[Cryobiological characteristics of bull sperm].

Investigations were carried out on the concentration of live spermatozoa and their viability in various layers of the pellets of frozen bull semen. Studied were also the 'nests' of dry snow for the presence of organisms and spermatozoa and the likeliness of their transmitting into the pellets of frozen semen. It was found that the concentration of live spermatozoa and their viability were highest in the central part (core) of the pellets, and lowest--in the peripheral layers. At freezing the semen following the pellet technology of Nagaze Niva there was the hazard of contaminating the pellets with organisms that remained from the preceding frozen ejaculates in the nests of dry snow. During the process of pelleting the semen the nests might enable the transference and mixing of spermatozoa of various breeds of animals, as live spermatozoa were found on their walls.