Condensed tannin concentrations found in vegetative and mature forage legumes grown in western Canada

Abstract

Berard, N. C., Wang, Y., Wittenberg, K. M., Krause, D. O., Coulman, B. E., McAllister, T. A. and Ominski, K. H. 2011. Condensed tannin concentrations found in vegetative and mature forage legumes grown in western Canada. Can. J. Plant Sci. 91: 669–675. There has been limited effort to examine condensed tannin (CT) concentrations of forage legume species grown in western Canada. Using the butanol-HCl technique, extractable CT concentrations were measured in Trifolium hybridum L., T. ambiguum M. Bieb, T. pratense L., T. repens L., Dalea purpurea Vent., Onobrychis viciifolia Scop., Lotus corniculatus L., Medicago sativa L., and Astragalus cicer L. collected from research and variety trial plots across the Canadian prairies. Above ground plant biomass was harvested at the vegetative and mature physiological stages for two growing seasons. Dalea purpurea, a native legume, had the highest mean CT concentration of 68.6±22.6 g kg−1DM, with minimum and maximum values ranging from 37.9 to 92.9 g kg−1DM. Onobrychis viciifolia had the second highest mean CT concentration (46.0 g kg−1DM) with a range of 16.3 to 94.4 g kg−1DM. The third highest mean CT concentration of 15.1 g kg−1DM was found in L. corniculatus with a range of 0.0 to 25.7 g kg−1DM. Forage biomass had higher CT concentrations (P<0.05) when harvested at the mature stage for all species except O. viciifolia, which had higher CT concentrations in the vegetative state. The potential benefit of inclusion of these species in ruminant diets at the observed concentrations requires further exploration.