Grazing a saltbush ( <i>Atriplex-Maireana</i> ) stand by Merino wethers to fill the autumn feed-gap experienced in the Western Australian wheat belt

Abstract

Three-year-old Merino wethers were grazed at 4 stocking densities (15, 20, 25 and 30 sheep/ha) in 3 consecutive autumns on saltbush forage. About 50% of edible material was leaf [70% digestible dry matter (DDM), 8.9% crude protein (CP)] and 50% was small stems &amp;lt;5 mm diameter (40% DDM and 4.5% CP). In 1992, 9-month-old wethers also grazed the saltbush stand at 30 sheep/ha. Liveweight initially increased by 1-3 kg during the first 14 days of grazing, then declined at 60-100 g/day until the diminishing forage reserves became critical, by which time the stand had provided for about 450 grazing-days/ha. The performance of the 9-month-old wethers was comparable with the 3-year-old sheep at equivalent grazing pressure. In 1992, the tensile strength of wool staples from the 3-year-old sheep grazed at the higher density of 30 sheep/ha, 17.2 N/ktex, was weaker (P&amp;lt;0.05) than staples from sheep grazed at 15 and 20 sheep/ha, 27.1 N/ktex, and 25 sheep/ha, 24.9 N/ktex. Saltbush plantations can be used to provide a feed source which could partly fill the 'autumn feed-gap' for &amp;lt;9-month-old dry sheep. Grazing at &amp;lt;20 sheep/ha, removal of sheep from the saltbush before the mean liveweight declines below that at the start of grazing, and provision of a reliable supply of water will avoid low staple strength wool. More productive stands of saltbush, grown together with winter-active plant species, are needed to improve the economic viability of this grazing resource.