Endocrine regulation of puberty in cows and ewes.

Abstract

Sexual maturation in cows and ewes is modulated through changes in hypothalamic inhibition. This inhibition results in little or no stimulation of the release of gonadotrophins from the anterior pituitary. The ovary has a primary role in inhibiting gonadotrophin secretion during the prepubertal period and the responsiveness to the negative feedback effects of oestrogen decreases during the peripubertal period. There is also an increased secretion of ovarian progesterone during the peripubertal period but its role in the process of sexual maturation is not clear. Photoperiodic cues and dietary intake act upon the hypothalamus to modulate gonadotrophin secretion during sexual maturation and, in turn, influence the time when puberty occurs.