A changed responsiveness to oestrogen in ewes with clover disease.

When clover-infertile ewes are subsequently exposed to non-oestrogenic pasture, they have a reduced fertilization rate, due to an inability to store spermatozoa in the cervix, and the cervical mucus has a reduced spinnbarkeit, caused by a slower response to oestrogenic stimulation. Vaginal cell keratinization and oestrous behaviour occurred more slowly after treatment of affected ewes with oestrogen. Other changes in affected ewes suggest that phyto-oestrogens have permanent mild differentiating effects on adults. Sexual behaviour is masculinized, the cervix takes on a uterine-like appearance and the genital tract becomes permanently oestrogenized. The manner in which these changes relate to the altered responsiveness to oestrogen remains to be clarified.