Improved conception rates in sows inseminated with cryopreserved boar spermatozoa prepared with a more optimal combination of osmolality and glycerol in the freezing extender

Abstract

Cryoprotectant agents (CPAs) are added in freezing extenders to prevent intracellular ice crystal formation. However, it has been reported that high dose of CPAs confer toxicity on spermatozoa. Recently, the reduction of intracellular water by a high osmolality solution has also resulted in the suppression of ice crystal formation in spermatozoa, suggesting that the optimal combination of glycerol concentration and freezing extender osmolality could contribute to the development of effective sperm cryopreservation techniques. In this study, we investigated the motility, membrane and acrosomal integrity of frozen-thawed boar spermatozoa treated with freezing extender (NSF) of varying osmolalities (300, 400, 500 mOsm/kg) and final concentrations of glycerol (0.5, 1, 2, 3%). The spermatozoa that were treated at 400 mOsm/kg and 2% glycerol showed significantly higher rates of motility and membrane integrity compared with those in other treatment groups. In addition, the conception and implantation rates of swine artificially inseminated with spermatozoa frozen by the novel freezing extender (conception; 79%, implantation; 57.5%) were significantly higher than those of frozen-thawed spermatozoa treated in the conventional NSF (300 mOsm/kg, 3% glycerol) (conception; 29%, implantation; 33.8%). From these results, we concluded that the novel hyperosmotic (400 mOsm/kg) and low-glycerol (final concentration 2%) freezing extender is beneficial for the cryopreservation of boar spermatozoa.

First report on in vivo fertility trial of frozen thawed boar semen in India#

“…The conception rate recorded in the present study was in close agreement with that reported by Einarsson et al (1973), but higher than that reported by Graham et al (1971) and lower than that reported by Okazaki et al (2009) in pigs inseminated utilizing frozen semen. The farrowing rate in the present study was comparable with the findings of Didion and Schoenbeck (1996), but higher than that reported by Bathgate et al (2008) and lower than that reported by Didion et al (2011).…”

The Effect of Glycerol Concentrations on the Post‐thaw In Vitro Characteristics of Cryopreserved Sex‐sorted Boar Spermatozoa

“…The results from the second experiment showed that a reduction from the commonly used 3% final glycerol concentration to 0.5–1% resulted in an increased maintenance of post‐thaw motility in both sex‐sorted and non‐sorted sperm frozen at low sperm concentrations. Beneficial effects on the post‐thaw motility of boar spermatozoa frozen in extenders containing a 2% final glycerol concentration, instead of the conventional 3%, have been previously described (Okazaki et al. 2009).…”

“…2002). In addition, it has been reported that these damaging effects are related to high glycerol levels (Okazaki et al. 2009) and are ultimately dependent on the number of sperm that are present (Colas 1975).…”

New strategies of boar sperm cryopreservation: Development of novel freezing and thawing methods with a focus on the roles of seminal plasma

“… Seminal plasma is immediately removed by centrifugation after semen collection. The sperm pellet is resuspended in pre‐treatment solution (Modena) that contains both common antibiotics, for example penicillin G and/or amikamycin, and polymyxin B. The resuspended semen is used to make frozen sperm according to Okazaki et al . (2009a).…”

“…2008). We also developed a novel freezing extender for pig sperm, which was adjusted for high‐osmotic pressure (400 mOsm/kg) and low‐glycerol concentration (final concentration: 2%) (Okazaki et al . 2009a).…”