Optimal beef cattle diets formulated by nonlinear programming.

A beef diet model based on National Research Council recommendations is significantly nonlinear for feed ingredients, daily gain and weight of cattle. Solving a diet model has been difficult, but advances in nonlinear programming now allow solutions that are quick and easy. This study developed a nonlinear programming method for optimally planning a feeding program by choosing feeds, daily gains and selling weight. Two types of diets are important for this purpose:optimal-return diets and least-cost-gain diets. For a given weight of cattle, an optimal-return diet chooses feeds and daily gain to maximize returns above feed costs. A least-cost-gain diet chooses feeds and daily gain to minimize feed plus yardage costs per kilogram of gain. In an optimal feeding program, a sequence of optimal-return diets is fed to increasing weights of cattle. Feed costs plus yardage per kilogram of gain rise to equal the actual selling price at the optimal selling weight, and the cattle are sold. Cattle feeders and researchers with access to a microcomputer can maximize net returns from a feeding program.