The effect of nutritive status on oestrus, ovulation, and Graafian follicles in Merino ewes

Abstract

Progesterone suppression of ovarian cycles and the subsequent "release" phenomena following cessation of injections were examined in three groups of ewes under different nutritional regimens. A significant delay in the period from the final progesterone injection to onset of oestrus occurred in ewes on a restricted diet compared with ewes on a maintenance diet. A strong relationship existed within the restricted group between body weight and the period to onset of oestrus. Gonadotrophin appeared to compensate for the effect of undernutrition.