AGRICULTURAL BIOLOGY, 2015, V. 50, ¹ 4, pp. 476-485 ISSN 2412-0324 (English ed. Online) (SEL’SKOKHOZYAISTVENNAYA BIOLOGIYA) ISSN 0131-6397 (Russian ed. Print) ISSN 2313-4836 (Russian ed. Online) doi: 10.15389/agrobiology.2015.4.476rus doi: 10.15389/agrobiology.2015.4.476eng MAIN FACTORS AFFECTING MARE INSEMINATION WITH CRYOPRESERVED DOMESTIC AND FOREIGN SPERM L.F. LEBEDEVA, M.M. ATROSHCHENKO, S.A. BURMISTROVA Divovo, Rybnoe Region, Ryazan Province, 391105 Russia, e-mail vniik08@mail.ru, Lebedeva-L18@yandex.ru A b s t r a c t Artificial insemination (AI) has the following advantages over natural mating: fast selection effect, easy transportation, wide dissemination of valuable genetic material, economic use of semen and rational use of sires, preventing sexually transmitted infections, reserving sperm in cryobanks. <...> Among the factors influencing the result of AI in horse breeding are time, frequency rate and insemination repetition, quality and quantity of semen, the depth of insertion of semen into the uterus of a mare, the observance of temperature mode and sanitary regulations during AI procedure, the reproductive performance of mares. <...> There are two main approaches to freezing of stallion sperm and thus two AI technologies for semen packaging and equipment for its introduction into the uterus of mares. <...> The first approach worked out and used in Russia is based on a sparing mode of semen cryopreservation in large volumes, 20-25 ml per dose. <...> The second method, developed abroad, provides pre-treatment of sperm by centrifugation and maximum removal of semen plasma. <...> In another procedure currently used in Russia the small volumes (5-6 ml) of semen are cryopreserved after centrifugation, removal of 50-60 % of semen plasma and thickening semen by dialysis. <...> Despite the technological differences, domestic and foreign approaches to the cryopreservation of stallion’s semen provide its similar qualitative characteristics after thawing. <...> The aim of our research was to identify the most significant factors affecting pregnancy rates in artificially inseminated mares when domestic and foreign protocols were used to freeze sperm. <...> Herein, an impact of five such factors (i.e. sperm packing/cryopreservation technology, time of insemination, reproductive state and gynecological soundness of the mares, the activity of sperm) on the effectiveness of AI with frozen semen was <...>