Genotyping of β-Lactoglobulin (β-Lg) gene by PCR-RFLP in indigenous cattle of Assam, India

The study was conducted to investigate the polymorphism in beta-Lactoglobulin (beta-Lg) gene in indigenous cattle of Assam. Genomic DNA from 53 indigenous cattle was extracted and used to study the polymorphism in beta-Lg gene using Polymerase Chain Reaction-Restriction Fragment Length Polymorphism (PCR-RFLP) technique. Genetic improvement by selective breeding provides enormous potential to enhance the performance of animals. But, it is a time-consuming exercise as generation interval of cattle is longer. Besides, milk production being a sex limited trait, it is not possible to select male animal on the basis of its own performance. To minimise these problems, selection based on markers can play an important role to carry out genetic improvement of animals before expressing actual target traits. APCR product of 262 bp obtained upon amplification was subsequently digested with restriction endonuclease BSuRI and yielded three types of restriction pattern, two fragments (153 and 109 bp) for AA genotype, three fragments (109, 79 and 74 bp) for BB genotype and, four fragments (153, 109, 79 and 74 bp) for AB genotype. The frequencies of alleles A and B were found to be 0.2547 and 0.7453 and those of AA, AB and BB genotypes were 0.0943, 0.3207 and 0.5849, respectively. From the present study it could be concluded that the beta-Lg B variant was predominant in the indigenous cattle with the highest frequency of BB homozygote followed by AB heterozygote (BB>AB>AA) and Chi-square (x(2)) test revealed that the population under study was in Hardy-Weinberg Equilibrium.