The article presents a comparative analysis of the currently used and promising methods of estimating the breeding value of milk productivity traits. The ВLUP AM method was found to be 12-17% more accurate than the daughter-herdmate comparison method used, with differences decreasing as the accuracy of estimation increases due to involvement of a large number of daughters estimated, but remaining within 6-10%. The advantages of the BLUP AM methodology over the current methodology were identified.

There is great scientific interest in various methods of stimulating the sexual function of billy goats in order to improve the qualitative and quantitative indicators of sperm production and its fertilizing ability. The article presents the research data, the purpose of which was to study the influence of integrated biophysical effect on reproductive performance of billy goats. It has been established that a single integrated biophysical effect makes it possible to obtain better results after 24 hours of storage of diluted ejaculates in terms of motility of goat gametes and promotes activation of spermatozoa vital activity processes, which allows to increase the pregnancy rate in female goats by 5-15 p.p.

The crucial task is to develop more advanced biotechnological methods and techniques that allow to increase the biological full-value of germ cells during their storage, so the purpose of our work was to study the efficiency of biophysical effects on the semen of billy goats during cryopreservation. Research has shown that it contributes to the preservation of biological full-value after thawing, and the developed treatment mode allows for the longest possible use of its genetic potential. Thus, the protocol of a single biophysical effect on male goats’ germ cells with a duration of exposure of 60 seconds contributes to long-term preservation of their biological full-value (up to 5 hours after depreservation), activation of spermatozoa vital activity processes, which allows to increase the pregnancy rate in female goats by 5-10 p.p.

The article presents the results of the study of the viability of depreserved goat embryos depending on different technological modes of thawing used in the technology of transplantation of small ruminants. It has been established that the use of a twostage thawing mode (successive heating of the straws in air at a temperature of +20°C for 10 seconds, and then in a water bath at +37 °C also for 10 seconds), in contrast to a single-stage thawing mode (thawing of frozen straws in a water bath at +37 °С for 10 seconds), allows to increase the number of embryos that have retained their original excellent quality by 19.3 p.p., 7.0 and 14.7 p.p., the proportion of cells ofexcellent and good quality - by 6.9 p.p., 6.8 and 11.4 p.p., the yield of embryos suitable for transplantation - by 3.6 p.p., 6.5 and 19.3 p.p. with cryopreservation of goat biomaterial in various cryoprotectants based on glycerol, ethylene glycol and dimethyl sulfoxide, respectively.

The athletic potential of horses depends on the efficiency of the animal’s use of energy produced through aerobic and anaerobic metabolic processes, not excluding other factors. In this regard, the aim of the study was to determine the relationship between the COX4I2 gene and the athletic performance of Trakehner and Hanoverian horses. Data obtained show that Trakehner and Hanoverian horses with the COX4I2ТТ genotype are superior to horses with the COX4I2СС and COX4I2СТ genotypes in trotting, cantering, jumping, work capacity, as well as in moving and jumping abilities at dressage, triathlon.

The article presents the materials of studies, the purpose of which was to form genetic profiles of pigs of maternal breeds with regard to their lineage and polymorphism of marker genes for reproductive and meat-and-fattening traits. The object of the studies was the purebred populations of Belarusian Large White, Belarusian Black-and-White, and Belarusian Yorkshire breed type pigs. Studies have shown that the genes ESR (reproductive traits), IGF-2 (fattening and reproductive traits), H-FABP and RYR 1 (meat quality traits) have the greatest influence on the animal performance.

When cattle oocytes are fertilized through intracytoplasmic sperm injection, the sperm is injected directly into the cytoplasm of the egg cell, allowing three natural barriers to be overcome outside the body. If the loss of highly valuable genetic material in a male or female parent is threatened, this may be the only way to preserve valuable hereditary traits with a high cost recovery, and it may also serve as the basis for further development of genetic engineering. In this regard, the Laboratory for Molecular Biotechnology and DNA Testing of the RUE “Scientific and Practical Center of the National Academy of Sciences of Belarus for Animal Breeding” has developed and studied conditions for preparation of cattle oocytes for in vitro micromanipulation. It has been established that it is preferable to use the ovaries in the luteal and follicular phases.

Molecular-genetic identification of genes in horse breeding allows the targeted formation of the genetic structure of the population of horses of riding breeds, which will significantly improve the efficiency of selection work. The article presents the materials of the work in which the breed-specific features of microsatellite DNA of riding horses bred in Belarus were studied. It has been found that a higher level of genetic diversity compared to animals of the Hanoverian breed is inherent in half-breed sport horses, in the genotypes of which 131 alleles were typed. Hanoverianhorses were characterized by somewhat lower allelic diversity, but had a distinctive genetic profile, with rare alleles at thirteen loci detected. Thus, the data on genetic diversity will allow a more reasonable approach to the problem of stocking farms with animals with different alleles in order to maintain the genetic structure characteristic of a particular breed.

He competitiveness of domestic horse breeding can only be ensured with appropriate directed breeding work, the most important part of which is conducting research to improve the system for assessing the genetic value of horses based on predicting their productivity using an extended database of ancestors and all available information contained in the family register. The article presents the results of the evaluation of selection traits and their variability in purebred horses of the main breeds in Belarus: Belarusian Harness, Russian Heavy Draft, Trakehner and Hanoverian. It has been established that over a 10-year period of using programs aimed to improve horses of these breeds, the indicators for evaluating stallions and mares have basically reached the target level, including measurements. They exceed the requirements of the breed standards, especially in the Russian Heavy Draft, where the horses are close to the parameters of large types in terms of development. The positive dynamics of changes in withers height and chest circumference of evaluated mares over the course of two generations of ancestors predominantly on the maternal side has been established. The horses studied are characterized by a comparative uniformity of exterior and constitution parameters, but a high variability of performance indicators.

The article presents data on meat productivity and meat quality of sheep of P×P and (R×P)×P genotypes. Scientific research was carried out in Combine “Vostok” JSC of Gomel district, in the laboratory for feed production technology and biochemical analysis and the laboratory for horse, fur and small animal breeding of the RUE “Scientific and Practical Center of the National Academy of Sciences of Belarus for Ani- mal Breeding”. It was found that control slaughter parameters in purebred animals were better than in crossbred animals, since the Precoce is a specialized meat breed and the Romanovskaya is a wool breed. The difference in the indices of physicochemical properties of the longissimus dorsi muscle in the studied genotypes is insignificant and unreliable. However, in terms of mass fraction of fat, color intensity and water holding capacity, the crossbred young animals were ahead of the purebred ones by 1.33%, 6.67 extinction units and 12.12%, respectively. The results of nutritional value and organoleptic evaluation of mutton have shown that meat and broth obtained from crossbred animals have 0.1 points better nutritional quality compared to purebred counterparts.

The article presents the results of using the Berkshire breed in the introductory crossbreeding with the Belarusian Black-and-White breed. The resulting two-breed pedigree pigs of new genotypes were evaluated in terms of their own productivity and underwent genetic testing for 12 STR-loci. It has been established that the use of the Berkshire breed reduces the prolificacy of the Belarusian Black-and-White sows byheads. At the same time, the growth rate and viability of crossbred suckling piglets were high. Two-breed replacement young animals and their age-mates of the Belarusian Black-and-White breed had the same level of self-development. The ancestors of four lines in the Belarusian Black-and-White breed were selected from the boars tested. A microsatellite analysis of purebred and crossbred animals was performed according to lineage affiliation. Private alleles were determined in animals of the created lines Azart 1796 and Abrus 239.

The article presents the results of studies aimed at identifying promising maternal and paternal lines in maternal breeds of pigs based on the index evaluation for reproductive, fattening and meat traits, and their genotypes based on the polymorphism of marker genes of performance traits. Differentiation of maternal breed pig lines into paternal and maternal ones has been established. Based on the data obtained as a result of polymorphism of the main marker genes of performance traits (ESR, IGF-2, H-FABP and RYR 1), preferable and undesirable genotypes for maternal and paternal lines of pigs of the following breeds were determined: Belarusian Large White, Belarusian Black-and-White and Belarusian Yorkshire breed type pigs.

Modern selection of beef cattle is impossible without a comprehensive assessment of the breeding value of an animal, which allows to analyze the transfer of a selection trait to offspring, to separate factors of production environment, to move from historically established phenotypic to genetic selection, in which selection of animals is formed only by their genotype. The article contains the results of research, the purpose of which was to study the genealogical structure and exterior-constitutional features of the Limousin breeding stock, bred in JSC “Turovschina” of Zhitkovichi district of Gomel region. It has been established that the greatest number of cows of the selection group belongs to the genealogical lines of bulls: KERN 767553941 (51 heads), NEB- ULEX 1096 (14 heads) and No. 4902116 (13 heads). Higher constitution indices (blockiness and breast) are typical for first-calf heifers, while boneiness and massiveness - for full-grown cows.

A high level of herd reproduction is achieved with the introduction of beef cattle breeding technology according to the “cow-calf” system, which provides for the maximum use of pastures and tour seasonal calving’s, the proper organization of which allows to get calves at a more favorable time of year and further to form uniform herds of young animals. In this regard, the goal of research was to study the efficiency ofyoung stock rearing at calving of beef cows in different seasons of the year. It was found that the animals of Aberdeen-Angus breed of the UE “Molodovo-Agro” of the spring and summer periods of birth were superior to their counterparts in terms of live weight dynamics, intensity of growth, relative growth rate and the level of multiplicity of live weight gain, which indicates the preferred comfort for starting capabilities of newborn calves and therefore requires calving at this time of year.

The article contains the materials of research, the purpose of which was to study the livability, growth and development of replacement heifers of red dairy breeds. The object of research were purebred cows and young replacements of Holstein and red dairy breeds. Studies have shown that under the same industrial housing conditions, replacement heifers of red dairy breeds aged from 6 months to the first insemination are considerably superior to their counterparts of Holstein breed in live weight and average daily weight gain. Their first insemination came 0.7 months earlier than that of their Holstein counterparts. The rate of withdrawal from the herd due to breeding culling in heifers of red dairy breeds was lower compared to their Holstein counterparts.

Creation of pedigree herds of dairy cattle with desirable β-casein genotypes in the Republic of Belarus is an urgent task of domestic dairy cattle breeding. Currently, along with the evaluation of basic selection traits, many countries around the world test and select cows with desirable β-casein genotypes in order to improve the quality characteristics of milk. The article presents the results of evaluation of 252 cows of breeding herds of different breeds for β-casein genotypes by the RFLP method, bred in SE “ZhodinoAgroPlemElita” of Smolevichi district, JSC “Gorodeya” of Nesvizh district, SE “Experimental base “Krinichnaya” of Mozyr district and UAE “Noviy Dvor - Agro” of Svisloch district. The Simmental cows showed the best ratio of de- sirable A2A2 and undesirable A1A1 genotypes - 64.0 and 4.0% respectively. To create breeding herds as well as to select dams of replacement bulls taking into account β-casein genotypes, preliminary selection of replacement heifers with the desirable genotype A2A2 is required.

Lack of important nutrients such as protein, macro- and microelements in diets leads to lower efficiency of feed use, shortage of a significant part of livestock products and increase in their cost. The article contains the materials of research, the purpose of which was to develop protein-vitamin-mineral supplements and to study the effectiveness of feeding them as part of grain forage to young cattle. It has been established that the inclusion of new protein-vitamin-mineral supplements in the feed ration of animals has a positive effect on the palatability of feed, digestion processes, metabolism and animal health, as well as promotes getting average daily gain of 629-710 g with feed consumption of 8,77-9,97 feed units per 1 kg of gain and reduces feed costs by 20%.

Sapropel has long been used as a feed additive to enrich the diet with minerals, amino acids, vitamins and biologically active substances. The purpose of the presented work was to study the effectiveness of the use of organic sapropel from the Udkhodva deposit in the Brest region in the diets of dairy cows. It was found that the inclusion of 4 and 6 % of organic sapropel in the compound feed for dairy cows had a positive effect on feed intake, physiological state and metabolic processes in the body of animals. This made it possible to increase milk productivity by 9.5 and 9.1%, reduce feed costs by 4.9%, the cost of milk - by 6.4 and 4.3%, get additional profit for all products and save 4-6% of grain in compound feed.

The article is devoted to the study of the effectiveness of the use of whole grain corn in feeding calves in order to determine the optimal norms for its inclusion in the diet. It was found that the inclusion of whole grain corn in the amount of 30 and 40% by weight of compound feed in the diet of young cattle at the age of 66-115 days had a positive effect on feed intake and intensity of animal growth, while reducing the feed costs and production prime costs. Thus, the daily live weight gain increased by 3.5% and 4.8% (774 and 784 g), while feed costs decreased by 1.1% and 1.8%, resulting in a 4.4% and 5.2% reduction in the prime cost of gain.

Optimization of phosphatides content in mixed fodder with and without fats, determination of the role of various sources of phospholipids in the feeding of pigs areurgent tasks, since the presence of fat and fat-like substances in their diets is not standardized. The article is devoted to the biological role of phosphoglycerides in the body of monogastric animals. The content of phosphoglycerides and their fractions in the grain components of mixed fodder for pigs was studied, the fractional composition of fatty acids of grain fodder was investigated. It was established that the introduction of 1% of “Dry lecithin” additive into mixed fodder for young pigs increased the growth rate of weaned piglets by 30 g, and 2% - by 51.8 g. Feeding the growing-finishing gilts with mixed fodder containing 1% and 2% of the studied additive increased their live weight gain by 29.8 and 37.9 g respectively.

The main reserve for increasing the production of fodder and its quality is theexpansion of the assortment of fodder crops, the introduction of new promising species and varieties. One way to solve these problems could be the widespread introduction into production of winter triticale as a potential source of fodder. Therefore, the purpose of the scientific work was to study the yield, biometric features of plant development and nutritive value of green mass of winter triticale of Belarusian and Russian selection during the booting stage. As a result of research, winter triticale varieties of the Belarusian selection Slavko, Zveno, Kovcheg and variety sample 1/17 of the Russian selection with high foliage and yield of green mass were revealed. It has been established that winter triticale for green fodder has a longer and wider lamina, higher foliage of plants compared to diploid and tetraploid rye, as well as surpasses in the content of crude and digestible protein and crude fat in terms of the chemical composition of green mass in 1 kg of feed. All the studied varieties and variety samples of winter triticale of Belarusian and Russian selection can be used in the selection process and for green fodder from the beginning of the booting stage.

The development of new domestic enzyme feed additives allows for the rotation of biologically active preparations in poultry feeding, and the study of their effectiveness allows to intensify work on import substitution and helps to reduce the cost of feeding the birds. The article contains materials of the comparative study of the effectiveness of using dry enzyme feed additives “Fekord-MP” (group 1), “Fekord-MP” (group 2) and “Fekord-MP-Sorb” in poultry diets, carried out at the premises of the Vitebsk State Academy for Veterinary Medicine. It was found that the dry enzyme feed additive “Fekord-MP” based on mannanase and pectinase, introduced into broilers’ diets by the method of multistage mixing at various concentrations and standards for introduction, contributed to an increase in the average live weight of broilers by 10.5-14.3% with a reduction in feed consumption per 1 kg of live weight gain by 3.4-3.9%.

Currently, compound feeds for poultry are enriched with various biologically active additives, which make it possible to maximize the genetic potential of birds and obtain the highest productivity indicators from them. In this regard, the effectiveness of the use of the regulatory complex “Bypass” was studied, which enhances the activity of fat decomposition in the liver with a sufficient amount of carbohydrates, Studies showed that the introduction of the regulatory complex “Bypass” into the diet at the rate of 3 kg/t of compound feed contributed to an increase in the profitability of poultry meat production by 2.49 percentage points or 4.73%.

Mycotoxins, being secondary metabolites of mold, represent a serious food safety problem, cause intoxication in animals and reduce their productivity. In this regard, it is necessary to know the toxicity and biotransformation of mycotoxins in different species of animals and humans in order to prevent the possibility of infection as well as their inactivation or harm reduction when morbidity is unavoidable. The article contains the results of studying the degree of mycotoxin contamination of feed and compound feed raw materials in the Republic of Belarus for the period 2011-2021. Materials for the study were 11089 samples of compound feed and its components. The results of studying the quality of cereal crops, soybean, sunflower and rapeseed meals and cakes, bran and fodder in total for mycotoxin content in dynamics over the last decade prove the necessity to use mycotoxin adsorbents in compound feed.

To achieve a high level of productivity during early lactation, a significant con- centration of metabolizable energy in the dry matter of the diet (up to 11-12 MJ) as well as crude fat (including protected) in the dry matter (5-6%) must be ensured. This can be achieved by additionally introducing vegetable oils and fats into the diet of animals. The contains the results of studying the effectiveness of the use of energyfat concentrates in cows’ diets. It was found that their use as a supplement to dairy cows instead of soybean meal made it possible to reduce the share of feed in the milk sale price structure. The profit from additionally obtained milk when using energy-fat concentrates amounted to 75.9 rubles, 106.3 and 60.7 rubles.

Due to the reduction of sources of traditional natural fodder in animal husbandry, it becomes relevant to use non-traditional feed components, in particular the pine, which has a positive effect on growth and development of calves, provides them with carotene, increases the average daily live weight gain, reduces feed costs per unit of weight gain and thereby improves the economic efficiency of fattening. The purpose of our research was to study the effectiveness of phyto additive produced by LLC STC “Khiminvest” in feeding calves. It was found that its use in the diets of animals aged 3-6 months had a positive effect on the physiological state of the animals, which provided an increase in gross live weight gain by 11.3-15.5 % with a decrease in EFU cost to obtain it by 10.3-13.3 %. The most effective scheme of feeding phyto additive to calves was 400 mg per 1 kg of live weight.

The use of recombinant proteins in diets has a positive effect on animal health, promotes intestine recovery and the creation of beneficial microbiota in the gastroin-testinal tract. The article contains the results of research in which the effect of frozen-thawed milk of goats producing recombinant lactoferrin on hematological parameters and productivity of calves at the age of 1-30 days was studied. Morpho-biochemical blood parameters were found to be within the physiological norms. The use of goat milk containing recombinant human lactoferrin in the diets of calves in the amount of 0.44-0.66 kg/head per day allows to increase the average daily live weight gain by 10,1-11,0% and reduce feed costs by 7.5- 7.7%.

With the growth of productivity in the body of animals there is an intensification of metabolic processes, which are greatly influenced by microelements, since they are their active participants. As a result of more efficient use of dietary nutrients, livestock production on the same feed is significantly increased. The article is devoted to the study of the patterns of the course of digestive processes in the rumen of young cattle and the metabolism in the body when feeding various forms of cobalt in the diet. It was found that the inclusion of cobaltous acetate in the compound feed for young cattle aged 3-6 months had no significant effect on the processes of ruminal digestion. All indices were within physiological norms. There was a tendency to increase the daily live weight gain by 3.1% with a decrease in the cost of feed to obtain it by 2.8%.

The article presents the results of research on the efficiency of using skim milk replacer in feeding young replacement cattle. Experiments were performed onreplacement heifers aged 66-115 days. It has been established that feeding the 10% skim milk replacer as a part of mixed fodder has a positive effect on the physiological state of animals and increases the average daily live weight gain by 3.2% while reducing feed costs by 2.1% compared to the control counterparts.

The main limiting factor in the consumption by ruminants of large quantities of bulk feed is the presence of fiber in plants, an increase in which above the optimal level has a negative impact on digestion, leading to a decrease in the digestibility of nutrients in the diet. By changing the structure of the diet and the ratio of nutrients in the diet, it is possible to stimulate or inhibit both the general nature of rumen processes and the level of nutrient utilization. This article presents the materials of the work aimed at studying the effect of different content of neutral detergent and acid detergent fiber in the diet of animals during the first phase of lactation on ruminal digestion. Studies showed that feeding cows of control and experimental groups in the first 100 days of lactation with diets with different content of structural carbohydrates predetermined some changes in the microbiological and enzymatic activity of ruminal digestion.

The level of structural carbohydrates in feed and diets has a significant effect on the dry matter intake of ruminants. The article presents the results of the work on studying the effect of different contents of neutral detergent and acid detergent fiber in the diet of cows during the first phase of lactation on feed intake, nutrient utilization and physiological state. Studies have revealed that the NDF content of 32-33% and ADF content of 21-22% provides an increase in feed intake, digestibility and nutrient utilization.

When rationing diets of young animals, special attention should be paid to theregulation of digestion and metabolism processes in the body of animals, as well as the choice of high-protein feed processing method to improve the efficiency of nutrient use. This article presents materials of scientific research, the purpose of which was to establish the effectiveness of feeding chemically treated protein feed to young bulls. It was found that the inclusion of lupine grain treated with organic acid in the diet of young bulls increased the average daily gain up to 917 g or 6.9% in relation to the control group, while reducing feed costs by 4.9%.