Quantification of condensed tannins in forage species comparing oven dryings vs. lyophilized samples for the Butanol-HCl methodology

Abstract

The present work was developed on the natural grassland of a silvopastoral system of the Lower Paraná Delta and had as objectives: a) To quantify the presence of Condensed Tannins (TC) in the dry matter (DM) in the main forage species and, b) Compare in this TC quantification the methods of oven drying vs. the lyophilization of the samples for the Butanol-HCl methodology, and to evaluate if there are significant differences in the results between the drying methods. The analyzed species are distributed in the EEA INTA Delta del Paraná, locality of Otamendi, Province of Buenos Aires. Nine herbaceous plants were selected: Alternanthera philoxeroides (lagunilla), Echinochloa polystachya (lagoon grass), Glyceria multiflora (water grass), Leersia hexandra (arrocillo), Cinnagrostis viridiflavescens (silver grass), Paspalum urvillei (male grass), Bromus catharticus (grass), Carex chilensis (straw), Lotus tenuis (lotus) and four woody species: Amorpha fruticosa (false indigo), Gleditsia triacanthos (black acacia), Populus sp. (poplar) and Salix sp. (willow), the latter two cultivated. For Populus and Salix leaves, the subsamples were divided into 2 categories: young leaves and adult leaves. The results show that TCs were detected only in three species and only in the freeze-dried samples: Salix spp. (Young willow leaf) 6.38% /DM, (Adult leaf willow) 4.34% DM; Amorpha fruticosa 6.12% /DM (False indigo) and Gleditsia triacanthos 6.71% /DM (Black Acacia).