Genetic polymorphism of bovine milk proteins in Holstein-Friesian and Fleckvieh breeds exploited in Spain

Abstract

Genetic variants of bovine milk proteins αs1-, αs2-, β-, κ-casein (-CN), and β-lactoglobulin (β-LG), were studied by isoelectric focusing using PhastSystem in milk samples of 429 Holstein-Friesian, and 174 Fleckvieh (German Simmental) breeds exploited in Spain. Genotype frequencies and allele frequencies were estimated. Variant αs1-CNA was present in the Holstein-Friesian, and was absent in Fleckvieh breed, while the variants β-CN C, αs2-CN D, and κ-CN C were only found in Fleckvieh breed. Significant differences in allele frequencies between the 2 breeds were observed at the αs1-, β-and κ-CN loci. Only the frequencies of the αs2-CN, and β-LG variants did not differ. The most common casein haplo-types were BA2A (αs1-, β- and κ-CN respectively) in the 2 breeds studied. These results were compared with those obtained in Holstein-Friesian and Fleckvieh breeds from the literature.