Genetic polymorphism of milk proteins in Polish Red Cattle:: a new genetic variant of β-lactoglobulin

Genetic variants of alpha(S1)-, alpha(S2)-, beta- and kappa-casein and of the whey proteins alpha-lactalbumin and beta-lactoglobulin were studied by isoelectric focusing with carrier ampholytes in milk samples of Polish and German Red Cattle. Genotypic frequencies and allelic frequencies were estimated. A new beta-lactoglobulin variant (beta-LG I) with a frequency of 0.014 was demonstrated in Polish Red Cattle by isoelectric focusing and discontinuous gel electrophoresis. For Polish Red Cattle significant differences in the allele frequencies from the results of 1982 and 1969 were found for alpha(S1)- and kappa-casein and beta-lactoglobulin which are mainly the result of using German Red Cattle and Red Danish Dairy Cattle during the Fast to improve milk production.