Effect of time of joining and rate of stocking on the production of Corriedale ewes in southern Victoria. 1. Mating and lamb numbers

Abstract

Mating and lambing over a three-year period (1968 to 1970) were studied for a flock of 540 ewes grazing annual pasture at Werribee, Victoria. Rams were joined with ewes over a six-week period either in February-March or in April-May and the ewes were stocked at three rates (5, 7.5 and 10 ewes per hectare). The proportion of ewes that lambed and the number of lambs born per ewe were greater when ewes were joined in April-May than in February-March. For the later joining there was little effect of stocking rate on either the proportion of ewes lambing or the number of lambs born per ewe. However, when ewes were joined in February-March, both the proportion of ewes lambing and the number of lambs born per ewe were reduced with each increase in stocking rate. Failure of ewes to lamb was a problem among maiden ewes in 1968 and was more pronounced for the ewes joined early than for those joined later in the breeding season. Among ewes stocked at 5 per hectare the proportion returning to service was higher than among ewes stocked at 7.5 and 10 per hectare.