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Experiments in spring and autumn comparing the growth of lambs on "Grasslands Ariki" and "Grasslands Ruanui" ryegrasses in association with white clover at Gore are described.In spring no difference in growth late or meat yield was detectable. In autumn growth rate was highest for animals on Ariki.The effects of set stocking, rotational grazing, and selenium dosing are also reported.

THE NEED for greater efficiency in pasture utilization is becoming more marked as stock numbers rise. In Southland, much of the increase is arising from higher stock concentrations and rates of almost 10 sheep per acre are known (Lawlor, 1970), although the average is considerably lower.

In the period 1973-77, 71% of pasture grasses certified in New Zealand were perennial ryegrasses. Data from one of the major seed merchants showed that during 1977-8 Ruanui comprised over 70% of the retail sales of perennial ryegrass cultivars, while Nui (17%) and Ariki (10%) were also important. Comparative production data between the New Zealand bred cultivars, some overseas cultivars and some uncertified local populations are presented. Overseas cultivars are generally inferior to New Zealand cultivars but some local populations are very promising in a number of environments. The newer cultivars Nui and Ariki often show a greater yield response to longer intervals between defoliations and increased nitrogen supply than Ruanui.