Resurrecting Perennial Legumes as a Livestock Feeding Strategy:An Improved High-Tannin Birdsfoot Trefoil Cultivar with Trans-Regional Potential

The high price of cereal grains and mineral N has created renewed interest in non-bloating nitrogen (N)-fixing perennial forage legumes as a ruminant feeding strategy, despite the higher management required. The disomic 4x legume birdsfoot trefoil (BFT) is non-bloating because of unique tannin that increases ruminant productivity. Only the tannin in BFT improves protein utilization by shielding excess plant proteins from digestion in the rumen but releasing them for digestion in the abomasum. Other demonstrated benefits are reduced parasite loads, reduced N losses from animal excrement, slowed N mineralization, a better fatty acid profile in meat, and high consumer acceptance of BFT-finished beef. BFT has produced exceptional season-long beef gains when pure stands are grazed. AU Dewey BFT, selected for rhizomatous nature, prostrate growth habit, and general vigor and adaptation, was released by the Alabama AES, Auburn University in 1986 but is currently not available commercially. It is of interest because of its higher condensed tannin concentration compared to other BFT releases. Rhizomatous BFT germplasm consistently contains higher tannin, but has not been successfully commercialized in the U.S. BFT is persistent under irrigation in ruminant grazing systems of the Intermountain West, and cultivars should be developed for broader use. AU Dewey has proven to be persistent across the northern Mountain West and has potential for broad use because it was originally selected from Yugoslavian germplasm that is persistent in Alabama. The long-term goal of this line of enquiry is to demonstrate not only the genetic determination of tannin concentration in BFT, but also the role of location, plant maturity, soil fertility, and associated mixture grasses in the expression of tannin, reduction of the susceptibility of BFT to disease, and identification of traits that increase BFT persistence in warm, humid environments.