The influence of individual genetic and paratypic factors on the duration and efficiency of lifetime use of cows of Holstein and Ukrainian Black-and-White dairy breeds

Scientific and production research was carried out in the herd of the private enterprise “Burynske” of the Pidlisniv branch in the Stepaniv territorial community of the Pidlisniv Starostat, which belongs to the company “Ukrlandfarming” for the breeding of Ukrainian Black-and-White dairy and Holstein breeds. Among the paratypic factors, influence of the age at first calving on longevity traits of Holstein cows was studied. Power of influence the age at first calving exerts a reliable (Р < 0.001), but not significant, pressure on life expectancy (14.4 %), productive use (11.9 %), lactation (18.4 %) and economic use coefficient (19.3 %). From the traits of lifetime productivity, the influence power of age at first calving has a 25.6 % effect on milk yield, 21.3 % on milk fat, and 11.8 % on milk yield per day of life (Р < 0.001). From the genetic factors, a relatively higher degree of influence on the phenotypic variability of investigated traits of the duration and efficiency of the lifelong use of Holstein cows is due to paternal origin (heritability). The phenotypic variability of the traits characterizing the life expectancy and use of cows in the test herd according to the strength of father influence differs by insignificant variability, from 26.1 % (by the coefficient of economic use) to 22.4 % (by life expectancy (P < 0.001). Traits of lifetime productivity of Holstein cows occupy the highest proportion of phenotypic variability that is controlled by the parents’ heredity, especially lifetime milk yield (39.7 %), milk fat (38.3 %), milk yield per day of productive use (37.4 %) and lactation (36.8 %) (P < 0.001). The strength of influence of the father's line on longevity traits is not so significant compared to the parents themselves. It occupies a share in the total phenotypic variability of longevity traits in the 12.9–15.4 % range. However, it has a significantly higher effect on lifetime milk yield (22.9 %), lifetime milk fat yield (23.7 %), milk yield per day of productive use (26.7 %) and lactation (25.6 %) (P < 0.001). The influence of the mother's line fades and, in general, for all longevity traits, ranges from 7.4 % in milk yield per day of lactation to 12.4 % in lifetime milk yield. The assessment of Ukrainian Black-and-White dairy cows for determining the influence of the age at first calving on longevity characteristics is similar to the values of Holstein cows. It varies from 12.6 % in terms of the duration of productive use to 18.7 % by coefficient of economic use. The age at the first calving of cows of the Ukrainian Black-and-White dairy breed reliably determines the variability of lifetime milk yield with a strength of 26.4 %, milk fat yield of 27.1 %, and milk yield for one day of life – 11.4 % (Р < 0.05). The power of the father's influence as a factor determining the indicators of his daughters' lifetime use varies from 30.3 %, according to the coefficient of economic use, to 26.6 % in terms of life duration. The power of the father's influence on the development of traits of lifetime productivity of his daughters amounts to 39.1 % in milk yield, 40.4% milk fat yield, 21.5 % milk yield per day of life, 37.7 % productive use, and 39.5 % lactation. Conditional blood of the Holstein breed cows has a slightly more significant effect on longevity traits. The share of its influence differs according to the traits that characterize the duration of use of cows with variability ηх2 = 27.4–29.5 % and lifetime productivity, from ηх2 = 15.3 % (Р < 0.01) according to the lifetime fat content, to ηх2 = 39.4 % based on the trait per day of lactation (Р < 0.001).