Effects of Environmental Estrogens on Reproductive Parameters in Domestic Animals

Shemesh, M. and Shore, L.S. 6 INTRODUCTION The present review describes a number of environmentally caused reproductive disorders in domestic animals which we have observed over the last five decades. This is of interest not only for animal husbandry but these environmental hormones may responsible for human health effects as well. However effects of phytoestrogens or other naturally occuring environmental hormones in humans have been very difficult to identify (1). Israeli scientists have been intensively interested in the effects of estrogenic substances since the early years of the State some sixty years ago (2). Mordechai Shemesh and Hans Lindner in conjunction with Natan Ayalon developed this initial interest into a major field of research to which Israel made major contributions (3,4). A major impetus to this work was Prof. Ayalon's clinical research on early embryonic death in cattle (5). First it was necessary to define the hormonal profile of estrus in cows and sheep. This was done using gas chromatography and recently developed competitive binding assays (6-10). Shemesh, Lindner and Ayalon then developed a radio-receptor assay for determining the presence of compounds with estrogenic activity in feed and forage (11). These methods were then used to demonstrate that the phytoestrogen (principally coumestrol) content in alfalfa (Medicago sativa) was increased following trauma (exposure to fungus) (12) and to identify the phytoestrogens in berseem clover (13). Legumes in particular produce phytoestrogens to activate the nod d gene on the Rhizobium to produce factors which will increase nodulation in the legume plant root (14). Each legume produces its own specific phytoestrogen, e.g., soya uses genistein. As mentioned, the principal phytoestrogen in alfalfa is coumestrol. A number of decades ago, we noticed a rise in the level of coumestrol in alfalfa plants to levels associated with reproductive disorders, unrelated to any known trauma to the plant. It was found that this rise in coumestrol was correlated with irrigation with treated sewage water. Using experimental hothouse and hydroponic experiments, it was found that the active agent in the sewage water was steroidal estrogen and that estrone was more potent than estradiol 17-β in promoting vegetative growth (14, 15). Effects of Environmental Estrogens on Reproductive Parameters in Domestic Animals