Condensed tannins concentration of selected prairie legume forages as affected by phenological stages during two consecutive growth seasons in western Canada.

Li, Y., Iwaasa, A.D., Wang, Y., Jin, L., Han, G.D., and Zhao, M.G. (2014). "Condensed tannins concentration of selected prairie legume forages as affected by phenological stages during two consecutive growth seasons in western Canada.", Canadian Journal of Plant Science, 94(5), pp. 817-826. doi : 10.4141/CJPS2013-234  Access to full text

Abstract

Although studies have shown that condensed tannins (CT) at appropriate concentration improves nutrient digestion in animals and influences ecosystem processes, knowledge on CT concentration in different phenological stages and different plant parts of legumes growing in western Canada prairie is lacking. Objective of this study was to determine the level and distribution of total CT (TCT), extractable CT (ECT) and protein-bound (PCT) or fiber-bound CT (FCT) concentrations in the whole plant of legume forages at different phenological stages and plant parts using Butanol-HCl procedure. Whole plant samples of Dalea purpurea Vent. (PPC), Dalea candida Michx. ex Willd (WPC), Onobrychis viciifoliav Scop. (SF) and Astragalus Canadensis L. (CMV) were collected in the 2011 and 2012 growing seasons from replicated small trial plots at vegetative, flowering and seed maturity stages. Significant species, phenological stages and their interactions all affected the TCT, ECT, PCT and FCT concentrations in whole plant and plant parts (P < 0.001). Concentrations of ECT and TCT increased for all species as they matured from vegetative to seed maturity, except for SF where the vegetative stage had the highest ECT and TCT levels. The highest mean ECT and TCT concentrations for PPC and WPC were found in the inflorescences part at flowering stage, while SF had the highest ECT and TCT concentrations in leaves at vegetative. There was little variation for PCT among different phenological stages in whole plant for species except for PPC and WPC which had higher (P < 0.05) PCT at seed maturity than at flowering stage. Only trace amounts of FCT were detected from either whole plant or different fractions of plant. Condensed tannins were not observed in CMV except for trace amounts in the seed coat at seed maturity stage. Results demonstrate that information of CT concentrations in forage legumes could potentially be utilized in pasture management practices to optimize ruminant performance and productivity.

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