Modeling optimum levels of balanced digestible protein for adult pacu (Piaractus mesopotamicus) and the development of an economic optimization procedure for different marketing strategies of the final yield

Abstract

Marketing strategies and feeding costs are key factors affecting the sustainability of intensive aquaculture systems. The present 44-day feeding trial aimed to model the optimum levels of balanced digestible protein (BDP) for adult pacu (Piaractus mesopotamicus) and develop an economic optimization procedure for the final yield. The experiment was conducted in a freshwater recirculation aquaculture system (RAS). A randomized block design with six treatments and three replicates was used. A total of 180 pacu adults with initial body weight of 1158.50 ± 21.59 g (± standard deviation) were distributed (10 fish per tank) among 18 concrete-tanks of 2000 L. Six consecutive isoenergetic experimental diets containing 163, 201, 238, 272, 315 and 348 g BDP kg−1 (dry matter basis – DM basis) were prepared through the diet dilution procedure. The triplicate groups of fish were hand-fed three times a day at 09:00, 12:00 and 17:00 h until apparent satiation. At the end of the trial, the productive and economic responses were evaluated through appropriate mathematical models and statistical analyses. The optimum levels of BDP were modeled as 232 and 245 g kg−1 (DM basis) by the quadratic model based on maximum final body weight (FBW) and body weight gain (BWG) of adult pacu, respectively. Using an individual based economic model, the economically optimized levels of BDP were modeled as 215, 217 and 222 g kg−1 (DM basis) for obtaining maximum profitability from the fish that are marketed in the form of whole-body, eviscerated and sliced adult pacu, respectively. The optimum levels of BDP modeled for maximum profitability were found considerably lower than those modeled for maximum FBW and BWG. The hypothesized scenarios confirmed that profitability and economically optimized levels of dietary protein were greatly affected by the fluctuations in feed costs and marketing strategy of the final yield.