Genotyping of Bovine Kappa-Casein Gene Variants in Sri Lankan Dairy Cows by Tetra-Primer ARMS-PCR Technique

Main goal of dairy cattle breeding is to improve the quality and quantity of milk in the resultant progeny. Genetic marker assisted selection is used to identify the best sires and dams in progeny selection. A and B allelic variants of bovine kappa- casein (κ-casein) gene are identified to be associated with production traits such as milk yield, composition and cheese yield in several dairy breeds. Objective of this study was  to genotype the dairy cows in upcountry farms in Sri Lanka for variants A and B of κ-casein gene by tetra-primer ARMS-PCR and to associate the genotypes with milk production and cheese quality traits.

Blood samples were collected from Ayrshire and its crossbreds in Ambewela farm (n=200) and DNA was extracted. ARMS-PCR technique was performed for 100 samples to identify the κ-casein variants in these animals. It was revealed that all three genotypes, AA, AB and BB of κ -casein are present in this population. Allele A was the major allele with a frequency of 0.79. AA genotype was present at a higher frequency (0.62), followed by AB (0.36) and BB (0.02) respectively. K-casein allele frequencies of Ayrshire and its crossbreds in Sri Lanka are similar to the frequencies obtained for several dairy breeds in other countries. We are in the process of genotyping more animals and collecting phenotypic data of them. Future studies will be conducted on association analysis of milk production and cheese quality traits with AA, AB and BB genotypes.