Crossbred lamb growth and carcase characteristics of some Australian sheep breeds

A breed comparison involving 31 2 crossbred progeny of three breeds of sire (Poll Dorset, Suffolk, and Lincoln) and five breeds of dam (Dorset Horn x Merino, Border Leicester x Merino, South Australian Merino, and Peppin Merino) was made between 1973 and 1975 in the western Riverina of New South Wales. The lambs were fed a post-weaning feedlot ration at one of two levels and were slaughtered when they reached 35 kg liveweight. Characters measured were: pre-weaning and postweaning growth rate, dressing percentage, carcase length, carcase leg length, kidney + pelvic fat weight, eye muscle length and depth, rib fat depth, and leg + loin fat and muscle percentage. Carcase characters were adjusted to a constant carcase weight. Important breed differences were those associated with rib fat depth and growth rate. The Suffolk- BL x M cross had high pre-weaning and post-weaning growth rates, but BL x M dams produced lambs with greater rib fat depths. The Suffolk-DH x M and Suffolk-DR x M crosses represented the best compromise between rib fat depth and growth, but their post-weaning growth rates were substantially less than the Suffolk-BL x M. These breed differences for rib fat depth and growth rate were not dependent on the level of post-weaning nutrition.