Vegetation changes and animal productivity under sheep and goat grazing on an arid Belah (Casuarina cristata) - Rosewood (Heterodendrum oleifolium) woodland in western New South Wales.

Abstract

In an arid (275 mm rainfall) belah (Casuarina cristata)-rosewood (Heterodendrurn olrifolium) woodland, goat does of feral origin and Merino ewes were grazed separately or in mived groups to.determine the relative effects of the different com- binations on the shrub and herbaceous vegetation, and on total animal production. The goats browsed the accessible foliage of trees, but did not obtain a substantial amount of their forage from that source. Thus they were competitive with sheep for the herbaceous layer (principally Stipa variabilis (variable speargrass) and Sclerolaet~a spp. (copperburrs). Grazing sheep and goats together did not achieve greater animal production than grazing them separately. Under drought conditions, those sheep grazing in conjunction with goats lost weight sharply in comparison with the goats, or to other sheep grazing without goat competition. The weights of the kids born in this trial were only 60% of the weights of the lambs, at both weaning and 1.5 years of age, although the net reproduction rate of does (120%) was twice that of the ewes (57%). Goat grazing did not suppress the unpal- atable shrubs. It is concluded that the grazing of feral goats. either alone or mixed with sheep, will not result in higher animal production or shrub control in this woodland community.