Proanthocyanadin (condensed tannin) content of Brachystegia spiciformis browse harvested at different stages of growth from three sites in Zimbabwe

Abstract

The extractable and insoluble (bound to protein or neutral detergent fibre [NDF] proanthocyanadin (PA) of the tree species Brachystegia spiciformis (Musasa) harvested at different stages of growth from three sites with different soil types in Zimbabwe was analysed by the n-butanol-HCl method. Brachystegia spiciformis samples from one site showed significantly lower (P < 0.05) PA values than those from the other two sites. Higher (P < 0.01) proportions of insoluble PA (insoluble PA/total PA) were observed in leaves than in twigs. Substantial levels of PA were detected as bound tannins, ranging from 470–804g kg^–1. These results suggest that measurement of bound condensed tannin is necessary when identifying forages containing condensed tannins. The higher contents of PA in the leaves that were harvested when mature than in young leaves could explain why animals prefer eating young rather than mature leaves of B. spiciformis.

Keywords: browse legume, proanthocyanidins n-butanol, stages

African Journal of Range & Forage Science 2006, 23(3): 197–200