In the conditions of the Republic of Belarus there were analyzed indices of impregnating ability and efficiency of stud bull mothers of various genotypes on a kappa-casein gene (CSN3). As a result of genotyping of kappa-casein gene by DNA-diagnostics method it is revealed three genotypes - CSN3АА, CSN3AB, CSN3BB. Frequency of occurrence of homozygous genotype CSN3AA at stud bulls - 87,3%; heterozygotic CSN3AB - 20,5%; homozygous CSN3BB - 1,2%. Statistically authentic difference between these indices depending on a genotype it is not established. Thus, authentic connection between indices of impregnating ability and efficiency of stud bull mothers and their genotype on a locus of a kappa-casein gene that specifies in absence of influence of the last on the given indices is not established and gives the chance to conduct selection on gene CSN3 without decrease in breeding value of stud bulls on reproductive qualities.

Data on working out a quantitative polymerase chain reaction (PCR) for revealing of virus of infectious bovine rhinotracheitis realized in the conditions of the Republic of Belarus was presented. The development of the qualitative PCR was realized in the following stages: analysis of viral genome and selection of primers; synthesis of primers and control of their specificity; optimization of conditions for PCR; obtaining of positive control and determination of its concentration; obtaining and testing of probe and optimization of its concentration for PCR; testing of the developed method and determination of sensitivity. The obtained method made it possible to determine not only presence of infectious bovine rhinotracheitis, but also its initial amount in sample. Due to application of probe constructed in accordance with molecular beacon technology the presented method proved to be highly specific. That was connected with the fact that fluorescence was registered only when the probe connected to complementary part of DNA, in other case the result was negative. Research results showed that the sensitivity of the given procedure made it possible to define in a sample presence of a virus with concentration 2 lg that corresponded to 2 DNA copies

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.

Research results on usage of DNA-markers (RYRI, FABP, ESRF18/FUTI) and other factors for industrial pork production were presented. It was determined that DNA-technologies let conduct interbreed crossing on industrial scale and get diverse (fat or meat, with different fat content) products, as well as increase pork production in general. The best variants of crossing combinations were pigs of the Belarus large white breed with Belarus meat and Dyurok, and also the Belarus large white breed with Landras and Dyurok. Research results showed, for in course of the whole period of breeding the daily average weight gain of hybrids of the large white with the Belarus meat and breeds Landras was higher than with the Estonian bacon on 25 and 18 g, respectively. Fattening of stores was finished at the period of achievement of body weight by 100-102,5 kg. The slaughter yield of meat products by groups (without intestinal fat) did not essentially differ and varied within 69,9 - 71,1%. There were noted no considerable distinctions in weight of internals (heart, lungs, kidneys, spleen, liver). Thickness of the salted pork fat at hybrids with animals of the Belarus meat breed was 1-2 mm lower than in other. The average meat yield of diverting weir was 61,9%, fat weight - 27,9%, bone weight - 10,2%. The organoleptic evaluation of beef-infusion broth quality showed that indicators of habit, aroma and taste and nourishing were at high level and compose 4,67; 4,59; 4,55 and 4,71 points, respectively. Tenderness, juiciness and taste of boiled meat also were at level 4,69; 4,76 and 4,87 points, respectively; fried meat - 4,57; 4,68 and 4,66 points

In the conditions of Vitebsk region of the Republic of Belarus there was realized a programme on creation of breed type of Hereford cattle. In course of the study there were realized experiments on increasing the number of livestock of beef cattle breeding by means of accumulation cross breeding of black-and-white cattle with Hereford producer bulls as well as by means of pedigree breeding of Hereford cows and calves imported from Russia and Hungary for the production of marbled beef. Breeding background of obtained purebred calves was determined by DNA-testing method in accordance with the international standard of certification. Into the breeding group of created meat type of Hereford cattle in the analyzed cattle breeding enterprise there were selected 1183 heads, including 24,2% of purebred animals and 17,2% hybrids of the third and fourth generations. The breeding estimation thoroughbred Hereford cattle showed that all producer bulls belonged to the class elite-record. The percentage of cows and heifers of the elite-record class was 89,3% in the conditions of growing number of a thoroughbred livestock on 98 heads. Purebred young stock in number of 45 heads and their mother passed the estimation of their origin by DNA method-testing.

During the investigation of nuclear DNA of boas of Belarusian meaty breed there was studied the polymorphism of EPOR, MUC4 and IGF-2 genes with the further determination of frequency of alleles and genotypes. Among boars tested for the polymorphism EPOR gene there was stated high percentage of heterozygous samples (EPOR**st): 43,3% for Belarusian meaty breed boars and 66,7% for Belarusian Kripnaya Belaya breed. In course of analysis of the genetic structure by MUC4 gene there was revealed the predominance of animals with the desirable d allele combination (MUC**cc): 60% for Belarusian Kripnaya Belaya breed and 82,2% for Belarusian meaty breed; by IGF-2 gene with homozygotic manifestation of recessive alleles: 46,4% and 63,4%, respectively. In the conditions of the Republic of Belarus there were determined the preferred boar genotypes with EPOR, MUC4 and ICF-2 genes and combinations which made it possible to increase the fattening and meaty qualities of posterity. The research results showed that in the selection breeding schemes it was necessary to consider not only maternal genotype, but also male genotypes giving preference to EPOR**st, MUC4**ss and ICF-2**qq genotypes