Carcass Composition of Different Cattle Types Related to Energy Efficiency2

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Abstract
Sixteen Maine-Anjou (MA) and 14 Gelbvieh (Gelb) steers from Angus or Hereford crossbred dams, and 16 Hereford × Angus (H× A-A×H) reciprocal crossbred steers were fed the same ration in individual pens until they reached an energy coefficiency endpoint of 8.0 Meal of NEp per kilogram gain. Gelb and MA crosses were fed an average of 70 days longer, averaged more than 94 kg heavier at slaughter, and gained an average of .21 kg more per day than Hx A-Ax H. On a gross basis, Hx A-Ax H were more than 1.4 kg DM per kilogram gain less efficient than MA and Gelb, ADG and gross efficiency were significantly related by both pooled and within-breed analyses. Faster gaining cattle were more efficient when fed to the same NEp efficiency endpoint, H× A-A× H carcasses showed no advantage in quality grade over MA and Gelb, although H×A-A×H averaged .48 cm more external fat at the 12th rib and .68 poorer yield grade than MA and Gelb, The left round of each carcass was physically separated into lean, fat and bone to estimate carcass composition; MA and Gelb had a higher percentage of carcass lean (P<.06) than H× A-A× H. Although predicted percentage of carcass lean differed by 3% between large and small cattle types, that difference is probably less than would have occurred using any other slaughter endpoint. Perhaps the calculations of NEm and NEp are not perfectly accurate for different cattle types and/or differences in environment, and possibly account for the 3% difference in estimated carcass lean. Copyright © 1978. American Society of Animal Science . Copyright 1978 by American Society of Animal Science.