effect of different harvesting techniques on the recovery and quality of bovine cumulus oocyte complexes

this study investigated the effect of different harvesting techniques on the recovery rate and quality of bovine cumulus oocyte complexes (cocs) and their subsequent developmental competence including in vitro maturation, fertilization and blastocyst formation. the cocs were retrieved from slaughter ovaries using aspiration, slicing, or aspiration followed by slicing. the cocs were examined microscopically then classed as a (at least three layers of cumulus), b (two layers of cumulus), c (one layer of cumulus, or degraded cytoplasm) or d (abnormal). the retrieved cocs yields per ovary differed (p≤0.05) between aspiration (2.31±0.21), slicing (6.65±1.65) and aspiration followed by slicing (3.72±1.43). differences in quality of collected cocs were observed for categories a, b and c but not for category d. oocyte diameter and in vitro developmental competence did not differ between the retrieving methods. in conclusion, aspiration can recover moderate numbers of oocytes ovary and about half of them can not be retrieved by this method. therefore when oocyte number is important, aspiration should be avoided and ovaries should be sliced.