New research into the management of non-Merino ewes has shown that the flock's liveweight and condition score profile can predict the productivity of ewes and the 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 (MLA).
Dr. Andrew Thompson from Murdoch University in Australia led the project in collaboration with Rural Industries Skill Training, the Victorian Department of Primary Industries and the South Australian Research & Development Institute.
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 regarding liveweight and condition score targets in non-Merino ewe flocks, an announcement from MLA said.
Condition scoring is used to assess the body reserves of a mature sheep by measuring the tissue cover over the loin area.
Thompson said the results imply that condition score targets at lambing of 2.7 (five-point scale) 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 fetuses,” 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,” Thompson added.
Richard Apps, MLA program manager-sheep research and development, said the project and resulting report provided valuable insights for lamb producers into breeding and pregnancy management, lamb survival and growth.
“For example, heavier or fatter maternal ewes conceived more lambs, and the response is linear to 90 kg or (a condition score of) 4.5. Ewes that were multiple bearers in the previous year achieved about 15% higher reproductive rate than single bearing ewes at the same liveweight,” Apps said, concluding that the research indicates that producers should aim for a condition score of 3.0 or higher at breeding.
Apps said MLA is currently investing in further work to better understand why maternal ewes performed better than predicted based on current knowledge. This and the work described in the final report then would inform whole-farm economic modeling to develop economically optimum condition score profile targets for maternal ewes.