ABSTRACT
Summary Mixed pastures of perennial ryegrass (Lolium perenne L.), kikuyugrass (Pennisetum clandestinum Hochst.), and white clover (Trifolium repens L.) are commonly found within warm-zone areas of New Zealand but are frequently disliked because of problems associated with kikuyugrass dominance. A grazing experiment was conducted to provide basic information on the response of such swards to grazing by cattle and sheep. The pastures were rotationally grazed with young sheep or cattle at two stocking levels each year from 1970 to 1975, with stocking rates adjusted twice yearly according to seasonal pasture growth. The pastures grazed by cattle produced 18% more total annual dry matter (DM) than those grazed by sheep, the advantage being largely confined to summer and autumn when kikuyugrass was the active grass component of the swards. High stocking levels of both sheep and cattle reduced annual yield by 25%, although there was minimal effect in summer. The level-of-stocking effect was greater in winter in sheep pastures than in cattle pastures, but in other seasons there were no differential effects. The botanical composition of the mixed pastures in spring was greatly altered by grazing treatment. Perennial ryegrass content was greatest in less heavily stocked sheep pastures, and kikuyugrass increased, at the expense of ryegrass, in the more intensely stocked cattle pasture. Annual Poa (Poa annua L.) content was higher in sheep than in cattle pastures; this component increased in all treatments over the experimental period. White clover content was variable between years but in general was lower in sheep pastures and occasionally lower, over all, in the more heavily stocked treatments. The results of this experiment suggest that a balanced subtropical-temperate grass mixture cannot readily be maintained by moderately high stocking levels of either sheep or cattle and that the pastoral changes induced would require compensatory changes in farming practice if high production levels were to be sustained.
