restriction site-PCR (CRS-PCR) and DNA sequencing methods, three allelic variant corresponding to the G -> A mutation at c.1252G > A in intron1, G -> A mutation at c.2534G > A and T -> C mutation at c.2569T > C in exon2 of bovine MBL1 gene, could be detected, respectively. The c.2534G > A was a nonsynonymous mutation, resulting in Valine (Val) to Isoleucine (Ile) amino acid replacement (p.Val24Ile). The correlation analysis between the MBL1 SNPs gene and milk SCS were analyzed and a significant correlation with milk SCS was detected in c.2534G > A. The value of milk SCS for individuals with genotype GG was significantly lower than those of genotype GA and AA. Results showed that genotype GG with the lowest milk SCS was favorable for mastitis resistance, whereas genotype AA with the highest milk SCS was easily for mastitis susceptibility. Although more investigations are needed to better clarify the role of these SNPs on mastitis resistance, MBL1 polymorphism appears to be a promising indirect marker to improve dairy mastitis resistance traits in cattle.