A new tool for determining the optimum fish meal and vegetable meals in diets for maximising the economicprofitability of gilthead sea bream (Sparus aurata, L.) feeding

Abstract

The economic profitability of fish meal replacement by soybean meal and pea-rice concentrate mixture, was analysed considering the economic conversion ratio (ECR) and the economic profit index (EPIst) as a proposal for evaluating the economic profitability in diets for sea bream. The optimal fish meal levels for minimizing the ECR were 33% (when soybean meal was included) and 14% (in the case of pea-rice concentrate mixture) and for maximizing the EPIst, optimal fish meal levels were 31% and 28.8%, respectively, considering the current market price of fish meal and vegetal ingredients. The EPIst, seems to be a better index than the ECR to estimate diet profitability, because it considers weight increment, feed conversion ratio, diet cost and fish sale price. A sensibility analysis was conducted, considering variations in the price of fish meal and vegetal ingredients. Finally, several multiple regressions were developed for estimating the optimal level of fish meal with each vegetable ingredient and the expected value of the economic profit as a function of the market price of both fish meal and plant protein. When fish meal prices increase, the highest beneficial level of the inclusion fish meal and the highest economic profit would be achieved with pea-rice mixture.