Comparison of the diets of goats and sheep on a Casuarina cristata–Heterodendrum oleifolium woodland community in western New South Wales

Abstract

The diets of sheep and feral goats grazing a semi-arid woodland in western New South Wales were assessed using oesophageal fistulated animals. The diet of the goats consisted largely of browse, with the leaves of Heterodendrum oleifolium (rosewood) a consistent component, although a large proportion of herbaceous material (mainly Bassia spp.) was eaten on occasions. The sheep showed a preference for the pasture species Stipa variabilis (spear grass) and Bassia spp. (copper burrs). When these plants were not available they were replaced in the diet by a higher proportion of browse, mainly of the tree Casuarina cristata (belah). Nitrogen contents of the diets ranged from 1.6 per cent to 3.0 per cent, with that of the goats generally being greater than that of the sheep. In vitro digestibility data indicated comparable values for both animal species, with lower values occurring under higher stocking pressures. The woody weed Eremophila sturtii (turpentine) was ignored by both sheep and goats at all stocking rates. Another weed shrub Cassia eremophila var. platypoda (punty) was browsed very sparingly. This indicates that the use of goats in an attempt to eliminate established stands of these species is unlikely to be successful at low to moderate stocking rates.