Effects of pasture availability on the composition and quality of the diet selected by sheep grazing native, degenerate and improved pastures in the Upper Shoalhaven Valley, New South Wales

Abstract

Sheep exhibited a high degree of species selection when grazed at different seasons on three contrasting pastures typical of the mosaic of communities occurring over the Shoalhaven Valley. They were 1 . a Themeda australis grassland-typical of native grasslands, 2, a Phalaris tuberosa-Poa labillardieri- Trifolium repens pasture-typical of semi-improved pastures, and 3. a P. labillardieri grassland-typical of degenerate pastures resulting from ineffective attempts to establish improved pasture. Under light stocking, associated minor pasture constituents such as Hypochoeris radicata, Trifolium repens, or both were selected avidly and made a major contribution to a diet of adequately high quality. However when these minor species had been consumed, sheep were forced to eat the dominant grasses and diet quality fell appreciably. The T, australis grassland was substantially inferior to both the P. tuberosa- P. labillardieri-T. repens and P. labillardieri pastures. Cutting or burning P. labillardieri improved its quality and intensive grazing is recommended for areas in which this species predominates.