Genotyping of β-lactoglobulin Gene in Pakistani Dairy Cattle (Sahiwal Breed) by Using PCR-RFLP

Genetic improvement of livestock is inevitable to increase per animal productivity and meet the dietary requirements of ever growing population. To improve efficiency and economic returns in dairy farming, conventional breeding takes many years to achieve targeted production. However advances in molecular biology have made it possible to identify candidate genes influencing the milk quality as well as yield. As choice of animals for attractive genotypes has been the premise in livestock development, the current research explains the use of Polymerase Chain Reaction (PCR) and Restriction Fragment Length Polymorphism (RFLP) technique to categorize bovine Beta-lactoglobulin (β-LG) gene polymorphisms in Sahiwal breed of Pakistani cattle. A segment of β-LG gene exon IV specifically (252 bp), comprised polymorphic positions for A and B allele was effectively amplified by PCR and subsequently digested with Hae III restriction enzyme. The yield was two types of restriction pattern i.e. 144 bp, 108 bp, 74 bp and 70 bp (four fragments) for genotype AB and similarly for genotype BB it was 108 bp, 74 bp and 70 bp(three fragments). The observed genotypes were AB and BB with a frequency of 0.60 and 0.40 respectively. Furthermore, frequency of the B allele was found higher (60%) than allele A (40%) in Sahiwal breed. Therefore β-LG genotyping by PCR-RFLP can be used in choosing superior animals for milk traits.