Nutritional composition and condensed tannin concentration changes as browse leaves become litter

Abstract

The role of condensed tannins (CT) in ruminant nutrition and health makes changes in leaf litter (LL) after abscission of interest. This study compared the effect of different drying methods of green leaves (GL) with that of natural drying of LL on CT, fibre, crude protein (CP) and phosphorus (P) concentrations in nine Texas browse species. Leaves harvested before autumn shedding were oven-dried (OD) or freeze-dried (FD). Where different (P < 0.05), extractable CT concentrations were higher while protein- and fibre-bound CT concentrations were lower in GL-FD than in LL. Drying method changed total CT concentration in three species. Where different, fibre fraction concentrations were greater in LL than in GL, regardless of drying method. In some species, CP and P concentrations were lower in LL than in GL, but in five species they did not change (P > 0.05) from GL to LL, with CP concentrations ranging from 63 to 151 g kg(-1) in the latter. Browse LL had high nutritive value and CT concentrations, explaining why browsing ruminants utilise this feed resource. However, changes in nutrient and CT concentrations as leaves become litter in some species mean that information on one is not necessarily applicable to the other.