[Attempts at freezing bull semen in a yolk-raffinose medium without glycerin].

A new medium was produced, containing no glycerin but rich in raffinose, egg yolk, and mineral water, adequate for freezing bull semen. It was tested parallel to a control extender, consisting of yolk, lactose, and glycerine. The absolute survival rate of the spermatozoa kept at 0-4 degrees C in a raffinose medium proved by 24.25 h higher than that of the spermatozoa in the control medium. No other essential differences were established as to motility, heat resistance and percent of pathologic forms of freshly diluted and frozen semen between the test and the control medium. The biologic test on a total of 133 cows resulted in a 71.4% conception rate at first insemination. The semen frozen in the control medium showed 62.6% conception at the insemination of 123 cows. The difference of 8.8% was in favour of the new synthetic medium. The insufficient number of animals (133) used in the investigations made it necessary to test the new medium on a wider production basis.