In the conditions of the Republic of Belarus there were determined the fattening and slaughter qualities of swine as well as the evaluation of their pork production in the conditions of inclusion into their diets of a biologically active substance on the basis of field caraway (Carum carvi L.). Research results showed that in the production conditions the administration of the biologically active additive in a dose of 7 gram per 100 kilogram of live weight of pigs made it possible to increase their daily average gain from 627,9 grams in a control group up to 687,2 grams (or on 9,44% (P less than 0,999)), to increase their preslaughter and slaughter weight respectively on 3,76% and 6,42%, dressing percentage and carcass yield – respectively on 1,71 and 1,67%. According to the indexes of meat quantity in diverting weirs of the experimental pigs surpassed the control group on 3,03%, or 2,70 kg. The fat content in the half carcasses of the experimental group was authentically lower than the indices of control animals on 0,48 kg or on 2,18%. The hock weight of experimental animals with high confidence exceeded pigs of the control group on 1,15 kg, or on 10,45%. They practically did not differ from the control group according the indexes of thickness of pork fat at the level of 6-7 chest vertebras, and in the area of a muscular eye surpassed them on 4,0 square сm or on 7,72%.

In the conditions of the Republic of Belarus there were analyzed the doses and efficiency of application of selenium in composition of a mixed fodder KP-2 in diets of bull calves of at their breeding for meat. In course of the study the was developed a formula of a mixed fodder with various doses (0,1; 0,2; 0,3 mg per 1 kg of a dry matter of a ration) of selenium; there was studied the influence of different selenium doses in mixed fodders on palatability of diets, their digestibility, use of nutritive elements and hematological indexes of animals. Also, there was analyzed the influence of different doses of selenium on bull calves growing intensity. There was given the zootechnical and economic evaluation of usage of selenium for bull calves. Selenium dose of 0.2 milligram per 1 kilogram of dry matter proved to be the most efficient and promoted the increasing of average daily body weight gain on 10.9%.

In the conditions of the Republic of Belarus there was analyzed the productivity of 13-18-month old young stock of cattle which was bred for meat with various levels of energy value nutrition. Also, there were noted their slaughter qualities and chemical composition of meat. Administration of diet rations with an increased level of exchange energy and the best indices of protein fissility rendered a positive influence on productivity of young stock of fattening cattle and made it possible to obtain 1103-1100 gram of body weight gain. As a result, the energy value gain was 22,9-22,6 MJ along with conversion of metabolizable energy at a gain - 24,7-25,3%. Consumption of metabolizable energy per 1 MJ along with body weight gain were within 4,7-5,0 MJ. Feeding of rations with various levels of the studied factor rendered the positive influence on slaughter qualities, made it possible obtain slaughter yield of 53,6-54,6% at an optimum ratio of nutrients in meat. Feeding of bull calves with diets with excessive content (up to 10%) of metabolizable energy made it possible to lower the prime cost of obtained breeding products on 0,55%.

In the conditions of the Republic of Belarus there was determined the genetic structure of population of breeding boars, sows, replacement and crossbred stores in accordance with RYR1 gene which was connected with stress resistance. Also, there was analyzed the influence of genetic polymorphism of this gene on meat productivity. In course of the study there was presented a genetic structure of breeds according to gene loci RYR1. There was analyzed the frequency of occurrence of alleles and genotypes in accodance with gene loci RYR1 of breeding boars and replacement stores of different lines. There were showed the indexes of meat productivity and acid capacity of purebred and crossbred stores with different RYR1 gene genotypes. As a result of study there was revealed a rather high level of presence of allele RYR**n in all sex and age specific groups of Belarusian meaty breed (21%) and crossbred stores of Large white x Belarusian meaty breeds (40%). But in the experimental group of three-breed cross breeds (Large white x Belarusian meaty) x Duroc there was not stated the presence of allele of malignant hyperthermia. High level of RYR**n allele presence in populations of meaty breeds and their crossbreeds proved the necessity of obligatory genetic control of pedigree as well as imported animals by means of DNA diagnostic.

In the conditions of the Republic of Belarus there was realized a complex evaluation of producer bulls of different genotypes of origin for the further correction and breeding in different categories of agricultural enterprises. In course of the study there was conducted a preliminary (without quality evaluation of daughters) estimation of bulls which gave a precise performance of each bull, made it possible to correct its type and direction of breeding. Research made it possible to considerably increase the genetic trend in accordance with indexes of milk productivity which would make it possible to form a regional type of black-and-white cattle with the given indexes of productivity and reproduction. In course of the study there were analyzed the following breeds: black-and-white, Holstein, Hungarian breeding, Swedish breeding. Comparative evaluation of reproductive qualities of bulls in accordance with age-specific and breed types was presented. Body conformations of bulls of Holsten and Black-and-white of different ae-specific groups were stated. Results of complex evaluation of full-grown, under 5 year-old and replacement producing bulls of Holstein and Black-and-white breeds were presented.

In the conditions of the Republic of Belarus there was studied the influence of a number of pigs in a group on swine productivity and blood indexes of pigs. In course of the study there were analyzed blood indexes of piglets before and at the end of the experiment. Research results showed that it was efficient to organize husbandry in small groups (10 heads per carriage). The adaptative period of animals in the conditions of husbandry in large groups (20 heads) was longer (the adaptation took place by the seventh day). In these conditions the average daily live weight gain of piglets was lower than in the conditions of small group husbandry on 5,1%. Research results showed that animal husbandry in the conditions of different number of heads per group did not render negative influence on morphological and biochemical blood composition.

In the conditions of the Republic of Belarus there was analyzed the influence of diets with different ratio of degradable and by-pass proteins on morphological and biochemical blood composition and productivity of bulls of black-and-white breed. In course of the study there was analyzed the average feeding diet of young stock of cattle in accordance with actually eaten fodders; morphological and biochemical blood indexes; live weight and average daily weight gain; results of a control slaughter. Research results showed the feeding at the finishing period of fattening-off with different ratios of degradable and by-pass proteins in ratio 60-65:40-35 made it possible to obtain 1049-1078 grams of live weight gain of bulls per day in the conditions of fodder expenses of 8,22-8,40 fodder units per 1 kilogram of weight gain. As a result the energy of weight gain was 20,1-21,2 mJ. Conversion of metabolizable energy at weight gain stage was at the level 20,4-21,8%. Expenses of metabolizable energy per 1 mJ at weight gain were 4,83-5,05 mJ, and prime cost of body weight gain lowered on 5% in comparison with control.

In the conditions of the Republic of Belarus there was determined the influence of experimental feed mixtures on the basis of humid preserved grain (conserved rolled grain of triticale; barley (Hordeum vulgare); oat (Avena sativa)) and protein, mineral and vitamin supplement (contains rape (Brassica napus) extraction cake; wheat bran; premix PKR-2; chalk; forage phosphate) on digestibility and metabolism of nutritive elements by young stock of cattle. There were presented recipes of the developed experimental feed mixtures and studied their influence on consumption and digestibility of nutritive elements of diets, metabolism of nitrogenous substances, calcium, phosphorous, as well as on hematological indexes. The proposed mixed fodders contained metabolizable energy; dry matter; crude protein; digestible protein; crude fat; fibre; starch; sugars; calcium; phosphorous; magnesium; potassium; sulphur; iron; copper; zinc; cobalt; manganese. In course of the study there was analyzed the consumption of the main nutritive elements; coefficients of their digestibility; nitrogen balance; balance of calcium and phosphorous; morphological and biochemical blood indexes.

In the conditions of the Republic of Belarus there was determined the efficiency of application of different levels of vitamins and trace elements in feeding of servicing bulls. In course of the study there was analyzed the influence of different levels of supply of servicing bulls with vitamins A, D, E and trace elements (copper; zinc; manganese; iron; cobalt; selenium) on their reproductive ability. On the basis of the experiment there was calculated the economic efficiency of application of the developed vitamin and mineral additive. Research results showed that application of the developed protein and mineral additive in diets of servicing bulls in winter and summer periods made it possible to increase the ejaculate volume on 7,4% and 12,4% (P less than 0,05), sperm activity on 6,7 % (P less than 0,05) and 7,3% (P less than 0,01), concentration of spermium in ejaculate on 6,3% and 7,8% (P less than 0,05). Also, it promoted the lowering of percentage of defective sperm doses.

In the conditions of the Republic of Belarus there were analyzed data on studying the species specificity of anatomic and topographic characteristics of the most important component of neuroimmunoendocrine system providing body homeostasis - thymus gland of 5-6 year-old European beavers (Myocastor coypus). As a result of studies taking into consideration the sexual dimorphism there was formed a database of morphometric indexes characterizing the degree of development of left and right lobes of thymus gland of European beavers, as well as to reveal their species-specific anatomic and topographic characteristics correlating with processes typical for age-specific and accidental involution.