Abstract

β-Lactoglobulin (β-LG) is the major protein in whey, making up about 50 to 60% of the total protein. A biological task for β-LG has been the subject of much speculation, but no specific function has been proven. About eleven protein variants of β-LG are known, of which variants A and B are common in most cattle breeds. The purpose of this study was to identify genotypes of the β-LG gene in Holstein and Iranian native cattle using polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) technique. Blood samples were obtained from 278 Holstein and 210 Iranian native cattle. The primers β-LG F and β-LG R amplified a 247 bp fragment. The HaeIII enzyme was used for restriction of the polymerase chain reaction (PCR) products. The frequency of allele A and B in Holstein and native cattle were 0.53, 0.47 and 0.23, 0.77, respectively. According to previous studies AA genotypes of β-LG gene is an important factor in increasing the milk production and the results of this study showed that high frequency ofAA genotypes in Holstein and Iranian native cattle and could be use in creating the next generation for increasing the milk production.

Key words: Polymorphism, β-lactoglobulin gene, polymerase chain reaction-restriction fragment length polymorphism, Holstein, native cattle.