The roads to efficiency in the ewe flock

There are numerous strategies for improving biological efficiency in the ewe flock, ranging from changes in management to modifying genetic selection objectives. This review discusses a range of options including selection for higher reproduction rate, a higher weight of lamb weaned, a different growth path to maturity, improved resilience to poor nutrition and improved feeduse efficiency. In addition the potential of modifying management to enable ewes to produce their first lamb at 12 months of age is also discussed. Selection for higher numbers of lambs weaned is currently practiced and is likely to deliver gains in system efficiency, particularly if selection pressure is applied to minimise the correlated increase in adult ewe weight. In addition, there is genetic variation in a range of traits that are currently not well understood or under direct selection that could improve the efficiency of energy use by the Australian ewe flock. Of the options discussed those showing the greatest promise are the development of management and breeding strategies that improve the success of mating Merino ewes at 7 months of age and the implementation of strategies that exploit genetic variation in the ability of ewes to handle periods of restricted nutrition. However all of the options discussed here require further investigation before they can be widely implemented across industry