EFFECT OF PROGESTERONE AND DURATION OF PASTURE INTAKE ON CERVICAL MUCUS RESPONSE TO PHYTO-OESTROGENS IN SHEEP

Progesterone administered to ewes at the rate of 10 mg per day during grazing of an oestrogenically active sward of Trifolium subterraneum L. cv. Dinninup reduced the magnitude of cervical mucus response to the test pasture. Doses of 0.1 and 1.0 mg of progesterone increased the magnitude and duration of the response. Cervical mucus responses to a strain of subterranean clover high in genistein (Northam A) were reduced when the ewes grazed on the test pasture for 8-10 days prior to bioassay. Reduction in response was significantly less on a strain high in formononetin (Dinninup). It was concluded that the rate of inactivation of genistein by the sheep is increased by a period of continuous ingestion. © 1969 CSIRO. All rights reserved.