Some effects of pastures species and stocking rate on sheep and pasture production : a thesis presented in partial fulfilment of the requirements for the degree of Master of Agricultural Science at Massey University
Agriculture in New Zealand as in other temperate regions of they World is dependent on the utilisation of pastures by the grazing animal. Species such as perennial rye grass (Lolum perenne L.) cocksfoot (Dactylis glomerata L.) and white clover (Trifolium repens L.) together, represent a large proportion of the feed available to sheep on the more improved pasture land of New Zealand. Considerable research has been done on the selection, establishment, and the productivity of these species for livestock. But this research has been predominantly concerned with pastures or with livestock as separate entities. Only occasionally have these two entities been studied in association. In general, pasture species have been extensively evaluated in terms of their dry matter yield and botanical characteristics under different systems of cutting but comparatively few pastures trials have been reported in which the evaluation has been made in terms of animal products. Higher growth rates of young sheep grazing white clover dominant pastures or grasses plus clover pastures as compared with pure grasses pastures were reported in New Zealand (Rae, Brougham, Glanday and Butler, 1963; Rae, Brougham and Barton, 1964; McLean, Thomson, Jagusch and Lawson, 1965; Hight and Sinclair, 1965, 1967) and in Australia (Gallagher, Watkin and Grimes, 1966; Wilson, 1966). Also differences were found in the growth rates of sheep grazing different types of grasses (Rae et al, 1964, McLean et al, 1965; Gallagher et al, 1966).