Stocking rate, joining time, fodder conservation and the productivity of Merino ewes. 1. Liveweights, joining and lambs born

Abstract

In an experiment at Hamilton in western Victoria, groups of 30 Merino ewes born in 1967 were stocked at 11.7, 15.4 or 19.2 ewes ha-1 and joined to Merino rams each year on April 5 or May 8 for five weeks. Hay was conserved on half the number of plots and fed back to the ewes at joining. Observations at mating and lambing in each year from 1970 - 73 are presented. Seasonal conditions exerted a greater effect upon liveweight change before joining than did the applied treatments but liveweight at joining declined significantly as stocking rate increased. Oestrus activity and the number of ewes returning to service were similar on all treatments. Both the number of lambs and the proportion of twin births declined linearly as stocking rate increased. It is concluded that a similar relationship between liveweight and ovulation rate existed on all treatments. Withholding the introduction of rams from April until May did not result in any change in the number of lambs born. Hay feeding failed to increase the number of lambs born. It is suggested that the ewes substituted hay for pasture.