Relationships among Soluble Phenolics, Insoluble Proanthocyanidins and Fiber in East African Browse Species

Abstract

Tannins and other phenolics interfere with the interpretation of results from the detergent system of forage analysis. Leaves and apices from browse can contain up to 50% of their organic matter as phenolics including tannins that are soluble in aqueous acetone. Leaves and apices from browse that contain soluble proanthocyanidins (condensed tannins) also contain proanthocyanidins that are insoluble in both aqueous acetone and neutral-detergent. The content of insoluble proanthocyanidins is positively correlated with neutral-detergent fiber (NDF) and fiber-bound nitrogen. Condensed tannins may bind protein and make it less soluble in neutral-detergent and increase the content of NDF. The behavior of phenolics and tannins in the detergent system of forage analysis is discussed in relationship to estimating the nutritive value of 17 East African browse species.