Ovarian function in cattle is controlled by complex local and systemic
feedback mechanisms which ensure that in >96% of estrous cycles only
one follicle will ovulate. Although there is a primary requirement for
gonadotropins in stimulating follicular growth, particularly during t
he final stages of follicle maturation, it is now becoming apparent th
at locally-produced factors, such as insulin-like growth factor-I (IGF
-I) and inhibin, have a modulating role. In addition to gonadotropins,
other systemic agents such as metabolic hormones (GH, IGF-I and insul
in), can also influence follicular growth. The ability to control the
growth of the dominant follicle, together with improved understanding
of the competing mechanisms controlling follicular recruitment and gro
wth, should enable more precise control of ovarian function and supero
vulation in cattle.