Seasonal Variations in Condensed Tannin Concentration of Three Lotus Species

Abstract

Condensed tannins (CTs) are commonly found in herbage of Lotus spp. and can have beneficial or detrimental effects on feed value and animal performance. Our objectives were to (i) determine the level of CT concentration and its seasonal variations in three widely grown Lotus spp.; (ii) assess the distribution of CTs in leaves, stems, and flowers; and (iii) determine if herbage of greenhouse‐grown Lotus spp. contains CT concentrations with equivalent rank to field‐grown plants. Field herbage samples were taken in spring, summer, and fall and analyzed for CTs by near infrared reflectance spectroscopy (NIRS). Herbage of big trefoil (L. uliginosus Schkur.) germplasm ARS‐1221 and narrowleaf trefoil (L. glaber Mill.) germplasm ARS‐1207 had the greatest and lowest CT concentrations averaging 154 and 8 g catechin equivalent (CE) kg−1 dry matter (DM), respectively. The birdsfoot trefoil (L. corniculatus L.) cultivar ARS‐2620 had a greater CT concentration than ‘Norcen’, but both had moderate CT levels averaging 39 and 23 g CE kg−1 DM, respectively. Herbage CT concentration of Norcen, ARS‐2620, and ARS‐1221 was higher in spring and summer compared with fall while that of ARS‐1207 was low in spring, summer, and fall. Generally, stems had less CT than leaves and flowers, but there was no detectable CTs in stems of ARS‐1207. The rankings of the four entries for herbage CT concentration in the greenhouse and field were the same. This is the first report of CT concentrations for the germplasms ARS‐1221 and ARS‐1207, which are suitable candidates for genetic improvement to develop cultivars with desirable CT levels.