Comparison of Harvesting Techniques and Corpus Luteum Bearing on Recovery and Quality of Sheep Oocytes

The aim of this study was to assess the effects of the slicing and puncture process and CL-bearing on the recovery and efficiency of oocytes from sheep ovaries. In the present study, 100 ovaries with corpus luteum (CL+) and without corpus luteum (CL-) were used. Ovaries weight, length, width, and thickness were measured. Using the slicing and puncture methods, the follicles were counted. The follicles were grouped in small follicles (< 2 mm), medium follicles (2-5 mm), and large follicles (> 5 mm). Oocytes have been categorized as compact cumulus / oocyte complexes (COCs), expanded (EXO), partially denuded (PDO), denuded (DO), and degenerated (DEG) oocytes according to their morphology. Our results revealed that the average weight of sheep ovaries CL+ (0.868 g) were significantly (P>0.05) greater than ovaries CL- 0.727 g, but there were no significant differences in length or width. The average number of total and compact oocytes/ovary when slicing was significantly (P>0.05) higher than puncture techniques were used (6.87 vs. 5.70) and (3.39 vs. 2.46), respectively. CL+ ovaries showed insignificantly (P<0.05) lower oocyte recovery rate in total, compact (COCs) and denuded oocytes, while the opposite of this trend in partial denuded and degenerated oocytes as compared to CL- ovaries. In conclusion, the cumulus-oocyte complexes obtained from sheep ovaries without CL and from the slicing rather than puncture method can be used for in vitro embryo production of sheep.