Economic theory often provides information on the variables to be included in economic relationships (e.g., demands are functions of prices) and sometimes provides information on the signs and magnitudes of first- and second-order derivatives (e.g., homogeneity and concavity information)....

Selection of cattle with greater feed efficiency is known to be profitable. Savings in southern Australian beef production systems of $6.55 per breeding cow per year have been estimated for selection for lower residual feed intake (RFI), and an additional saving of $4.34 per breeding cow per...