Characterization and growth-depressing activity for chickens of several natural phenolic materials

Several natural phenolic materials were analyzed for gallic acid and were further characterized for dialyzability and flavonoid content. These materials were added to a diet and fed to broiler strain chicks for 4 weeks. The depression in growth caused by these phenolic materials was compared with that of tannic acid on a gallic acid equivalency basis. The activities relative to tannic acid (congruent to 100) were as follows: methyl gallate, 195; valonia, 117; wattle, 114; allepo tannic acid, 107; eucalyptus, 105, myrobalan, 98; tara crystals, 76; mangrove, 72; quebracho, 39; gallic acid, and ellagic acid, O. It was impossible to clearly relate the growth depressing activity of the materials to hydrolyzability or relative content of smaller phenols.