USE OF A QUADRATIC RESPONSE MODEL TO ESTIMATE OPTIMUM COMBINATIONS OFNUTRITIONAL VARIABLES

Quadratic response surface modeling was used to estimate the optimum c ombination of feeding rate and percentage of dietary protein for growt h of 3-6-week-old blue tilapia Tilapia aurea. Sixteen treatments consi sting of all combinations of four dietary protein levels and four feed ing rates were replicated in a recirculating-water aquarium system at 23-degrees-C for 3 weeks. Quadratic response surfaces fitted to the da ta were similar for the two replicates and identified treatment combin ations supporting maximum growth. Dietary protein, feeding rate, and t heir interaction significantly affected food conversion by blue tilapi a. The quadratic response surface model yielded results that generally agreed with published values for juvenile tilapias. This approach off ers a promising research pathway to project optimum culture conditions from short-term trials.