Content of phenolics and tannins in leaves and pods of some Acacia and Dichrostachys species and effects on vitro digestibility

Four browse legume foliages (leaves and pod fruits) from three species of Acacia (A. polyacantha, A. tortilis, A. nilotica) and Dichrostachys sp. native to Tanzania were evaluated for nutritive potential to establish levels and effect of normal phenoloics and tannins antinutritive factors (ANFs) on in vitro feed digestibility (IVD). Total extractable phenolics (TP), tannins (TT) were estimated by Folin-Ciocalteu assay, and condesed tannins (CT) by butanol/HCl assay. In leaves, total proanthocyanidins were assayed into constituent anthocyanidins' flavonids by high performance liquid chromatography (HPLC). Organic matter degradability (OMD) was estimated in vitro by gas production technique. Phenolics and tannins ANFs could limit utilization of browse fodder nutritive potential as supplements to ruminants consuming low quality roughages. Utilization of browse legume fodder could be optimized through reduction of tannin antinutritive activity. Under farmers' conditions, optimal utilization of browse could be achieved through feeding mixture of tanniferous browse with other feeds especially high in nitrogen to dilute tannin antinutritive activity