Milk protein genotypes and milk coagulation properties of Estonian native cattle

The genetic variation of alpha(s1)-, beta- and kappa-caseins and b-lactoglobulin was determined and their effects on the rennet coagulation properties were examined using 335 milk samples from 118 Estonian Native (EN) cows. We found 16 aggregate casein genotypes alpha(s1)-, beta-, kappa-caseins), of which four- namely, BB A(2)A(2) AA(21.2%), BB A(1)A(2) AB (16.9%), BB A(1)A(2) AA (14.4%), and BB A(2)A(2) AB (10.2%) - occurred among nearly two-thirds of the analysed cows. Aggregate casein genotype had a significant overall effect on rennet coagulation parameters. Better rennet coagulation properties were found for aggregate casein genotypes CC A(2)A(2) AB and BC A(1)A(2) BB, among frequent genotypes for BB A(1)A(2) AB. Of the cattle breeds raised in Estonia, milk from EN had the best coagulation properties and highest frequency of favourable kappa-Cn B allele.