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Protein and Dry-Matter Degradability of European- and Mediterranean-Derived Birdsfoot Trefoil Cultivars Grown in the Colder Continental USA

Grabber, J. H., Coblentz, W. K., Riday, H., Griggs, T. C., Min, D. H., MacAdam, J. W., Cassida, K. A.
Crop science 2015 v.55 no.3 pp. 1356
Lotus corniculatus, amino acids, crude protein, cultivars, digestible protein, excretion, in vitro digestibility, livestock, plant adaptation, plant proteins, proanthocyanidins, protein degradation, provenance, rumen, rumen fermentation, Europe, Mediterranean region, Michigan, Utah, West Virginia, Wisconsin
Recent work suggests several European- and Mediterranean-derived cultivars of birdsfoot trefoil (BFT, L.) are well adapted to the colder continental United States and produce forage with greater condensed tannin (CT) concentrations, but comparable neutral detergent fiber (NDF) and slightly lower crude-protein (CP) concentrations than the commonly grown cultivar Norcen. In the current study, thirteen of these foreign-derived cultivars and Norcen were harvested under two- or three-cut management during 2006 in Michigan, Utah, Wisconsin, and West Virginia and analyzed in vitro for rumen degradable and undegradable protein on a CP and dry-matter (DM) basis (RDP, RDP, and RUP) and for rumen degradable and true degradable DM (RDDM and TDDM). Foreign-derived cultivars usually produced forage with greater RUP and lower RDP, RDP, RDDM, and TDDM than Norcen. The low NDF cultivar Bokor uniquely combined high CT and RUP with high TDDM. The highest yielding cultivar Lotar also produced herbage with moderate to high CT, RUP, and TDDM. Concentrations of CT and CP influenced RDP, RDP, and RDDM, while CT affected RUP, and fiber components influenced TDDM; relationships were greatly influenced by growth environment. Reductions in RDP exceeded gains in RUP as CT increased, thus, feeding of high-CT cultivars could mainly curb urinary N excretion from excess RDP rather than boost amino acid supply from potentially digestible RUP. Additional work is needed to improve the nutritional consistency of harvested BFT across environments and to develop higher-yielding cultivars with optimal RDP and RUP and high TDDM for maximizing livestock performance.