In this study, bovine oocytes were classified according to morphology and quality. A total of 105 ovaries recovered from slaughterhouse, 2-4 h to our laboratory. After inspection of the functional mass on the ovarian surface for determination of cyclic phases, ovaries were classified as follicular (n=66), luteal (n=33) and noncyclic (n=6).

Cumulus oocyte complexes (COCs) were aspirated and examined stereomicroscopically. Each COCs was assigned to one of three quality based groups on the appearance of the cumulus cells: COC-A: the oocytes with homogenous ooplasm surrounded by multilayer (>3 layers) compact and bright cumulus cells, COC-B: less compact and surrounded by a layer dark cumulus cells, and COC-C: strongly expanded cumulus with dark spots or denuded.

Totally 975 COCs, consisting of A class (n=341), B class (n=374) and C class (n=260) were determined. The mean COCs counts were 3.52±0.38 in A class, 3.42±0.28 B class and 2.36±0.24 C class in follicular phase group; 2.79±0.51 A class, 3.82±0.41 B class and 2.64±0.43 C class in luteal phase group. There was no significant difference between the mean COCs counts recovered from follicular and luteal ovarian phase (p>0,05).

In conclusion, there is no effect of ovarian phase on COCs quality and counts. Therefore, recovered oocytes from follicular and/or luteal phases are suitable for in-vitro studies.