Genotyping of cattle based on kappa-casein and alpha-lactalbumin genes

Milk yield, protein and fat content are regulated by milk protein genes. However, genetic makeup of different milk protein genes of cattle available in Bangladesh is not known. This study determined the genetic variants of kappa-casein (κ-CN) and α-lactalbumin (α-LA) gene in cattle. DNA was extracted from 50 blood samples collected from indigenous and crossbred cattle. Polymerase chain reaction (PCR) was performed with gene specific primers. For genotyping PCR products of κ-casein gene was digested with HindIII and HaeIII restriction enzymes while the PCR products of α-LA gene was digested with Bsp1286I. Overall from all the tested samples we could amplify specific DNA viz. 935 and 429 bp for κ-CN and α-LA genes, respectively. In case of κ-CN gene 30 samples were analyzed for genotyping and of these 66.67, 30.00 and 3.33% samples were genotyped as AA, AB and BB, respectively. AA genotype was found dominant for κ-CN gene. Allele frequency for A was 82%. AA genotype was found higher in indigenous (0.366) than crossbred (0.30) animals. Homozygous BB genotype was not found in crossbred animals. For α-LA gene 50 samples were genotyped and all the samples (100%) were belonging to AA genotype. Three genetic variants of κ-CN gene viz. AA, AB & BB and one genotype (AA) of α-LA gene were detected in tested samples. Alleles of both the genes are reported to be associated with higher milk, protein, and fat yields.