Productive longevity and lifelong productivity of daughters of Holstein bulls-producers with different variants of kappa-casein genotype

Abstract

Reducing age of economic use of cattle is one of the problems of modern cattle breeding. One of the options for increasing productivity in cattle breeding is breeding for productive longevity, through the search and use of genetic markers. We have selected the genotype of the kappa-casein protein as a genetic marker. If the influence of allelic forms of this gene on milk productivity is well studied, then the question of its interaction with lifelong productivity indicators remains open. The purpose of our research was to determine the effect of the kappa-casein genotype of Holstein bulls on the longevity and lifelong productivity of their daughters. The analysis included the indicators of 1,476 animals with at least one completed lactation. Depending on the linear affiliation and genotype of the kappa-casein gene of the breeding bulls, their daughters were divided into 4 groups. The frequency of occurrence of the CSN3A allele in the studied bulls was 81.91%, the CSN3B allele — 18.09%. The highest frequency of occurrence of the desired CSN3B allele was in bulls of the Reflection Sovering line — 20.83%, which is 3.69% more than in bulls of the Vis Back Ideal line. The analysis of the life expectancy of animals showed that it turned out to be the longest in the daughters of bulls from the Reflection Sovering line (2.46 lactation) and especially with the CSN3B genotype — 2.59 lactation. The greatest lifetime milk yield (18,490 kg) was characterized by the daughters of bulls with the CSN3AB genotype in the Reflection Sovering line. Their superiority over animals from the same lineage, but with the CSN3AA genotype, was 1004 kg, the Vis Back Ideal line with the CSN3AA genotype was 1472 kg and with the CSN3AB genotype was 1343 kg. The highest average milk yield in 1 day of a cow’s life was also in animals of the Reflection Sovering line with the CSN3AB genotype — 9.05 kg.