Incidence of permanent separation of ewes from lambs in a South Australian Merino flock.

The Australian Merino is renowned for its low reproductive performance, the main reason in South Australia (S.A.) being high lamb mortality (Kleemann et al. 1991). Poor nutritional conditions and the need to supplement feed regularly during the autumn is a feature of S.A. sheep husbandry. Resultant disturbance and possible permanent separation of ewes from lambs could be an important factor limiting lamb survival. Two flocks of 485 and 110 mature S.A. Merino ewes were observed during day light hours in mid April and late May 199 1, respectively, for 5-15 days at the peak of lambing. Time spent by the ewe and her lamb(s) at the birthsite (TB, min), birthweight (BW, kg) and lamb vigour (LV, 1 = poor, 3 = good) were recorded. Criteria of Alexander et al. (1983) for desertion of the birthsite and for permanent (PS) or no (NS) separation were adopted. Results are given in Table 1.