Proportionality Among Nutrients in Least Cost Feed Formulation

The data file for feed formulation of a major broiler integrator was used in studies of formulation techniques that affect proportionality among required nutrients. 1) The current practice, often called “optimum density” or “nutrient factoring,” was examined. In optimum density rations, the constraint on the weight of the diet is relaxed. It was demonstrated that this method merely results in proportionate changes in specified nutrient and ingredient minimums and maximums. Optimum density rations may reduce the cost of the diet in terms of cost per unit of energy only because of the altered constraints. 2) In a formulation related to optimum density, mixing and farm distribution cost was added to the feed mix problem on a per ton basis. This cost did not affect the constraint proportions of the ration (optimum density) until in excess of $100/ton. 3) A method of creating proportionality coefficients that allows nutrient ratios to be specified instead of levels and ranges is presented. It is expected to be helpful to nutritionists in formulating rations in which nutrients are desired to be in precise ratios without altering the weight of the ration.