CHEMICAL-COMPOSITION AND IN-VITRO DIGESTIBILITY OF LINES OF LOLIUM-PERENNE SELECTED FOR HIGH-CONCENTRATIONS OF WATER-SOLUBLE CARBOHYDRATE

Differences in the water-soluble carbohydrate concentrations of herbag e of northern European perennial ryegrass cultivars (Aurora, Melle, Ca riad) grown under southern Australian conditions, and a New Zealand pe rennial ryegrass cultivar (Ellett) which yields well in southern Austr alia, were investigated in relation to their nutritive value. The wate r-soluble carbohydrates (WSC), total nitrogen, in vitro dry matter dig estibility (IVDMD), neutral detergent fibre (NDF), and digestibility o f NDF (NDFD) were measured in all cultivars. Aurora and Cariad exhibit ed higher WSC concentrations than the other cultivars, particularly du ring summer. This buffered the decline in IVDMD that was due to declin ing NDFD at that time of the year and resulted in an improvement in IV DMD of between 2 and 6%. Although WSC and nitrogen concentrations of t he herbage were negatively correlated, this was due mainly to divergen t seasonal variation in these components of the herbage.