Identification of Novel Milk Protein Gene Variants in Sahiwal Cattle Breed of Pakistan

This novel study was aimed at identification of new genetic variants in Sahiwal cattle breed of Pakistan and determined the effects of these variants on milk yield. Five major milk protein genes in Sahiwal cattle were analyzed and two single nucleotide polymorphisms identified through bi-directional sequencing. These include A to T in exon XI at position 11462 of the alpha s1 casein gene; resulting in a Glutamic Acid (GAA) to Aspartic acid (GAU) substitution at position 84 of alpha s1 casein protein and T to C change at position 8491 of the exon VII in beta-casein gene resulting in a Valine to Alanine substitution at position 197 of beta casein protein. Amplification Refractory Mutation System (ARMS) and SNaPshot genotyping protocols were optimized for genotyping new genetic variants. The genotypes in both the alpha-s1 casein and beta casein genes were found associated with milk yield but their influence was not statistically significant. However, the least square means of milk yield for TT genotypes of alpha s1 casein and of beta casein genes were higher compared to other genotypes.