Harvest alternatives to reduce the alkaloid content of reed canarygrass forage

Abstract

Growing conditions favorable to the accumulation of alkaloids in reed canarygrass (RCG) can result in gramine concentrations exceeding tolerable levels for grazing animals. Alternative harvest techniques for this forage material include silage and hay production. A replicated trial with 22-L mini-silo units showed that gramine and hordenine concentrations in RCG herbage do not decrease as a result of ensiling. Reed canarygrass regrowth cut and field-wilted to 74.9% dry matter (DM) had reduced (P < 0.05) gramine and hordenine concentrations. A second trial using RCG regrowth, dried under laboratory controlled conditions also showed decreases (P < 0.05) in forage gramine and hordenine concentrations. Hay baled at 73.1% DM and stored for 32 d had a further reduction (P < 0.05) in hordenine concentrations. No change in gramine concentration was observed during storage of forage as hay, but this may be due to low initial levels in the baled hay. An intake and digestibility study with growing ram lambs showed DM and neutral detergent fiber digestibilities for the β-carboline and tryptamine free cultivars, Rival and Venture, to be comparable to timothy, cultivar Champ, when regrowth was cut at the same stage of maturity. This study suggests that RCG forage considered to be too high in gramine for grazing animals could be harvested as hay to reduce forage alkaloid concentrations. Key words: Reed canarygrass, gramine, hordenine, silage, hay