A COMPARISON OF THREE PERENNIAL RYEGRASS CULTIVARS UNDER CATTLE GRAZING IN THE WAIKATO

Three perennial ryegrass cultivars (L&urn perennr L.), Grasslands 'Ruanui', Grasslands 'Nui' and Yates 'Ellett' were sown in two experiments on different peat soils at Moanatuatua. Both experiments were alternately mown and grazed with Friesian cattle after an establishment period on each soil. Ruanui swards, grown with white clover (Trfolium repens L.) were the least productive one both a partially-developed and a well-developed peat. "Ellett' and 'Nui' swards produced 28% and 20% more total DM than 'Ruanui' on a well developed peat and 16% and 5%, respectively, on a partially-developed peat, over a 21 cut period from September 1976-September 1979. Pasture growth rates were generally lower on the partially-developed peat and cultivar differences were minimized in this experiment. Peak sward growth rates occurred in December-January on both peat soils. Whereas all three ryegrass cultivar swards reached a peak growth rate of approximately 70 kg DM/ha/day on the partially-developed peat, and Ruanui and Nui reached similar levels on the developed peat, Ellett swards attained higher growth rates (90 kg DM/ha/day) on the more fertile peat. Sward growth rates of Ellett and Nui pastures were consistently higher than those of Ruanui in the autumn. Ellett pastures contained more ryegrass and less white clover than Ruanui swards with Nui being intermediate in grass and clover composition. The value of Ellett and Nui on fertile, organic soils in the Waikato is emphasised.