Successful pregnancies in cows following double freezing of a large volume of semen | Réussite de gestation après double congélation de grand volume de sperme chez la vache
2002
Arav, A. ((Agricultural Research Organization (ARO), Bet Dagan (Israel). The Volcani Center, Institute of Animal Science)) | Zeron, Y. | Shturman, H. | Gacitua, H.
The objective of the following paper is to describe a new technology for large volume and double freezing of semen in 12 mL test tubes. Semen from two different bulls was frozen with a new technique using 12 mL test tubes and was refrozen after thawing in mini straws. All freezing was done in a Multi thermal gradient (MTG) freezing apparatus, which moves the container at a constant velocity (V) through a thermal gradient (G) producing a controlled cooling rate B = (G)x(V). Each of the two bulls ejaculated were evaluated for post thaw motility in the lab and then in a field trial which was carried out in a split sample mode. 105 cows were inseminated after a double freezing/thawing cycle, and another 123 cows were inseminated with semen frozen in mini-straws and a conventional method. The results showed a 75 +/- 5 per cent post thaw motility after freezing a 12 mL test tube and 50 +/- 5 per cent after a second freezing/thawing in mini-straws, respectively. Controlled vapour freezing showed a 60 +/- 10 per cent post thaw motility. The results of the field trial showed a pregnancy rate of 44 per cent (47/105) for the double freezing group in comparison to 45.5 per cent (56/123) for the controlled group. These results can be beneficial for large volume freezing, and therefore for bull semen cryobanking in a large volume which will be followed by second freezing in a regular insemination volume
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