Optimization of the Thawing Protocol for Iberian Boar Sperm.

Abstract

Simple SummaryLimited attention is paid to sperm thawing protocols, and their study could be relevant to endangered species or breeds, especially for cryopreserved material present in the existing gene banks. The aim of this study was to determine the most optimal thawing protocol for Iberian boar sperm through testing different thawing rates and different modifications of the thawing extender. Based on the findings, the most optimal results were obtained thawing at 70 °C for 8 s with the inclusion of cyclodextrins loaded with cholesterol (CLC) in the extender, revealing the importance of adapting the thawing protocols.Thawing protocols have been barely studied, and their modifications may lead to a substantial improvement in post-thawing sperm quality, which could be of great relevance to existing sperm banks, such as those for Iberian pig breeds with varieties in danger of extinction. For that, the study aimed to evaluate different thawing rates and to evaluate modifications in the composition of the thawing extender (basic pH to 8–8.2, incorporation of cyclodextrins loaded with cholesterol [CLC] and the incorporation of ion chelators [EDTA and EGTA]). After thawing, overall sperm motility and kinematic parameters, acrosome status and sperm membrane integrity were evaluated. The most optimal results were obtained with the thawing rate reaching 70 °C for 8 s with the inclusion of 12.5 mg of CLC/500 × 106 spermatozoa in the thawing extender, which showed an improvement compared to the control at 70 °C. In conclusion, to adapt the thawing conditions may be relevant, especially for endangered species or breeds such as some varieties of Iberian pig, since this process could also be used in samples cryopreserved in gene banks.