[Effect of various temperature regimens for thawing on the quality of bull spermatozoa]

Investigations were carried out to test the effect of various temperature regimes of thawing (40 degrees, 50 degrees, 60 degrees, 70 degrees C) of bull semen frozen after the method of Nagase-Niwa (1964) in the form of pellets sizing 0.15 to 0.20 cm3. It was found that with the rise of water bath temperature the number of restored spermatozoa after thawing also rose. The higher temperatures of thawing led to a reliable shortening of the time of exposure needed for the thawing of individual pellets. Tested was a method and a device for the more effective and safe thawing of semen at higher temperatures. Artificial insemination carried out with semen thawing after the new method--55 degrees C--made it possible to raise the conception rate of the first service by 5.39 per cent as compared to the traditionally employed technology of thawing--38 degrees--40 degrees C--in cattle breeding practice.