Kappa-casein gene polymorphism in Holstein and Iranian native cattle by polymerase chain reaction restriction fragment length polymorphism (PCR-RFLP)

Caseins amount to nearly 80% of the protein output in cow milk. Caseins are biologically important proteins and they are also a raw material for the cheese making industry. The aim of this study was to identify kappa-casein genotype in Holstein and Iranian native cattle. DNA was extracted from 457 blood samples of 247 Holstein and 210 native cattle for identification and genotyping of kappa-casein gene by polymerase chain reaction restriction fragment length polymorphism (PCR-RFLP) assay using HindIII and TaqI restriction endonucleases. The PCR product of the specific primer K-F and K-R gives the 379 bp specific band. Digestion of 379 bp fragment by restriction endonuclease HindIII generated two fragments of 156 and 223 bp. Result of the cut with this enzyme indicate there genotypes AA, AB and BB in the samples. Also, the amplified DNA (379 bp) from the samples remained undigested by TaqI restriction enzyme. These findings suggest that BB genotype could be a good factor for increase of fat and protein content of milk.