The comparative productivity of five ewe breeds. 1. Lamb growth and survival

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Abstract
An experiment was conducted at Temora Agricultural Research Station to compare birth weights, growth rates to weaning, and survival of lambs from five breeds. These data formed part of a larger study comparing the productivity of these breeds as possible dual-purpose ewe breeds. The breeds were a Border Leicester X Merino fixed halfbred (BLM), Corriedale, Polwarth, and a South Australian strong wool (S.A. Merino) and a medium wool Peppin strain of Merino. The descending order of ranking of the breeds on birth weight and growth rate to weaning was BLM, Corriedale, S.A. Merino, Polwarth and Peppin Merino. A significant breed x year interaction in pre-weaning growth rate was recorded, since the absolute differences between breeds increased as the overall mean growth rate increased. Breed means for the survival rate of single-born lambs ranged from 80.7 to 86.4 lambs weaned per 100 lambs born and they were not significantly different from each other. The mean survival rate of multipleborn lambs from the S.A. Merino and Polwarth breeds were 65.0 and 69.5 respectively, and these were significantly lower than the survival rate of multiples from the other breeds (76.8 to 80.4). Within breeds, birth weight was found to be positively related to survival at low birth weights but negatively related to survival at high body weights