Natural and anthropogenic environmental oestrogens:
the scientific basis for risk assessment

Clover phytoestrogens in sheep in Western Australia

N. R. Adams
CSIRO Division of Animal Production, PO, Wembley WA 6014 Australia.
E-mail: [email protected]

Abstract: Oestrogenic isoflavone compounds in clover continue to cause reproductive losses in sheep in Western Australia. The phytoestrogens can cause two infertility syndromes in sheep, one of which resolves after the phytoestrogen is removed, while the other form of infertility is permanent and increases in severity with continued exposure to phytoestrogen. There is often a poor association between the extent of exposure to phytoestrogens 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 phytoestrogens were not appreciated.

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