Rapid n 3

The third set of macroalgae and polychaetes was placed on aluminum foils and dried in oven at 60 °C for 48 h. Dried material was then ground to obtain algal (AS) and polychaete (PS) powder to be used as ingredient to prepare the experimental fish feed. For this purpose, oil and dry ingredients were thoroughly mixed, whereby water was then blended into the mixture to attain an appropriate consistency for pelleting using a meat grinder. Pellets were dried overnight at 50 °C and refrigerated at 6 °C until utilization. Two feeds were prepared: A control fishmeal-based feed (CTRL) and an innovative feed (innovative meal = IM) containing 10% polychaete (PS) and 5% algae (AS). The composition of the two feeds is reported in Table 2.
The prepared feeds (CTRL and IM) were also analyzed (n = 3) to determine their proximate composition in accordance with standard methods [45 ].
The gross energy (GE) content was determined by an adiabatic calorimetric bomb (IKA C7000, Staufen, Germany). Total nitrogen content was determined in accordance with the Dumas method, using a nitrogen analyzer (Rapid N III, Elementar Analysensysteme GmbH, Hanau, Germany). The crude protein was calculated as total N × 6.25.

In order to evaluate the nutritional profile of lyophilized silkworm pupae, the dry matter (DM) (#930.15) and the ash (#924.05) were assessed according to the AOAC procedures (AOAC International, 2003 ). The total nitrogen (N) content was determined using a nitrogen analyzer (Rapid N III; Elementar Analysen system GmbH, Hanau, Germany) according to the Dumas method and the gross energy was measured using an adiabatic calorimetric bomb (C7000; IKA, Staufen, Germany).

The samples were oven-dried at 55 °C for 48 h and ground to a 2-mm mesh-screen size using a feed mill (DF-20, Wenling Linda Machinery Co. Ltd., Wenling, Zhejiang, China). Dry matter (DM; method 930.15) and ash (method 942.05) were analyzed by AOAC methods (2000) [14 ]. Nitrogen was determined using a protein analyzer (Rapid N III, Elementar Inc., Germany), and CP was calculated as the percentage of nitrogen × 6.25. Further, crude fiber (CF), neutral detergent fiber (NDF), and acid detergent fiber (ADF) were determined using a fiber analyzer (ANKOM A220, ANKOM Technology Corp., Macedon, NY, USA). Ether extract (EE) was extracted using an automatic extractor (ANKOM XT101, ANKOM Technology Corp., Macedon, NY, USA). Nitrogen-free extract (NFE) was calculated using the formula: w(NFE) = w(DM) − w(CP) – w(EE) – w(CF) – w(Ash). The chemical compositions and digestibility of each sample were calculated in triplicate.