DNA Polymorphisms in the β-lactoglobulin and κ?casein Genes Associated with Milk Production Traits in Dairy Cattle

In recent years, the polymorphism of the milk proteins has been used as marker systems in modern animal breeding programmes. The current study was designed to evaluate significant associations between single nucleotide polymorphisms (SNPs) and milk production traits in Chinese Holstein cows. In this study, we detected the polymorphism of β-lactoglobulin and κ?casein genes by Matrix-assisted laser desorption/ ionization time of flight mass spectrometry (MALDI-TOF) and DNA sequencing methods in 752 individuals from Chinese Holstein cattle breeds. A single nucleotide polymorphism (g.1810C>T) in exon III in β-lactoglobulin gene and two single nucleotide polymorphisms (g.10888T>C and g.12703G>T) in exon IV and intron IV in κ?casein gene were detected. Polymorphism g.10888T>C was predicted to result in an amino acid replacement from threonine (ACC) to isoleucine (ATC) in the κ?casein protein whereas polymorphism g.1810C>T was predicted to silent mutation (asparagines>asparagines) in β-lactoglobulin protein. The results revealed the significant effects (P<0.05) of all identified SNPs of β-lactoglobulin and κ?casein genes on the milk production traits in Chinese Holstein. Our result demonstrated that the β-lactoglobulin and κ?casein genes possibly contributed to conducting association analysis and can be recognized as genetic marker in programs of gene- assisted selection for the genetic improvement of milk production traits in dairy cattle.