LIVEWEIGHT CHANGE, WOOL PRODUCTION AND WOOL QUALITY OF MERINO LAMBS GRAZING BARLEY GRASS PASTURES SPRAYED TO CONTROL GRASS OR UNSPRAYED

Barley grass (Hordeum spp.) dominant pastures were sprayed to control grass in September 1990 or left unsprayed and stocked with woolly Meri no lambs from September to December 1990, after which, the lambs were slaughtered. A second group of Merino lambs grazed the same pastures f rom September 1991 to May 1992. For the second group of lambs, the gra ssy pastures were mechanically slashed and half the lambs on both past ure types were shorn in October 1991. All lambs were shorn in May 1992 producing subgroups of once- and twice-shorn lambs. Lamb liveweights were greater on the sprayed pastures in both seasons. Wool production was greater on the sprayed pastures in the second group of lambs only as the first group of lambs had grazed the pastures for only 47 days b efore shearing. Vegetable fault in wool from the grassy pastures was d ouble that of the sprayed pastures in the first season when grasses (h ence seeds) were not controlled. In the second season, vegetable fault was slightly higher in wool from the sprayed pastures due to an incre ase of Burr medic (Medicago polymorpha) and the invasion of Erodium sp ecies. Net returns per animal from wool were higher for the sprayed gr oup in both years and for the once-shorn group in the second year. Sup plementary feeding over summer was restricted to lambs grazing the uns prayed pastures in the second year.