Genetic Polymorphism of Milk Proteins and Their Association with Production Traits in Ayrshire, Jersey, Brown Swiss, and Canadienne

Note:Genetic variants of milk proteins were used as genetic markers for production traits during three lactations in Ayrshire, Jersey, Brown Swiss, and Canadienne. Frequency distribution of genetic variants was first investigated for the analysis of production traits. At the asè-casein locus, the B variant accounted for more than 97.0% in Ayrshire, Brown Swiss and Canadienne compared to 56.9% in Jersey. The A2 variant of B-casein was highest among Jersey (49.9 %) and Brown Swiss (51.8 %) While the A1 constituted 60.1 % in Ayrshire and 58.5 % in Canadienne. The A variant of K-casein occurred in 88.1% of Ayrshire and in only 26.0% of Jersey. K-Casein C was detected only in Brown Swiss and Canadienne with vecy low frequencies (