Most donors of embryos are inseminated, so fertilization occurs in vivo. With in vitro fertilization (IVF), sperm are added to the oocytes in a test tube or petri dish.
Usually, the processes of in vitro maturation, fertilization and culture go together.
IVF has been successful in all farm animals, but it has proven especially difficult in horses and has been commercially applied most frequently to cattle, especially to females with infertility problems.
To obtains oocytes from cows, a long needles is inserted into the ovary through the vaginal wall in the same way that oocytes are recovered from infertile women for IVF.
Ultrasonography is used to guide the needle so oocytes can be aspirated from ovarian follicles.
An often used, alternative approach is to obtain oocytes from slaughterhouse ovaries to produce relatively inexpensive IVF-derived embryos for research, specific export markets and for getting dairy cattle pregnant in heat-stressed environments.
In Vitro Fertilization of Dairy Cattles
