The degradation of red clover isoflavones was studied in vitro using a rumen fluid buffer system. Various amounts of red clover extract (5–75 mg) together with hay or concentrate‐rich diet were added to 40 ml of rumen fluid obtained from non‐lactating and lactating dairy cows, respectively, and incubated for 0, 3, 6, 12 or 24 hr. Following incubation, concentrations of daidzein, genistein, formononetin, biochanin A and equol were determined in the samples. After 3 hr of incubation, isoflavone metabolism and equol production could be observed. The results obtained indicate that hay diet provides better conditions for isoflavone metabolism, as concentrations of daidzein, formononetin and biochanin A were higher in incubations based on the concentrate‐rich diet and the production of equol was higher in incubations based on the hay diet. Furthermore, in incubations with higher amounts of added clover extract, a decrease in equol production was observed. Further studies are needed to clarify the role of adaptation of rumen microflora on isoflavone degradation kinetics and to clarify the interrelationship between various dietary factors, rumen microbiota and isoflavones. The knowledge of isoflavone metabolism kinetics in dependence on studied factors will be useful for the optimization of feeding dose.

中文翻译：

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瘤胃液中红三叶草异黄酮的体外代谢。

使用瘤胃液缓冲系统在体外研究了红三叶草异黄酮的降解。将不同量的红三叶草提取物（5-75 mg）与干草或富含浓缩物的饲料分别加入 40 ml 非泌乳和泌乳奶牛的瘤胃液中，培养 0、3、6、12或 24 小时。孵育后，测定样品中黄豆苷元、染料木黄酮、芒柄花素、生物链素 A 和雌马酚的浓度。孵育 3 小时后，可以观察到异黄酮代谢和雌马酚的产生。获得的结果表明，干草饮食为异黄酮代谢提供了更好的条件，因为基于富含浓缩物饮食的孵化中黄豆苷元、毛豆角苷和生物素 A 的浓度更高，而基于干草饮食的孵化中雌马酚的产量更高。此外，在添加更多三叶草提取物的孵化过程中，观察到雌马酚产量下降。需要进一步的研究来阐明瘤胃微生物群的适应性对异黄酮降解动力学的作用，并阐明各种饮食因素、瘤胃微生物群和异黄酮之间的相互关系。依赖于研究因素的异黄酮代谢动力学知识将有助于优化喂养剂量。