It was determined in the studies that high milk production in the herd of «Kombayn» farm was registered with cows of 36 families (89,7 %), in SPK «Abodimovsky» - 15 families (93,8%). The milk yields in 305 days of the highest lactation exceed 4000 kg of milk. 38 families were identified, including 27 at farm «Kombayn» and 11 at SPK «Abodimosky», combining high milk yield, performance and desirable inbreed type. In 35-55% of families a high heritability (h²≥0,40) of basic selection traits was determined.

A high variability in reproductive traits in purebred and crossbred sows when crossed with Duroc and Landrace boars was determined (9,39-18,9 %). In addition a high positive correlation in three breed combination was revealed between indicators of litter weight at weaning - number of piglets at weaning (BM×Y)×D (r=0,88) (P ≤ 0,01).

Methods to reduce embryonic mortality and improve reproductive traits of animals in pig breeding were developed and improved. The methods represent a set of measures to establish compatibility of parental pairs for insemination, estrus induction expressed as an increase of piglets output, early ultrasound diagnosis of pregnancy, as reflected in biotechnology.

Fertility of sows inseminated by intrauterine method was higher compared to animals after vaginal insemination by 10-15% and amounted to 95%. Decrease of the semen amount in the experimental groups to 60 ml did not have a negative impact on this indicator. With intrauterine insemination method of sows by reduced dose of 2.5 billion of mobile sperm cells the multiple pregnancy increased by 0.3 animals.

Method of direct (without removing the cryoprotectant) transplantation of embryos was developed. The method is based on the use of protective environments and optimal cooling conditions at cryopreservation of embryos at different developmental stages, allowing diagnostic of pregnancy in recipients after transplantation of biomaterial is 54,2-56,0 % of cases.

On the basis of the frequency of allele marker genes for performance traits of pigs of Belarusian large white breed (RYR1, ESR, ECRF18, H-FABP, IGF-2) their genetic profile was created. A comparative analysis of the actual and reference genetic profiles of the breed of pigs was carried out, interrelations are determined and further variants of work are proposed to improve the performance traits of pigs of Belarussian large white breed.

It is determined that the Hannover breed of horse, as well as the Trakehner, is widely used in pedigree sports horse breeding in Belarus. Genealogical structure includes all the lines of the breed. In a small number there are descendants of the major pioneers of thoroughbred riding Trakehner, Arabic and French breeds. A program of breeding of these horses, the system of breeding until 2018 are developed, which provide for an increase in the number of horses and improvement of quality.

The main results of breeding work with Belarussian plant type of Yorkshire breed of pigs for productive traits were analyzed. The positive dynamics of breeding animals development is determined, the trend toward a higher reproductive traits of sows, fattening and meat traits of young animals is determined. So, multiple pregnancy during the reporting period increased by 1,0 %, age values of reaching live weight decreased by 1,8 %, feed consumption - by 2,2 %, backfat thickness - by 13,8 %.

It was determined that creation in the basic pedigree enterprises of breeding herds of sows of Belarusian black-motley breed exceed the average values of the breed: on multiple pregnancy - 0,8 animals, or 7,9 %, on milkiness - 0,9 kg, or 1,7 %, on the number of piglets at weaning - 0,3 animals, or 3,0 %. Created breeding herds are the basis of selection process for improvement and development of Belarusian black-motley breed.

Morphological and biochemical indices of rabbits of meat breeds of foreign selection are determined depending on the breed and breed combinations. Based on the data obtained priorities for further selection of the breed and combinations are identified. They have higher activity of gas exchange and redox reactions, intensity of carbohydrate, protein exchange, as well as natural resistance.

The studies established reliable associations of complex genotypes RYR1^NN MUC4^CC ECR F18/FUT1^АА Mx1^{AC or АА}, MUC4^CC ECR F18/FUT1^АА, MUC4^СС Mx1^АА with a lower (by 1-5-1,9 mm) values for backfat thickness, genotype ECR F18/FUT1^АА Мх1 ^{AC or АА} - with a higher (by 1,2 cm) body length values as well as the tendency of the positive impact of genotypes RYR1^NN MUC4^CC ECR F18/FUT1^АА Mx1^{AC or АА}, MUC4^CC ECR F18/FUT1^АА, ECR F18/FUT1^АА Мх1 ^{AC or АА} и MUC4^СС Mx1^АА on a number of traits of self-performance of replacement boars of Belarusian meat breed.

Peculiarities of growth and development are studied, assessment on self-performance is carried out and selection intensity of Landrace and Yorkshire breed of pigs in conditions of a breeding farm is determined. It was revealed that young animals of the studied breeds differed with high average daily weight gain, thin backfat and high lean meat content in body. Young pigs of all age periods from birth to 106 days were characterized by stable and dynamic development.

Method of integrated assessment of breeding and productive traits of cows of Belarusian black-motley breed was developed and adopted, which provides for the inclusion in the complex index of breeding values of the following indices: performance (including milk yield, the amount of milk fat and protein), exterior (on the classification index), the duration of economic use (including the number of somatic cells in milk, udder depth, index of limbs and fertility), udder health (including the number of somatic cells in milk) and reproductive (including service period).

As a result of the studies it was determined that milk production ranges from 4971 kg to 6181 kg of milk per lactation, fat level - at the level of 3,7-4,0 %. With increasing age there is an increase in milk yield of cows in the second and third lactation. The average duration of use of cows of red dairy breed at a farm is 4-5 lactations. The best lifetime milk performance was observed in cows that belong to the factory line Banko in 5,33 lactation - 24678, 9 kg and 948,9 kg of butterfat. Minimum gross milk yield observed in cows of factory line Valiant (17350 kg of milk with butterfat content of 3,715 %) at the duration of the use of 4,25 lactations.

The outcome of calves per 100 cows and heifers is 86 animals, with that the average live weight of newborn calves is on the level of 32,5 kg for steers and 30.8 kg for heifers. At weaning at 7 months of age live weight of young animals is 223-232 kg. The average daily weight gain at the final fattening of calves - 1219 g. Animals of both age groups were well-built, they have a broad and deep body, a well-developed chest, good rear third part of body, which is typical for animals with a strong constitution and a potentially high meat productivity. Adult cows are stretched and massive, hip-and-chest index, indexes of blockiness and meatiness say about belonging to the class of elite-record and corresponds to the breed standard.

The viability of thawed bovine embryos obtained in-vitro and reproduced using exocellular substances was studied. It was determined that the use of polyalcohol in the media for cryopreservation, as well as sucrose when filling payette or after thawing at deduction of cryophylactic allows to maintain the viability of 15,8 % of frozen-thawed bovine embryos. A higher tolerance of early bovine embryos to low temperatures is determined using sucrose as compared with trehalose.

Research results on exterior and constitutional traits of rabbits of four meat breeds farmed at farm with exterior cage management system. Three basic constitutional types of meat breeds of rabbits are identified: leptosomatic (shallow-bodied), mezosomatic (intermediate), airysomatic (broad-bodied). Superiority in live weight of individuals of Czech albino breed of rabbits is shown.

It was determined that young animals of Belarusian black-motley breed significantly surpassed on water-holding capacity samples of all imported species by 4.32-5.51 p.p., loss of meat juice were lower than in young animals of imported selection by 1,7-4.41 p.p. Analysis of chemical composition of muscle tissue showed that samples of meat of young animals of Belarusian black-motley breed had significantly more protein than samples of young animals of Landrace and Yorkshire meat breeds by 1.93 and 1.90 percentage points, respectively, and moisture content was lower by 2.66 p.p. Animals of Belarusian selection had higher intramuscular fat content level than animals of imported selection by 0.66-1.35 p.p. Chemical composition analysis of fat tissue showed that young Landrace and Yorkshire breed animals was inferior to animals of Belarusian selection for fat content, and also had a higher moisture content level.

French and Ukrainian selection of Charolais breed cows DNA typing identified the high frequency of B allele (0.3373) and homozygous BB genotype (0.1446) of the kappa-casein gene. The growth hormone gene V-allele frequency of the Ukrainian selection cattle was up to 3 times higher than the French selection animals, and with high frequency in equal parts by 45% of French selection animals had LL and LV genotype, 10% - homozygous VV genotype; for the Ukrainian selection Charolais cows this marker was at about 49 %.

In general blood bio-chemical indices of cattle indicate high adaptation ability of cattle of Aberdeen Angus breed to the changing external environment in the freezing conditions of winter in Belarus. In the analysis of biochemical parameters of blood serum of experimental animals it was determined that the amount of albumins in cows of import selection was 40,19 g/l, which was 3,91 g/l less than in cows of domestic selection. By α₁-globulins content import selection cows differed from the control group by the lowest indices - 2,43 vs. 2,47 g/l, respectively. Ratio of albumin/globulin in experimental cows was 0.71 units (imported) and 0,77 units (domestic). General protein in the blood of cows from both groups was 96,62 to 101,48 g/l, while it was 4,86 g/l (or 5,0 %) more in domestic selection animals. Calcium content at value 3.2 mmol/l (imported selection animals) was below 0,67 mmol/l (or 17,3 %) compared with group of domestic selection animals. Level of phosphorus and iron in blood of experimental animals was in the range of 1,91 to 2,0 mmol/l and from 11,08 to 12,76 mcmol/l.

As a result of research an improved nutrients media for maturation of oocyte and cultivation of early embryos using surfagon and timestrophan was developed, providing the level of oocyte maturation to the stage of metaphase II of 78,4-94,1 %, at the level of cleavage - 39,7-47,6 % and output of preimplantation embryos - 13,5-19,1 %.

This article highlights the experimental research results of the comparative cytogenetic and biotechnological analysis of Ukrainian stud breeds stallions. At the raised level of the general chromosomal instability at stallions of the Ukrainian riding and thoroughbred breeds respectively 6,45 % and 6,08 % biotechnological suitability of their sperm made respectively 60,87 % and 67,86 %. At increase of admissible level of the general chromosomal instability of trakenen breed stallions for 0,91 % biotechnological suitability of their sperm made 72,73 % at deterioration of indicators of sperm after thawing. At the raised level of chromosomal instability of manufacturing stallions of factory breeds of Ukraine quantitative and quality indicators of sperm after a de-conservation worsen. It is offered to carry out a cytogenetic assessment of horses on structural abberations for increase of efficiency of their breeding use in Ukraine.

Traits for evaluation of breeding values of pigs are determined, as well as their accounting and standardization methods. Index evaluation of breeding values of pigs in various age and sex groups is developed.

The studies generally helped to determine that on the total number of NLC Yorkshire, Belarusian large white and Duroc bbreeds prevailed - 45,25-46,98 %, indicating a more rigid structure and calorie content in fat. In samples of Landrace breeds, Belarusian meat and Black-motley breed in contrast dominated MUFA (45,20-49,48 %), they are less harmful to health than NLC, and have a positive effect on lipid metabolism, but more rapidly undergo oxidation. It was determined that the highest content of polyunsaturated fatty acids was peculiar of Yorkshire and Landrace animal breeds. They significantly surpassed all other breeds by 1.03-3.44 pp (P ≤ 0,001). Among Belarusian breeds the highest content of PUFA (10,02 %) was determined with animals of Belarusian black-motley breed. The lowest PUFA content was determined with animals of Duroc breed - 8,38 %.

The results of study of reproductive qualities of sows are resulted in the conditions of pedigree farm and economy on the production of pork. The use of Landraca and Welsh animal breeds is studied as a maternal and intermediate paternal form in the systems of threebreed -linear hybridization with the terminal boars Alba and Optimus.

The results of studies on the impact of mating variants of Romanov, Finnish, Prekos, Lincoln breeds on woolyield of F₁ and F₂ hybrids, obtained in variants of direct and backcrossing are presented. A statistically significant difference (P≤0,001) for woolyield from three-breed crossbreds with ¼ blood quantum of polycarpous species in comparison with other genotypes is determined.

Fattening and meat traits of young pigs of Belarusian large white breed using breeding and genetic methods were evaluated. Animals were evaluated on an index developed by the meat-fattening properties (IRIC) and genotypes by gene IGF-2 (mutation in intron 3). Analysis of studies revealed a close interrelationship between genotypes of boars on gene IGF-2 and IRIC (Syabr 903 (52,0 points/QQ) and Scarb 5007 (52,79 points/qq)).

Results of the research on interrelation and forecasting ofe reproduction traits of boars of Belorussian Meat Breed and Large White Breed are presented. Statistically reliable (Р≤0,05 - 0,001) interlinking between boar^יs sperm concentration, its survival rate and activity, its fertilization capability and uterus multiple pregnancy is determined. For forecasting of reproduction traits of boars of Belarusian Meat Breed data of concentration of the sperm and its volume may be used, for Large White Breed - survival and activity of sperm

The results of the experiments described in this article indicate that the most preferred pigs for selection to improve multiple births are pigs of Large white and Belarusian meat breeds. At directional selection and breeding of sows of these breeds there is a specific combining ability. Sows of Belarusian black-motley and Duroc breeds are not desirable to use as a basis for crosses because of negative general combining ability and low specific one that will reduce multiple births.

The experiments revealed that crossing of crossbred sows LW×Y and L×LW with hybrid boars L×D has a positive effect on increase in multiple pregnancy, milkiness and the amount of piglets at weaning by 3,5-4,4 %, 4,5 - 3,7-6,5 and 5,8 % in comparison with the best two-breed variant LW×L. It is determined that obtained from crossing of crossbred sows LW×Y and L×LW with hybrid boars L×D the final hybrids significantly surpassed by fattening traits the best two-breed variant LW×L. Good fattening traits were shown as well by three-breed hybrids (BM×L)×D and (BM×L)× L with average daily weight at the level of 801-803 g at feed cost of 3,38-3,40 kg per 1 kilogram of weight gain. It is determined that at agrokombinat «Snov» the longest carcass (97,6-98,7 cm), thin backfat (15,1-17,5 mm), large loin area (46,6-48,8 cm²) and heavy ham was peculiar of four-breed young animals of combinations (L×LW)×(L×D) and (LW×Y)×(L×D), which parameters exceeded the corresponding figures in the control group by 1,0-2,1 %, 1,8-2,7 (P≤0,05-0,001), 10,2-15,4 (P≤0,05-0,001) and 3,6-6,3 % (P≤0,05-0,01), respectively. At CJSC «Klevitsa» in the offspring obtained by crossing of crossbred sows of LW×BM and BM×L with Landrace breed boars of Canadian selection, the carcass length was the highest and made 99,6 cm and 100,5 cm, respectively, which is higher in comparison with the results of the control group (LW× BM)×D by 1,1 cm (P <0,001) and 2,0 cm (P <0,001).

It was determined that use of Landrace boars of Canadian selection at crossing with sows of Belarusian meat breed allowed to reduce fat content in carcass by 2,1 % and increase meat yield to 65,2 % in hybrids compared to pure breed peers of Belarusian meat breed. Meat obtained from hybrids is characterized by high water holding capacity and minimal losses of meat juice indicating its high quality.