The object of the project is physiological, biochemical and morphological processes in boar semen under influence of low temperatures by various technological treatments. The goal is to find structural, biochemical and physiological characteristics of boar semen under different conditions of cryopreservation and develop biotechnological methods to improve quality and fertilizing ability of boar spermatozoa. Methods: biotechnological (sperm collection, artificial insemination), physiological (progressive motility, longevity, sperm concentration, HOST), cytological (light and phase-contrast microscopy), morph-biochemical (determination of LDH activity (plasma membrane integrity) and acrosin (acrosome intactness), kinematic (computer analysis of sperm motility), statistical (biometric data results processing). Novelty: on the basis of studies using morph-biochemical, physiological and biotechnological methods it was improved method of boar semen cryopreservation. It was revealed the nature of changes in sperm quality parameters at different steps of semen cryopreservation process and after thawing. For the first time it was scientifically proved and developed an effective packaging system for cryopreserved boar semen in "Zip-Lock" bags. Results: revealed, the possibility of fresh boar spermatozoa incubation in semen plasma for 1 hours and semen exposure to "Ecosperm" extender up to 16 hours, which significantly improves sperm plasma membranes and acrosomes integrity (p<0,05-0,01). Improved methods for boar semen preparation regimes before freezing: 1600g centrifugation for 5 min decreases sperm loss by 52,2 % (p<0,001), the cooling rate of 1°C/min in the temperature range from +15 to +5 °C, which saves about 2 hours of semen processing, equilibration of boar spermatozoa in the extender with 6 % glycerol for 1 min increases the number of sperm cells with intact acrosomes by 19,9 % (p<0,05) and longevity by 12,7 % (p<0,05). The use of "Zip-Lock" bags for the packaging of boar semen significantly (p<0,05) increased sperm plasma membrane integrity and production of TBA-active products after thawing, and developed effective thawing rate of the boar semen packed in "Zip-Lock" bags was -70 °C for 8 s. Established the optimal regimes of boar semen freezing: cooling rate of 5°C/min ranging from +5 to - 6 °C and 40°C/min from - 6 to - 70 °C, which provided the significantly (p<0,05) higher progressive motility of spermatozoa, plasma membrane integrity, acrosome intactness and longevity after thawing.
