Phytoestrogen Content of Birdsfoot Trefoil and Red Clover: Effects of Growth Stage and Ensiling Method

Abstract

The phytoestrogen content of birdsfoot trefoil (Lotus corniculatus L.) and red clover (Trifolium pratense L.) was determined. In addition, the effects of growth stage, wilting and ensiling additives on content were studied. Birdsfoot trefoil raw material and silage contained only traces of phytoestrogens. In red clover raw material and silage, the phytoestrogen content varied from 0.8% to 1.1% of dry matter. Content was affected by growth stage of the plant and wilting. Formononetin concentration decreased as the plant matured from budding to flowering stage, and wilting from 25% to 40% of dry matter content decreased genistein and biochanin A content. The phytoestrogen content of red clover silage was 18% higher than that of raw material. Silage additives also affected the content. Silage ensiled with an additive containing Lactobacillus plantarum bacterial inoculate had higher concentrations of genistein and biochanin A than silage made with formic acid.

Keywords:

• biochanin A
• formononetin
• genistein
• Lotus corniculatus
• silage
• Trifolium pratense

Acknowledgments

This study forms part of an EU-funded international research project, known as Low-input animal production based on forage legumes for silage (LEGSIL) (Nissinen et al., 2000).