In the Republic of Belarus, the main breed for dairy and pedigree production is Holstein dairy cattle of domestic selection, the productivity potential of which is at the level of 12-14 thousand kg of milk per lactation. However, the experience of many countries shows that as a result of intensive selection of animals of this breed to increase milk productivity, reproductive performance and health have significantly deteriorated. This explains the increased interest in the use of alternative competitive breeds in milk production, one of which is the red breed of dairy cattle. In the course of the work we studied the current state and assessed the prospects for further work on the creation of the Belarusian red dairy cattle breed. Thus, as a result of the implementation of the following stages of work on the creation of the domestic breed, the number of cows of the red dairy cattle selection herds at the basic farms in 2030 will amount to 2800 heads with productivity of 7500 kg of milk per lactation, which will allow for all necessary activities on its approbation.

   This paper contains the materials of scientific work, as a result of which an optimal statistical model for assessing the breeding value by BLUP (AM) method for milk productivity traits of Holstein cattle of Belarusian selection was developed. A comparative analysis of the distribution of milk productivity traits by gradations of environmental factors was carried out, the significance of their influence on the variability of traits in the population of breeding animals was determined. This model will be used to calculate the selection and genetic parameters (heritability, variability (variances)) and breeding value of milk productivity traits using the BLUP and GBLUP methods for Holstein cattle in the Republic of Belarus.

   The quality and quantity of viable sperm cells influence both fertilization and the overall development of the embryo.

   In this regard, the procedure of selection and preparation of sperm for in vitro fertilization, aimed at improving its quantitative and qualitative characteristics, is an integral part of assisted reproductive technologies.

   This paper contains the results of research aimed at studying the effect of various concentrations of Percoll in the preparation of a step density gradient on the isolation of the most viable sperm cell fraction during capacitation of bull semen. In the process of using single-, double- and triple-layer density gradient columns in various concentrations, the effectiveness of single-layer 90% Percoll was established for the main indicators of sperm motility.

   Implementation of effective selection-genetic and biological methods in the selection process contributes to the improvement of native breeds and lines of pigs. The use of DNA markers is a promising method for studying traits that have low heritability and sex-limited manifestations. This paper contains the results of research in which the genetic information of prolactin receptor (PRLR), follicle-stimulating hormone (FSHB) genes was studied in order to establish genotypes preferred for selection, determining the reproductive traits of pigs of various breeds bred at breeding enterprises of the Republic of Belarus, and their use in selection and breeding work. Genotyping of pigs for the studied genes was carried out using the PCR-RFLP method. Polymorphism of PRLR, FSNB genes was observed in all breeding animals belonging to five breeds.

   The study of blood composition is an important stage of scientific work, as it characterizes the metabolic pathway, the state of health of animals and their ability to adapt to housing conditions.

   This paper contains the materials of research aimed at studying hematological and biochemical indicators of blood of Aberdeen-Angus and Charolais cows and suckling calves in the winter stall-feeding period.

   It was found that in the winter stall-feeding period, hematological indicators of the animals under study were mainly within the physiological range, but the average content of platelets in the blood was below the minimum value and amounted to 171.6×109/l in Aberdeen-Angus cows and 197.22×109/l in Charolais cows, while the norm was 260-700×109/l.

   Drugs for stimulation of estrus in animals should be relatively harmless, i.e. rapidly excreted from the body, have a high therapeutic effect and be economically available. All these properties are possessed by phytogenic drugs, one of which is the synthetic steroid hormone epibrassinolide. The research examined its effect on dominant follicle atresia to initiate a new wave of ovarian follicle growth in donor cows and subsequent gonadotropic induction of superovulation. It was found that the inclusion of epibrassinolide in the superovulation induction regimen for donor cows significantly increased the yield of usable embryos by 0.5 with a simultaneous decrease of 0.17 cells unsuitable for embryo transplantation. Fertilization after using the phytohormone increased by an average of 3.0 percentage points. In this regard, it is recommended to include epibrassinolide solution in the hormonal treatment regimen for donor cows to induce dominant follicle atresia and initiate a new wave of follicle growth and subsequently increase the yield of embryos suitable for transplantation.

   Currently, there is a need to improve the regimens for inducing superovulation in cows in order to increase the number of animals responding to the administered hormonal drugs and to obtain embryonic material from them suitable for transplantation. However, preparations of follicle-stimulating hormone used to induce multiple ovulation are not always capable of causing a response in the animal to the administered gonadotropin. Therefore, in embryo transplantation technology, along with gonadotropins it is necessary to use drugs that have general strengthening and immunomodulatory effects, acting on the ovaries of animals indirectly. The paper contains the results of research aimed at studying the effect of immunomodulatory drugs meloxicam and dexamethasone in superovulation induction regimens for donor cows. It has been established that the use of solutions of these drugs in the hormonal treatment regimens for donor cows during the induction of polyovulation does not adversely affect the morphological and qualitative composition of intact cattle embryos, allows obtaining more embryos suitable for transplantation and reducing the number of rejected cells.

   This paper contains the results of a scientific work aimed at studying the influence of different concentrations of the delipidating agent forskolin as part of protective media on the regenerative capacity of frozen-thawed cattle embryos.

   The studies revealed an increase in cryoresistance of frozen-thawed embryos of donor cows when using protective media based on glycerol, ethylene glycol and dimethyl sulfoxide with the introduction of the lipolysis stimulator forskolin at a concentration of 10 μM, which allows for minimal deterioration in the quality of the biomaterial (0.36-0.73 points) and an increase in the yield of embryos suitable for transplantation.

   Nowadays, the problem of conservation of genetic resources of domestic animals has become one of the most urgent in the world. In this regard, research aimed at monitoring genetic processes in small-numbered populations, necessary to identify reserves for increasing genetic diversity, are of scientific and practical importance for the conservation and restoration of the endangered and unique gene pool of horse breeds bred in Belarus. In the course of the research, the allele pool of small-numbered horse breeds of the republic (Belarusian draft and Russian heavy draft breeds, Polesye population of draft horses) has been studied. It has been established that all of them are characterized by a high level of genetic diversity. The total number of alleles for 17 STR loci ranges from 123 (horses of Polesye population) to 149 (Belarusian draft breed), which is quite a high figure. In each of the breeds, “private” alleles have been identified. A rare (q < 0.05), so-called “short” allele B, characteristic of riding breeds, has been identified in horses of the Belarusian draft and Polesye populations. The obtained results allowed us to estimate genetic polymorphism in the domestic population of small-numbered breeds of horses, providing the efficiency of its use when making plans for pedigree selection.

   A mandatory element of selection activities is the systematic progeny testing of stud rams, which allows using for reproduction those animals that are guaranteed to produce offspring of the best quality depending on the selection direction chosen.

   The paper contains the results of research aimed at evaluating semifine-wool sheep breeds of Belarusian selection, using improved approaches to this process.

   In the course of the work, the requirements for the most rational implementation of zootechnical measures for evaluation of pedigree sheep, containing the list of controlled parameters for semifine-wool sheep breeding, and for their productivity indicators have been substantiated. The introduction of improved zootechnical rules will ensure increased accuracy and reliability of sheep herd evaluation, will allow predicting the quality of an individual based on its phenotype at an early age, will increase the cost of marketable pedigree young stock by 8-12 % and will reduce the costs of keeping low-productive
comparables by 10-15 %.

   To obtain competitive products in livestock breeding, along with the use of traditional methods, it is also necessary to use the latest achievements in the field of genetics, including DNA marking of quantitative and qualitative traits of productivity and DNA diagnostics of hereditary and infectious diseases.

   In this regard, the aim of the work, the results of which are presented in this paper, was to determine the genetic structure of Duroc pigs using the marker genes RYR1, PRLR, ECR F18/FUT1, IGF2, MUC4, H-FABP (allele systems H and D).

   Thus, it was found that the frequency of occurrence of preferred genotypes for RYR1NN, IGF2QQ and MUC4CC genes was 100 %. The desired PRLRАА, H-FABPHH and H-FABPdd genotypes were found in pigs with a frequency of 21.7-25.7 %, 57.1-87 and 20-60.9 %, respectively. The association of genes with animal productivity indicators was studied.

   The paper presents an analysis of population genetic parameters of Duroc pigs bred at SE “ZhodinoAgroPlemElita”, using microsatellite DNA data. 68 alleles were identified. The average number of alleles per locus amounted to 4.53. The average index of polymorphism level (Ae) was 2.41. The actual heterozygosity index in Duroc pigs ranged from 0.029 (S0355) to 0.875 (S0005). The fixation index value for 15 MS DNA loci was -0.016. In the studied population, 8 of 15 MS DNA loci were in a state of genetic equilibrium. The accuracy of assignment of the studied animals to “their” population was 100 %.

   In modern dairy cattle breeding, milk flow rate is of great importance for evaluation and selection of animals suitable for robotic milking under conditions of industrial milk production technologies. Using methods of correlation analysis, it is possible to determine the degree of relationship between milk flow and various morphofunctional properties of the udder and subsequently use the obtained result in the selection process.

   The paper contains the materials of research aimed at studying the correlations between the main indicators of milk flow rate in red dairy cows.

   In the course of research, the creation of a phenotypic database on milk flow rate indicators of red dairy cattle was initiated. Correlations between the main indicators of milk flow rate of cows were studied. Based on the data obtained, it was found that daily milk yield and lactation number had a positive effect on milk flow rate. Increase in daily milk yield by 1 kg is associated with an increase in milk flow rate by 0.068 kg/min (p < 0.001).

   Feed protein deficiency remains one of the main problems in farm animal feeding, which cannot be solved without sufficient knowledge of the processes of feed protein breakdown and microbial protein synthesis in the rumen.

   This is of particular importance in the development of scientifically based animal feeding, so the purpose of the scientific work was to determine the effect of feeding young cattle synthetic nitrogenous non-protein substances (diammonium phosphate and urea phosphate) on protein breakdown in the rumen and digestibility of nutrients of diets.

   Studies have shown that in compound feed containing the studied substances, the breakdown of protein, VFA in rumen fluid, the number of ciliates, total and protein nitrogen increases, and the accumulation of ammonia in rumen fluid decreases. The digestibility of nutrients and fiber in animals consuming 10% diammonium phosphate and urea phosphate also increased compared to the control group.

   The paper presents a comprehensive comparative analysis of the results of experiments on feeding phytoncidal coniferous feed additive to down-calving and freshly calved cows, performed in different seasons of the year. It was found that the productivity of cows of all groups was at the same level, but a smoother “lactation curve” was observed in animals of the experimental groups that consumed the studied additive, compared to the control, which increased the number of cows from those unfertilized after the first insemination scheme that showed full synchronous estrus and were successfully inseminated the second time. Milk productivity of cows of the I experimental group was higher by 3.1 kg and the increase in milk yield in relation to the beginning of the experiment was higher than in the control group by 2.5 kg. Milk quality was higher in animals of the experimental group: fat - by 0,36-0,07 %, protein - by 0,05-0,08 %. The economic efficiency per day in terms of productivity was 19.74 rubles.

   One of the problems on the way to high productivity and productive longevity of goats is inadequate feeding, which leads to metabolic disorders, the birth of weak and non-viable young animals, etc. To increase efficiency and reduce the cost of diets, non-traditional feedstuffs are often used, in particular coniferous mass, the vitamin and mineral composition of which has a favorable effect on animal health, and also allows to use expensive premixes in smaller quantities. In the course of research it was found that feeding conifer energy supplement contributed to the intensification of metabolic processes in the body of goats. The introduction of the studied supplement into the diet of goats during the transition period increased milk productivity during the 1^st month of lactation by 10.81-22.51 %, increased the content of fat and protein in milk by 2.80-5.40 % and 1.88-3.14 %, respectively, as well as reduced feed costs for obtaining products by 12.5 and 15.63 %.

   At present, there is an acute shortage of protein in cow diets, which is most often compensated by the use of expensive high-protein supplements (oilcakes and meal). At the same time, the expansion of grain legume crops and perennial legume grasses provides the cheapest protein. The paper contains the results of research on the efficiency of preserved alfalfa fodder (haylage, silage) in the diets of dairy cows. It was established that the use of alfalfa silage in the diet of dairy cows had a complex positive effect on its nutritional value, physiological state of animals, milk productivity and economic efficiency of milk production. The data of studies of biochemical parameters of blood serum and milk quality in experimental animals allow us to conclude that it is safe to use alfalfa silage in feeding dairy cows. The use of the proposed variant of feeding cows will reduce the cost of daily ration per 1 kg of milk with basic fat content by 12.1 %.

   In order to develop beef production in the Republic of Belarus it is necessary to reduce dependence on imported protein feed additives. In this regard, the use of oil cake – an available local raw material rich in energy, high-quality protein and polyunsaturated fatty acids – is a promising trend that can positively affect the productivity of cattle and the economy of the industry. The paper presents the materials of research on the influence of oilseed flax cake feeding on digestive processes of young cattle. It was found that feeding of oilseed flax cake in the amount of 20 % by weight of compound feed instead of sunflower meal intensified physiological and biochemical processes in the rumen, had a positive effect on hematological indicators of animals, and also contributed to an increase in nitrogen deposition in the body of animals by 28.0 %.

   A wide range of fodder resources is used in animal feeding. Highly nutritious early green fodder and high-quality forage can be obtained from triticale, which is characterized by high yield and product quality, increased resistance to diseases and adverse soil and climatic conditions. The paper contains the results of research aimed at studying the nutritional yield of green mass of green-mown triticale per unit area at different harvesting times. As a result of research, it was found that the control variety Borets was early maturing, and varieties E 4/20 and E 12/20 were late maturing, which allows extending the terms of their use in the green conveyor for 7-9 days. Experimental varieties were superior to the control variety Borets in terms of nutritional yield of green mass per unit area during the booting, heading and harvesting stages.

   The results of numerous scientific studies and practical experience show that it is impossible to obtain high productivity and maintain the health of animals without providing them with microelements in the required amount and available form. Metal nanoparticles have higher bioavailability because they have new characteristics: higher specific surface area, surface activity, catalytic efficiency and adsorption capacity.

   The purpose of the research, the results of which are presented in this paper, was to study the effectiveness of feed additives containing nanozinc and nanoselenium in the diets of young fattening pigs.

   It was found that the use of the studied feed additives contributed to an increase in gross live weight gain for the whole period of the experiment by 4.7 and 11.3% and additional profit of 0.21 and 0.49 rubles per 1 kg of live weight, respectively.

   One of the promising methods to solve the problem of reducing the content of cesium-137 in animal diets is the development of complex organomineral adsorbents. This paper contains the results of studying the effect of adsorbent produced on the basis of activated coal from peat at the Institute of Nature Management of the National Academy of Sciences of Belarus on the transfer of this radionuclide from feed to the body of cattle in the territory of radioactive contamination of Belarus. It has been established that the studied adsorbent, introduced into the diets of fattening steers and lactating cows at a dose of 40 g/head, is an additive that reduces the accumulation of cesium-137. With an average total activity of the daily diet of cows of 3.022 ± 0.749 kBq/day, from the 5^th to the 20^th day of using the composite sorbent, a decrease in the content of this radionuclide in the milk of cows from 1.7 to 4.5 times is observed. At the same time, the transfer of cesium-137 into milk in the group with this sorbent is 61 % less.

   The paper deals with the efficiency of using dried living yeast culture Saccharomyces boulardii in diets of dairy cows. The research was carried out on dairy cows in the conditions of dairy farm of the branch of JSC “BELAZ” APC “Pervomaysky” of Smolevichi district of Minsk region, which were fed different doses of yeast supplement in the amount of 3, 5, 10, 15 and 20 g/head/day. The results of scientific and economic experience showed that the supplement contributed to the increase in milk yield, improvement of milk quality (fat, protein) and ruminal digestion, allowing to increase economic efficiency due to additional profit from the increase in milk productivity.

   The use of non-traditional forages is one of the available ways to strengthen the fodder base of livestock breeding. One of the promising components of animal diets is vinasse, a by-product of yeast production, which is used as an additional component in fodder production. The paper contains the results of studying the effect of this feed additive on productivity and hematological parameters of young cattle. Studies showed that vinasse included in the diet had a positive effect on the blood parameters of animals. The studied additive also contributed to an increase in average daily gain, a decrease in the cost of production by 11.6 and 9.9 %, and an additional profit of 52.8 and 46.1 rubles per animal during the experimental period.