β-lactoglobulin genetic variants in Serbian Holstein-Friesian dairy cattle and their association with yield and quality of milk

In 765 Holstein-Friesian cows, the following ratios of beta-lactoglobulin genotypes were found: 0.23 AA, 0.58 AB and 0.19 BB. The cows of AA genotype yielded more milk and milk fat than cows of genotype AB and BB. Cows with beta-lactoglobulin AA and AB genotypes yielded respectively 224 and 190 kg more milk per lactation when compared to cows of BB genotype but the differences were not significant. There were significant (P<0.01) differences in the yield of milk protein produced by cows of the AB, BB and AA genotypes. Milk from cows of genotype AA and BB contained a slightly higher percentage of milk fat when compared to milk of cows with lactoglobulin genotype AB. Percentage of milk protein was higher in the milk of cows of genotype BB and AB. beta-lactoglobulin genotype had a significant impact on the yield of milk protein (P<0.01), but had no influence on the other observed properties of milk.