The developed methodical approaches to improvement of black-and-white cattle in the western region of Ukraine presented in the dissertation. They formulated based on population-genetic analysis of the parameters of ontogenetic development, milk productivity, chemical composition of milk, morphological and functional properties of the udder, reproductive ability, morphological and biochemical parameters of blood, indicators of natural resistance, duration of economic use and the influence of various factors on the formation of milk cow productivity. The optimal parameters of the stage-by-stage selection of repair heifers and first-born cows by linear growth are theoretically substantiated and practically developed. The parameters of selection of animals by live weight and indicators of reproduction ability are specified. Selection tests for selection of animals according to a set of characteristics are recommended. A method of optimizing selection and a way of forming high-value genotypes in dairy cattle populations has been developed. The expediency and the prospect of use in selection work with black-and-white cattle developed parameters of animal selection has been proved.
The formation of milk productivity of the cows was influenced by the intensity of their weight and linear growth during the period of growth, as well as the live weight after the first, second and third calving and the size of the body of the cows after first calving. The correlative variability of the live weight of animals during the period of growth and feeding was 0,018-0,604, the body measurements during the period of cultivation and fertilization – 0,170-0,458, live weight after the first, second and third palates, and infusion – 0,413-0,551, the body measurements of the fetuses and infusion – 0,297-0,478. The most significant impact on the future dairy productivity of the cows was made by their live weight at the age of 18 months and after the first calving, high-altitude measures, the circumference of the chest on the shoulder blades, and the skid length of the trunk, and the smallest - the live weight at birth and the circumference of the heel.
The influence of the lines on yield of milk, depending of the farm and lactation, was 9,6-39,0, the fat content of milk – 2,9-32,2 and the yield of milk fat – 9,7-38,8 %, the strength father's influence – 6,9-49,3; 7,4-68,4 and 6,8-51,0 % respectively. The coefficients of inheritance on the path along the "mother-daughter", depending of the farm and lactation, were within 0,034-0,618, fatty milk – within 0,032-0,762.
The highest yield of milk were in cows, which age of the first fertile insemination amounted to 487-547 days with a live weight of 400 kg, service life period – 120 and more, for dry period – 45-54 and inter calving – 430 days or more. Between the parameters of reproductive capacity and milk yield of cows, different strength and direction of connection are established. The strength of the duration of the service-period on milk yield, the fat content of milk and the yield of milk fat, depending on the farm and lactation, was 9,1-29,5, respectively; 7,0-28,2 and 8,2-29,7, the duration of the interotional period for the same indicators – 9,2-30,9; 9,1-29,5 and 8,8-31,8 and the dry period – 9,3-23,4; 9,3-23,2 and 9,2-23,8 %.
Profitability of milk production by cows, which calved first time, selected by the method developed by us, was higher by 8,4-23,2 % than that of animals of other groups, and net profit per cow a year from them received more by 2473,86-6776,64 UAH. Using the recommended animal selection parameters for linear growth at 18 months of age, the indicated indices, as compared to those that do not correspond to these parameters, were higher by 16,6 % and 4805,19 UAH in accordance.
