The performance of Merino ewes and lambs grazing two cultivars of Trifolium subterraneum at Kybybolite, South Australia

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Two cultivars of subterranean clover, Trikkala and Mt Barker, were continuously grazed by Merino ewes and lambs at 3 stocking rates (8, 13, 18 ewes/ha) from 1976 to 1981. The sheep were assessed for liveweight, fleeceweight, fibre diameter, staple length, wool yield and lambing performance including lambing, marking and weaning percentage. From September 1978 onward, ewes grazing Trikkala pastures were consistently heavier than those grazing Mt Barker pastures, and they produced heavier fleeces in 1978 and 1980, with a 3 and 9% greater total wool production. The heavier fleeces of 1980 were associated with a larger fibre diameter. There were no cultivar differences in lambing performance. Cultivar treatment had no effect on lamb birthweight, but in 1980 the Trikkala lambs were, on average, 3.5 kg heavier at weaning. These lambs also produced heavier fleeces than lambs on the Mt Barker pastures. Higher stocking rates produced decreases in all of the animal performance variables measured. The results of this study suggest that improved livestock performance may only occur if animals are grazed on higher performing cultivars for at least 3 years.