Plasma progesterone concentrations during the reproductive cycle of ewes grazing Yarloop clover.

Abstract

Peripheral plasma progesterone concentrations were determined throughout the reproductive cycle of ewes grazing oestrogenic (Yarloop clover) pastures to provide an index of corpus luteum function. In ewes failing to conceive, luteal function declined after Day 13 and plasma progesterone concentrations had fallen to low `oestrus' values by the 15th day after mating. In contrast, normal cyclic ewes grazing non-oestrogenic pastures maintained significant luteal function until the 15th day after mating. The mean periods between matings in both groups