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The effect of estrogenic alfalfa consumption in cyclic ewes : the plasma gonadotropin profile throughout the estrous cycle Hettle, J. Alan L.


Phyto-estrogens are known to cause reproductive failures in the ewe by interacting with uterine estrogen receptors. Further studies have demonstrated anomalous ovarian steroid levels which implicate the hypothalamus and pituitary. Estrogen receptors which bind phyto-estrogens have been recently demonstrated in ovine hypothalamic and pituitary tissues. It would then seem logical to assume that estrogen interactions in these tissues will be altered and result in abnormal gonadotropic synthesis or secretion. This project employed vaginal cytolological studies and ovine Luteinizing Hormone radioimmunoassays to characterize the plasma LH profiles and estrous cycles in ewes fed orchard grass hay or phyto-estrogenic alfalfa. Results indicate that the consumption of phyto-estrogenic activity will decrease the pulsatile nature of LH secretion and delay the LH peak further into the estrus period when compared with ewes fed a ration devoid of phyto-estrogenic activity. Vaginal cytological studies also demonstrate phyto-estrogenic activity through elevated karyopyknotic index values.

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