Kappa-Casein(csn3) Gene Allelicpolymorphismin Black-Pied Seed Bulls

Abstract

The leading role in increasing dairy cow performance is played by seed bulls; 90-96% of the herd genetic progress depends on them. This is due to the fact that for this group of animals the genetic evaluation of the individuals used is reliably carried out and the worst andmoderate animals in terms of breeding qualities are most intensively culled from reproduction. Therefore, when pure-breeding and choosing seed bulls for the herd, the information on the genotypes of milk protein alleles, in particular the kappa-casein gene (CSN3), should be taken into account. The experimental studies were carried out in the livestock breeding operation of the AO “Plempredpriyatiye Barnaulskoye”. It has been found that the prevailing genotype in the Black Pied seed bulls is the CSNAA genotype; its frequency reaches 0.578; the alternative CSN3ВB genotype is found in single ani-mals. The allele A accounts for 0.756, and B -0.245. Among the Black Pied seed bulls, no statistically significant shift in genetic equilibrium was found for any of the three genotypes of kappa-casein gene locus. The studies of the polymorphism of the kappa-casein gene in the seed bulls taking into account their line belonging have revealed that only in the Vis Back Ideal line there is a BB genotype asso-ciated with the processing properties of milk, while it lacks in the bulls of the Montwick Chieftain and Reflection Sover-ing lines. The genotype CSN3AA prevails in the seed bulls of all lines; the highest frequency occurs in the Reflection Sovering line -0.625, and the lowest in the Vis Back Ideal line -0.542. The differences in the allele frequencies be-tween the lines, apparently, are associated with the peculi-arities of the origin of the seed bulls and the direction of the selective breeding work with the Black Pied cattle.