Effect of Glutathione on Cryopreservation of Buck Spermatozoa

Abstract

The aim of this study was to assay supplementation of glutathione into the traditional egg yolk extender for cryopreservation of goat spermatozoa. Semen ejaculates were collected from three fertile baladie bucks, aged 2–3 years using artificial vagina. Collected semen was divided into four aliquots; the first was diluted with Tris–egg yolk extender without any supplementation (Control), while the others were diluted with Tris–egg yolk extender supplemented with glutathione at levels of 2, 4 and 6 mM. Semen diluted at a rate of 1:4 and placed into a refrigerator at 5°C for 4 h to equilibrate. At the end of equilibration period, extended semen was packaged in liquid 0.25 ml French straws and stored in liquid nitrogen at –196°C. Thereafter, frozen semen was thawed by dipping the straws into a water bath at 37°C for 30 seconds. Percentages of progressive motility, live sperm, sperm abnormalities, plasma membrane and acrosome integrity were evaluated post dilution, equilibration period and post–thawing of spermatozoa. The results revealed that there were significant differences (P<0.05) of various sperm characteristics (percentages of sperm motility, live spermatozoa and sperm abnormalities, plasma membrane and acrosome integrity) in post–diluted, post equilibration and post thawing of goat semen. Treatment supplemented with 6 mM of glutathione led to significantly (P<0.05) improve the percentages of progressive motility, live spermatozoa and sperm abnormalities, plasma membrane and acrosome integrity of buck spermatozoa during different stages of cryopreservation compared to control and other levels of glutathione addition. While the extender supplanted with 2 mM glutathione was recorded the lowest value of semen parameters approximately. In conclusion, supplementation of Tris–egg yolk extender used for buck semen extender during freezing–thawing process with 6 mM of glutathione improves percentages of progressive motility, live spermatozoa, sperm abnormalities, plasma membrane and acrosome integrity of frozen–thawed buck spermatozoa.