[Investigations in central Hessia on the occurrence of estrogenic activity content of cattle feed]

In 21 farms which requested consultation for reasons of infertility problems 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 (glycosid) bound oestrogen activity. Following sample preparation and extraction, the oestrogenic activity was determined using a radioreceptorassay and only those samples leading to a 50% displacement of the 3H-estradiol-17 beta-tracer were classified as oestrogen-positive; values 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 with the intention to allow an assignment of the oestrogenic activity to the following reference compounds, coumestrol, genistein, daidzein, formononetin, biochanin A, zeeralenon. With regard to free oestrogenic activity (aglycon) most of the grass silages were positive while-with one exception -the cornsilages were negative as were the hay-samples. The brewers grain samples were likewise positive and negative. Distinctly lower concentrations were found for the glycosidic bound oestrogenic 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 oestrogen-positive cornsilage-sample the activity found corresponded with zearalenon. Types and concentrations of the oestrogenic activity allow the conclusion that negative effects on reproduction cannot be excluded.