Beef production from lucerne and subterranean clover pastures. 3. Composition and quality of the diet selected

During 1976 and 1977 in southern New South Wales, diet samples were obtained at approximately 3-week intervals from oesophageally fistulated steers grazing a lucerne (Medicago sativa) and subterranean clover (Trifolium subterraneum) pasture (LC) and a subterranean clover (C) pasture. On LC, green lucerne was the predominant diet component for much of the 2 years. On C, the diet consisted mainly of dry material during a drought in autumn-winter 1976, green wireweed (Polygonurn aviculare) until late autumn 1977, green clover and grass in winter and spring 1977, and finally dry material again. During 1976 and early 1977, diets on LC had a higher digestibility (61.7% vs 49.4%) and nitrogen content (2.55% vs 2.04%) than those on C. This difference was due to the contribution of lucerne on LC, and also because the wireweed on C was of very low quality, even when green. During the latter part of 1977, LC and C had equivalent digestibility and nitrogen levels. The information on the diets helped explain changes in liveweight and the incidence of bloat of cattle grazing the plots.