A comparison of two recovery methods of ovine oocytes for in vitro maturation

Ewe and ewe lamb ovaries obtained from a slaughterhouse were used to study the influence of the oocyte collection technique (aspiration and slicing) on the quantity and quality of immature oocytes recovered during the non-breeding season. In the aspiration technique, all visible follicles (2–6 mm in diameters) were aspirated with a 2 ml syringe (20-gauge needle) using PBS containing heparin and in the slicing technique; the follicles were incised with the aid of scalpel blade. The oocytes were classified on the basis of the cumulus cover and cytoplasmic appearance into four classes. The total number of ewe oocytes recovered and the yield of good-quality oocytes recovered per ovary by aspiration and slicing were 8.1 and 1.8, and 6.3 and 3.3, respectively. The corresponding values for ewe lambs were 3.7 and 0.8, and 4 and 1.7, respectively. The recovery of good quality oocytes using the slicing technique yielded more oocytes per ovary than aspiration in both ewe and ewe lambs during the non-breeding season.