Date of this Version
Economical and biological efficiencies of beef production to weaning and to slaughter were estimated in three groups, different in milk available (low, medium, and high) to the calves but with the same potential for growth. Data from different breed groups of cows (low [L] = Hereford x Angus, medium [M] = Red Poll x Angus, and high [H] = Milking Shorthorn x Angus) were used. Economical efficiency was the ratio of income to expenses and biological efficiency was the ratio of calf weight to total feed energy required. Income was derived from cull cows and calves at weaning or carcasses of calves fed to slaughter. Feed and non-feed expenses for the cowherd and for calves to weaning or to slaughter were included in economical efficiency. Efficiencies were estimated assuming observed reproductive rates and energy requirements for maintenance, as well as for equal reproductive rates and equal energy requirements for maintenance in the M and H groups. With slaughter were 28.1, 27.2, and 27.5 g of weaning weight and 22.0, 20.4, and 20.3 g of carcass weight per megacalorie of ME for L, M, and H, respectively; the corresponding values using equal reproduction and equal maintenance in M and H were 28.3, 27.2, and 27.4 g of weaning weight and 22.1, 20.5, and 20.5 g of carcass weight per megacalorie of ME. Economical efficiencies (dollars of income x 100/dollars of expense) under the observed reproductive rates and maintenance requirements were 90.3, 89.2, and 88.1 to weaning and were 99.5, 96.5, and 95.3 to slaughter for L, M, and H, respectively; under equal reproduction and equal maintenance in M and H, the efficiencies at weaning were 91.0, 88.4, and 88.9 and at slaughter were 100.0, 95.7, and 95.1. Across the two scenarios, L was always the most economically efficient, especially when evaluated at slaughter of calves. Economical efficiency comparisons agreed closely with the observed reproductive rates and maintenance biological efficiency comparisons of the three cattle requirements, biological efficiencies to weaning and to groups.