Wether bioassay of annual pasture legumes. IV. The oestrogenic activity of annual medic pastures

Abstract

The oestrogenic activity of seven medic pastures measured at the time of flowering , by wether bioassay was highly correlated with their coumestrol content. The most active varieties M. littoralis (Harbinger) and M. truncatula (Cyprus) produced wether teat length increases equivalent to those resulting from injection of 8 µg of stilboestrol daily. M. scutellata (snail medic) and M. polymorpha (common burr medic) had no measurable activity.

Medic pastures had only low coumestrol contents in the pre-flowering stages. Dry annual medic swards had greater coumestrol contents than the green pastures.

At the burr development stage most coumestrol is found in the mature leaves, with only relatively insignificant quantities in the stems and pods. In dry material, however, the stems and pods had very high coumestrol contents.

A table is presented of the coumestrol content of representative medic species tested at the flowering stage.