Survivability of caprine oocytes vitrified in conventional and open pulled straws

Abstract

The aim of this study was to compare the efficacy of conventional straw vitrification with open pulled straw vitrification in terms of cryosurvivability and damages caused to the oocytes. Two hundred immature goat cumulus oocyte complexes (COCs) were vitrified in a solution of ethylene glycol, dimethyl sulfoxide, and sucrose using either conventional straws (100 COCs) or open pulled straws (100 COCs). The COCs were warmed and observed for morphological damages and viability after 7 days of preservation in liquid nitrogen. Among the 100 COCs cryopreserved in each case, only 83 COCs were recovered after warming in conventional straw vitrification as compared to 94 COCs in open pulled straw vitrification. In terms of morphological survivability, the percentage of morphologically normal oocytes was greater (P < 0.01) in the case of open pulled straw vitrification (86.2%) as compared to conventional straw vitrification (59.0%). Viability percentage of live oocytes was greater (P < 0.01) in the case of open pulled straw vitrification (90.4%) as compared to conventional straw vitrification (66.3%). The results indicate that open pulled straw vitrification is better than conventional straw vitrification for rapid freezing of immature goat COCs in terms of both morphological survival and viability.