Yield, Morphological Development, and Forage Quality Characteristics of European- and Mediterranean-Derived Birdsfoot Trefoil Cultivars Grown in the Colder Continental United States.

North American birdsfoot trefoil (BFT) cultivars such as Norcen produce forage with low condensed tannin (CT) concentrations that may be insufficient for optimal livestock performance. Our objective was to identify European and Mediterranean cultivars with higher CT concentrations that would be suitable for production in the colder continental United States. Fourteen BFT cultivars were established during 2005 in MI, UT, WI, and WV and harvested under a two- or three-cut management to determine morphological development, chemical composition, and degradability of herbage in 2006 and dry matter yield (DMY) in 2006 and 2007. During 2006, variances in crude protein (CP), neutral detergent fiber (NDF), acid detergent fiber (ADF), acid detergent lignin (ADL), and in vitro true dry matter degradability (IVTDMD) were mainly influenced by location-harvest environments, while CT and protease undegradable protein (PUP) were equally influenced by cultivar and environment. Earlier-maturing cultivars such as Bokor, AU Dewey, Rodeo, and Grasslands Goldie produced herbage with relatively high concentrations of CT and PUP, but not undesirably low CP and IVTDMD or high NDF, ADF, and ADL concentrations compared with Norcen. The high CT cultivar Bokor was noteworthy because it possessed relatively low fiber concentrations, but high IVTDMD and PUP suggesting it may have a greater intake potential and feed use efficiency than most other BFT cultivars examined in our study. By the second production year in 2007, total DMY in UT exceeded WI by twofold and MI by ninefold, and total DMY of the moderate CT-containing cultivar Lotar surpassed most other cultivars, suggesting it may be well suited for forage production in the United States. Additional studies are needed to identify optimal CT concentrations in BFT for ruminants and to improve the compositional uniformity and yield of harvested BFT in various environments.