Comparison of wool production and reproductive rate of South Australian strain Merinos and locally bred Peppin Merinos in the semi-arid tropics of Queensland

Abstract

Three experiments were conducted to provide information on the wool production and reproductive rates of different strains of Merino sheep, and on the role of heat tolerance in determining the productivity of sheep in north-western Queensland. The locally bred Peppin Merinos had a significantly (P<0.05) lower rectal temperature (RT) and respiratory rate (RR) under heat load than the South Australian (SA) strain Merinos. Place of birth of SA Merinos had no effect on their RT and RR. At 16 months of age the Peppin sheep produced significantly (P<0.05) less clean wool (1.55 v. 1.82 kg) and had significantly (P<0.05) lower liveweights (28.5 v. 31.6 kg) than the SA group reared in the same environment. Although differences between the groups were not always statistically significant, there was a trend for a consistent increase in wool production, fibre diameter and liveweight as the proportion of SA in the cross increased. The impact of these differences on proceeds from wool sales is discussed. At maturity the SA strain ewes were heavier (P<0.05) than their Peppin counterparts (48.4 v. 44.1 kg) and produced heavier (P<0.05) lambs at 6 weeks of age (7.0 v. 6.2 kg) and at weaning (13.9 v. 12.5 kg). Milk yield at 6 weeks post-lambing was significantly (P<0.05) greater for the SA sheep than the Peppin Merinos (303 v. 216 mL/day). Lamb survival from 6 weeks to 3 months was 64% for the SA Merinos and 45% for the Peppin Merinos, but this difference was not statistically significant. The SA strain Merinos produced more clean wool and heavier offspring than locally bred Peppin sheep and demonstrated a similar reproduction rate in the face of severe drought conditions.