The article dwells on study of the efficiency of the rank system of evaluation and selection of ewes for breeding purposes of Merino herd improving of Public joint-stock company PJSC «Breeding farm "Krasniy Chaban"» according to integrated productivity level. As a result, production and laboratory studies conformity of chosen ewes performance with the best plant herd of sheep in the breed standards was determined (body weight - 55.2 kg, pure wool clip - 3.31 kg). Ewes’ belonging to the best breeding ranks provide high selection differentials according to body weight (8.1 kg, or 14.7 %), length of staple (1.8 cm, or 17.8%), and pure wool clip (0.68 kg or 20.5 %). The high-performance group of ewes according to body weight (kg 57.9-66.8), pure wool clip (3.72-4.26 kg), length of staple (11.2-12.7 cm) had been formed. Animals with record performance according to body weigh (68 kg), length of staple (14 cm), pure wool clip (5.09 kg) are determined.

The aim of the research was to determine the best parameters for sturgeon semen dilution to increase the period of its short-term storage. The results of researches have shown that dilution can influence qualitative and quantitative indices of sturgeon semen, 4 tomes (up to 4 days) increasing the total short-term storage period with no cryopreservation. The perfect dilution concentration was 1:10. The obtained results are of practical interest for artificial reproduction of sturgeon.

The physical and chemical parameters (pH and osmosis) are the most stable, the degree of distal cytoplasmic drops is minimal, and the conditionally pathogenic and pathogenic microorganisms are absent in ejaculates with rhLF added in the amount of 10 and 15 mg/liter of the diluent. In addition, higher rates of mobility of boars’ gamete for 24, 48 and 72 hours of storage were determined.

Intramuscular treatment of cows with 1.5 % solution of meloxicam promotes increase in the number of animals in estrus, up to 60.0 % in comparison with the control, increase in frequency of pregnancy according to the results of two inseminations by 49.1 p.p. Meloxicam solution in embryo transplantation technology has a positive effect on viability and acceptability of the frozen-and-thawed biomaterial of satisfactory quality and allows to increase its safety by 21 percentage points, to obtain more pregnancies at transplantation to recipients by 23.3 p.p.

Analysis of the results of evaluation of performance of sows of Belarusian large white breed according to reproductive traits showed that the highest safety of piglets was shown by the sows of the lines and related groups of Drachun 562 (93.5 %), Skarb 5007 (95.2 %) and Svitanak 3884 (95.3 %). The reproduction traits indices (RTI) were recorded in sows of lines Svat 3487 (126.0 points), Skarb 799 (127.0) and Secret 8549 (127.2 points). The polymorphism of ESR gene in sows of the Belarusian large white breed has been studied depending on their linear affiliation. It was determined that animals of the same lines and related groups may have different polymorphism of ESR gene, sometimes even all genotypes - AA, AB, BB (Svitanak 3884, Smyk 46706) may present. It can be noted that within the lines, multiparty of sows with preferred genotypes AB and BB tends to increase by 0.9-22.6% in comparison with AA genotypes. The reproductive traits of sows are estimated based on integrated system of selection and genetic methods and techniques. It was determined that boars of the lines and related groups carrying predominantly undesirable AA genotype in their genome, had index of reproductive qualities lower by 3.2-9.8% compared to their coevals with genotypes AB and BB. At the same time, in groups of animals with mostly desired genotypes AB and BB of the ESR gene in their genome, the RTI indices were significantly higher and made 120.0-128.3 points.

The polymorphism of IGF-2 gene and its effect on the meat traits of the pigs of maternal breeds have been studied. It was determined that fattening young pigs of maternal breeds with genotype QQ of IGF-2 gene tended to superiority of animals with genotype q: in carcass length - by 0.6-1.37 %, backfat thickness - by 6.8-10.3 %, loin area - by 2.0-2.2 %, weight of rear third half-carcass - by 1.8-10.7 %. A stable positive tendency of all the meat traits increase in pigs of maternal breeds with the preferred genotypes dd and HH of the H-FABP gene was noted: in carcass length - by 2.3 %, backfat thickness - by 10.9-19.1 %, loin area - by 4.2-13.6%, weight of rear third half-carcass - by 3.2-5.6 %. It was determined that the following trend is typical for animals of maternal breeds of domestic selection (Belarusian large white, Belarusian black-motley breeds): there is a decrease in reproductive traits with the growth of meat production indices. Animals carrying in their genome the preferred genotypes BB and AB of the ESR gene, surpass their analogues with the AA genotype by reproductive traits by 11.8-0.8 %, but inferior in meat traits by 28.7-0.6 %. As for the animals of the Belarusian plant type of Yorkshire breed are characterized by both high meat and reproductive traits. This is due to breeding work carried out with the plant type, which resulted in prevalence of the preferred genotypes of ESR, IGF-2 and H-FABP genes in the animals’ genome.

As a result of the conducted researches it was determined that during selection work with the Ukrainian red dairy breed an increase in the intensity of selection of animals according to genesis from 0 to 50 % entails reduction of both productive and life longevity by 7.5-18.7 %, but contributes to increase in the level of dairy performance, which is reflected in the increase in the indicator of milk yield as of the day of economic use by 11.7 %. Selection of animals by genesis taking into account the breeding value of the both parents within 30 % will promote increase in the genetic progress of productivity in the population up to 198 kg of milk with insignificant reduction in duration of productive use by 0.38 lactations, which will positively influence the efficiency of dairy cattle industry in conditions of experimental farming.

It has been determined that riding breeds of horses at basic farms (RCOPKS and K Establishment of Minsk, OJSC Polochany of Molodechno, KSUP Teplichnoye of Gomel, RSUP Sovkhoz Lidsky of Lida, OJSC Polesskaya Niva of Stolin districts) are representatives of Trakehner, Hanover , Westphalian, Dutch, Brandenburg, Latvian and Oldenburgian thoroughbred breeds. The dynamics of expert evaluation, external-and-constitution parameters and quality in the process of breeding and use in Belarus from 2011 to 2016 are studied. The mares selected for breeding exceed the requirements of the breed standard according to all the estimation parameters.

Sports efficiency of 273 horses of Trakehner, Hanover, Holstein and other riding breeds was estimated in the various equestrian organizations of Belarus, which have been taking part in international competitions in classical equestrian sports since 2000. Using the FEI tests, the results of the competitions are differentiated according to the level of complexity and the achieved indicators. It is shown that triathlon eventing is the most active and successful type of equestrian sport in Belarus. The effect of horses origin on their athletic performance is determined. Clear sport specialization is determined among the progeny of a number of producing animals.

Based on the researches, a “List of selection and genetic measures to preserve the lines of the Belarusian black-motley breed” has been developed, which will make it possible to create a unified system for breeding and using pedigree animals at gene pool enterprises, to increase efficiency of centralized management of selection process for preserving and efficiently using the Belarusian black-motley breed lines.

It was determined that composition of nutrient media for in vitro maturation of bovine oocytes was optimized due to including 5 % of estrial, fetal, or bovine serum in combination with 50 μl of cell conditioned granulose or the medium oviduct, the cleavage level was 47.9-53.3 %. Surfagon at concentration of 0.02 ng/ml increases the number of cleaved cells by 21.6 percentage points. Epibrassinolide at concentration of 2х10^-8 и 2х10^-9 mol/l makes it possible to achieve the cleavage level of 50.0-53.8 %, and in combination with conditioned somatic cells increase the researched index by 5.6-8.7 percentage points.

Reproductive ability by insemination index in heifers of the Ukrainian red dairy breed, depending on the genotype of the fathers and the birth season were studied. Correlation been determined between the fertilizing ability of heifers and the genotype of their fathers. So, the largest index of insemination was shown by daughters of bull Roman 660886883 (1.58±0.10), and the smallest one - of bulls Record 635654455 and Satchel 646.530.45 (1,00) of Starbuck line 352.790.79. Heifers born in autumn had a higher insemination index by 0.18-0.31 or 6.1-28.9 % compared to the coevals born in winter-spring-summer period, which contributed to later fertilization by 2-6.5 days.

Genotyping of pigs according to H-HABP and RYR1 genes by PCR-RFLP method was carried out. The research subject were the pigs of the Belarusian black-motley breed (BMB), reared at the breeding enterprises of the republic. Molecular genetic testing helped to reveal the polymorphism of H-HABP and RYR1 genes in animals of different populations and sex-and-age groups (producing boars, sows) represented by alleles H-HABP^H, H-HABP^h, H-HABP^D, H-FABP^d, RYR1^N, RYR1ⁿ, and the following genotypes were identified: H-HABP^Hh, H-HABP^Hh, H-HABP^hh, H-HABP^dd, H-HABP^dd, H-HABP^dd, RYR1^NN and RYR1^Nn. It was determined that the highest concentration of the preferred H-HABP^Hн genotype in the experimental populations was observed in producing boars - 73.53 % (KSUP “P/z “Lenino”), and the lowest in sows - 50 % (JSC “SGC “Vihra”). The average frequency of this genotype occurrence for the breed made 62.77 %. The preferred genotype H-FABP^dd was found only in sows at KSUP “P/z “Lenino”, its concentration was 1.04%, the average for the breed - 0.53% In general, the concentration of the preferred H-FABP^d allele in animals of researched breed was low and made 0-0.111. According to RYR1 gene, the average frequency of occurrence of animals with genotype RYR1^NN free of mutation made 90.48 %, carriers of the mutant allele RYR1^Nn - 9.52 %.

Researches carried out with young animals of Aberdeen-Angus breed showed that the body of steers is more extended with well-developed chest and posterior part of the body. The animals are built up well, they have rather pronounced meat forms. At the same time, according to the stretch index, the steers were significantly superior to heifers by 8.0 p.p., the advantage made 5.2 according to the massiveness index. The intensity of steers growth from 7 to 15 month of age made 1020 g, and from 7 to 17 months - 1095 g. The average pre-slaughter body weight of steers made 513.7 kg, while the slaughter weight varied from 281.6 to 288, 1 kg. The weight of internal fat in the experimental steers was minimal - 5.6 kg, which averaged to 1.1 % of the slaughter weight. A high carcass slaughter yield (55.5%) and carcass yield (54.5 %) was determined. The meatiness ratio made 4.54 units.

The estimation of polymorphism effect of insulin-like growth factor gene 2 - IGF-2^(in-2) in boars of Belarusian large white breed on meat performance of their progeny is studied in the paper. It has been determined that animals with AA genotype showed the best meat traits: they had carcass length of 97.9 cm, backfat thickness - 23.5 mm, loin area - 39.1 cm², slaughter carcass output - 68.94 %.Progeny of boars with preferred BB and AB genotypes similar indices were a bit lower: Carcass length - by 0.2 cm, or 0.2 %, backfat thickness - 0.8-1.4 mm, or 3.6-6.3 %, loin area - 0.1-0.6 cm², or 0.3-1.6 %, rear third of half carcass weight - 0.6 kg, or 5.6 %, slaughter carcass output - by 0.05-0.27 p.p., respectively.

Th paper dwells on results of researching the productivity of producing boars depending on the breed and the genetic profile according to DNA markers: the ryanodine receptor gene (RYR-1), the estrogen receptor gene (ESR), the meat performance gene (FABP). The data is presented confirming the expediency for genetic diagnostics in the reproducing part of the herd of both the boars and sows, which allow to objectively identify the alleles preferred for breeding. Selection of such animals as parental pairs will significantly increase the productivity of pigs. Besides the gene diagnostics, it is desirable to take into account the quantitative and qualitative indicators of semen product when including producing boars in the reproductive process, proceeding from real age of the animals and the breed, rather than being guided by exterior and weight indices. Preferred genotypes from the breeding point of view are BB (ESR gene), HHdd (H-FABR gene) and NN (RYR-1 gene). The AB, HhDd and Nn genotypes of the above mentioned genes are intermediate for selection, and AA, hhDD and nn are undesirable and unacceptable for further selection.

Efficiency of dairy cattle breeding has been determined depending on the methods of lines selection. According to milk productivity the best was progeny obtained both from intralinear breeding and from individual variants of inter-linear crosses. The level of differentiation of the estimated groups of animals according to the milk yield at intralinear selection (6215-8579 kg) and line cross (6283-8376 kg) proves the reliable influence of heredity of lines on the milk productivity traits of black and motley breed of cattle according to the data of higher lactation. Highly reliable difference between extreme variants, respectively, was 2364 kg (P <0.001) and 2193 kg (P <0.001), depending on the selection variants. The reliable difference in variability of fat content in milk (3.74-3.92 %, P <0.001) according to the highest lactation data confirms the motivation of expediency of regular monitoring with the evaluation of line compatibility in the breeding process of dairy breeds in the system of linear breeding. Repeated application of the most successful line variants in selection and abandoning ineffective ones will contribute to improving the dairy performance of livestock.

According to the results of testing of mixed linear regression models, it was determined that the following models correspond to the structure of the studied data most accurately: according to the average daily weight gain and lean meat content - a model including fixed factors of the breed, sex and farm; according to the backfat thickness - breeds and farms with random factors “father”; according to multiplicity of sows - a model that includes fixed factors of the breed, farm, regression to the farrowing number; according to the litter weight - breed, farm, regression to the farrowing number and litter weight with a random factor “animal”. Calculation of breeding (genetic) value of producing boars and sows was carried out based on mixed linear models by the BLUP method.

It was determined that crosses of hybrid sows of LW×Y and L×LW with hybrid boars of L×D boars had a positive effect on increase in multiple pregnancy, milk yield and number of piglets at weaning by 3.5-4.4 %, 4.5-5.8 and 3.7-6.5 % compared to the best two-breed variant LW×L. Duroc boars use as paternal form in combination with cross-bred sows of LW×BM and BM×L has negative effect on the reproductive traits of sows (reduces multiple pregnancy by 10.8 %, milk yield by 2.6-4.2 %, number of piglets - by 14.7-16.3 %, litter weight by weaning by 19.4-21.5 % compared to sows of similar origin in combination with boars of Landrace breed. It was determined that final hybrids obtained as a result of crossing the hybrid sows of LW×Y and L×LW with hybrid boars of L×D were significantly superior to the best two-breed variant LW×L in terms of fattening traits (the age of reaching 100 kg is 8.5-9.4 %, the average daily weight gain is 12,0-13,1 %, feed costs per 1 kg of weigh gain lower by 4,7-6,2 %). Three-breed hybrids (BM×L)×D and (BM×L)×L showed good fattening traits with an average daily weight gain of 801-803 g at feed costs of 3.38-3.40 kg per 1 kg of weight gain. According to physical properties, the meat of young pigs of experimental and control groups at the both farms can be classified as good quality pork suitable for processing.

The aim of the work was to study fishery indicators of breeding families of the fourth generation of the new breed of Belarusian mirror carp. It was determined that among the families of the second generation of the second line of breeding mirror carp, the families 23 and 26 were characterized by increased fishery indices at the age of underyearlings with the survival rate and average body weight exceeding the standard requirements for underyearlings (body weight - 40 g, survival - 40.0 %). Among the yearlings according to set of fishery indicators, the advantage of families 23 and 24 was determined. At the age of two-yearlings families 26 and 27 were the most productive ones. Among the families of the third generation of the first line of the breeding mirror carp, the family 28 was characterized by increased fishery farming indicators at the age of underyearlings, families 33 and 34 - at the age of the yearlings, and family 33 - at the age of two-yearlings.

The aim of the research was to study physiological and biochemical parameters of blood serum of species of young repair groups of mirror carp and their correlation with the main fishery characteristics. It was determined that the best level of the total protein content in blood serum was shown by the 2nd line of underyearlings and yearlings of families 25 and 26, and in the 1st line - families 31 and 34. Changes in glucose levels in breeding families before and after winter period (underyearlings-yearlings) vary significantly in the 2nd line from 0.99 (family 27) to 10.15 mmol/l (family 25), average 4.82 mmol/l, in the 1st line - from 2.21 to 17.21 mmol/l (average 7.25 mmol/l). As for cholesterol level in blood serum of yearlings, the average variability level made: in the 1st line - 2.73 mmol/l, in the 2nd line - 4.51 mmol/l. Increased cholesterol levels were determined in families 30 and 31 in the 1st line and family 27 in the 2nd line.

Feeding young cattle with 10 % of granulated lupine in the compound feed has a positive effect on physiological state of animals. Compound feeds with granulated lupine contributes to increase of the average daily weigh gains. So in the course of research with young cattle at the age of 3-6 months the average daily weight gain made: in the experimental group - 928.6 g, which is 6.1 % higher than in the group where animals received ground high-protein additive. As a result, feed costs per 1 kilogram of weight gain decreased by 2.62 % and made 4.08 feed units.

Researches were carried out to study the efficiency of extruded lupine in compound feed on performance of young cattle aged 3 to 6 months. It was determined that feeding young cattle with extruded lupine added to the compound feed in the amount of 10% had a positive effect on physiological state of the animals, as evidenced by increase in the total protein level in blood by 8.9%, glucose by 8.5%, and decrease in the urea level - by 8.5%. Decrease in the urea level in blood of animals indicates the decrease in the amount of ammonia due to decrease of protein decomposition intensity, which is associated with normalization of protein metabolism in the body and better conditions of ruminal digestion. Compound feeds used with extruded lupine also contribute to increase in average daily weight gain by 6.4%, decrease in feed costs for weight gain by 4.9%, and a cost price of weight gain by 4.78%.

High digestibility ratios of crude protein (at the level of 80.8-83.4) and nitrogen-free extractives (86.4-91.1) of all high-protein feeds were determined. However, there were differences between the cultures themselves: thus, availability of crude protein in rape seeds was 1.6%, and crude fat 6.6% lower than the availability of these nutrients in soybeans. Digestibility of protein from feed beans made 80.8%, of fat - 68.8%, and was the lowest of all the cultures researched. According to the amount of the first limiting amino acid (lysine), local protein feeds showed 1.3-2.0 times higher indices of its content requirement in the “ideal protein”. All the samples, excluding rapeseed, were deficient in methionine and cystine. Deficiency of 25% of threonine was determined in forage beans, and in lupine grain very little tryptophan level was determined. According to the level of valine, leucine, isoleucine, arginine, histidine, phenylalanine and tyrosine, all the protein cultures had a positive balance in comparison with the “ideal protein”. Assessment of availability of lysine in protein feeds in vitro using 2,4-dinitrofluorobenzene showed that the in vitro digestibility of lysine in all the samples was 1.1-10.5% higher than the table values of standardized ileal digestibility of feeds. Lysine loss in rapeseed seeds amounted to 0.437 mg per 100 g of feed, in narrow-leaved lupine - 0.197, field pea (maple pea) - 0.247 and forage beans - 0.132 mg. Discrepancies between the results obtained and table data are explained by the fact that the digestibility of protein and amino acids in vivo depends on the loss of endogenous protein, and these losses are not considered in the in vitro method.

The paper presents the results of researches of lactulose-containing feed additive “Lactumin” effect on calves’ body weight gains. Studies have shown that feed additive “Lactumin” in the amount of 6 and 12 grams per animal per day in diets for young cattle of up to months of age increases the consumption of concentrated feed by 5.5 and 2.9% and the average daily weight gain by 12.3 and 5.7%.

The aim of the research was to study the efficiency of various doses of lactulose in calves' diets from birth to 4 months of age. It was determined that adding lactulose in the amount of 2, 4 and 6 g per animal per day contributed to increase in consumption of concentrated feed by 20.5% in the first month of rearing, by 17.2% in the second month of rearing and by 6.9% in the third month of rearing. Adding lactulose in diets for young cattle from birth to four months of age in amount of 2, 4 and 6 g per animal per day contributes to increase in average daily weight gain by 7-11% and decrease in the cost of weight gain by 0.9-2.5%.

The aim of the research was to study the intensity of metabolism in calves during lactating period at various doses of prebiotic lactulose introduced into diet. It has been determined that feeding calves with 6 g of lactulose per animal per day increases the digestibility of dry and organic matter by 2.6 and 2.5 percentage points, crude protein by 3.0 percentage points, raw fat by 1.0 percentage points, BEV - by 2.7 percentage points and crude fiber - by 16.5 percentage points, and also contributes to a significant increase in nitrogen consumption with diet feeds by 4.8% and its deposition in the body. When 6 g of lactulose was included in the diet for calves per animal per day, the deposition of calcium, phosphorus and magnesium in the body increases, based on the total amount of minerals consumed by 2.7 p.p., 7.5 and 2.8 p.p.