Effects of Collection Methods on Recovery Efficiency, Maturation Rate and Subsequent Embryonic Developmental Competence of Oocytes in Holstein Cow*

Holstein cow ovaries obtained at a slaughterhouse were used to study the influence of the oocyte collection methods (slicing, puncture, aspiration I and II) on recovery efficiency and subsequent in vitro maturation and embryonic development competence of immature oocytes recovered. In the slicing method, the whole ovarian was chopped into small pieces with a surgical blade. In the puncture method, the whole ovarian surface was punctured by 18-g needle. In other 2 aspiration methods, collected oocytes by aspirating from the visible follicles using an 18-g needle attached to a 5 ml syringe (aspiration I) or using a constant negetive pressure (-80 mmHg) with a vacuum pump (aspiration II). The oocytes were classified into 4 classes on the basis of the morphology of cumulus cells and cytoplasmic appearance of oocyte. Slicing (9.6±0.4) and puncture (9.7±0.4) yielded a larger number of oocytes per ovary than other two aspiration methods (aspiration I and II were 5.8±0.3 and 5.6±0.4, respectively) (p<0.05). The number of the highest quality oocytes (grade A) per ovary was significantly higher in slicing (4.2±0.2) and puncture (4.6±0.1) methods than in other methods (aspiration I and II were 1.2±0.2 and 1.4±0.2, respectively) (p<0.05). The rate of nuclear maturation of the highest and higher quality oocytes (grade A and grade B, respectively) was not affected by the oocytes collection methods. The oocytes collection methods also did not influence subsequent embryonic developmental competence after in vitro fertilization with M II stage oocytes. It is concluded that slicing and puncture methods of the ovaries can be used as an alternative techniques to aspiration by the syringe or vacuum pump. (