Comparison between linear and nonlinear systems of feed formulation for broilers

Two experiments were simultaneously carried out to compare feed formulation models: a linear model for minimum cost with a nonlinear model for maximum profitability for one-to 42-d-old broilers. One-d-old male or female Cobb 500 broilers (n=2368) were allocated to one of the two trials according to sex. The experiments were performed simultaneously in an experimental poultry farm. Two housing densities were used: high density (HDH), with 14 birds/m2, and low density (LDH), with 10 birds/m2. The following treatments were evaluated: linear feed formulation and LDH (LF10); nonlinear formulation and LDH (NF10); linear formulation and HDH (LF14); and nonlinear formulation and HDH (NF14). A completely randomized design with four treatments of eight replicates each was applied. Performance and cost per kg of poultry were evaluated. Both formulation systems promoted similar broiler performance. However, the high-density feed using linear formulation reduced body weight in 42-d-old males, but not when nonlinear formulation was used. The NF10 treatment yielded the worst feed conversion ratio (p<0.05) and the lowest cost/kg broiler (p