Studies on the oestrogenic potency of subtrerranean clover (Trifolium subterraneum L.) in South-Western Australia

Abstract

The oestrogenic activity of three varieties of subterranean clover (Trifolium subterraneum L.) — Dwalganup, Yarloop, and Mount Barker — was measured by means of the response in fresh weight of uterus + cervix in both ovariectomized virgin and ovariectomized cast-for-age ewes. The standard oestrogen used was diethylstilboestrol, administered intramuscularly. There was no difference between virgin and aged sheep in the slope of the dose-response curve. Thus aged sheep can be used for biological assay of oestrogens. The varieties Yarloop and Dwalganup were highly potent; Mount Barker produced only slight increases in uterine weight. The relevance of these varietal differences in oestrogenic potency is discussed in relation to the sheep infertility problem associated with oestrogenic pastures.