Assessing the nutritional value of an enzymatically processed soybean meal in early juvenile red drum, Sciaenops ocellatus L

We assessed the nutritional value of an enzymatically processed soybean meal (HP300, Hamlet Protein Inc., Findlay, Ohio, USA; hereafter ESBM) in the diet of red drum, Sciaenops ocellatus. A digestibility and two growth trials (Trials I and II) were conducted to: i) assess the in vivo digestibility of ESBM and commodity soybean meal (SBM); ii) assess the maximum replacement of the digestible protein (DP) from fishmeal (FM) with ESBM (MAX REPLESBM); iii) validate the estimated MAX REPLESBM and compare it against SBM. All experimental diets were formulated to contain 32% DP, 12% lipid, and an estimated 13.8 kJ g(-1) digestible energy. Seven experimental diets were designed in Trial I: a FM reference diet (FM-100), designed to contain all its protein from Special Select menhaden FM; and six test diets designed to replace the DP from FM in the FM-100 diet on a isonitrogenous basis, at 15% incremental levels (ESBM-15 to ESBM-90). Each diet was fed to juvenile red drum (5.72 g) in duplicate aquaria connected as a closed recirculating system. After 6 weeks of feeding, responses of red drum fed the various diets differed considerably, with survival ranging from 78 to 95%, final weight from 24.5 to 40.0 g, weight gain (% of initial) from 330 to 597%, and feed efficiency (FE) from 0.7 to 1.0. Second order polynomial regression analysis of weight gain and FE data indicated a MAX REPLESBM of 72 and 63%, respectively. After feeding the FM-100, ESBM-70, and a SBM-70 diets to juvenile red drum (1.7 g) in Trial II (8 weeks, n = 3), no differences in production performance of fish were found among treatments. These results indicated that either ESBM or SBM can replace up to 70% of FM DP in the diet of early juvenile red drum without detrimental effects on production performance. Statement of relevance: The currently study represents an addition to the increasing number of studies evaluating alternative protein sources in the diet of carnivorous fish species. We used red drum as a model and demonstrated the applicability of soybean products as partial substitutes for dietary fishmeal. Once replicated under commercial production settings, our results will contribute for a more sustainable aquaculture industry. (C) 2016 Elsevier B.V. All rights reserved.