association of genetic variants ofb-lactoglobulin gene with milk production in a herd and a superior family of holstein cattle

polymorphism of the b-lactoglobulin (b-lg) gene in 101 cows belonging to the holstein herd and a superior cow, producing more than 150 kg milk/day, together with four offsprings was investigated by the polymerase chain reaction-restriction fragment length polymorphism (pcr-rflp) method. in the holstein herd, the alleles a and b of the b-lg gene had frequencies of 0.53 and 0.47, respectively. the genotypes aa, ab and bb of the b-lg gene were estimated to have frequencies of 0.257, 0.544 and 0.198, respectively. genotypes were distributed according to the hardy-weinberg equilibrium. results indicated that the b-lg genotypes significantly affected (p< 0.01) milk yield (genotype aa being more effective than genotype bb). the superior cow and her progenies were all heterozygotes (ab).