GENETIC POTENTIAL FOR MILK AND CHARACTERISTICS OF LACTATION ACTIVITY OF COWS OBTAINED BY PUREBRED BREEDING AND CROSSING

The intensification of dairy farming involves the rational use of cows to obtain the highest possible milk yield for each lactation. In practice, various indicators are used that can qualitatively assess the potential and actual level of productivity of cows. The nature of the course of lactation is a relatively independent, genetically determined trait of cows that can be used for breeding evaluation. The importance of this indicator is confirmed by the positive correlation of the constancy of lactation with productivity. It has been established that each increase in maximum yield by 1 kg leads to an increase in yield per lactation by approximately 200 kg. Therefore, the evaluation of the constancy of lactation of cows is of urgent importance. The aim of the research to study the peculiarities of the lactation activity of first-born cows obtained from bulls of the Montbeliard, Norwegian red and Holstein breeds. Materials and methods of research. The research was conducted in 2019–2022 on the basis of 4 breeding farms of Cherkasy region. It is taken into account 137 heads of Holstein cows, 125 heads of Ukrainian Black- and-White Dairy cows, 127 head of Ukrainian Red-and-White Dairy breeds, 138 head of first-generation crossbreeds of Red-and-White Dairy breed and Montbeliard, 80 head of first-generation crossbreeds of Ukrainian Black- and-White Dairy breed and Norwegian Black-and-White, 138 heads of crossbreds of the second generation. Comparative evaluation of animals according to productive characteristics was carried out within breeding herds, taking into account the structure of the genotype of animals. The genetic potential of animals was determined by the formula of M. Z. Basovsky. The lactation activity of cows of different genotypes was evaluated according to the index of lactation stability according to H. Turner; index of lactation constancy by I. Johanson and A. Hanson; index of completeness of lactation according to V. B. Veselovskii-A. Zhirnov; index of lactation resistance according to J. I. Weller et al.; the lactation decline index according to D. V. Elpatyevsky; index of the shape of the lactation curve according to P. Mahadevan. Biometric processing of experimental data – statistical, correlation and analysis of variance were performed according to the according to generally accepted methods on a PC. Research results. In order to increase the quantitative and qualitative composition of milk, Holstein, Montbeliard and Norwegian Red were used to reproduce breeding stock in the studied farms. The obtained herd is represented by animals of different share of heredity, which is of great interest for determining the genetic potential based on the milk yield of animals of the created genotypes and the degree of its realization depending on the blood share of the original breeds. The genetic potential of the animals of the studied herds is different – approximately 10–15 thousand kg of milk per lactation. Such a difference is due to the potential of breeds kept on farms. Herd in conditions agricultural limited liability company "Agroko" is formed on the basis of the wide use of the gene pool of the Holstein breed. The male in this stage of the level of genetic potential is the highest and 15062 kg with a degree of realization of 73.4%. For the past year 2022, the farm received 11.050 ± 41.6 kg of firstborns in 305 days. In terms public joint-stock company breeding farm subsidiary farm "Zolotoniske" the lowest degree of realization of genetic potential was obtained from purebred Holstein firstborns – 56.5%. Realization of the genetic potential at the level of 64.8–65.0% was obtained from the firstborns of the Ukrainian Red-and-White Dairy breed and animals of conditional blood 1/2URS1/2М. The Holstein breed, having an absolutely high potential for milk production, needs an appropriate level of operating conditions. The genetic potential of the herd in the conditions of the agricultural limited liability company "Lan" dairy farm was increased due to the use of Norwegian Red and Holstein breeds. The degree of realization of the genetic potential of animals was at the level of 60.0–62.2% and had a tendency to decrease as the level of genetic potential increased. The milking consistency index, calculated according to H. Turner, among the studied groups of cows was 7.1–7.6 points. The difference according to the given index was not probable. According to the index of lactation constancy, calculated according to I. Johanson and A. Hanson, which shows the degree of decrease in monthly milk yield, a significant advantage was observed for crossbreeds obtained from breeders of the Montbeliard and Norwegian Red breeds: from 90.9 (among animals of genotypes 1/4URS1/4М1/2H and 1/2UВS1/2NR) to 100.3 ± 0.79 (among animals of the 1/2URS1/2М genotype). The lactation curve of first-born crossbred cows was uniform, without sharp decreases in milk yield. A pronounced decrease in milk yield in the second half of lactation was observed among first-borns of Holstein (from 62.8 ± 2.35 to 87.1 ± 1.03%) and Ukrainian Black-and-White Dairy breeds (from 80.8 ± 1.56 to 89.6 ± 2.01%). The economic evaluation of the use of first-born cows of different breeds and genotypes in experimental farms was carried out taking into account the actual material costs per cow per year (without taking into account the cost of the original products), the costs of primary processing of milk and the sales price of 1 t of milk depending on its quality in terms of fat content and squirrel. Technological approaches to keeping and feeding Holstein cattle in farms are different. In particular, in the conditions of "Agroko": no tethering technology, balanced feeding (highly nutritious feed mixtures balanced in terms of micro and macro elements with nutrition (per cow per year): exchangeable energy 85.500 mJ, energy feed units – 8.465 ECO, dry matter 7.695 kg, digestible protein 812.2 kg, gray fiber – 1.556 kg), careful adherence to technology and prescribed regulations, which gives tangible results. Over 11.000 kg of milk with a fat content of 3.65% and protein content of 3.25% is maintained here for 305 days of lactation. High marketability of milk (94.6%) is ensured by the scheme of drinking young animals, in which full-fledged substitutes are widely used. Modern technologies of procurement, preparation and distribution of fodder with the use of a complex of mineral and vitamin supplements, the organization of veterinary support and the process of reproduction of the herd require additional costs. The total cost price of products obtained from Holstein firstborns under the conditions of "Agroko" is almost twice the cost of obtaining products from Holstein firstborns under "Zolotoniske" conditions. However, thanks to modern genetics, established technology, which enables cattle to realize their genetic potential, and high productivity of animals, they received 20.245 UAH of net profit for each first-born, and the level of profitability was 20.2%. The intensive technology of rearing repair young, calving of the first-born at the age of 21.4 months and their high productivity contribute to reimbursing the costs of their rearing in 2.0 lactations. "Zolotoniske" has implemented a tethered system of keeping, milking in the milk duct, the same type of feeding (with nutrition (per cow per year): exchangeable energy 65.000 mJ, feed energy units – 6.240 ECO, dry matter 5.850 kg, digestible protein 614.3 kg, crude fiber – 1.130 kg) and raising young animals using whole milk without substitutes. Using a large amount of milk for one's own needs leads to a decrease in its marketability. First-borns yielded a profit of UAH 10.800 per head per year. The level of profitability of keeping 1 head was 10.8%. Depending on the level of marketability of milk in farms, milk with a basic fat content of 7.476–7.558 kg was sold from cross-breeds. First of all, to obtain a high marketability of dairy raw materials, they received up to UAH 20.288 net profit per skinned firstborn per year. The use of breeders of the Norwegian red breed made it possible to obtain first-borns, which in terms of productivity and profitability had a short payback period for raising the first-born than their contemporaries of the Ukrainian Black-and-White Dairy breed: among the first-born UВS – 4.0 lactations, the first-born of the genotype 1/2UВS1/2NR – 2.1 lactations, genotype 1/4UВS3/4NR – 1.9 lactations. Conclusions. The genetic potential of cows is different and depends primarily on the potential of breeding bulls that were used in herds. While the degree of realization of the genetic potential depended primarily on the technological conditions in which the animals were kept. The lactation curve of first-born cows obtained from breeders of the Montbeliard and Norwegian Red breeds was uniform, without sharp decreases in milk yield. In first-borns obtained from Holstein breeders, the decrease in monthly milk yield occurred much faster. First-born cows with a share of heredity of the Montbeliard and Norwegian Red breeds received milk raw materials with a fat and protein content that exceeded the basic values, which contributed to the increase in the profitability of keeping these groups of animals. Breeds that have been reproduced using Holstein genetics in recent years began to require the provision of a certain technological level in the conditions of maintenance and feeding. Neglecting these requirements significantly reduces the profitability of the industry. Prospects for further research include: assessment of the nature of inheritance of milk productivity traits, that will determine the justified direction of further rational selection; establishing the duration of use of brood stock and the main reasons for their disposal, which will determine the lifetime effectiveness of the use of animals.