Dynamics of live weight of famale calves of holstein cattle breed of different selection depending on the genotype of the father by gene of kappa-casein
Genotyping of 51 Holstein bulls of German and Dutch breeding on the Kappa-casein gene showed that the highest frequency of occurrence of the desirable allele CSN3<sup>B</sup> was recorded in Dutch breeding bulls (21.43%), which is 4.4% higher than its occurrence in German bulls. Most desirable CSN3<sup>BB</sup> genotype of Kappa-casein in the studied population were not identified. Frequency of genotype CSN3<sup>AB</sup> of the gene Kappa-casein bulls from the Netherlands amounted to 42,86%, or 8.8% higher than the German bulls. Influence of the bulls of golshtinsky breed of different origin differing on gene genotypes of a Kappa-casein on dynamics of live mass of their female calves from the birth to the age of the 3rd lactation is studied. It is established that heifers with higher live weight were born from the bulls with genotype CSN3<sup>AB</sup>both the German and Dutch breeding; moreover, the female calves of bulls with genotype CSN3<sup>AA</sup> grow better in the period from 6 to 18 months regardless of origin. The live weight of female calves of bulls of the German selection at the first insemination was the same, in the Dutch selection female calves of bulls with genotype CSN3<sup>AB</sup> of the gene Kappa-casein had advantage of 20.4 kg. The maximum live weight by the age of the 1st lactation had female calves of bulls of German selection with genotype CSN3<sup>AB</sup> - 521 kg, female calves of bulls of Dutch selection-with genotype CSN3<sup>AA</sup> (520.5) kg. - with a genotype of CSN3<sup>AA</sup> (520.5) kg had the maximum live weight. The 3rd lactation cows had the highest live weight with CSN3<sup>AB</sup> genotype - 568.5 kg and 581.3 kg, in groups of the German and Dutch selection, respectively.