Calf Production by In Vitro Fertilization of Follicular Oocytes Matured In Vitro
The procedure for bovine in vitro fertilization (IVF) involving the collection of ovaries at the slaughterhouse, maturation of oocytes in vitro (IVM), capacitation and insemination in vitro and development to blastocysts in vitro is well established. Transportation of ovaries in physiological saline at 23 and 38℃ afforded a large number of oocytes capable to develop to blastocysts after in vitro maturation and fertilization. The follicular contents were scrubbed out with a small spoon after incision of the follicle to collect a large number of oocytes (13.4 per pair of ovaries) rather than aspiration with an 18-G needle (7.2 per pair of ovaries). Cleavage ability after maturation and in vitro fertilization depended on the characteristics of the cumulus cells surrounding the oocytes. A period of 20 hr for the culture to achieve maturation and for the time of the insemination was preferable to 24 or 28 he for the development to blastocyst. For in vitro capacitation of sperm, heparin was effective and the oocytes fertilized by heparin-treated sperm developed well to full term after transfer to recipient cattle. Bovine IVM/IVF can be used for commercial beef calf production and for the supply of embryos with known stages of development for research purposes and for the development of new technologies.