Abstract
Effects of the surfactant Sodium Dodecyl Sulfate (SDS) on the motility and viability of boar semen after thawing were evaluated. For such purpose, semen of twelve adult boars was collected twice a week, the rich portion of this semen was separated and frozen with different concentrations of SDS (0; 2.5; 5; 10; 20 and 40 mM). For freezing the semen was subjected to a cooling curve in an Ice Cube Freezer with a programmed curve as follows: From 5 to -5°C to -6°C/min, from -5 to -80 to -40°C/min in which semen was for 30 minutes. From -80 to -150 semen was cooled at a slope of -60°C/min being then plunged in liquid nitrogen. After collecting, before and after freezing/thawing, semen was evaluated for pH, cell concentration, viability and motility, as well as the percentage of normal sperm cells and agglutination level. Results indicated that before freezing sperm quality obtained from the different boars was always alkaline and very similar among boars. On average, pH was 7.50±0.27 ranging from 7.05 to 7.79 Viability, motility and agglutination level was respectively 62.7±9.9%: 4.8%±0.3 and 9.3%±1.82. After thawing, the best sperm quality was obtained when the semen was frozen with an SDS concentration of 0.2% W/V, in which values of viability reached 30.1% (±3.7). Based on the results one can conclude that SDS can be used to preserve boar semen for long periods, retaining semen quality after thawing.
Highlights
A large part of the boar’s population remains unqualified for semen freezing programs because of unsatisfactory post-thaw sperm quality and fertility rates
Besides cryopreservation of spermatozoa has been a great resource for the trade-in genetic material and gene banks, cooling and freezing are traumatic events for spermatozoa, the extent of these effects varies with the species
In the 4 h refrigeration process in which semen was diluted with the different extenders, no loss of viability, motility, or agglutination was observed, showing that, even for the highest concentrations of Sodium Dodecyl Sulfate (SDS) used, no chemical toxicity occurred (Table 2)
Summary
A large part of the boar’s population remains unqualified for semen freezing programs because of unsatisfactory post-thaw sperm quality and fertility rates. Besides cryopreservation of spermatozoa has been a great resource for the trade-in genetic material and gene banks, cooling and freezing are traumatic events for spermatozoa, the extent of these effects varies with the species. The increasing use of cryopreserved boar semen has motivated the research and development of extenders, cryoprotectants and freezing protocols, intending the preservation of semen in optimal conditions after thawing, but results still not satisfactory and a breakthrough in a commercial application has not yet occurred. Its use in some commercial production applications such as genetic transfer projects, frozen boar semen has not been used under production conditions as efficiently as liquidpreserved semen, due to the high susceptibility of boar spermatozoa to damage during cryopreservation and a complicated process of deep freezing. As a result of this transition, the cell may leak its contents to the surrounding medium
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