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Discussion on Research Summary: Improved freezing technique for semen
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Moderator:
DrO
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Posted on Thursday, Nov 8, 2007 - 8:03 am:
I am not sure what the directional freezing technique, based on a multi-thermal gradient (MTG) is but it looks hopeful for the hit and miss method currently used in horses for freezing semen. MTG appears to be a device that controls the temperatures during freezing. It appears to take the semen through a series of step wise temperature changes with the goal being to minimize ice crystal formation to preserve the semen cells.
DrO
Reprod Domest Anim. 2007 Dec;42(6):610-615.
Directional Freezing of Equine Semen in Large Volumes.
Saragusty J, Gacitua H, Pettit MT, Arav A.
Institute of Animal Sciences, Agricultural Research Organization, The Volcani Center, Bet Dagan, Israel.
Despite its potential impact on the horse industry, sperm cryopreservation is not an established technology throughout the industry, for a number of reasons that include a reduction in pregnancy rate and increased cost per pregnancy. We have evaluated a novel directional freezing technique, based on a multi-thermal gradient (MTG), by comparing it with the conventional, controlled-rate cryopreservation method (CRCM). Ninety-seven ejaculates with >/=50% motility, collected from 31 stallions were each divided into two parts and subsequently frozen by either MTG or CRCM. Frozen samples were then stored in liquid nitrogen until thawing. The two treatments were evaluated by three methods: progressive linear motility (PLM), viability stain and hypoosmotic swelling (HOS) test. High correlation was found between the three evaluation methods for all post-thaw samples. Eighty-eight per cent of the ejaculates frozen by MTG had post-thaw PLM >/=35%, whereas only 59% of the ejaculates frozen by CRCM had such motility. Post-thaw evaluations of samples frozen by MTG and CRCM were: PLM - 50.2 +/- 1.5% and 37.4 +/- 1.5%, respectively; viability - 53.6 +/- 1.5% and 39.5 +/- 1.4%, respectively; membrane integrity, as evaluated by HOS - 36.2 +/- 1.3% and 26.5 +/- 1.1%, respectively. The differences according to all the evaluation methods were highly significant (p < 0.001), and the results indicate that freezing stallion semen by MTG is superior to CRCM.
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