Mathematical model for economic analysis of diets: an application in the evaluation of different cereals in feedlot lamb´s diets

Abstract

This study presents a mathematical model for economic analysis of diets composed of different ingredients. Variables such as intake and weight gain, and economic variables such as relative prices of the ingredients were considered. Twenty-four crossbred lambs, with initial age and weight of 70 days and 22 ± 1.61 kg, respectively, and final live weight of 37 ± 2.16 kg, were fed with high concentrate diets, containing different types of grains (cracked corn, whole grain corn, sorghum and millet). The animals were distributed in a complete randomized block design with four treatments and six replications, fed during 66 days and then slaughtered. The economic analysis was performed through three steps: a comparison of the productivities of production factors, comparison of commercial gross margins and comparison of the relative prices of factors of production. There was no statistical difference between the technical efficiency of the four treatments (P>0.05). Treatments based on whole maize and millet presented higher economic efficiency. The use of cracked corn to replace the whole maize would only be recommended with certainty whether their prices were 24% lower than whole maize. Observing the historical behavior of prices of sorghum and millet, they could replace corn with no significant loss of production performance.