Abstract:
Proc. Aust. Soc. Anim. Prod. Vol. 19 PERFORMANCE OF SHEEP GRAZING SALT TOLERANT FORAGES ON REVEGETATED SALTLAND B. E. WARREN and TESS CASSON Sheep and Wool Branch, W.A. Dept of Agriculture, Katanning, W.A. 6317. Forage from revegetated saltland may not be well utilised because of a lack of information on the importance of the various components of the system. For example, in a pen feeding experiment provision of a low salt forage with saltbush markedly improved sheep performance (Warren et al. 1990) and there are other reports indicating that the low salt, understorey grasses are important in a saltland system. Therefore, the aim of this experiment was to examine the relative importance of saltland pasture components for sheep production and to examine differences between 2 saltbush (Atriplex) species. A 6 ha, saline site sown in May 1989 with Agropyron elongatum (tall wheat grass) (TWG), was mounded in July 1989 with a Mallen Nich Seeder (Malcolm and Allen 1981), and subdivided into 9 plots (3 blocks x 3 treatments) of 0.65 ha each. One plot in each block was sown at the same time with Atriplex Zentiformis (Quail brush) and 1 with A. undulata (Wavy leaf saltbush) with 1 remaining as TWG alone. In February 1991, 120 adult wethers (mean liveweight 64.4 * 3.5 kg) were divided equally into 10 groups and allocated to the 9 plots, 1 group was returned to the main mob for monitoring. Liveweight and wool growth were measured after 28 and 56 days. Sheep in the group in the main mob were subjected to normal farm management practices and supplemented with about 125 g oats/day. At the beginning of the experiment, TWG provided 9.98 + 2.02 t dry matter (DM)/ha across all plots; this had an in vitro DM digestibility (DMD) of 0.46 for leaf and 0.45 for stem. Atriplex undulata contributed 0.35 t/ha edible DM (leaf and stem <2 mm diameter) (DMD 0.73), and A. Zentiformis 0.18 t/ha edible DM (DMD 0.78). Sheep on the TWG plots lost more weight (PcO.05, Table 1) over the 56 days of the experiment than did any of the other sheep. Wool growth did not differ (-0.05) between treatments but declined from 6.4 g/m2.day in period 1, to 5.1 g/m2.day in period 2. Table 1. Liveweight change (g/head.day) of sheep grazed on tall wheat grass (TWG), TWG + saltbush, or dry pasture supplemented with oats, over two 2%day periods For comparison of dry pasture + supplement with other treatments s.e.m.= 13.2 While saltbush forage was only a small percentage of the total DM on offer, it had a large influence on the performance of the sheep. Although not measured, it was apparent that relatively little of the TWG was consumed by the sheep and most of the leaf and small stem material from the saltbushes was eaten within the first 28 days. The TWG was of very poor quality, reflecting no prior grazing, and the highly digestible leaf material of the saltbush acted as a supplement to this low quality material. This supports the earlier pen feeding work of Warren et al. (1990) which showed complementarity between low quality chaff and dried saltbush material. MALCOLM, C. V. and ALLEN, R. J. (198 1). Aust. Rangelands J. 3: 106-9. WARREN, B. E., BUNNY, C. J. and BRYANT, E. (1990). Proc. Aust. Sot. Anim. Prod. 18: 424-7. 237