To study the anatomical and physiological factors that affect the bovine cumulus-oocyte complexes (COCs) quality, were examined 396 ovaries obtained after slaughter of 198 Bos indicus females. Ovaries were categorized in nulliparous vs multiparous and progesterone (P4 - a corpus luteum at least one ovary) vs without progesterone (NP4 - absence of corpus luteum). All follicles were measured and categorized into small (<6mm), medium (6 to 9mm) or large (>9mm). Then all follicles were punctured and COCs recovered and assessed morphologically. There was no difference in COCs recovery rate or quality from nulliparous vs multiparous females. The rate of denuded or degenerated oocytes was higher in NP4 and expanded COCs were higher in P4. The COCs recovery and grades I and II rates were similar in P4 vs NP4 groups. Small follicles have lower COCs recovery rate than medium or large follicles, but the grade I oocytes rates was higher in small and medium follicles. In conclusion, the category of donor female and progesterone did not affect the quality of COCs selected for PIV and smaller follicles present best quality of COCs.
Cumulus-oocyte complex; follicles; OPU; progesterone, cattle.