O

Glossary

Oestrus Period of sexual receptivity.

OIE International Office of Epizooties.

Oocytes Immature ova.

Ordinal scale A number which defines a thing (trait) in a standard scale.

Organogenesis The production of organ systems during animal embryogenesis.

Ovulation Release of the female germ cell (egg or ovum) by the ovary. Cows usually ovulate several hours (up to 15 hours) after the end of estrus or standing heat.

Ovum Pick Up technique (OPU) Collection of eggs from donors through an ultrasonically guided needle inserted into the ovary.