INVESTIGATIONS ON THE OCCURRENCE AND CONTENT OF ESTROGENIC ACTIVITY IN CATTLE FEED IN THE STATE OF CENTRAL HESSIA, GERMANY

In 21 farms which requested consultation for reasons of infertility pr oblems feed samples (grass silage, n = 20; cornsilage, n = 19; hay, n = 9; cereal mixture, n = 3, brewers grains, n = 5, ensiled sugar beet tops, n = 1) were drawn for assay of free (aglycon) and glycosidic (gl ycosid) bound oestrogen activity. Following sample preparation and ext raction, the oestrogenic activity was determined using a radioreceptor assay and only those samples leading to a 50 % displacement of the H-3 -estradiol-17 beta-tracer were classified as oestrogen-positive; value s were expressed as ng 17 beta-estradiol equivalents per g dry matter. Selected samples clearly oestrogen-positive in the aglycone fraction were submitted to separation by HPLC and cytograms were established wi th the intention to allow an assignment of the oestrogenic activity to the following reference compounds, coumestrol, genistein, daidzein, f ormononetin, biochanin A, zearalenon. With regard to free oestrogenic activity (aglycon) most of the grass silages were positive while - wit h one exception - the cornsilages were negative as were the hay-sample s. The brewers grain samples were likewise positive and negative. Dist inctly lower concentrations were found for the glycosidic bound oestro genic activity with highest levels determined in hay. Results obtained after application of HPLC showed that the oestrogenic activity could particularly be attributed to daidzein and biochanin A. In the only oe strogen-positive cornsilage-sample the activity found corresponded wit h zearalenon. Types and concentrations of the oestrogenic activity all ow the conclusion that negative effects on reproduction cannot be excl uded.