The objective of this study was to estimate (co)variances and genetic parameters and to predict genetic trends for weight at 120 (W120), 210 (W210), 365 (W365), and 450 (W450) days of age in Nelore cattle raised in the northern region of Brazil. The database comprised records of 30,387 animals born between 2000 and 2013 in the Brazilian North. Estimates were calculated by the Restricted  Maximum Likelihood (REML) method, in single- and multi-trait analyses in an animal model. Heritability as obtained using single- and multi-trait models for W120 (0.22 and 0.31), W210 (0.20 and 0.34), W365 (0.51 and 0.51), and W450 (0.49 and 0.51) indicated moderate to high magnitudes, with the possibility of genetic selection and incorporation into the herd. Genetic correlations between growth traits were favorable, ranging from 0.78 to 0.96. Genetic trends for W120 and W210 varied largely, from -0.31 to 4.68 and -0.53 to 7.62 kg/year, respectively. Smaller fluctuations were observed in genetic trends for W365 and W450, which ranged from -1.08 to 10.90 and -1.29 to 12.51 kg/year, respectively. Selection for W365 and W450 proved to be the criterion of choice for Nelore herds raised in the region; however, it may compromise adult performance because of higher costs and time for production. A thorough analysis of mattings is recommended to allow the selection of earlier-developing animals.

The relationship of muscle and bone structure to limb weakness was examined in 60 Duroc pigs from 3 lines divergently selected for thoracic limb weakness. The lines were designated high, control, or low, with the low line having inferior thoracic limb structure. At approximately 100 kg, 10 pigs of each line and gender were scored for thoracic limb structure and movement. Right and left thoracic limbs were collected at slaughter. A computerized morphometric image analysis system was used to determine cross-sectional areas of muscles, bones, and soft tissues at levels through the brachium, antebrachium, metacarpus, and digits. The statistical model that was used to analyze the data included the effects of line, sire, gender, and side (left vs right), with weight as a covariate. Total bone area was similar for all 3 lines of pigs at all cross-sectional levels, but significant differences in muscle and other soft tissue areas were observed, including significantly greater extensor area for the antebrachium (P less than 0.001) in low-line pigs than in control- and high-line pigs, smaller total area (P less than 0.05) of the metacarpus in low-line pigs than in control and high-line pigs, and less total area of the medial digit (P less than 0.01) in low-line pigs than in control- or high-line pigs. Total area of bone and soft tissue for each cross-sectional region was significantly greater (P less than 0.05) in boars than in gilts. Side differences also were observed in total cross-sectional areas of bone and soft tissue of the antebrachium, metacarpus, and digits. Pigs selected for inferior thoracic limb structure had less total soft tissue cross-sectional areas in distal limb regions than did control- or high-line pigs. Limb weakness may be related to altered distribution of soft tissue supporting structures of the thoracic limb.

The diseases in poultry cause huge losses in the form of mortality in acute infections or as substandard performance due to chronic illness. Biosecurity and vaccination are considered as two important primary strategies for disease prevention in poultry. On the other hand, breeding for disease resistance is an alternate strategy to combat the damages of diseases. Although, attempts were initiated to develop disease resistant poultry by breeding almost a century before, this branch of science renewed the interest among scientists because of catastrophic emerging and reemerging diseases like Avian influenza. It has proven over a period of time that poultry  exhibits genetic resistance to viral diseases like avian leukosis complex, Marek’s disease, avian influenza and Newcastle disease, bacterial disease like salmonellosis and may parasitic infestations. The key genes responsible for resistance to specific diseases have also been demonstrated. The breeding attempts for developing disease resistant poultry has yielded positive results with varying degree of success. The advent of sophisticated molecular methods like genomic selection using highdensity SNP chips, RNA-seq technique and identification of key marker genes and transgenesis could complement the conventional breeding methods to a larger extent in developing disease resistant poultry.

National audience

Research of the selection efficiency of boars of Belarusian meaty and Large White breeds for reproduction and productivity indices was realized in the selection and breeding centre Zadneprovski in the Republic of Belarus. The influence of 25-percentage level of boar selection for sperm production with the dominancy of relative average values of an initial population on statistically significant difference within the limits P less than 0,05-0,001 was proved. Application of an evaluation criterion of animal breeding abilities by the degree of frequency of departures from a population level with a value which reflects the intensity of selection in shares of an average quadratic deviation made it possible to raise the breeding value of boar of both genotypes in accordance with the productive qualities of descendants in comparison with average sizes of populations of two breeds on statistically authentic difference at P less than 0,05-0,001. Decreasing in the studied indicators of efficiency of offsprings concerning initial fatherly forms could be explained by a stronger influence of environment conditions rather than genetic predisposition of genotypes to the given traits

In the research the genetic structure of populations of bulls Vitebsk of cattle breeding state farm and cows of Belarusian Black-and-White breed of Joint-Stock Company Olgovskij of Vitebsk region (Republic of Belarus) on a locus of a gene of kappa-casein was analyzed. As a result of genotyping a gene of kappa-casein by DNA-diagnostics method there were revealed three genotypes CSN3**AA, CSN3**AB, CSN3**BB. Frequency of occurrence of homozygous genotype CSN3**AA at cows has made 69,5%, at bulls of Vitebsk cattle breeding state farm - 78,3%; heterozygotic genotype CSN3**AB - 26,3% and 20,5%; homozygous genotype CSN3**BB - 4,2% and 1,2%, respectively. Frequency of CSN3**A allele in population of cows and bulls has made 0,83 and 0,88; CSN3**B - 0,17 and 0,11%, respectively. The presence of authentic influence of polymorphic variants of a gene of kappa-casein on level of milk yield and fat and protein content in cow milk was stated. The highest milk productivity in course of 305 days of lactation was observed at cows with homozygous genotype CSN3**BB (5984 kg), that was on 890 kg higher than in animals with genotype CSN3**AB (5094 kg), and on 1406 kg higher (Р less than 0,05), than at animals with CSN3**AA genotype (4578 kg). Cows with B kappa-casein allele in genome were characterized by higher fat content in milk (CSN3**AB - 3,61%, CSN3**BB - 3,72%) than animals with a CSN3**AA genotype - 3,60%. Cows with genotype CSN3**BB had higher level of protein in milk (3,28%) in comparison with the animals with CSN3**AA genotype (3,18%). In animals with CSN3**AB genotype the mentioned above index 3,19%. Research results showed that genetic variants of the gene of kappa-casein are important for selection practice as they could be used as breeding-genetic markers which could raise milk yields and protein content in milk

In the conditions of the Republic of Belarus there was realized the evaluation of genetic inheritance indexes of producing bulls at a cattle breeding enterprise in Belarus depending on a selection source (in accordance with an average productivity of female ancestors) in order to use them properly for the increasing of genetic potential of black-and-white Belarusian cows in Gomel region. The carried out analysis allowed to draw a conclusion, that bulls of national breeding lines according to the indexes of cow milk yields concede foreign bulls, i.e. delivered of Sweden on 2744 kg of milk or on 27,5% and from Russia and Hungary - on 1272-2906 kg of milk or 12,7-29,1% (Р less than 0,001). In accordance with butter-fat yielding capacity of bull mothers obtained at breeding farms of Belarus and in accordance with groups delivered from the other countries there were stated no essential distinctions (0,05). Butter-fat yielding capacity percentage of bull mothers varied within 3,99-4,10%. However, the yield of dairy fat per lactation the difference was in favour of bull mothers delivered from Sweden (114 kg or 27,9%) at P less than 0,001. Distinctions on milk producing ability of bull mothers from various cattle breeding enterprises of Belarus were revealed. It was established, that at mothers of bulls delivered from Hungary the variability of milk yield was the highest (3032 kg or 23%). Low variability indexes of milk yield and butter-fat yielding capacity percentage was typical for bull mothers of the Belarusian selection. The standard deviation at them made 872 kg of milk yield with 9% variability coefficient, and 0,03% - for butter-fat yield and 7% respectively. Variability on all indicators of dairy efficiency of bull mothers from various cattle breeding enterprises of Belarus in most of the cases was low - from 2,3 to 13%.

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.

Investigation of morphological changes in bone marrow of young hens in the conditions of application of associated virus vaccines and sodium thiosulphate immunostimulant was realized in the Republic of Belarus. The associated virus vaccine was applied against infectious bursal disease, infectious bronchitis, infectious laryngotracheitis, and Newcastle disease. Research results showed that under the influence of inactivated vaccine against mentioned above diseases there was noted the increasing of quantity of granulocytic cells, there was stated an active hyperplasia of pseudoeosinophil cells. Immunization of young hens with the presented vaccine developed in the Institute of Experimental Veterinary Medicine of the National Academy of Sciences of Belarus promoted a short-term increasing of leucoerythroblastic index. Application of an alternative vaccine developed by Scientific and Production Enterprise Avivak did not render substantial influence on the morphology of bone marrow of chickens. Sodium thiosulphate applied in combination with associated vaccines (in 7% concentration in vaccine) caused the hyperplasia of lymphoid and thrombocyte cells, strengthened the proliferation and maturity of granular leukocytes

In the article showed results of the researches of the influence on productive longevity of cows of such factors, as a linear belonging, a genotype of the father, type of selection are stated. The lead researches have shown, that more longer duration of use characterized the animals belonging to line Siling Trajdzhun Rockit 252803 - 4,5 lactations. Among daughters of various bulls the greatest term of productive use daughters of the bulls the Silach 158 - 5,0 lactations differed. At the maximal deviation in efficiency of ancestors (6001-7000 kg of milk) longevity of their daughters was the greatest and has made 4,18 lactations. The greatest influence on duration of economic use of cows was rendered by specific features of bulls (32,2%) and a linear accessory -12,0%. While the selection variant practically does not influence longevity of animals - a share of influence of 3,7%