In the last decade the dairy and beef bovine farms had an increment in their breeding programs that include the use o ovum pick-up and in vitro production (OPU/IVP). Oocytes retrieved by OPU vary in quality and its reduced number requires appropriated culture conditions for IVP. To evaluate the effect of the number of embryos and volume of the media in the in vitro culture of bovine embryos, 1428 zygotes were cultured in groups of 5, 10 or 20 in 1, 5 or 10mL of medium. Groups of 20 oocytes matured in vitro in 200mL of TCM+rFSHh+ 10% estrus cow serum (ECS). The fertilization was performed in groups of 20 oocytes/200mL of Fert-Talp medium, for 18h with 1x10(6) spermatozoa/mL. The culture was done in SOFaaci+5%ECS for 8 days. Considering D0 as the fertilization day, the IVP was evaluated on day 2 (cleavage), day 7 (blastocyst) and in day 9 (hatching rates). The cleavage rates were higher when embryos were cultured in groups of twenty. However, it was not affected by the medium ratio of 1:1, 1:5 and 1:10. The use of 1:5 and 1:10mL of culture medium ratio showed higher embryo production rates in D7 (P<0.05) than 1:1mL proportion. The culture of 20 embryos per drop affected the blastocyst production on day 7. Likewise the hatching rates in D9 were higher with 1:5 and 1:10 than 1:1. Similarly, the hatching rates were higher in cultured of 10 or 20 embryos/drop when compared to groups of 5 embryos/drop. The reduction of embryos and the proportion of the medium volume in culture affects the development indexes on bovine embryos in vitro production. | Na última década, os produtores de leite e carne bovina incrementaram consideravelmente o uso da aspiração folicular (OPU) associada à produção in vitro de embriões (IVP). Oócitos recuperados pela OPU têm qualidade diversificada e seu número reduzido requer condições diferenciadas de cultivo para a IVP. Para determinar o efeito do número de embriões e volume de meio sobre a IVP, 1428 embriões bovinos foram cultivados em grupos de 5, 10 e 20, em 1:1, 1:5 e 1:10mL de meio. Grupos de 20 oócitos foram maturados in vitro em 200mL de TCM-199+ rFSHh+10% de soro de vaca em estro (SVE), por 24h. A fecundação in vitro foi em grupos de 20 oócitos/200mL de meio Fert-Talp, por 18h com 1x10(6) espermatozóides/mL. O cultivo foi em SOFaaci+5% SVE por 8 dias. Considerando-se o dia da fecundação como D0, conduziu-se as avaliações no D2 (clivagem), D7 (blastocistos) e no D9 (eclosão). A taxa de clivagem foi superior quando o cultivo foi com 20 embriões e não foi afetada quando a proporção de meio variou (1:1; 1:5 e 1:10). Com as proporções de meio de cultivo 1:5 ou 1:10, a taxa de embriões em D7 foi superior (P<0.05) à 1:1. O número de embriões cultivados influenciou a produção de blastocistos em D7 (P<0,05) com 20 embriões/gota. Estes resultados também se refletem nos percentuais de blastocistos eclodidos em D9, sendo que 1:5 e 1:10 foram superiores (P<0,05) à 1:1. Da mesma forma, a taxa de eclosão foi superior (P<0,05) com o cultivo de 10 ou 20 embriões/gota quando comparado ao grupo de 5 embriões/gota. A redução do número de embriões e da proporção de volume de meio no cultivo, afeta os índices de desenvolvimento na produção in vitro de embriões bovinos.

In the conditions of the Republic of Belarus there was realized a cultivation of pasteurellas by different methods in Hottinger broth in 37 deg C temperature in course of 24 hours. Tissue culture properties were studied in accordance with the character of bacteria growth in liquid nutritive media and at the agar surface. Research results showed that in 7 hours after cultivation in media with application of shuttel apparatus and addition of glucose it was possible to obtain the highest quantity of viable pasteurellas with a high degree of virulence. The obtained culture on the basis of obtained results was proposed to be used for the production of virulence antigen.

In the conditions of the Republic of Belarus there was determined of a dose of input and efficiency of feeding with rape oil cake and protein meal produced on the basis of a new rape (Brassica napus) variety Yavar as a part of a mixed fodder KR-2 in diets of young stock of cattle. Rape oil cake and protein meal with the content of 1,4-1,9% glucosinolates and 27-30 mcM per 1 kg of a dry matter of erucidic acid can be included into composition of the mixed fodder КR-2 for bull calves in a dose up to 20% on weight. Feeding with the mixed fodders КR-2 with inclusion of rape oil cake and protein meal made it possible to receive daily average weight gain of calves at a level of 827-906 gram at expenses of forages of 5,4-5,9 forage units per 1 kilogram of a weight gain. It was caused by cheaper rape forages. In course of the study there was analyzed the chemical composition of rape oil cake and protein meal; indexes of rumen digestion of experimental bull calves; morphological and biochemical blood structure; changes of body weight; daily average weight gain and expenses for forages.

Research and production experiment on studying the efficiency of calve growing depending on the methods of their husbandry at the prophylactic and lactic periods was realized in the conditions of the Republic of Belarus. It was established, that calves which were kept in course of the analyzed periods in group cages of a calf-house at the age of 180 days had live weight on 9 kg (or on 5,4%) higher than cattle kept in course of the prophylactic period in individual cages of a prophylactorium calf house, and at the same time their live weight was on 3 kg higher (or on 1,7%) rearers kept in the same period in group cages on the open air conditions. The average daily live weight gain of cattle was also higher on 7,2 and 1,6%, respectively. However, in the conditions of the group husbandry of growing stock in the calf houses there was stated that the analyzed animals were more often ill, so it could be concluded that the presented animal husbandry method could be used only in favorable epizootic conditions in animal husbandry farms. In the conditions of an open air husbandry the ways of infection diseases incidence was substantially lower, and calves showed high development indices in case of complete feed diets application

In the conditions of the Republic of Belarus there was determined the influence of nutritional medium composition on pathogenic properties of leptospirosis bacteria, by an example of 6 pathogenic strains: Leptospira pomona; Leptospira tarassovi; Leptospira grippothyphosa; Leptospira icterrohaemorragia; Leptospira conicola; Leptospira hardjo. During the study there were used the following media: serum-supplemented vitaminized medium on the basis of buck serum; serum-supplemented medium with a growth factor; serum-supplemented vitaminized medium with antlbody biosynthesis growth factor; semisynthetic Russel's medium. According to the results of realized studies there was developed a correlation between terms of leptospirosis bacteria survivability in laboratory animals depending on cultivation medium. In course of the study there were analyzed terms of Leptospira persistence in guinea pigs.

Data on changes of infectious titer of Porcine Reproductive & Respiratory Syndrome (PRRS) virus depending on variability of cultivation conditions was analyzed in the conditions of the Republic of Belarus. There were determined the regimes of cultivation which made it possible to minimize the terms of virus containing material production up to 3 days. The following factors influenced the infectious titer of PRRS: adaptation to cell culture; completeness of cell culture monolayer; number cells moving into stage of logarithmic growth; infectious dose of virus; storage duration; usage intensity.

Results of researches on studying of efficiency and quality of structure of long-term leguminous-cereal coenoses are presented. Productivity of green weight of a multicomponent mix on the average for five years' use has made 336,0 c/hectares. Economic efficiency of a laying and use multicomponent grass mixture is calculated. At use of a multicomponent mix within five years industrial expenses pay off within 1 year

For soil – climatic conditions of a northeast part of the Republic of Belarus is recommended cultivating four-componential – fodder grass with two leguminous components (meadow clover + Lucerne sowing+ meadow timothy+ meadow fescue), productivity of which green weight has made 500 – 550 centers per hectare, gathering of crude fiber-19-21 centers per hectare. Inclusion of Lucerne sowing in clover-cereal fodder grass has provided a share of a leguminous component on average for four years no less than 75%