New research into the management of non-Merino ewes has shown the liveweight and condition score profile of a flock can predict the productivity of ewes, and survival rates and growth of their progeny to weaning.
The findings are contained in the final report of the research and development project, Lifetime Maternals: Development of management guidelines of non-Merino ewes, funded by Meat & Livestock Australia.
Andrew Thompson from Murdoch University led the project in collaboration with Rural Industries Skill Training, the Agriculture Victoria and the South Australian Research and Development Institute.
Non-Merino ewes produce about 45 per cent of Australia’s lamb supply.
Condition scoring is used to assess the body reserves of a mature sheep by measuring the tissue cover over the loin area.
Dr Thompson said the results implied that condition score targets at lambing of 2.7 for single-bearing ewes and at least 3.3 for multiple-bearing ewes are likely to achieve near-maximum lamb survival and weaning rates.
‘‘This clearly demonstrates the value of pregnancy scanning ewes and differentially managing those with multiple foetuses,’’ Dr Thompson said.
‘‘Further work is still required to establish the scenarios whereby carefully managing feed on offer prior to and during lambing may mitigate potentially adverse effects of poor pregnancy nutrition on the birth weights and survival of twin lambs.
‘‘However, it is clear that improving feed on offer from late pregnancy until weaning does not fully counteract the adverse effects of poor nutrition during pregnancy on weaning weight of lambs from non-Merino ewes.’’
MLA sheep R&D program manager Richard Apps said the project and resulting report provided valuable insights for sheepmeat producers around joining and pregnancy management, lamb survival and growth.
‘‘For example, heavier or fatter maternal ewes conceived more lambs and the response is linear to 90kg or CS 4.5,’’ Mr Apps said.
‘‘Ewes that were multiple bearers in the previous year achieved a reproductive rate around 15 per cent higher than single bearing ewes at the same liveweight.’’
The project involved eight large trials using a range of maternal ewe genotypes, including first cross and composite breeds, and the final report contains a number of key findings around liveweight and condition score targets in non-Merino ewe flocks.