Permanent infertility in ewes exposed to plant oestrogens [sheep; subterranean clover; Trifolium subterraneum]
1990
Adams, N.R. (Commonwealth Scientific and Industrial Research Organisation, Wembley (Australia). Div. of Animal Production)
Ewes grazing oestrogenic pastures develop lesions which result from an 'organisational' action of oestrogen, causing a mild sexual transdifferentiation to occur in ewes during adult life, with the main lesion being found in the cervix. Diagnosis of the problem depends primarily on detection of the pathological changes, rather than history or clinical signs. On average, affected flocks have around a 10 percent increase in non-pregnant ewes, but most farmers can achieve an acceptable lambing rate by increasing their management and feed inputs to produce more twin lambs. Agronomic approaches have been used in the past to combat 'clover disease', but further progress with the present problem may depend on the development of animal-based solutions.
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