Association of premating liveweight to lambing performance of medium wool Merinos ewes

Analysis of data collected at Merredin and Wongan Hills between 1964 and 1969 showed that premating liveweight and lambing performance of medium woolled Merino ewes were correlated. For each 10 lb increase in liveweight of ewes there was: 1. a 2.9 per cent increase in lambs born at May-June lambing, 379 2. a 6.4 per cent increase in lambs born at July-August lambing, 3. a 3.2 per cent increase in twin births at May-June lambing, 4. a 5.6 per cent increase in twin births at July-August lambing. Equations for per cent ewes lambing demonstrated a reduction in ewes lambing both at low and high premating 1ive.weights for ewes lambing in July-August but not for those lambing in May-June. Significant interactions of premating liveweight and time of lambing were noted for both the per cent lambs born and the per cent ewes bearing twins.