Genetic polymorphism of milk protein and their relationships with milking traits in Chinese yak

Abstract

Milk protein polymorphisms were genotyped by polyacrylamide gel electrophoresis (PAGE) from 109 Maiwa and 100 Jiulong yaks. The relationships between milk protein polymorphisms and 3 milking traits were studied. The results showed that β-CN, κ-CN and α-La were monomorphic, and αs1-CN and β-Lg were polymorphic, with αs1-CN D and β-Lg E as dominant genes, respectively. The frequencies of αs1-CN D were 0.8073 and 0.6000 in two populations and β-Lg E were 0.9770 and 0.9700. The mean heterozygosities were 0.1021 and 0.1867 in the two populations. No significant effects on milking traits and milk protein compositions were observed except for αs1-CN locus on fat percentage in Jiulong yak.