Bull sperm morphological and functional indicators during cryopreservation

The purpose of the study is to analyze the influence of the freezing and thawing cycle on the morphofunctional parameters of bull sperm. The study was conducted at Nizhegorodskoe LLC on breeding work in the Kstov municipal District of the Nizhny Novgorod Region, on the basis of the Department of Physiology and Anatomy of the Institute of Biology and Biomedicine of the Nizhny Novgorod State University named after N.I. Lobachevsky and the Department of Physiology, Animal Biochemistry and Obstetrics of Nizhny Novgorod State Technical University. The object of the study is the sperm production of black-and-white bulls. Semen was diluted with sterile BioXcell medium. Native diluted sperm and sperm after deep freezing were studied. Motility and the average speed of sperm movement were analyzed on a sperm analyzer SA-500 from Biola (Russia). To assess the ultrastructure of spermatozoa, a Hitachi SU8220 electron microscope (Japan) was used. Using a laser interference microscope MIM-340 (Russia, Yekaterinburg), the morphology of spermatozoa was studied in real time without fixation or staining. After cryopreservation of the sperm, there was a decrease in the biological usefulness of sperm, which is confirmed by a decrease in motility by 13.77% (p ≤ 0.05) and the average speed of sperm movement by 12.95% (p ≤ 0.05). Using electron and laser interference microscopy, it was shown that the chromatin of thawed spermatozoa was insufficiently condensed and contained fibrils. After cryopreservation, the position of the acrosome was changed in 6.23% (p ≤ 0.05) of sperm, and the shape of the acrosome was changed in 18.64% (p ≤ 0.05) of cells. After freezing and thawing, 7.01% of sperm showed a decrease in head length, 17.90% - a decrease in body length, and 9.53% - a decrease in sperm tail length. The use of modern methods for assessing sperm viability is of great importance for understanding the processes occurring during sperm cryopreservation and allows us to develop ways to improve the quality of sperm during freezing and thawing.