Clover phyto-oestrogens in sheep in Western Australia

Oestrogenic isoflavone compounds in clover continue to cause reproductive losses in sheep in Western Australia. The phyto-oestrogens can cause two infertility syndromes in sheep, one of which resolves after the phyto-oestrogen is removed, while the other form of infertility is permanent and increases in severity with continued exposure to phyto-oestrogen. There is often a poor association between the extent of exposure to phyto-oestrogens and the severity of the infertility, but the reason for this is not fully known. The balance between epidemiological and laboratory-based research over the past 50 years has not always been optimal, delaying the application of measures to control the problem. To a large extent, this imbalance arose because numerous differences between species in their response to phytooestrogens were not appreciated.