Reasons for Anestrus in Japanese Brown Cows Fed Soybean Waste

Abstract

The residue of sorting, soybean waste is a mixture of numerous plant fragments and defective seeds. Japanese Brown cows fed this waste demonstrated anestrus. To investigate the reasons for this phenomenon, reverse-phase HPLC was used to measure plant-estrogen isoflavonoids in the feed. These measurements showed that, in addition to daidzein and genistein, soybean waste contains a great deal of formononetin (76.48μg/g) and coumestrol (89.01μg/g).Coumestro1, daidzein, and equol were detected in the serum of anestrous cows. After amounts of soybean waste in the diet were reduced, estrus occurred again within a month. At this time, no isoflavonoids were detected in the blood. These results indicate the possibility that isoflavonoids in soybean waste may have caused anestrus in the animals examined.