Biochanin A improves fibre fermentation by cellulolytic bacteria

Aims The objective was to determine the effect of the isoflavone biochanin A (BCA) on rumen cellulolytic bacteria and consequent fermentative activity. Methods and Results When bovine microbial rumen cell suspensions (n = 3) were incubated (24 h, 39 °C) with ground hay, cellulolytic bacteria proliferated, short chain fatty acids were produced and pH declined. Biochanin A (30 μg mL-1) had no effect on the number of cellulolyic bacteria or pH, but increased acetate, propionate and total SCFA production. Addition of BCA improved total digestibility when cell suspensions (n = 3) were incubated (48 h, 39 °C) with ground hay, Avicel®, or filter paper. Fibrobacter succinogenes S85, Ruminococcus flavefaciens 8, and R. albus 8 were directly inhibited by BCA. Synergistic antimicrobial activity was observed with BCA and heat killed cultures of cellulolytic bacteria, but the effects were species dependent. Conclusions These results indicate that BCA improves fiber degradation by influencing cellulolytic bacteria competition and guild composition. Significance and Impact of the Study BCA could serve as a feed additive to improve cellulosis when cattle are consuming high fiber diets. Future research is needed to evaluate the effect of BCA on fiber degradation and utilization in vivo. This article is protected by copyright. All rights reserved.