Comparison of alkaloid content and nutritive value for tryptamine- and β-carboline-free cultivars of reed canarygrass (Phalaris arundinacea L.)

Abstract

Breeding programs for reed canarygrass (RCG) have resulted in the development of cultivars free of antinutritional compounds such as β-carbolines and tryptamines. The first study was designed to compare nutrient and alkaloid concentrations for four recently released cultivars (Rival, Venture, Palaton, Vantage) and one β-carboline- and tryptamine-containing cultivar (Castor) of RCG. The study was conducted at two locations, over 2 yr, with a two-cut harvest schedule. Cultivar differences were not observed (P > 0.05) for forage crude protein (CP) or neutral detergent fiber (NDF) levels. Rival was observed to have higher (P < 0.05) gramine levels than Venture in 1988 and higher (P < 0.05) hordenine levels than Venture in 1989. A second study was conducted to compare the intake and digestibility for RCG cultivars Rival and Venture using growing lambs. Comparisons were made for initial growth and regrowth forage. Fresh forage was harvested from two paddocks for each cultivar, chopped, bagged with dry ice nuggets 10% wt wt−1 and placed in storage (−10 to −20 °C) until time of feeding. Cultivar differences were not observed (P > 0.05) for intake with the initial growth or the regrowth forage. Apparent digestibility of dry matter was 8.4 and 5.5% units higher (P < 0.05) in Rival than in Venture for initial growth and regrowth, respectively. Similarly, apparent digestibilities of acid detergent fiber and NDF were higher (P < 0.05) for Rival than for Venture at both stages of growth. Forage CP levels differed between cultivars for initial growth; however, levels were comparable for regrowth. In the regrowth, apparent digestibility of CP for Rival was greater (P < 0.05) than for Venture. Key words: Reed canarygrass, low alkaloid, gramine, hordenine, intake and digestibility