Cervical mucus changes in infertile ewes previously exposed to oestrogenic subterranean clover

Characteristics of cervical mucus were compared between groups of ewes which had previously grazed for long periods on either potently oestrogenic clover pasture (group A), mildly oestrogenic pasture (group B) or non-oestrogenic pasture (group C). No phytooestrogens were fed at the time of the study. The chloride content of mucus from group A ewes was significantly decreased, on a dry weight basis. The motility and survival of ram spermatozoa appeared similar in cervical mucus from groups A and B. There was no statistically significant difference between groups of ewes in either the total wet weight of mucus, the proportion of dry weight, or the degree of arborisation of mucus, at the time of oestrus. Mucus from group A ewes had a significantly decreased spinbarkheit, and a decreased ability to orientate sperum migration, when compared with group B. The group B ewes had a significantly smaller spinbarkheit than group C. Measurement of cervical mucus spinbarkheit offers promise as a diagnostic test for permanent clover infertility.