Content of isoflavones and macroelements in five clover species (Trifolium spp.) grown on pasture: the influence of a slope aspect

This study aimed to determine the content of isoflavones (biochanin A, daidzein, formononetin and genistein) and macroelements in 5 clover species: 1) hare’s-foot clover ( Trifolium arvense L.), 2) field clover ( T. campestre Schreb.), 3) suckling clover ( T. dubium Sibth.), 4) alsike clover ( T. hybridum L.), 5) zigzag clover ( T. medium L.) collected from different slope aspects (north-and south-facing slopes) of pasture in Northeastern Bulgaria. The content of biochanin A (0.317 mg g -1 ), daidzein (0.201 mg g -1 ) and genistein (0.205 mg g -1 ) was found to increase significantly on the south-facing slope of pasture. Zigzag clover (0.117 mg g -1 ) and hare’s-foot clover (0.119 mg g -1 ) samples from the north-facing slope had the lowest content of daidzein, which was higher in the other clover samples. Alsike clover on the south-facing slope of pasture had signifi- cantly higher genistein content (0.219 mg g -1 ) than the other clovers. The highest concentration of formononetin was detected in alsike clover (0.167 mg g -1 ) and field clover (0.175 mg g -1 ) on the south-facing slope of pasture. The south-facing slope resulted in significantly higher potassium (27.00 g kg -1 ), calcium (24.50 g kg -1 ), magnesium (2.30 g kg -1 ) and phosphorus (3.24 g kg -1 ) content in the plants than the north-facing slope of pasture. The content of these isoflavones and macroelements depended on the slope aspect and clover species. The clover grown on the southern slope of pasture had high content of isoflavones and macroelements. The content of isoflavones and macroelements revealed in the present study could provide useful information for development of clover cultivation management strategies, such as the selection of species, to ensure healthy animal feeding.