Lifetime Maternals - development of management guidelines for non-Merino ewes.

Summary

​Non-Merino ewes produce about 45% of lamb supply from Australia.  Eight large experiments using a range of ewe genotypes generated production responses relating changes in ewe liveweight and condition score (CS) during pregnancy to lamb birth weights, weaning weights and survival.  Condition score targets at lambing of 2.7 for singles and 3.3 for multiple-bearing non-Merino ewes are likely to achieve near-maximum lamb survival and weaning rates.  However, poor nutrition during pregnancy reduces weaning weight and these impacts cannot be overcome by improving feed on offer from late pregnancy until weaning.  Whole-farm profitability is sensitive to the ewe liveweight and CS profile, however, the development of management guidelines for non-Merino ewes to maximise profitability was prevented by a discrepancy between measured liveweight change and liveweight change predicted using Australian Feeding Standards for Ruminants.  More specifically, the high rates of liveweight gain measured could not be feasibly achieved in the feed budget, either because the predicted intake for non-Merino ewes is too low and/or the predicted energy requirements for maintenance or weight gain are too high.  Further modelling highlighted the importance of each component of the intake and energy equations in determining the optimum nutrition profiles for non-Merino ewes to establish priorities for future research.