Comparison of oocyte collection methods using caprine ovaries and in vitro embryo culture

Abstract

The objectives of this study were to elucidate the efficiency of oocyte recovery through different techniques, grading of oocytes, and optimization of the caprine in vitro embryo production system. Ovaries were collected from the local slaughterhouse and classified based on the presence of a corpus luteum (CL). A total of 442 cumulus-oocyte complexes (COC) were retrieved from 178 ovaries aseptically through aspiration, slicing, and slashing techniques. Collected COC were categorized according to the compactness of cumulus cells around the oocyte and the homogeneous cytoplasm. In vitro maturation of graded COC was done for 27 h. In vitro fertilization (IVF) of the matured oocytes was performed using frozen semen. At 16 h of IVF, presumptive zygotes were in vitro cultured for 7 d. It was found that 31% of ovaries had a CL and 69% did not have a CL. The number of oocytes recovered per ovary (2.89 ± 0.22) and the percentage of excellent oocytes, grade A (29.84 ± 4.00%) and B (44.80 ± 2.32%), were significantly greater from the slashing technique than from the aspiration (2.16 ± 0.30 and 11.80 ± 0.61%, 30.80 ± 3.56%, respectively) and slicing technique (2.40 ± 0.15 and 22.62 ± 7.81%, 16.10 ± 1.29%, respectively). Results revealed a significantly greater ( P < 0.05) rate of grade A (61.14 ± 5.83%, 36.04 ± 0.32%, and 22.51 ± 3.07%) and grade B oocytes (23.31 ± 1.61%, 28.90 ± 7.47%, and 28.29 ± 5.04%) reached the metaphase II stage recovered from 3 methods (slashing, slicing and aspiration, respectively). The cleavage and blastocyst rates of presumptive zygotes were found to be 74.15 ± 6.80% and 37.50%, respectively. This study suggests that the slashing technique is more suitable for harvesting a greater number and superior quality of COC. The culture conditions used in this experiment were found to be optimal and efficiently supported in vitro maturation, IVF, and subsequent development of goat embryos to the blastocyst stage. Based on the results of this study, the culture conditions and slashing technique could be used in caprine in vitro embryo production and advanced biotechnology research.