ON FARM SHEEP PRODUCTIVITY Mixed results for lambing density research Aproject examining Murdoch University PhD smaller mobs and at lower “This equated to a 2% the effect of mob student Amy Lockwood has stocking rates,” Amy said. decrease in lamb survival for size and stocking been managing the data each extra 100 twin-bearing under the supervision of “A total of 61 research sites ewes in the mob.” rate on twin-born lamb were run on commercial survival has proved project managers Lyndon farms across southern Amy said the effect of mob and disproved some Kubeil from Agriculture Australia during 2016 and size was consistent for long-held theories. Victoria, Dr Serina Hancock 2017. Another nine sites will twin-bearing ewes with a from Murdoch University, and be completed this year.” condition score of 2.6 to 3.5 Lifting lamb survival rates consultant Dr Jason Trompf. at lambing. offers numerous benefits to “The key point is that Adult twin-bea g er o Australia’s sheep industry, or non-Merino ewes were “After we’ve completed the with improved animal welfare pregnancy scanning and randomly allocated into one additional research sites for outcomes and on-farm managing the nutritional of four treatments on day 140 the national project this year, productivity among them. requirements of single from joining: high (average we’ll do a full benefit–cost and twin-bearing ewes 240 ewes) or low (average analysis of reducing mob Limited previous research separately is priority number 100 ewes) mob size, and high size and develop practical had suggested increasing one,” Amy said. (7–8 ewes/ha) or low (5–6 guidelines for producers.” the mob size or stocking “Once we have these key ewes/ha) stocking rate. rate of ewes at lambing Feed on offer plays may increase the risk of factors in place, we can then Feed on offer and ewe a part mismothering and lamb achieve an extra couple condition scores were Further experimental work mortality. of percent improvement in assessed 140 days after conducted by Amy as part survival by reducing mob size. joining and at lamb marking. of her PhD suggested the The ‘Improving lamb survival The number of lambs at relationship between mob by optimising lambing Experiment design size and lamb survival may density’ project has so far “The research aims to test marking was recorded for each mob. be influenced by feed on found stocking rate has no the hypothesis that the offer at lambing. effect on lamb survival, but survival of twin-born lambs Data was also collected smaller mob sizes improve on commercial farms in from a large network of A higher mob size decreased the survival of twin-born southern Australia will be producers to assess the the survival of twin-born lambs, regardless of breed. greater when ewes lamb in effects of mob size and lambs when feed on offer was stocking rate at lambing below 400kg dry matter (DM)/ on lamb survival, across a ha at lambing and ewes were range of environmental and being supplementary fed. management conditions. However, another Mixed results experiment found the survival of single and “So far we’ve found stocking twin-born lambs was not rate doesn’t have any influenced by mob size when significant effect on twin- feed on offer exceeded lamb survival,” Amy said. 2,700kg DM/ha at lambing. “However, the survival of “Although our national project lambs born at the low mob didn’t find any relationship Geoff Casburn, Dr Gordon Refshauge, Michael Short and Richard Knightsize was 2.8% greater thanbetween mob size, feed on drafting and counting ewes into mobs for lambing at a research site inthose born at the high moboffer and lamb survival, these Wallendbeen, NSW. size, regardless of breed. mixed results have prompted 26