Use of a Quadratic Response Model to Estimate Optimum Combinations of Nutritional Variables

Quadratic response surface modeling was used to estimate the optimum combination of feeding rate and percentage of dietary protein for growth of 3–6-week-old blue tilapia Tilapia aurea. Sixteen treatments consisting of all combinations of four dietary protein levels and four feeding rates were replicated in a recirculating-water aquarium system at 23°C for 3 weeks. Quadratic response surfaces fitted to the data were similar for the two replicates and identified treatment combinations supporting maximum growth. Dietary protein, feeding rate, and their interaction significantly affected food conversion by blue tilapia. The quadratic response surface model yielded results that generally agreed with published values for juvenile tilapias. This approach offers a promising research pathway to project optimum culture conditions from short-term trials.