Abstract

Nine ryegrass cultivars (3 perennial, 3 hybrid, 3 Italian types) were sampled during the winter of 2007 to measure chemical composition, degradation parameters and leaf morphology and to define differences that may be applicable to winter growth in dairy pastures. The grasses were harvested after seven and nine weeks of regrowth on June 18 and August 2. There were no differences between ryegrass types in the concentration (g/kg dry matter (DM)) of crude protein (227) but neutral detergent fibre was higher in perennial (468) than hybrid (435) or Italian (414) ryegrass types. Leaves were largest and widest for the Italian type, and shortest and narrowest for the perennials (P <0.001). Italian ryegrasses had the highest concentration of soluble DM. There were differences in the degradation rate (h-1) of insoluble DM; Italian (0.20), hybrid (0.18) and perennial (0.13) ryegrasses (P = 0.06). Ryegrass sampled after 9 weeks of regrowth, had a lower crude protein concentration than the earlier sampling (208 vs. 246) and a lower neutral detergent fibre concentration (392 vs. 486) but leaf characteristics, proportion of DM in the soluble fraction, and DM degradation rates were similar (P >0.05). The identification of differences in composition and degradation will assist with planning grazing management over winter.

XZ, Sun, GC Waghorn, and H Clark

Proceedings of the New Zealand Society of Animal Production, Volume 70, Palmerston North, 206-212, 2010