In vitro technology is one of the most dynamically developing and more and more stable biotechnological methods today accelerating selection, intensifying reproductive and genetic potential of breeding animals, allowing to increase breeding young animals production by one champion cow up to 5–10 calves per year, reduce generation interval and significantly accelerate process of updating and qualitative improvement of livestock. However, obtaining oocytes competent for in vitro development is one of the critical factors determining success of the method and depending on a number of biological and technical factors. This paper presents results of studies on effect of biological factors of direct and indirect impact on efficiency of obtaining oocytes in the system of transvaginal aspiration for the first time conducted in the Republic of Belarus. Yield of excellent and good quality oocytes increased during aspiration during the luteal phase of estrous cycle and remained almost unchanged during aspiration into the follicular phase. Presence of follicles with diameter over 8 mm in the ovaries during aspiration reduced yield of excellent and good quality oocytes averagely by 9.4 percentage points. Removing the dominant follicle 72 hours prior to aspiration allowed increasing the number of aspirated follicles by 41 %, and yield of oocytes – by 22.9 %. Microstimulation of ovaries prior to aspiration by follicle-stimulating hormones FSG-super and Plusset increased efficiency of aspiration in terms of the main indicators by 19.2–45.9 %. Follicular cyst or persistent corpus luteum in one of the ovaries reduced both quantitative and qualitative indicators of aspiration. The data obtained are of practical importance for development of technology for in vitro embryo production in the system of transvaginal aspiration of oocytes which will help to accelerate breeding process and increase efficiency of breeding work in livestock production in general.Acknowledgments. The research was conducted within the two state research programs: “Biotechnology”, subprogram “Development of biological science, biological education and biological industry for 2007–2011 and for the period up to 2020”, “High technologies and equipment for 2016-2020”, subprogram 1 “Innovative biotechnologies–2020”.

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In the Republic of Belarus, as well as around the world, there is a continuous search for ways and methods of efficient struggle against the varroatous invasion of bees, however, no significant decisions are found in this struggle. In the context of this problem, scientific studies were conducted on development of modern technology of beekeeping on the background of spread varroatous invasion. Technological methods are proposed in the fight against varroatous invasion of bees, proving efficiency of the joint use of zoothechnical, biological and mechanical methods of combating the Varroa tick. It has been shown that purposeful rearing and selection of the drone brood reliably reduces the tick contamination of bee families by 5.7-17.4%. It has been substantiated that the use of intraulic pollen collector significantly reduces the number of ticks in the bees families, especially in the early spring period, when the ticks are mainly located on bees and are especially vulnerable to mechanical impact. The use of the feeding frame allows to purposefully obtain, conveniently and easily select the drone brood, and along with the drone brood, remove the Varroa tick form the bee nest. The use of the developed technology will allowed to reduce the number of tick, obtain additional products in the form of a homogenate of trutone larvae. Such system will increase the preservation of bee families, productivity of honey harvest and, as a result, increase the profitability of beekeeping production, as well as the effectiveness of pollination of entomophilic agricultural crops and their yield.

In cows of the Belarusian black-motley breed, the polymorphism of genes for lactoferrin and mannose-binding leсtin was established. The genotypes LTFAA, LTFAB and MBL1TT, MBL1TC, MBL1CC were identified. The milk productivity (yield, fat content, amount of milk of basic fat content), the number of somatic cells in milk were studied, and the economic efficiency of milk production from cows with different genotypes for the genes of lactoferrin and mannose-binding leсtin was calculated. It was found that the profit in cows with the LTFAA genotype was 7.91 rubles higher than in cows with the LTFAB genotype, in individuals with the MBL1CC and MBL1TT genotypes, and a higher profit per head was obtained from cows with the LTFABMBL1CC and LTFAAMBL1TC genotypes, which amounted to 3249.49 and 2855.40 rubles respectively.