Thesis is dedicated to studying of economically useful characteristics of cows of Ukrainian black-and-white dairy breed under absorbing crossbreeding with Holstein in the conditions of Polissia. Complex analysis of characteristics under inquiry of the cows on a stud farm (PAF) «Yerchyky» Popilnia district Zhytomyr oblast has been analyzed in 5 groups with different relative inheritance portion on Holstein breed: І – up to 50%; ІІ – 50,1-62,5; ІІІ – 62,6-75,0; IV – 75,1-87,5 and V – 87,6-100%.
It was found, that with an increase in the inheritance rate in cows of an improved breed except the first group was observed a significant increase in body live mass as well as in animal body size under maximal indices in 5th group of animals, except wrist circumference and skin thickness. Most of the correlation coefficients of mass-and-metric indices of holsteinized cows with milk yield for 305 days or a short lactation period (61 of 75, or 81,3%) proved to be reliable, which testifies to a great influence of cows mass-and-metric parameters such as live mass, height at the shoulder, chest circumference, oblique body and hindquarter length, width in hook bones, as well as a complex index – overall dimensions, on cows productivity. The increase in the inheritance portion of Holstein breed has resulted in the increase in blackness indices, as well as in thigh plumpness on the one hand, and in the decrease in the form indices as well as in deep chest on the other hand.
Milk yield productivity of holsteinized cows increased with the increase in the inheritance rate of the improved breed, and as well as under lower butterfat content, also significantly improved the cows adaptivity to machine milking. But the increase in Holstein breed inheritance portion in animal’s genotype was accompanied by the reproductive capacity worsening: the duration of a service period and the period between calving increased.
A single-factor variance analysis has elucidated a reliable power of influence of cows conditional blood share by Holstein breed on the live mass and measurements of body constitution of cows (1,5-19,9%), indices of body constitution (0,4-8,7%), milk productivity (0,3-9,8%), morphologo-functional characteristics of the udder (0,6-8,7%), reproductive capacity (0,8-3,0%) (P<0,05-0,001).
In the absorbing crossbreeding of black-and white breed with Holstein the dynamics of the parameters of cows economic use was characterized by a curvilinear type: they increased in animals with relative Holstein breed inheritance portion from 50 to 62,5 and 75%, and when it increased by more than 75% the parameters worsened. Except the second group cows with a minimal number of cows, it has been found that the duration of a lactation period reduced alongside with an increase of a milk yield per one lactation day, economic use and life. Some additional correlation, but not significant one and in most cases unreliable, has been found between cows economic use and their milk yield during 305 lactation days on the one hand, and the butterfat and protein production on the other hand. A distinct and highly reliable additional correlation relation has been found in cows between the lifetime production indices (except the total duration of a lactation period) on the one hand, and the milk yield, butterfat and protein production on the other hand. Among the studied indices of lifetime use of cows, the relative Holstein breed inheritance portion had the most significant influence on milk yield per one lactation day (9,1%), on economic use (8,0%), life (4,2%), as well as on the period of rearing (3,7%) and the number of lactations per life (4,4%) under highly reliable indices. In the absorbing crossbreeding of black-and white breed with Holstein there is a tendency to the increase in cows pulse frequency and respiratory movements, as well as a higher level of oxidation and renewal processes, of protein and mineral metabolism in blood.
While organising the prognosticating and cows indirect selection with the purpose of raising their milk productivity, milk yield in particular, it is necessary to pay attention to points and exterior and constitutional characteristics. A considerable and highly reliable level of intergroup differentiation of cows of various linear belonging as well as of half-sisters by the bull has been determined on the economically useful characteristics. By means of single-factor variance analysis it has been determined that the paternity has a more significant effect on the economically useful characteristics of cows, than the belonging to the line. From economic point of view under conditions of PAF «Yerchyky», to increase of produce milk it is expedient to breed holsteinized high half-bred first-calf cows of Ukrainian black-and-white dairy breed, as they appeared to be more competitive.
