DIET SELECTION IN 6 STYLOSANTHES-GRASS PASTURES AND ITS IMPLICATIONS FOR PASTURE STABILITY

Diet selection in 6 Stylosanthes-grass pastures was studied over 43 mo nths at Lansdown, north-east Queensland. The Stylosanthes accessions w ere S. humilis cv. Paterson, S. hamata cv. Verano, S. scabra cv. Seca, S. scabra cv. Fitzroy, S. viscosa CPI 34904 and S. viscosa CPI 40264B . They were sown together with Cenchrus ciliaris into native pasture d ominated by Heteropogon contortus, Themeda triandra and Bothriochloa s pp. All stylos except 40264B, which did not persist well, contributed significantly to the diet. The proportion of legume in the diet was gr eatest in the dry season and least in the wet season, when grass was p referred. High levels of dietary nitrogen were maintained for most of the year and cattle grazing the two annual stylos, S. humilis and S. h amata, recorded higher dietary nitrogen levels than those consuming pe rennial styles. Relative preference indices showed that, with the exce ption of S. humilis, grass was eaten in preference to legume over the duration of the experiment. In Seca and 34904 pastures, increasing leg ume dominance was associated with an increased selection for grass as the experiment progressed. The implications of such diet selection tre nds for long-term pasture stability are discussed.