The article presents the materials of scientific work, the purpose of which was to study the sperm motility of non-transgenic and rLF gene transgenic males of F4-5 generation, taking into account the kinematic parameters of sperm motility. The studies showed that all the billy goats used in the experiment were characterized by biologically complete sperm with fast-moving and linearly progressive sex gametes with a predicted high fertilizing ability. Indicators of sperm motility and kinematics both in transgenic and in common billy goats had the same level of values, which means that the presence of a foreign gene in the organism of transgenic males of F4-5 generation does not affect their reproductive functions.

Exposure of sexual gametes to low-intensity optical radiation is considered to be one of the biosafe methods of increasing the semen fertilizing capacity. We studied the effect of laser irradiation of the red spectrum region on physicochemical parameters (pH and osmosis) of breeding boars’ semen. The studies were conducted on four groups (control and three experimental groups) of animals of different breeds aged 18-24 months. It was found that when diluted semen of breeding boars was exposed to a semiconductor low-intensity red laser with a wavelength of 620-760 nm and a power density of 3 mW/cm2 for 10-30 minutes, the pH level ranged from 7.14 to 7.40 after three days of storage, which corresponded to the norm for the use of ejaculate in artificial insemination. Osmotic pressure increased with increasing storage time of diluted ejaculates and after 72 hours was within acceptable values ranging from 314.76 to 316.85 mOsm/L. 

It is now possible to identify genes directly or indirectly associated with economically useful traits. Identification of preferred variants of such genes in pigs from the point of view of selection allows selection directly at the DNA level. The aim of the scientific work was to establish interrelationships of quantitative traits of productivity of maternal breed pigs and their lines determined according to microsatellites and genetic markers of production traits. This research found that the genetic distances between paternal and maternal lines of boars of maternal breeds differed significantly. Thus, in boars of paternal genotypes, genetic distances between lines were shorter by 0.09. Animals of paternal genotypes were characterized by genetic similarity. The selection work carried out with these genotypes to improve meat-and-fattening traits influenced the frequency of occurrence of the desired IGF-2 gene allele A responsible for fattening traits, which was significantly higher in them (by 0.33 shares per unit) than in animals of maternal genotypes. 

In order to solve the problem of preservation and further development of the Belarusian Large White breed at the breeding enterprises of the republic, it is necessary to evaluate pigs at the genome level, i.e. according to the true genetic potential. In the course of research, the rhyanodine receptor (RYR 1), estrogen receptor (ESR), HFABP gene, insulin-like growth factor 2 (IGF-2) were studied as genetic markers of production traits of Belarusian Large White pigs of practical interest. In the process of genetic testing and establishing the frequency of occurrence of genotypes and alleles of genetic markers of production traits in the genome of pigs of Belarusian Large White breed, the lines were differentiated into maternal and paternal ones. Based on the research conducted, a comprehensive program has been developed for the improvement and use of breeding herds of pigs of Belarusian Large White breed at pig breeding enterprises of the republic, which will make it possible to create the uniform system of breeding and use of pedigree animals at breeding enterprises, to increase the efficiency of using lines and related groups when improving and using breeding herds. 

In modern dairy and beef cattle breeding, embryo transfer allows for the accelerated breeding of animals with high productivity rates, which provides vast opportunities in breeding and reproduction of cattle to improve the efficiency of breeding work. This technology has been worked on for more than a decade, but still a number of technological and biological problems remain unsolved. The aim of our research was to study the effect of various paratypical factors on embryo survival rate. The work was carried out during 2019-2020 in JSC “Gastellovskoe”, Minsk district. Holstein lactating mature cows and heifers aged 11-12 months were used as donors. According to the results of the research, 249 pregnant recipients were identified out of 476 embryo transfers, which amounted to 52.3%. Embryo transfer in winter decreased the pregnancy rate by 11.0 p.p., 4.9 p.p. and 9.2 p.p. compared to spring, summer and fall, respectively. September was the most effective month, with a pregnancy rate of 73.9%. 

One of the objectives of embryo transfer is to reproduce the offspring of outstanding parents in order to select among them and subsequently reproduce offspring of even higher quality. The presented material contains the results of research on the influence of the category of donor (cow or heifer) and stud bull on the efficiency of embryo transfer. It was found that the survival rate of embryos obtained from cows and heifers was practically the same and amounted to 51.7 and 50%, respectively. In contrast to cows, in which the pregnancy rate did not depend on the side of transfer, embryo transfer in heifers was more effective when transferred to the right horn compared to the left one by 16.6 p.p. The survival rate of embryos at the morula stage from cows was 4.7 p.p. higher when transferred to the left horn, while in heifers it was 14.7 p.p. higher in the right horn. The survival rate of blastocysts obtained from both cows and heifers was higher when transferred to the right horn. The survival rate of embryos decreased as their quality declined, regardless of either the donor or the horn into which they were transferred. Overall, pregnancy rates ranged from 20 to 80% depending on the bull. There was quite a high variability in the survival rate of embryos from donors inseminated by the same bulls. 

ICSI (intracytoplasmic sperm injection) is an important step in assisted reproductive technology to overcome the causes of infertility. However, the effectiveness of this technique on farm animals, particularly cows, remains low. In this regard, the study of developmental potency of cow oocytes after the ICSI procedure is relevant. Studies have revealed that cell viability after sperm microinjection procedure is ensured by injection of sperm directly into the oolemma of the oocyte with the position of the first polar body at 6 or 12 o’clock. Aspiration into the microneedle is performed with the head forward, hence transportation to the oolemma after perforation of the membrane is performed with the tail part of the male gamete. The bending angle of the micropipette in its distal part should be 25-30°. A total of 6 dividing cells were obtained from 52 oocytes in the experiment, representing 11.5% of all successful microinjections. Compliance with the specified technical parameters of the procedure of intracytoplasmic sperm injection allows preserving the viability of 19.2% of the operated oocytes with the potency for fertilization and subsequent division. 

The article contains the materials of research, the purpose of which was to develop biometric models and to carry out the calculation of selection-genetic parameters of selectable traits of breeding pig population. Based on variance analysis of systemic environmental factors, optimal forecast equations (biometric models) for the development of selectable traits of breeding pigs were elaborated. In the course of variance analysis of fixed factors of reproductive traits of maternal breed sows, it was found that the average values of all traits in the context of factors had significant differences in all studied variants of models. On the basis of the developed optimal statistical models describing the development of selectable traits, the components of the total variance, as well as the inherited (additive) genetic part of the total phenotypic variability - inheritance coefficients - were determined. 

Ensuring the normal manifestation of reproductive function in animals is an urgent problem. One of the ways of its solution is the use of quantum photostimulation, which contributes to the improvement of cellular immunity of the organism, resulting in increased productivity, normalization of the function of reproductive tract organs, spermatogenesis and ovogenesis, increase in the quality and quantity of sexual gametes of male and female, improved morphological composition and survival rate of embryos. The article contains the materials of research, the purpose of which was to study the influence of light quanta of blue and red visible spectrum on the efficiency of embryo transfer in cattle. It has been established that exposure of donor cows to light quanta of blue and red visible spectrum causes activation of oogenesis processes in the organism of exposed animals and improves the embryo material obtained, increasing the viability of frozen-thawed embryos by 11.1 p.p., and the survival rate of freshly obtained and depreserved embryos by 2.8 and 12.5 p. p.p., respectively.

One of the most important stages of practical application of embryo transplantation is the possibility of long-term preservation of embryos outside the body in deepfrozen state in order to use them most effectively to obtain offspring from high-value animals in cattle selection and breeding programs. In this regard, the use of biologically active compounds with lipolytic action in embryo transplantation is of interest in the context of studying the possibility of reducing the influence of negative environmental factors and the impact of low temperatures on biomaterial while it is outside the body. The article presents the materials of the study of the effect of L-carnitine as part of the embryo extraction medium on the viability and survival of frozen-thawed bovine embryos. It was found that the use of L-carnitine in the washout medium did not lead to significant changes in the morphology of embryos after thawing compared to the control group. When adding the lipolytic substance L-carnitine to the medium for extracting embryos from donor cows, there was a tendency of qualitative improvement of frozen-thawed embryos and an increase in the efficiency of transfer of defrosted embryo material.

The potential of a riding horse can be determined by its athletic performance. In general, horse performance belongs to the traits of complex polygenic nature and has a fairly low inheritance coefficient (0.11-0.13), which prompts the search for the most effective (in economic and breeding terms) ways of early prediction of this trait. This paper contains the results of evaluation of performance of riding horses depending on the presence of certain alleles in 17 microsatellite DNA loci. Horses with alleles K (AHT5), Q (ASB2), J (ASB23), I (CA425), M (CA425), H (HMS2), M (HMS2), J (HMS3) in the corresponding microsatellite loci showed the best athletic performance. The revealed peculiarities are recommended to be used for predicting the athletic performance of horses at an early age, replacement selection in the absence of the possibility of conducting factory tests in farms, culling and sale of unpromising for breeding and sport young stock.

The aim of the presented work was to establish the relationship between the index assessment of animals and the measurement values of the selected traits included in the index assessment. The research was conducted on the population of pigs of two planned breeds, Landrace and Yorkshire, having a sufficient number of animals with measured values of selected traits of their own productivity and available in the state information system in the field of pedigree pig breeding as of December 31, 2022 in the number of 2,915 main sows and 76 main stud boars. It was found that all selected traits included in the complex indices of sows and stud boars had positive correlation values of medium and high degree: for sows: average daily gain – 0.915-0.835, prolificacy – 0.179-0.487, litter weight at weaning – 0.482-0.377; for stud boars: backfat thickness – - 0.297 – ( - 0.225) for Landrace and Yorkshire breeds, respectively, average daily gain - 0.999, which indicates the possibility of using the developed indices in selection and breeding work.

Forecasting future animal productivity is one of the main factors determining the pace of the selection process. The index method is the most common method for assessing the breeding value of animals, as selection by breeding indices provides for the maximization of complex evaluation. The article presents the results of research on improvement of breeding and production abilities of pigs depending on the methods of selection and matching. It was found that the prolificacy rate, milk yielding capacity, number of piglets and litter weight at weaning at 35 days in sows exceeded the intrabreed indicators by 1.6-16.9%, suggesting high reproductive ability of animals.

Obtaining high productivity of farm animals is largely determined by the level and balance of feeding, both in the pre- and post-weaning periods. These periods in the life of calves are the most effective with respect to the formation of their type of digestion and metabolism, which necessarily manifests itself in the desired type of their constitution. The purpose of the conducted scientific work was to study the physiological state and productivity of calves in the post-weaning period depending on the type of corn grain fed during the pre-weaning period. It was found that feeding animals in the pre-weaning period with mixed fodders containing whole and crushed corn grain in the amount of 30 % by weight allowed in the post-weaning period to obtain average daily gains at the level of 888 and 871 g or by 5.5 and 3.5 % above the control value with a decrease in the cost of gain by 4.8 and 2.7%.

To fully unleash the genetic potential of meat productivity of cattle, a detailed study of all major factors affecting the production abilities of animals is required, one of which is energy consumption. Energy rationing is the most important condition of nutrition, which determines the level of animal productivity. The paper contains the materials of research aimed at determining the productivity of young cattle of 13-18 months of age raised for meat at different levels of energy nutrition. It was found that feeding diets with high level of metabolizable energy and optimum rate of protein breakdown to young bulls made it possible to obtain 1103-1100 g of body weight gain. Raising young bulls on the studied diets had a positive effect on slaughter traits and made it possible to obtain a slaughter yield of 53.6-54.6 %.

Sunflower and soybean meals, which contain a wide range of minerals, amino acids and proteins, are used as a basis for the preparation of compound feed. However, they are imported from abroad, which significantly increases the cost of manufactured products and reduces the efficiency of the livestock industry. With that in mind, it is reasonable to look for alternative sources of protein among available local raw materials, in particular, oil cake. The article contains the materials of research, the purpose of which was to study the influence of different levels of oil flax cake on physiological state of young cattle, digestibility and utilization of nutrients. In the course of the research, the optimal input rate of oil flax cake as a fully-featured substitute for sunflower meal in compound feed for calves has been established, which is 20% by weight, providing an increase in the digestibility of dry matter of diets by 1.7 p.p., crude protein – by 0.5, fiber – by 4.3, fat – by 6.1 p.p., along with improving the use of nitrogen by 1.7 p.p.

Winter triticale is characterized by high yield and nutritive value of green mass and is a good source for obtaining high-quality feed in the early spring. The aim of the research was to study the yield, morphological indices of plant assimilation apparatus and their correlation with yield, as well as nutritive value of collection varieties of winter triticale during the booting stage. As a result of the research, the following varieties of Belarusian selection were identified: Gurman, Zarechye, Slavko, Verdikt, Kovcheg, Pervenets and the Russian selection variety Tornado, which in the booting stage surpassed the control variety Borets by 1.2-61.8% in green mass yield and by 1.6-24.4% in lamina surface area. These varieties can be used in the selection process when creating new green cut varieties, as well as for establishing pastures and feeding pure green forage, starting from the booting stage and ending with the beginning of earing. A high correlation between the area of the third, fourth leaf, total lamina area and green mass yield was established – r=0.760, 0.715 and 0.755, respectively.

In recent years, there has been increasing interest in the use of microelements in nanoforms in feeding various animal species, in particular nanosized selenium, which is part of the antioxidant defense system of the body, is less toxic and has increased bioavailability. Unlike antibiotics, selenium nanoparticles are able to exert their effect permanently. The paper presents the results of research on the effectiveness of the use of feed additive containing the preparation “Nano-Se” in the diets of young fattening pigs. The research has shown that the use of feed additive containing the studied preparation in the diets of young fattening pigs makes it possible to increase the daily live weight gain by 4.7 %, as well as to obtain additional attributable profit per 1 kg of live weight gain in the amount of 0.21 rubles.

In order to maximize the genetic potential of farm animals and poultry and to obtain high productivity, it is necessary to compensate for the deficiency of macroand microelements in diets, which play an important role in all metabolic processes of the body. In the field of veterinary medicine and animal breeding there is a growing interest in the use of metal nanoparticles characterized by higher bioavailability. Nanoselenium is one of such elements. The article presents the results of research on the effectiveness of its use in the diets of young fattening pigs. Based on the data obtained, it was established that the use of the nanoselenium preparation administered with water in a dose of 0.10 and 0.20 mg per 1 kg of dry matter of compound feed for young fattening pigs made it possible to obtain additional attributable profit per 1 kg of live weight gain in the amount of 0.03 and 0.15 rubles, respectively.

Successful development of dairy cattle breeding is impossible without proper arrangements for biologically adequate feeding, which improves productivity and reduces the risk of diseases in high-yielding animals. For this purpose, commercial dairy complexes and farms of the republic use biologically active feed additives in animal feeding, which are very diverse and can help solve most problems in cattle feeding. The article presents the results of research on optimization of vitamin and mineral nutrition of high-yielding cows in the middle of lactation through the use of adapted premix. In the course of research, a toxicological assessment of the MuMix standard premix for high-yielding cows was carried out, which made it possible to refer it to hazard class IV (low-hazard substances). As a result of scientific and economic experiment, it was established that the use of the developed premix in the diet of highyielding cows in the middle of lactation in the amount of 150 g per head per day increased the average daily milk yield by 5.1%, milk production in standard weight by 3.7%, milk fat mass fraction by 0.11 p.p., protein mass fraction by 0.06, lactose mass fraction by 0.24, MSNF mass fraction by 0.09 p.p. and reduced the number of somatic cells by 5.0%.

The period of use of stud bulls and the quantity and quality of semen obtained from them depend largely on the conditions of their rearing and complete feeding. Vitamins and mineral elements are involved in all physico-chemical processes in the body, so their deficiency in the diet adversely affects the health of animals, their productivity, longevity and reproductive function. The purpose of the research described in the article was to establish the features of formation of production traits of breeding bulls with different supply of biologically active substances. As a result of the scientific work conducted, it was established that the use of increased doses of vitamins and microelements in the feeding of replacement young bulls and stud bulls promoted the formation of production traits of breeding bulls in postnatal ontogenesis, which was expressed in the increase of average daily gain in live weight by 9.0-9.4%, the quantity and quality of semen – by 6.3-30.8%.

Mycotoxins entering the body of animals with contaminated feed contribute to the development of diseases that reduce their productivity, reproductive traits and immune status of animals. One of the promising methods to solve the problem of reducing the content of mycotoxins in raw materials is the development of complex organomineral adsorbent. The article presents the results of studying the effect of “Mycotoxin adsorbent “Belasorb” feed additive based on tripoli, yeast and post-alcohol bard on morphological and biochemical blood parameters of young cattle. During the period of scientific and economic experiment, it was established that the use of 0.5% of the studied organomineral adsorbent in animal diets (recipe No. 1 and recipe No. 2) at the beginning of the research contributed to an increase in the content of erythrocytes in the blood by 2.7 and 3.5%, hemoglobin – by 7.4 and 3.4%, hematocrit – by 5.3 and 6.2%, glucose – by 6.7%, cholesterol – 18.3 and 39.7% and triglycerides – by 41.1 and 22 .1%, respectively.

Increasing the production of animal products is an important task facing the food and agricultural industry in Belarus. One of the ways for its solution is the development and use of biologically active feed additives in the animal diet. Such additives include feed products containing living (active) yeast used in the feeding of farm animals as probiotic to optimize digestive processes, improve the livestock productivity and livability. The article presents the results of studying the effect of the MDK feed additive produced by JSC “Yeast Plant”, containing Saccharomyces boulardii living yeast, on the productivity of young cattle. During the period of scientific and economic experiment, a positive effect of the yeast-based feed additive on morpho-biochemical parameters of animal blood was established. It was also found that the use of feed additive in the diets of young cattle in the amount of 10 g per animal per day contributed to an increase in average daily gains by 17.0%, which made it possible to reduce the cost of production by 10.4% and obtain an additional profit of 39.9 rubles per animal.

The use in the post-weaning period of starter compound feed containing the necessary amount of protein and biologically active substances will ensure the preservation of gains at the level of 700-850 grams. At present, feed additives including wastes of oil extraction industry and food industry are used in feeding young cattle. This paper contains the results of research on the effectiveness of reducing the amount of soybean meal in the composition of KR-1 concentrated compound feed. It was found that with the reduction of soybean meal in the composition of KR-1 concentrated compound feed from 21 to 12 %, the average daily gain of calves increased by 3.0-3.1 %, and the cost of gain decreased by 2.2-3.5 %. Complete replacement of soybean meal contributed to an increase in average daily gain by 4.3-5.3 % while reducing the cost of gain by 4.6-10.3 %.

For successful industrial cattle breeding we should pay greater attention to adequate feeding and improve the efficiency of feed. For this purpose, it is necessary to create rations balanced in terms of microelement composition and biologically active substances. Recently, in this regard, biologically active preparations such as long-acting metal nanopowders, which are able to increase the activity of biochemical and physiological processes in the body, have been used in animal feeding. This article contains the results of work on studying the effectiveness of feeding different levels of the preparation “Nano-Selen (Se)” to young cattle in the pre-weaning period. The research has shown that the use of the studied preparation in the amount of 0.10 mg Se (nanoparticles) per 1 kg of dry matter of the diet in the feeding of young cattle in the pre-weaning period has a positive effect on the efficiency of its growth. Thus, average daily gain increased by 5.2 %, cost of gain decreased by 5.2 %, additional profit per head amounted to 47.4 rubles.

The paper contains the results of research aimed at studying the dependence of protein metabolism indicators in the rumen of young cattle and the efficiency of protein utilization in the body of animals on the frequency of feeding. The research showed the positive effect of three times a day feeding on physiological state of animals, indicators of rumen digestion and protein metabolism in young bulls aged 3-6 months. So, more efficient protein utilization in the rumen and intensification of microbial synthesis processes were revealed, the efficiency of productive effect of feed increased. The average daily weight gain increased by 4.9%. As a result, feed and protein costs decreased by 2.3% and 2.8%, respectively.

In the process of increasing the efficiency of livestock production, great attention is paid to feeding balanced in vitamins, minerals and biologically active substances. With increasing productivity there is an intensification of metabolic processes in the body of animals, which are greatly influenced by microelements, the lack of which in the diet adversely affects the health and life expectancy of the animal. To compensate for this deficiency, feed additives are widely used, which have a comprehensive positive effect on the entire body. The aim of the work was to study the regularities of digestive processes in the rumen and metabolism in the body of young cattle fed an organic zinc compound. In the course of research, it was found that the use of an organic form of zinc instead of zinc sulphate in the amount of 50 %, 75 and 100 % in the diets of young cattle of 9-12 months of age allowed increasing the productivity of animals by 1.3-3.7 % with a decrease in feed costs for weight gain by 0.7-2.0 %.

Manufacturing of compound feed containing various protein, mineral and biologically active supplements makes it possible to fully satisfy the needs of animals for various nutritional elements. Currently, new varieties of rape, lupine and other highprotein forages with a minimum amount of anti-nutrients are being cultivated in the Republic of Belarus. Grains of these crops can replace scarce and expensive components such as sunflower and soybean meal in existing supplements. In the course of research, feed supplements containing new sources of protein, energy, mineral and biologically active substances were developed. This allows for production of compound feed for replacement heifers of 12-16 months of age, which is not inferior in feed and nutritional value to standard compound feed KR-3. Feeding these supplements to animals in the amount of 25% by weight of compound feed during the winter season makes it possible to increase the average daily gain in live weight by 7.0% with a decrease in feed costs by 6.7%.