Publication details

Study of soybean-derived isoflavones metabolism in the rumen of lactating dairy cows



Year of publication 2011
Type Conference abstract
MU Faculty or unit

Faculty of Science

Description In order to study quantitative aspects of the isoflavones metabolism in the rumen, it is neccesary to quantify accurately their levels in rumen fluid. The objective of the study was to optimise and validate the HPLC method for the determination of isoflavones genistein, daidzein, glycitein and metabolite equol in bovine rumen fluid. The experiment was carried out on three lactating Holstein cows fitted with rumen cannulas. The experiment lasted 14 days and was divided into an adaptation period (10-d) followed by a 4-d collecting period. Cows were fed individually twice daily the diet based on maize silage, lucerne hay and supplemental mixture that contained extruded full-fat soya as a source of isoflavones. During the collecting period individual samples of ruminal fluid were taken in five time intervals – T0, T1, T2, T3 and T4, it is prior feeding and 2, 4, 7, 10 h post feeding, respectively. Extruded full-fat soya used in the study contained 377.9 mg/kg of daidzein, 558.2 mg/kg of genistein and 129.6 mg/kg of glycitein, resulting in average total isoflavones intake of 1330,8 mg/d (it is 456.0 mg/d of daidzein, 693.3 mg/d of genistein, 181. 5 mg/d of glycitein). Concentration of daidzein in the rumen fluid varied from 88.8 ug/L (T2) to 102.3 ug/L (T1) with an average value of 95.8 ug/L. Mean concentration of equol, a metabolite of daidzein, in rumen was 41.1 ug/L. The lowest concentration (19.4 ug/L) was found at T1 and then raised up to 56.2 ug/L (T3). Average concentration of genistein in rumen fluid was 237,4 ug/L. The lowest concentration (209.5 ug/L) was determined prior feeding (T0). Concentration of genistein in other collection times was relatively stable ranging from 241.6 to 248.0 ug/L. Concentration of glycitein was on average 22.4 ug/L and did not vary greatly among collecting times.
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