Main content area

Condensed tannin concentration of rhizomatous and nonrhizomatous birdsfoot trefoil in grazed mixtures and monocultures

Wen, L., Roberts, C.A., Williams, J.E., Kallenbach, R.L., Beuselinck, P.R., McGraw, R.L.
Crop science 2003 v.43 no.1 pp. 302
Lotus corniculatus, genotype mixtures, forage crops, cultivars, seasonal variation, pastures, grazing, Missouri
Condensed tannins in forage legumes can be beneficial or detrimental to ruminant livestock performance, depending on concentration. The objective of this research was to determine condensed tannin concentration in birdsfoot trefoil (Lotus corniculatus L.) without rhizomes (BFT) and with rhizomes (RBFT) from grazed monocultures and mixtures. An additional objective was to investigate possible fluctuation of condensed tannin concentrations through the spring grazing season. In 1997, 'Norcen' BFT and 'ARS-2620' RBFT were sown into pastures located at Columbia, MO; pastures were pure stands or mixtures with tall fescue (TF; Festuca arundinacea Schreb). Pastures were grazed in 1998 and 1999, and the BFT and RBFT components were hand clipped every 14 d throughout the spring of 1998 and 1999. Samples were analyzed for condensed tannin concentration by near infrared (NIR) reflectance spectroscopy with calibrations based on the vanillin-HCl colorimetric method. Condensed tannin concentrations of grazed BFT were lower in this study than concentrations reported in other studies. Averaged over both years, BFT contained 11.4 g catechin equivalents (CE) kg(-1) DM, and RBFT contained (P < 0.05) three times that amount (38.6 g CE kg(-1) DM). Also, condensed tannin concentrations of the BFT component were 100% higher when BFT was grown in a mixture instead of a pure stand (P < 0.10); in 1999, they were 55% higher (P < 0.05). Finally, condensed tannin concentration fluctuated over the spring of 1998 (P < 0.05), but not the spring of 1999. We concluded that condensed tannins in BFT are much lower than in RBFT, that condensed tannins in BFT decrease when grown with a tall fescue companion grass, and that concentrations can fluctuate in the spring as they do in the autumn.